DeadAir's wording: cut the dead air (#172)

The switch, the button's tooltip, the toasts and the time saved now say
what the name already pictures, the dead air cut, instead of explaining
it as silences shortened each time. The caption says the voice keeps its
own pace, which is the part people doubt, and names the shows to leave
out: stories whose pauses are part of the telling.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- DeadAir: turn it on for a show in its settings, or with the button beside the speed while it plays, and its episodes play with long silences shortened, so podcasts finish sooner without sounding sped up. Your place carries over when you turn it on or off, each episode says how much shorter it is, and Settings shows the time it has saved you. It is off for every show until you turn it on (#171, #172).
+
+### Fixed
+
+- Cover art up to 20 MB is shown, instead of nothing for anything over 5 MB, as for five of the Glass Cannon Network's feeds.
+- Seeking in an episode while many people listen answers in about 10 ms instead of 40, and files stream about four times as fast: each connection now sends what is ready without waiting for the browser to acknowledge the last part.
+- Artwork that could not be fetched is not fetched again for an hour, instead of on every page load, and the server's log says which image it was and why.
+
 ## [0.10.3] - 2026-10-09
 
 ### Changed

Cargo.lock

@@ -1820,7 +1820,7 @@ checksum = "791930b43c0d5973160d90a8f3894509f2b273430f5c5c73b668636d0287c5c0"
 
 [[package]]
 name = "ipx"
-version = "0.10.3"
+version = "0.10.4-dev"
 dependencies = [
  "ammonia",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ipx"
-version = "0.10.3"
+version = "0.10.4-dev"
 edition = "2024"
 
 [dependencies]
@@ -26,7 +26,7 @@ sea-orm = { version = "2.0.3", default-features = false, features = ["sqlx-sqlit
 serde = { version = "1.0.229", features = ["derive"] }
 serde_json = "1.0.151"
 sha2 = "0.10.9"
-tokio = { version = "1.53.1", features = ["rt-multi-thread", "macros", "fs", "io-util", "net", "sync", "time", "signal"] }
+tokio = { version = "1.53.1", features = ["rt-multi-thread", "macros", "fs", "io-util", "net", "sync", "time", "signal", "process"] }
 toml = "1.1.5"
 tower = { version = "0.5.3", features = ["util"] }
 tower-http = { version = "0.7.1", features = ["fs"] }

Dockerfile

@@ -24,8 +24,10 @@ COPY web ./web
 RUN touch src/main.rs && cargo build --release --locked
 
 FROM debian:bookworm-slim
+# ffmpeg is DeadAir's (#171): it finds the silences and copies the frames kept. Debian's adds
+# about 480 MB, once: the layer stays cached until the base image changes.
 RUN apt-get update && apt-get install -y --no-install-recommends \
-        ca-certificates gosu \
+        ca-certificates gosu ffmpeg \
     && rm -rf /var/lib/apt/lists/*
 COPY --from=build /src/target/release/ipx /usr/local/bin/ipx
 COPY docker-entrypoint.sh /usr/local/bin/

src/art.rs

@@ -2,6 +2,9 @@
 //! of each publisher's server for every visit, and still there when a publisher is not.
 
 use std::path::{Path, PathBuf};
+use std::collections::HashMap;
+use std::sync::{LazyLock, Mutex};
+use std::time::{Duration, Instant};
 
 pub fn dir() -> PathBuf {
     crate::config::data_dir().join("art")
@@ -38,6 +41,36 @@ pub fn write(file: &Path, kind: &str, body: &[u8]) -> std::io::Result<()> {
     std::fs::rename(&tmp, file)
 }
 
+/// How long an address that could not be fetched is answered from memory before it is tried again.
+const RETRY: Duration = Duration::from_secs(60 * 60);
+
+/// Addresses that could not be fetched lately, and why. Without it a page shown again fetched
+/// them again: five covers too big to keep were downloaded from Patreon on every load (#169).
+// ponytail: in memory, and an entry goes only when it is asked for after RETRY. It holds at most
+// one per artwork address a feed or item names; move it to disk or prune it on trim if that grows.
+static FAILED: LazyLock<Mutex<HashMap<String, (Instant, String)>>> = LazyLock::new(Default::default);
+
+/// Why `url` could not be fetched, if it failed less than an hour ago.
+pub fn failed(url: &str) -> Option<String> {
+    failed_as_of(url, Instant::now())
+}
+
+fn failed_as_of(url: &str, now: Instant) -> Option<String> {
+    let mut map = FAILED.lock().unwrap_or_else(|e| e.into_inner());
+    match map.get(url) {
+        Some((at, why)) if now.duration_since(*at) < RETRY => Some(why.clone()),
+        Some(_) => {
+            map.remove(url);
+            None
+        }
+        None => None,
+    }
+}
+
+pub fn fail(url: &str, why: &str) {
+    FAILED.lock().unwrap_or_else(|e| e.into_inner()).insert(url.to_owned(), (Instant::now(), why.to_owned()));
+}
+
 /// Removes the least recently used images until what is kept fits in `limit` bytes; 0 empties it.
 /// Returns how many went.
 pub fn trim(dir: &Path, limit: u64) -> usize {
@@ -89,4 +122,15 @@ mod tests {
         assert_eq!(trim(&d, 0), 2);
         let _ = std::fs::remove_dir_all(&d);
     }
+
+    #[test]
+    fn a_failure_is_remembered_for_an_hour() {
+        let u = "https://example.com/a-failure-is-remembered.png";
+        assert_eq!(failed(u), None);
+        fail(u, "larger than 5 MB");
+        assert_eq!(failed(u).as_deref(), Some("larger than 5 MB"));
+        assert_eq!(failed_as_of(u, Instant::now() + RETRY), None);
+        // Asked for after the hour, it is forgotten, not just ignored.
+        assert_eq!(failed(u), None);
+    }
 }

src/db.rs

@@ -2,7 +2,7 @@
 //! per-feed .ipxd plists, history.dat and qmcache.dat.
 
 use anyhow::{Context, Result};
-use crate::entity::{api_tokens, blocklists, catalogue, enclosures, entries, feeds, hidden, sessions, settings, subscriptions, users};
+use crate::entity::{api_tokens, blocklists, catalogue, deadair_prefs, enclosures, entries, feeds, hidden, sessions, settings, subscriptions, users};
 use sea_orm::sea_query::{Expr, Func};
 use sea_orm::{
     ActiveModelTrait, ColumnTrait, ConnectionTrait, EntityTrait, PaginatorTrait, QueryFilter, QueryOrder, Set,
@@ -60,6 +60,9 @@ async fn create_missing(orm: &sea_orm::DatabaseConnection) -> Result<()> {
         schema.create_table_from_entity(blocklists::Entity),
         schema.create_table_from_entity(hidden::Entity),
         schema.create_table_from_entity(api_tokens::Entity),
+        schema.create_table_from_entity(deadair::Entity),
+        schema.create_table_from_entity(deadair_prefs::Entity),
+        schema.create_table_from_entity(deadair_saved::Entity),
     ] {
         orm.execute(table.if_not_exists()).await.context("creating the schema")?;
     }
@@ -198,6 +201,7 @@ impl From<enclosures::Model> for EncRow {
     fn from(e: enclosures::Model) -> Self {
         EncRow {
             id: e.id,
+            deadair: None,
             feed_id: e.feed_id,
             guid: e.guid,
             url: e.url,
@@ -299,6 +303,13 @@ impl Db {
     /// A SQLite file of its own (two connections to one ":memory:" would be two databases); or,
     /// with IPX_TEST_DATABASE_URL set, a Postgres schema of its own on that database, so the
     /// same tests prove the SQL on both.
+    /// Runs a statement as it is, for a test outside this module setting up what it needs.
+    #[cfg(test)]
+    pub async fn sql(&self, sql: &str) -> Result<()> {
+        self.orm.execute_unprepared(sql).await?;
+        Ok(())
+    }
+
     #[cfg(test)]
     pub async fn memory() -> Result<Self> {
         static N: std::sync::atomic::AtomicU32 = std::sync::atomic::AtomicU32::new(0);
@@ -1050,12 +1061,22 @@ impl Args {
 /// The FROM and WHERE that `entries_in` and `count_in` share: whose read state, which feeds
 /// (one, or every feed the person subscribes to), the filter, and a case-insensitive search of
 /// title and description.
-fn entries_from(a: &mut Args, user_id: i64, feed_id: Option<&str>, filter: Filter, search: Option<&str>) -> String {
+fn entries_from(
+    a: &mut Args,
+    user_id: i64,
+    feed_id: Option<&str>,
+    filter: Filter,
+    search: Option<&str>,
+    guid: Option<&str>,
+) -> String {
     let user = a.p(user_id);
-    let scope = match feed_id {
+    let mut scope = match feed_id {
         Some(f) => format!("e.feed_id = {}", a.p(f)),
         None => format!("e.feed_id IN (SELECT feed_id FROM subscriptions WHERE user_id = {user})"),
     };
+    if let Some(g) = guid {
+        scope = format!("{scope} AND e.guid = {}", a.p(g));
+    }
     let search = match search.map(|q| q.trim().to_lowercase()).filter(|q| !q.is_empty()) {
         Some(q) => {
             let like = a.p(format!("%{q}%"));
@@ -1159,6 +1180,10 @@ impl Filter {
 #[derive(Debug, Clone, serde::Serialize)]
 pub struct EncRow {
     pub id: i64,
+    /// Seconds DeadAir's copy of this file saves, when the person asking plays it from one
+    /// (`deadair::for_reader`). None from the database.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub deadair: Option<i64>,
     pub feed_id: String,
     pub guid: String,
     pub url: String,
@@ -1183,9 +1208,31 @@ impl Db {
         offset: i64,
         limit: i64,
         order: &str,
+    ) -> Result<Vec<EntryRow>> {
+        self.entries_where(user_id, feed_id, filter, search, None, offset, limit, order).await
+    }
+
+    /// One entry as `entries_in` gives it: what the player asks for again when the clock it
+    /// plays in changes (DeadAir, #171).
+    pub async fn entry(&self, user_id: i64, feed_id: &str, guid: &str) -> Result<Option<EntryRow>> {
+        let order = order_sql("published", "desc");
+        Ok(self.entries_where(user_id, Some(feed_id), Filter::All, None, Some(guid), 0, 1, &order).await?.pop())
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    async fn entries_where(
+        &self,
+        user_id: i64,
+        feed_id: Option<&str>,
+        filter: Filter,
+        search: Option<&str>,
+        guid: Option<&str>,
+        offset: i64,
+        limit: i64,
+        order: &str,
     ) -> Result<Vec<EntryRow>> {
         let mut a = Args::default();
-        let from = entries_from(&mut a, user_id, feed_id, filter, search);
+        let from = entries_from(&mut a, user_id, feed_id, filter, search, guid);
         let sql = format!(
             "SELECT e.guid, e.feed_id, e.title, e.link, e.published, e.description,
                     coalesce(s.read, false) AS read, coalesce(s.flagged, false) AS flagged, e.image,
@@ -1248,7 +1295,7 @@ impl Db {
         search: Option<&str>,
     ) -> Result<i64> {
         let mut a = Args::default();
-        let sql = format!("SELECT count(*) AS n {}", entries_from(&mut a, user_id, feed_id, filter, search));
+        let sql = format!("SELECT count(*) AS n {}", entries_from(&mut a, user_id, feed_id, filter, search, None));
         let r = self.rows(&sql, a.0).await?;
         Ok(r.first().context("count(*) always returns a row")?.try_get("", "n")?)
     }
@@ -2192,6 +2239,188 @@ pub fn step(of: &'static str) -> tracing::Span {
     if tracing::Span::current().is_none() { tracing::Span::none() } else { tracing::info_span!("step", of) }
 }
 
+/// A file on disk with no DeadAir copy made since it was downloaded (issue #171).
+#[derive(Debug, Clone)]
+pub struct DeadAirTodo {
+    pub id: i64,
+    pub feed_id: String,
+    pub guid: String,
+    pub path: String,
+}
+
+/// An enclosure's DeadAir copy: where it is, what it left out, and how much that came to.
+#[derive(Debug, Clone)]
+pub struct Copy {
+    pub enclosure_id: i64,
+    pub path: String,
+    pub cuts: Vec<crate::deadair::Cut>,
+    pub saved_ms: i64,
+}
+
+impl Db {
+    /// DeadAir settings as (person, feed, wanted), everyone's or one person's. An empty feed is
+    /// the switch beside the speed.
+    pub async fn deadair_prefs(&self, user_id: Option<i64>) -> Result<Vec<(i64, String, bool)>> {
+        let mut a = Args::default();
+        let only = match user_id {
+            Some(u) => format!("WHERE user_id = {}", a.p(u)),
+            None => String::new(),
+        };
+        self.rows(&format!("SELECT user_id, feed_id, wanted FROM deadair_prefs {only}"), a.0)
+            .await?
+            .iter()
+            .map(|r| Ok((r.try_get("", "user_id")?, r.try_get("", "feed_id")?, r.try_get("", "wanted")?)))
+            .collect()
+    }
+
+    /// Sets one DeadAir setting, or with None takes it away: for a feed, that is following the
+    /// switch (or the feed's group) again.
+    pub async fn set_deadair(&self, user_id: i64, feed_id: &str, wanted: Option<bool>) -> Result<()> {
+        match wanted {
+            None => {
+                deadair_prefs::Entity::delete_by_id((user_id, feed_id.to_owned())).exec(&self.orm).await?;
+            }
+            Some(w) => {
+                self.exec(
+                    "INSERT INTO deadair_prefs (user_id, feed_id, wanted) VALUES ($1, $2, $3)
+                     ON CONFLICT (user_id, feed_id) DO UPDATE SET wanted = excluded.wanted",
+                    vec![user_id.into(), feed_id.into(), w.into()],
+                )
+                .await?;
+            }
+        }
+        Ok(())
+    }
+
+    /// Files on disk with no copy made since they were downloaded, oldest first.
+    pub async fn deadair_todo(&self) -> Result<Vec<DeadAirTodo>> {
+        self.rows(
+            "SELECT e.id, e.feed_id, e.guid, e.path FROM enclosures e
+               LEFT JOIN deadair d ON d.enclosure_id = e.id
+              WHERE e.path IS NOT NULL AND e.state = 'done'
+                AND (d.enclosure_id IS NULL OR d.made_at < coalesce(e.downloaded_at, 0))
+              ORDER BY e.id",
+            vec![],
+        )
+        .await?
+        .iter()
+        .map(|r| {
+            Ok(DeadAirTodo {
+                id: r.try_get("", "id")?,
+                feed_id: r.try_get("", "feed_id")?,
+                guid: r.try_get("", "guid")?,
+                path: r.try_get("", "path")?,
+            })
+        })
+        .collect()
+    }
+
+    /// Whether any of these people subscribes to the feed.
+    pub async fn subscribed_any(&self, users: &[i64], feed_id: &str) -> Result<bool> {
+        if users.is_empty() {
+            return Ok(false);
+        }
+        let mut a = Args::default();
+        let feed = a.p(feed_id);
+        let ids: Vec<String> = users.iter().map(|&u| a.p(u)).collect();
+        let sql = format!(
+            "SELECT 1 AS one FROM subscriptions WHERE feed_id = {feed} AND user_id IN ({}) LIMIT 1",
+            ids.join(", ")
+        );
+        Ok(!self.rows(&sql, a.0).await?.is_empty())
+    }
+
+    /// Who has an item marked read, which playing it to the end or past 90% does.
+    pub async fn readers(&self, feed_id: &str, guid: &str) -> Result<Vec<i64>> {
+        self.rows(
+            "SELECT user_id FROM entry_state WHERE feed_id = $1 AND guid = $2 AND read",
+            vec![feed_id.into(), guid.into()],
+        )
+        .await?
+        .iter()
+        .map(|r| Ok(r.try_get("", "user_id")?))
+        .collect()
+    }
+
+    /// Records the copy made of an enclosure, or with no path that it has none.
+    pub async fn store_deadair(&self, enclosure_id: i64, path: Option<&str>, cuts: &str, saved_ms: i64) -> Result<()> {
+        self.exec(
+            "INSERT INTO deadair (enclosure_id, path, cuts, saved_ms, made_at) VALUES ($1, $2, $3, $4, $5)
+             ON CONFLICT (enclosure_id) DO UPDATE SET path = excluded.path, cuts = excluded.cuts,
+                 saved_ms = excluded.saved_ms, made_at = excluded.made_at",
+            vec![enclosure_id.into(), path.map(str::to_owned).into(), cuts.into(), saved_ms.into(), now().into()],
+        )
+        .await?;
+        Ok(())
+    }
+
+    /// The copies there are of these enclosures, made since each was last downloaded.
+    pub async fn copies(&self, enclosure_ids: &[i64]) -> Result<Vec<Copy>> {
+        if enclosure_ids.is_empty() {
+            return Ok(vec![]);
+        }
+        let mut a = Args::default();
+        let ids: Vec<String> = enclosure_ids.iter().map(|&i| a.p(i)).collect();
+        let sql = format!(
+            "SELECT d.enclosure_id, d.path, d.cuts, d.saved_ms FROM deadair d
+               JOIN enclosures e ON e.id = d.enclosure_id
+              WHERE d.enclosure_id IN ({}) AND d.path IS NOT NULL AND e.path IS NOT NULL
+                AND d.made_at >= coalesce(e.downloaded_at, 0)",
+            ids.join(", ")
+        );
+        self.rows(&sql, a.0)
+            .await?
+            .iter()
+            .map(|r| {
+                let cuts: String = r.try_get("", "cuts")?;
+                Ok(Copy {
+                    enclosure_id: r.try_get("", "enclosure_id")?,
+                    path: r.try_get("", "path")?,
+                    cuts: serde_json::from_str(&cuts).context("reading DeadAir's cuts")?,
+                    saved_ms: r.try_get("", "saved_ms")?,
+                })
+            })
+            .collect()
+    }
+
+    /// Counts an episode towards the time DeadAir has saved someone, once however often it is
+    /// played.
+    pub async fn count_deadair(&self, user_id: i64, feed_id: &str, guid: &str, saved_ms: i64) -> Result<()> {
+        self.exec(
+            "INSERT INTO deadair_saved (user_id, feed_id, guid, saved_ms, at) VALUES ($1, $2, $3, $4, $5)
+             ON CONFLICT (user_id, feed_id, guid) DO NOTHING",
+            vec![user_id.into(), feed_id.into(), guid.into(), saved_ms.into(), now().into()],
+        )
+        .await?;
+        Ok(())
+    }
+
+    /// An episode's length as someone's player measured it, else as its feed gives it.
+    pub async fn entry_duration(&self, user_id: i64, feed_id: &str, guid: &str) -> Result<Option<i64>> {
+        let rows = self
+            .rows(
+                "SELECT coalesce(s.duration, e.duration) AS duration FROM entries e
+                   LEFT JOIN entry_state s ON s.user_id = $1 AND s.feed_id = e.feed_id AND s.guid = e.guid
+                  WHERE e.feed_id = $2 AND e.guid = $3",
+                vec![user_id.into(), feed_id.into(), guid.into()],
+            )
+            .await?;
+        Ok(rows.first().map(|r| r.try_get::<Option<i64>>("", "duration")).transpose()?.flatten())
+    }
+
+    /// The time DeadAir has saved someone, in ms.
+    pub async fn deadair_total(&self, user_id: i64) -> Result<i64> {
+        let rows = self
+            .rows(
+                "SELECT CAST(coalesce(sum(saved_ms), 0) AS BIGINT) AS total FROM deadair_saved WHERE user_id = $1",
+                vec![user_id.into()],
+            )
+            .await?;
+        // Cast: Postgres sums bigints as NUMERIC, which does not read as an i64.
+        Ok(rows.first().map(|r| r.try_get::<i64>("", "total")).transpose()?.unwrap_or(0))
+    }
+}
+
 /// Unix seconds. Everything time-shaped in the DB is stored this way.
 pub fn now() -> i64 {
     std::time::SystemTime::now()
@@ -2204,6 +2433,51 @@ pub fn now() -> i64 {
 mod tests {
     use super::*;
 
+    #[tokio::test]
+    async fn deadair_copies_are_made_once_per_download_and_counted_once_per_episode() {
+        let db = Db::memory().await.unwrap();
+        let u = db.create_user("dee", None, false).await.unwrap();
+        db.set_deadair(u, "f", Some(true)).await.unwrap();
+        db.set_deadair(u, "g", Some(false)).await.unwrap();
+        db.set_deadair(u, "g", None).await.unwrap();
+        assert_eq!(db.deadair_prefs(Some(u)).await.unwrap(), vec![(u, "f".to_string(), true)]);
+        for sql in [
+            "INSERT INTO enclosures (id, feed_id, guid, url, path, state, downloaded_at)
+             VALUES (1, 'f', 'g', 'http://x/a.mp3', '/x/a.mp3', 'done', 100)",
+            "INSERT INTO enclosures (id, feed_id, guid, url, path, state) VALUES (2, 'f', 'h', 'http://x/b.mp3', NULL, 'reaped')",
+            "INSERT INTO entries (feed_id, guid, first_seen, duration) VALUES ('f', 'g', 1, 600)",
+        ] {
+            db.orm.execute_unprepared(sql).await.unwrap();
+        }
+        let todo = db.deadair_todo().await.unwrap();
+        assert_eq!(todo.iter().map(|t| t.id).collect::<Vec<_>>(), [1], "only a file on disk");
+
+        db.store_deadair(1, Some("/x/a.deadair.mp3"), "[[1000,3000]]", 2000).await.unwrap();
+        assert!(db.deadair_todo().await.unwrap().is_empty());
+        let c = db.copies(&[1, 2]).await.unwrap();
+        assert_eq!((c.len(), c[0].cuts.as_slice(), c[0].saved_ms), (1, &[crate::deadair::Cut(1000, 3000)][..], 2000));
+        // Downloaded again since: the copy is stale until made again.
+        db.orm.execute_unprepared(&format!("UPDATE enclosures SET downloaded_at = {} WHERE id = 1", now() + 60)).await.unwrap();
+        assert_eq!(db.deadair_todo().await.unwrap().len(), 1);
+        assert!(db.copies(&[1]).await.unwrap().is_empty());
+
+        assert!(!db.subscribed_any(&[u], "f").await.unwrap());
+        db.subscribe(u, "f").await.unwrap();
+        assert!(db.subscribed_any(&[u], "f").await.unwrap());
+        assert!(db.readers("f", "g").await.unwrap().is_empty());
+        db.set_entry_flag(u, "f", "g", EntryFlag::Read, true).await.unwrap();
+        assert_eq!(db.readers("f", "g").await.unwrap(), [u]);
+
+        assert_eq!(db.entry_duration(u, "f", "g").await.unwrap(), Some(600));
+        db.set_position(u, "f", "g", 10, Some(590)).await.unwrap();
+        assert_eq!(db.entry_duration(u, "f", "g").await.unwrap(), Some(590), "what the player measured");
+
+        assert_eq!(db.deadair_total(u).await.unwrap(), 0);
+        db.count_deadair(u, "f", "g", 2000).await.unwrap();
+        db.count_deadair(u, "f", "g", 2000).await.unwrap();
+        assert_eq!(db.deadair_total(u).await.unwrap(), 2000, "a replay counts once");
+    }
+
     #[tokio::test]
     async fn a_read_does_not_wait_for_a_write_in_progress() {
         use sea_orm::TransactionTrait;

src/deadair.rs

@@ -0,0 +1,520 @@
+//! DeadAir (issue #171): podcasts play from a copy with their long silences shortened, so they
+//! finish sooner without sounding sped up.
+//!
+//! The copy is the original's own frames with the silent ones left out, copied by ffmpeg with
+//! nothing re-encoded: about 10 s an hour of audio on one core, finding the silences included.
+//! It is made in the background, one file at a time, for files in feeds someone has DeadAir on
+//! for, and kept beside the original (`copy_path`) until `download::remove` takes both.
+//!
+//! Positions stay in the original's time. What the copy left out is stored as `Cut`s of the
+//! original's time, and the server converts both ways (`to_copy`, `to_original`): the iOS and
+//! Android apps save positions themselves, from their own player, so converting in the page
+//! would miss them.
+
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+use anyhow::{Context, Result, bail};
+use serde::{Deserialize, Serialize};
+
+use crate::Ctx;
+
+/// Quieter than this for longer than `MIN_SILENCE` is a silence: what the measurements on the
+/// issue used. A podcast's room tone sits well below it and speech well above.
+const THRESHOLD: &str = "-38dB";
+const MIN_SILENCE: f64 = 0.35;
+/// Kept at each end of a silence, so the frames on both sides of a cut are silent. Decoding
+/// blends a frame with the one before it, and an MP3 frame can begin in the bytes of the frame
+/// before (the bit reservoir): the first frame after a cut decodes against the wrong neighbour,
+/// which nobody hears between two silent frames and everyone hears at the start of a word.
+const KEEP: f64 = 0.1;
+/// ffmpeg takes the frames to drop as one argument, and Linux refuses an argument over 128 KiB.
+// shortcut: a file with more silences than this keeps only its longest; about 9 hours of
+// conversation at the rate measured. Pass the list some other way if a feed ever gets there.
+const MAX_CUTS: usize = 4000;
+/// How long the maker waits when there is nothing to do: a download or a feed turned on is
+/// picked up this long after, at most.
+const IDLE: std::time::Duration = std::time::Duration::from_secs(120);
+
+/// A span of the original, in milliseconds, that the copy leaves out.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Cut(pub i64, pub i64);
+
+/// Where the copy of `original` goes: beside it, `name.deadair.mp3` for `name.mp3`.
+pub fn copy_path(original: &Path) -> PathBuf {
+    let stem = original.file_stem().map(|s| s.to_string_lossy()).unwrap_or_default();
+    let name = match original.extension() {
+        Some(ext) => format!("{stem}.deadair.{}", ext.to_string_lossy()),
+        None => format!("{stem}.deadair"),
+    };
+    original.with_file_name(name)
+}
+
+/// The silences silencedetect reported, as (start, end) seconds. One still open at the end of
+/// the file has no end and is left alone.
+pub fn parse_silences(log: &str) -> Vec<(f64, f64)> {
+    let mut out = Vec::new();
+    let mut start = None;
+    for line in log.lines() {
+        if let Some(v) = after(line, "silence_start: ") {
+            start = Some(v);
+        } else if let Some(v) = after(line, "silence_end: ")
+            && let Some(s) = start.take()
+        {
+            out.push((s, v));
+        }
+    }
+    out
+}
+
+fn after(line: &str, key: &str) -> Option<f64> {
+    let rest = &line[line.find(key)? + key.len()..];
+    rest.split_whitespace().next()?.parse().ok()
+}
+
+/// Which frames to drop for these silences, as inclusive ranges of frame numbers, and the same
+/// as `Cut`s. Frame `n` plays from `first + n * frame` seconds. Only frames wholly inside a
+/// silence, `KEEP` in from each end, go.
+pub fn plan(silences: &[(f64, f64)], first: f64, frame: f64) -> (Vec<(u64, u64)>, Vec<Cut>) {
+    let mut spans: Vec<(u64, u64)> = silences
+        .iter()
+        .filter(|(s, e)| e - s >= MIN_SILENCE)
+        .filter_map(|&(s, e)| {
+            let a = ((s + KEEP - first) / frame).ceil().max(0.0) as u64;
+            let b = ((e - KEEP - first) / frame).floor() as i64 - 1;
+            (b >= a as i64).then_some((a, b as u64))
+        })
+        .collect();
+    if spans.len() > MAX_CUTS {
+        spans.sort_by_key(|&(a, b)| std::cmp::Reverse(b - a));
+        spans.truncate(MAX_CUTS);
+        spans.sort();
+    }
+    let ms = |n: u64| ((first + n as f64 * frame) * 1000.0).round() as i64;
+    let cuts = spans.iter().map(|&(a, b)| Cut(ms(a), ms(b + 1))).collect();
+    (spans, cuts)
+}
+
+/// A time in the original, in ms, as the same moment in the copy. A time inside a cut is where
+/// the cut was made.
+pub fn to_copy(cuts: &[Cut], ms: i64) -> i64 {
+    let mut out = ms;
+    for &Cut(s, e) in cuts {
+        if ms >= e {
+            out -= e - s;
+        } else {
+            if ms > s {
+                out -= ms - s;
+            }
+            break;
+        }
+    }
+    out
+}
+
+/// A time in the copy, in ms, as the same moment in the original.
+pub fn to_original(cuts: &[Cut], ms: i64) -> i64 {
+    let mut out = ms;
+    for &Cut(s, e) in cuts {
+        if out >= s {
+            out += e - s;
+        } else {
+            break;
+        }
+    }
+    out
+}
+
+pub fn saved(cuts: &[Cut]) -> i64 {
+    cuts.iter().map(|Cut(s, e)| e - s).sum()
+}
+
+/// Whether someone with these settings plays a feed from its copies. Off for every feed until
+/// they turn it on for that one, or for the group it came in (an OPML or a Patreon creator),
+/// which a feed of the group can still say otherwise to.
+pub fn wants(prefs: &HashMap<String, bool>, feed: &str, group: Option<&str>) -> bool {
+    prefs.get(feed).or_else(|| group.and_then(|g| prefs.get(g))).copied().unwrap_or(false)
+}
+
+/// The settings of each person with DeadAir on for something, and each managed feed's group,
+/// which is what `wants` needs.
+pub struct Wanting {
+    pub people: HashMap<i64, HashMap<String, bool>>,
+    pub groups: HashMap<String, String>,
+}
+
+impl Wanting {
+    pub async fn load(ctx: &Ctx, only: Option<i64>) -> Result<Self> {
+        let mut people: HashMap<i64, HashMap<String, bool>> = HashMap::new();
+        for (user, feed, wanted) in ctx.db.deadair_prefs(only).await? {
+            people.entry(user).or_default().insert(feed, wanted);
+        }
+        people.retain(|_, p| p.values().any(|&w| w));
+        let groups = if people.is_empty() {
+            HashMap::new()
+        } else {
+            ctx.db.managed_feeds().await?.into_iter().map(|m| (m.id, m.group_id)).collect()
+        };
+        Ok(Self { people, groups })
+    }
+
+    pub fn wants(&self, user: i64, feed: &str) -> bool {
+        self.people
+            .get(&user)
+            .is_some_and(|p| wants(p, feed, self.groups.get(feed).map(String::as_str)))
+    }
+}
+
+/// What each person is playing from a copy, by (person, feed, guid): set when `/media` serves
+/// them a copy and cleared when it serves the original, so a saved position is converted from
+/// the clock it was measured in, whether the page saved it or a native app did.
+// shortcut: in memory, so a restart forgets it. A position saved before the player next asks
+// for more of the copy is then taken as the original's, which resumes a little early, never late.
+pub type Playing = Arc<std::sync::Mutex<HashMap<(i64, String, String), Arc<crate::db::Copy>>>>;
+
+/// Puts a page of entries in the clock of what this person will play: for each file with a
+/// copy they play, `deadair` is the seconds it saves, and the entry's position and length are
+/// the copy's. The page plays `/media/{id}/deadair` for a file that has it.
+pub async fn for_reader(ctx: &Ctx, user: i64, rows: &mut [crate::db::EntryRow]) -> Result<()> {
+    let wanting = Wanting::load(ctx, Some(user)).await?;
+    if wanting.people.is_empty() {
+        return Ok(());
+    }
+    let ids: Vec<i64> = rows
+        .iter()
+        .filter(|r| wanting.wants(user, &r.feed_id))
+        .flat_map(|r| r.enclosures.iter().filter(|e| e.path.is_some()).map(|e| e.id))
+        .collect();
+    let copies: HashMap<i64, crate::db::Copy> =
+        ctx.db.copies(&ids).await?.into_iter().map(|c| (c.enclosure_id, c)).collect();
+    for r in rows.iter_mut() {
+        let mut converted = false;
+        for e in &mut r.enclosures {
+            let Some(c) = copies.get(&e.id) else { continue };
+            e.deadair = Some(c.saved_ms / 1000);
+            // One position an item, however many files: the first with a copy sets the clock.
+            if !std::mem::replace(&mut converted, true) {
+                r.position = to_copy(&c.cuts, r.position * 1000) / 1000;
+                r.duration = r.duration.map(|d| to_copy(&c.cuts, d * 1000) / 1000);
+            }
+        }
+    }
+    Ok(())
+}
+
+/// A position and length a player saved, in the clock of what it was playing, as the
+/// original's. Past 75% of a copy, the episode also counts towards the time DeadAir has saved
+/// this person.
+pub async fn on_save(
+    ctx: &Ctx,
+    playing: &Playing,
+    user: i64,
+    feed: &str,
+    guid: &str,
+    secs: i64,
+    duration: Option<i64>,
+) -> Result<(i64, Option<i64>)> {
+    let copy = playing.lock().unwrap().get(&(user, feed.to_owned(), guid.to_owned())).cloned();
+    let Some(c) = copy else { return Ok((secs, duration)) };
+    let original = |s: i64| to_original(&c.cuts, s * 1000) / 1000;
+    let (secs, duration) = (original(secs), duration.map(original));
+    let len = match duration {
+        Some(d) => Some(d),
+        None => ctx.db.entry_duration(user, feed, guid).await?,
+    };
+    if let Some(len) = len
+        && len > 0
+        && secs * 4 >= len * 3
+    {
+        ctx.db.count_deadair(user, feed, guid, c.saved_ms).await?;
+    }
+    Ok((secs, duration))
+}
+
+/// Makes copies until stopped: the next one anyone wants, or a wait of `IDLE` when there is
+/// none.
+pub async fn run(ctx: Arc<Ctx>, mut stop: tokio::sync::watch::Receiver<bool>) {
+    if !have_ffmpeg().await {
+        tracing::warn!("ffmpeg is not installed, so DeadAir makes no copies");
+        return;
+    }
+    loop {
+        // Dropping the pass on a signal kills the ffmpeg it is running (`kill_on_drop`).
+        let made = tokio::select! {
+            _ = stop.changed() => return,
+            made = next(&ctx) => made,
+        };
+        match made {
+            Ok(true) => continue,
+            Ok(false) => {}
+            Err(e) => tracing::warn!(error = %format!("{e:#}"), "DeadAir could not make a copy"),
+        }
+        tokio::select! {
+            _ = stop.changed() => return,
+            _ = ctx.deadair.notified() => {}
+            _ = tokio::time::sleep(IDLE) => {}
+        }
+    }
+}
+
+async fn have_ffmpeg() -> bool {
+    tokio::process::Command::new("ffmpeg")
+        .arg("-version")
+        .stdout(std::process::Stdio::null())
+        .status()
+        .await
+        .is_ok_and(|s| s.success())
+}
+
+/// Makes one copy someone wants, if there is one to make. A file everyone who would play the
+/// copy has already finished gets none: finished episodes are rarely played again.
+// shortcut: those stay on the list and are looked at again each pass, one query each; record
+// them as passed over if a large library makes the pass slow.
+async fn next(ctx: &Ctx) -> Result<bool> {
+    // Nobody with DeadAir on for anything, which is most passes: nothing more to ask the database.
+    let wanting = Wanting::load(ctx, None).await?;
+    if wanting.people.is_empty() {
+        return Ok(false);
+    }
+    for t in ctx.db.deadair_todo().await? {
+        let users: Vec<i64> =
+            wanting.people.keys().copied().filter(|&u| wanting.wants(u, &t.feed_id)).collect();
+        if users.is_empty() || !ctx.db.subscribed_any(&users, &t.feed_id).await? {
+            continue;
+        }
+        let readers = ctx.db.readers(&t.feed_id, &t.guid).await?;
+        if users.iter().all(|u| readers.contains(u)) {
+            continue;
+        }
+        let src = crate::download::playable(Path::new(&t.path));
+        let started = std::time::Instant::now();
+        let made = make(&src).await;
+        let (path, cuts) = match made {
+            Ok(Some((path, cuts))) => (Some(path.display().to_string()), cuts),
+            Ok(None) => (None, vec![]),
+            Err(e) => {
+                // Recorded as having none, so a file ffmpeg cannot read is not tried every pass.
+                tracing::warn!(path = %src.display(), error = %format!("{e:#}"), "DeadAir could not make a copy");
+                (None, vec![])
+            }
+        };
+        let saved_ms = saved(&cuts);
+        ctx.db.store_deadair(t.id, path.as_deref(), &serde_json::to_string(&cuts)?, saved_ms).await?;
+        tracing::info!(
+            ev = "deadair",
+            feed = t.feed_id,
+            path = %src.display(),
+            cuts = cuts.len(),
+            saved_s = saved_ms / 1000,
+            took_ms = started.elapsed().as_millis() as u64,
+            "DeadAir copy made"
+        );
+        return Ok(true);
+    }
+    Ok(false)
+}
+
+/// Makes the copy of one file. None for a file it does not apply to: video, anything but MP3
+/// and AAC, or one with no silence long enough to cut.
+pub async fn make(src: &Path) -> Result<Option<(PathBuf, Vec<Cut>)>> {
+    let Some((first, frame)) = probe(src).await? else { return Ok(None) };
+    let log = ffmpeg(&[
+        "-hide_banner", "-nostats", "-i", &src.display().to_string(), "-map", "0:a:0",
+        "-af", &format!("silencedetect=n={THRESHOLD}:d={MIN_SILENCE}"), "-f", "null", "-",
+    ])
+    .await
+    .context("finding the silences")?;
+    let (frames, cuts) = plan(&parse_silences(&log), first, frame);
+    if cuts.is_empty() {
+        return Ok(None);
+    }
+    let drop: Vec<String> = frames.iter().map(|(a, b)| format!("between(n\\,{a}\\,{b})")).collect();
+    let dst = copy_path(src);
+    // Written under another name and moved into place, so a copy cut short by a restart is
+    // never served.
+    let tmp = dst.with_file_name(format!(
+        "{}.part.{}",
+        dst.file_stem().unwrap_or_default().to_string_lossy(),
+        dst.extension().unwrap_or_default().to_string_lossy()
+    ));
+    ffmpeg(&[
+        "-v", "error", "-y", "-i", &src.display().to_string(), "-map", "0:a:0", "-c", "copy",
+        "-bsf:a", &format!("noise=drop='{}',setts=ts=N*DURATION", drop.join("+")),
+        &tmp.display().to_string(),
+    ])
+    .await
+    .context("copying the frames kept")?;
+    tokio::fs::rename(&tmp, &dst).await.with_context(|| format!("moving into {}", dst.display()))?;
+    Ok(Some((dst, cuts)))
+}
+
+/// When the first audio frame starts and how long each lasts, in seconds, for a file DeadAir
+/// can copy; None for one it cannot. A cover picture in an MP3 is not video.
+async fn probe(src: &Path) -> Result<Option<(f64, f64)>> {
+    let path = src.display().to_string();
+    let out = run_out("ffprobe", &[
+        "-v", "error", "-show_entries", "stream=codec_type,codec_name:stream_disposition=attached_pic",
+        "-of", "json", &path,
+    ])
+    .await?;
+    let v: serde_json::Value = serde_json::from_str(&out).context("reading ffprobe")?;
+    let streams = v["streams"].as_array().cloned().unwrap_or_default();
+    let video = streams
+        .iter()
+        .any(|s| s["codec_type"] == "video" && s["disposition"]["attached_pic"] != 1);
+    let audio = streams.iter().find(|s| s["codec_type"] == "audio");
+    if video || !audio.is_some_and(|a| a["codec_name"] == "mp3" || a["codec_name"] == "aac") {
+        return Ok(None);
+    }
+    let out = run_out("ffprobe", &[
+        "-v", "error", "-select_streams", "a:0", "-show_entries", "packet=pts_time,duration_time",
+        "-read_intervals", "%+#1", "-of", "csv=p=0", &path,
+    ])
+    .await?;
+    let mut f = out.trim().split(',').map(|x| x.trim().parse::<f64>());
+    match (f.next(), f.next()) {
+        (Some(Ok(first)), Some(Ok(frame))) if frame > 0.0 => Ok(Some((first, frame))),
+        _ => bail!("no audio frame in {path}"),
+    }
+}
+
+/// Runs ffmpeg and gives back what it wrote to stderr, where silencedetect reports.
+async fn ffmpeg(args: &[&str]) -> Result<String> {
+    let out = command("ffmpeg").args(["-nostdin", "-threads", "1"]).args(args).output().await?;
+    let log = String::from_utf8_lossy(&out.stderr).into_owned();
+    if !out.status.success() {
+        bail!("ffmpeg failed: {}", log.lines().rev().take(3).collect::<Vec<_>>().join(" / "));
+    }
+    Ok(log)
+}
+
+async fn run_out(prog: &str, args: &[&str]) -> Result<String> {
+    let out = command(prog).args(args).output().await.with_context(|| format!("running {prog}"))?;
+    if !out.status.success() {
+        bail!("{prog} failed: {}", String::from_utf8_lossy(&out.stderr).trim());
+    }
+    Ok(String::from_utf8_lossy(&out.stdout).into_owned())
+}
+
+fn command(prog: &str) -> tokio::process::Command {
+    let mut c = tokio::process::Command::new(prog);
+    c.kill_on_drop(true).stdin(std::process::Stdio::null());
+    c
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn silences_are_read_from_the_log_and_an_open_one_is_left() {
+        let log = "[silencedetect @ 0x1] silence_start: 1\n\
+                   [silencedetect @ 0x1] silence_end: 3.00002 | silence_duration: 2.00002\n\
+                   [silencedetect @ 0x1] silence_start: 10.5\n";
+        assert_eq!(parse_silences(log), vec![(1.0, 3.00002)]);
+    }
+
+    #[test]
+    fn cuts_leave_silent_frames_either_side_and_skip_short_silences() {
+        // MP3 frames, 26.122 ms; one silence of 2 s, one too short to touch.
+        let frame = 1152.0 / 44100.0;
+        let (frames, cuts) = plan(&[(1.0, 3.0), (5.0, 5.3)], 0.0, frame);
+        assert_eq!(frames, vec![(43, 110)]);
+        let Cut(s, e) = cuts[0];
+        assert!(s >= 1100 && e <= 2900, "{cuts:?}");
+        assert!(s - 1100 < 27 && 2900 - e < 27, "no more than a frame kept beyond KEEP: {cuts:?}");
+        // AAC in MP4 starts a frame early, for the encoder's priming.
+        let (frames, _) = plan(&[(1.0, 3.0)], -0.02322, 1024.0 / 44100.0);
+        assert_eq!(frames, vec![(49, 124)]);
+        // A silence the margins use up entirely is left alone.
+        assert!(plan(&[(1.0, 1.21)], 0.0, frame).0.is_empty());
+    }
+
+    #[test]
+    fn positions_convert_both_ways() {
+        let cuts = [Cut(10_000, 20_000), Cut(30_000, 35_000)];
+        assert_eq!(to_copy(&cuts, 5_000), 5_000);
+        assert_eq!(to_copy(&cuts, 15_000), 10_000, "inside a cut is where it was made");
+        assert_eq!(to_copy(&cuts, 25_000), 15_000);
+        assert_eq!(to_copy(&cuts, 40_000), 25_000);
+        for t in [0, 5_000, 10_000, 15_000, 19_999, 20_000, 25_000, 40_000] {
+            let back = to_original(&cuts, to_copy(&cuts, t));
+            // A time inside a cut comes back as the cut's end: the copy has nothing between.
+            let expect = if (10_000..20_000).contains(&t) { 20_000 } else { t };
+            assert_eq!(back, expect, "{t}");
+        }
+        assert_eq!(saved(&cuts), 15_000);
+    }
+
+    #[test]
+    fn off_for_every_feed_until_turned_on_for_it_or_its_group() {
+        let p = |v: &[(&str, bool)]| v.iter().map(|(k, w)| (k.to_string(), *w)).collect::<HashMap<_, _>>();
+        assert!(!wants(&p(&[]), "a", None), "off until turned on for the feed");
+        assert!(!wants(&p(&[("b", true)]), "a", None), "another feed's says nothing of this one");
+        assert!(wants(&p(&[("a", true)]), "a", None));
+        assert!(wants(&p(&[("g", true)]), "a", Some("g")), "on for its group");
+        assert!(!wants(&p(&[("g", true), ("a", false)]), "a", Some("g")), "kept out of its group's");
+    }
+
+    #[test]
+    fn the_copy_sits_beside_the_original() {
+        assert_eq!(copy_path(Path::new("/d/show/ep 1.mp3")), Path::new("/d/show/ep 1.deadair.mp3"));
+    }
+
+    /// The whole of it, on a clip ffmpeg makes: a second of tone, two of silence, and so on.
+    /// Skipped where ffmpeg is not installed.
+    #[tokio::test]
+    async fn a_copy_is_shorter_by_what_was_cut_and_plays() {
+        if !have_ffmpeg().await {
+            eprintln!("no ffmpeg; skipped");
+            return;
+        }
+        let dir = std::env::temp_dir().join(format!("ipx-deadair-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        for (ext, codec) in [("mp3", "libmp3lame"), ("m4a", "aac")] {
+            let src = dir.join(format!("t.{ext}"));
+            ffmpeg(&[
+                "-v", "error", "-y", "-f", "lavfi", "-i",
+                "aevalsrc='if(lt(mod(t,3),1),0.5*sin(2*PI*440*t),0)':d=12:s=44100",
+                "-c:a", codec, &src.display().to_string(),
+            ])
+            .await
+            .unwrap();
+            let (dst, cuts) = make(&src).await.unwrap().expect("a copy");
+            assert_eq!(cuts.len(), 4, "{ext}: {cuts:?}");
+            // About 1.8 s from each of the four 2 s silences.
+            let cut = saved(&cuts);
+            assert!((7_000..7_300).contains(&cut), "{ext}: {cut}");
+            let len = |p: &Path| {
+                let p = p.display().to_string();
+                async move {
+                    run_out("ffprobe", &["-v", "error", "-show_entries", "format=duration", "-of", "csv=p=0", &p])
+                        .await
+                        .unwrap()
+                        .trim()
+                        .parse::<f64>()
+                        .unwrap()
+                }
+            };
+            let short = len(&src).await - len(&dst).await;
+            assert!((short * 1000.0 - cut as f64).abs() < 100.0, "{ext}: {short} s shorter, {cut} ms cut");
+            // Decodes without a complaint.
+            assert!(ffmpeg(&["-v", "error", "-i", &dst.display().to_string(), "-f", "null", "-"]).await.unwrap().is_empty());
+        }
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
+}
+
+/// A real episode, for trying the cut on something other than a test tone:
+/// `IPX_DEADAIR_FILE=/path/ep.mp3 cargo test real_file -- --ignored --nocapture`. The copy is left
+/// beside it to listen to.
+#[cfg(test)]
+#[tokio::test]
+#[ignore]
+async fn real_file() {
+    let src = PathBuf::from(std::env::var("IPX_DEADAIR_FILE").expect("IPX_DEADAIR_FILE"));
+    let t = std::time::Instant::now();
+    let (dst, cuts) = make(&src).await.unwrap().expect("a copy");
+    eprintln!("{} cuts, {:.1} min saved, {:.1?} -> {}", cuts.len(), saved(&cuts) as f64 / 60_000.0, t.elapsed(), dst.display());
+}

src/download.rs

@@ -211,7 +211,12 @@ pub async fn place(d: &Downloaded, dir: &Path) -> Result<PathBuf> {
 /// down as. `remove_file` refused the folder, so the reaper warned on every pass and freed nothing,
 /// and Delete failed (#158).
 pub fn remove(path: &Path) -> std::io::Result<()> {
-    if path.is_dir() { std::fs::remove_dir_all(path) } else { std::fs::remove_file(path) }
+    if path.is_dir() {
+        return std::fs::remove_dir_all(path);
+    }
+    // Its DeadAir copy goes with it, if it has one; it is no use without the original (#171).
+    let _ = std::fs::remove_file(crate::deadair::copy_path(path));
+    std::fs::remove_file(path)
 }
 
 /// The file to play for an enclosure's path: the path itself, or for a torrent of several files,

src/entity.rs

@@ -354,3 +354,69 @@ pub mod settings {
 
     impl ActiveModelBehavior for ActiveModel {}
 }
+
+/// DeadAir's copy of an enclosure: the same file with long silences shortened (issue #171).
+/// `cuts` is what the copy leaves out, as `[[start_ms, end_ms], ...]` of the original's time,
+/// which is what converts positions between the two. `path` is NULL for a file that cannot have
+/// one (video, or not MP3 or AAC), so it is looked at once and not every pass.
+pub mod deadair {
+    use sea_orm::entity::prelude::*;
+
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "deadair")]
+    pub struct Model {
+        #[sea_orm(primary_key, auto_increment = false)]
+        pub enclosure_id: i64,
+        #[sea_orm(column_type = "Text", nullable)]
+        pub path: Option<String>,
+        #[sea_orm(column_type = "Text")]
+        pub cuts: String,
+        pub saved_ms: i64,
+        /// Against the enclosure's `downloaded_at`: a file downloaded again needs its copy again.
+        pub made_at: i64,
+    }
+
+    #[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+    pub enum Relation {}
+
+    impl ActiveModelBehavior for ActiveModel {}
+}
+
+/// Who has DeadAir on, for which feeds: it is off for every feed until someone turns it on for
+/// that one or its group, and `wanted` false keeps one feed of a group out of the group's.
+pub mod deadair_prefs {
+    use sea_orm::entity::prelude::*;
+
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "deadair_prefs")]
+    pub struct Model {
+        #[sea_orm(primary_key, auto_increment = false)]
+        pub user_id: i64,
+        #[sea_orm(primary_key, auto_increment = false, column_type = "Text")]
+        pub feed_id: String,
+        pub wanted: bool,
+    }
+
+    owned_by_user!();
+}
+
+/// The time DeadAir has saved someone: one row per episode they got 75% through on a copy, so
+/// replaying it never counts twice. Their total is the sum.
+pub mod deadair_saved {
+    use sea_orm::entity::prelude::*;
+
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "deadair_saved")]
+    pub struct Model {
+        #[sea_orm(primary_key, auto_increment = false)]
+        pub user_id: i64,
+        #[sea_orm(primary_key, auto_increment = false, column_type = "Text")]
+        pub feed_id: String,
+        #[sea_orm(primary_key, auto_increment = false, column_type = "Text")]
+        pub guid: String,
+        pub saved_ms: i64,
+        pub at: i64,
+    }
+
+    owned_by_user!();
+}

src/main.rs

@@ -3,6 +3,7 @@ mod art;
 mod auth;
 mod config;
 mod db;
+mod deadair;
 mod entity;
 mod download;
 mod feed;
@@ -152,6 +153,9 @@ pub struct Ctx {
     // own, and a change in flight here can still store over theirs; take the copy from the
     // database rather than memory if that ever happens.
     pub cfg_write: tokio::sync::Mutex<()>,
+    /// Wakes DeadAir's maker when a show is turned on, so its copies start at once instead of
+    /// at the next pass (#171).
+    pub deadair: tokio::sync::Notify,
 }
 
 /// A copy of the config to change, holding off every other change until `store_cfg` keeps it.
@@ -344,6 +348,7 @@ async fn main() -> Result<()> {
         detach_torrents: is_daemon,
         retry: Default::default(),
         cfg_write: Default::default(),
+        deadair: Default::default(),
     });
 
     let result = match cli.command {
@@ -635,6 +640,9 @@ async fn daemon(
         shutdown().await;
         let _ = tx_stop.send(true);
     });
+    // Off the worker: the first pass over a library is hours of ffmpeg, and scans and downloads
+    // must not wait behind it.
+    tokio::spawn(deadair::run(ctx.clone(), rx_stop.clone()));
 
     // Runs one job, abandoning it if a signal arrives. Returns false to end the loop.
     async fn until_stopped(
@@ -765,6 +773,7 @@ async fn start_web(
         cmds: cmds.clone(),
         events: events.clone(),
         access,
+        playing: Default::default(),
     };
     Ok(Some(tokio::spawn(async move {
         if let Err(e) = web::serve(state, &bind).await {
@@ -2453,6 +2462,7 @@ mod tests {
             detach_torrents: false,
             retry: Default::default(),
             cfg_write: Default::default(),
+            deadair: Default::default(),
         }
     }
 
@@ -2478,6 +2488,59 @@ mod tests {
         assert!(ctx.db.subscription(stays, "shared").await.unwrap().is_some());
     }
 
+    #[tokio::test]
+    async fn deadair_hands_out_the_copys_clock_and_saves_in_the_originals() {
+        let ctx = test_ctx(config::Config::default()).await;
+        let db = &ctx.db;
+        let u = db.create_user("dee", None, false).await.unwrap();
+        db.subscribe(u, "f").await.unwrap();
+        for sql in [
+            "INSERT INTO entries (feed_id, guid, first_seen, duration) VALUES ('f', 'g', 1, 600)",
+            "INSERT INTO enclosures (id, feed_id, guid, url, path, state, downloaded_at)
+             VALUES (7, 'f', 'g', 'http://x/a.mp3', '/x/a.mp3', 'done', 100)",
+        ] {
+            db.sql(sql).await.unwrap();
+        }
+        // Two minutes cut, both before the place saved.
+        db.store_deadair(7, Some("/x/a.deadair.mp3"), "[[60000,120000],[200000,260000]]", 120_000).await.unwrap();
+        db.set_position(u, "f", "g", 300, None).await.unwrap();
+        let order = db::order_sql("published", "desc");
+        let page = || {
+            let (order, ctx) = (order.clone(), &ctx);
+            async move {
+                let mut rows = ctx.db.entries_in(u, Some("f"), db::Filter::All, None, 0, 10, &order).await.unwrap();
+                deadair::for_reader(ctx, u, &mut rows).await.unwrap();
+                rows.remove(0)
+            }
+        };
+        let off = page().await;
+        assert_eq!((off.position, off.enclosures[0].deadair), (300, None), "off until turned on for the feed");
+
+        db.set_deadair(u, "f", Some(true)).await.unwrap();
+        let on = page().await;
+        assert_eq!((on.position, on.duration, on.enclosures[0].deadair), (180, Some(480), Some(120)));
+
+        // Saved from the copy at 3:20 of its 8:00: 5:20 of the original's 10:00, short of 75%.
+        let playing = deadair::Playing::default();
+        let copy = db.copies(&[7]).await.unwrap().remove(0);
+        playing.lock().unwrap().insert((u, "f".into(), "g".into()), Arc::new(copy));
+        let saved = deadair::on_save(&ctx, &playing, u, "f", "g", 200, Some(480)).await.unwrap();
+        assert_eq!(saved, (320, Some(600)));
+        assert_eq!(db.deadair_total(u).await.unwrap(), 0);
+        // Past 75% (6:00 of the copy is 8:00 of the original), counted once.
+        for _ in 0..2 {
+            deadair::on_save(&ctx, &playing, u, "f", "g", 360, None).await.unwrap();
+        }
+        assert_eq!(db.deadair_total(u).await.unwrap(), 120_000);
+        // Playing the original again: saved as it is.
+        playing.lock().unwrap().clear();
+        assert_eq!(deadair::on_save(&ctx, &playing, u, "f", "g", 200, Some(600)).await.unwrap(), (200, Some(600)));
+
+        // Turned off again: the original's clock.
+        db.set_deadair(u, "f", Some(false)).await.unwrap();
+        assert_eq!(page().await.enclosures[0].deadair, None);
+    }
+
     #[tokio::test]
     async fn two_changes_to_the_catalogue_at_once_both_keep() {
         let ctx = Arc::new(test_ctx(config::Config::default()).await);

src/retention.rs

@@ -61,7 +61,11 @@ pub async fn run(cfg: &Config, db: &Db, dry_run: bool) -> Result<Report> {
         tracing::info!(feed = id, "forgot a failing feed nobody subscribes to");
     }
 
-    let candidates = db.reap_candidates().await?;
+    let mut candidates = db.reap_candidates().await?;
+    // A file's DeadAir copy is on the disk too, and goes when it goes (#171).
+    for c in &mut candidates {
+        c.bytes += copy_bytes(&c.path) as i64;
+    }
 
     if cfg.general.max_age_days > 0 {
         let cutoff = now() - (cfg.general.max_age_days * 86_400) as i64;
@@ -100,7 +104,7 @@ async fn remove(db: &Db, c: &Candidate, dry_run: bool) -> Result<u64> {
     let size = std::fs::metadata(&c.path)
         .ok()
         .filter(|m| m.is_file())
-        .map_or(c.bytes.max(0) as u64, |m| m.len());
+        .map_or(c.bytes.max(0) as u64, |m| m.len() + copy_bytes(&c.path));
     // Missing is fine: the point is that it is gone.
     if let Err(e) = crate::download::remove(std::path::Path::new(&c.path))
         && e.kind() != std::io::ErrorKind::NotFound
@@ -112,6 +116,10 @@ async fn remove(db: &Db, c: &Candidate, dry_run: bool) -> Result<u64> {
     Ok(size)
 }
 
+fn copy_bytes(path: &str) -> u64 {
+    std::fs::metadata(crate::deadair::copy_path(std::path::Path::new(path))).map_or(0, |m| m.len())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/web.rs

@@ -32,6 +32,7 @@ pub struct WebState {
     pub events: broadcast::Sender<Event>,
     /// Cloudflare Access's signing keys, fetched once and kept.
     pub access: Arc<crate::access::Keys>,
+    pub playing: crate::deadair::Playing,
 }
 
 pub fn router(state: WebState) -> Router {
@@ -45,6 +46,7 @@ pub fn router(state: WebState) -> Router {
         .route("/api/feeds/{id}", patch(patch_feed).delete(remove_feed))
         .route("/api/feeds/{id}/entries", get(entries))
         .route("/api/entries", get(all_entries))
+        .route("/api/entries/{feed_id}/{guid}", get(one_entry))
         .route("/api/entries/{feed_id}/{guid}/flags", post(set_flags))
         .route("/api/entries/{feed_id}/{guid}/position", post(set_position))
         .route("/api/feeds/{id}/read-all", post(read_all))
@@ -67,6 +69,7 @@ pub fn router(state: WebState) -> Router {
         .route("/admin", get(admin_page))
         .route("/admin.js", get(admin_js))
         .route("/media/{id}", get(media))
+        .route("/media/{id}/deadair", get(media_deadair))
         .route("/api/art", get(art))
         .layer(middleware::from_fn_with_state(state.clone(), auth))
         // Signing in cannot require being signed in, so these sit outside the auth layer.
@@ -91,9 +94,17 @@ pub fn router(state: WebState) -> Router {
 }
 
 pub async fn serve(state: WebState, bind: &str) -> Result<()> {
+    use axum::serve::ListenerExt;
+    // Nagle off, as axum 0.7 had it: under load a response goes out in parts, and with Nagle
+    // on its last small part waits for the browser's delayed ACK, up to 40 ms (#170).
     let listener = tokio::net::TcpListener::bind(bind)
         .await
-        .with_context(|| format!("binding {bind}"))?;
+        .with_context(|| format!("binding {bind}"))?
+        .tap_io(|tcp| {
+            if let Err(e) = tcp.set_nodelay(true) {
+                tracing::debug!(error = %e, "could not set TCP_NODELAY");
+            }
+        });
     tracing::info!(bind, "web ui listening");
     axum::serve(
         listener,
@@ -365,8 +376,10 @@ async fn me(
     let url = state.ctx.cfg().web.sign_out_url.clone();
     let sign_out = (by_proxy && !url.is_empty()).then_some(url);
     let blocked = state.ctx.db.blocklist(user.id, "").await.unwrap_or_default();
+    let saved = state.ctx.db.deadair_total(user.id).await.unwrap_or(0) / 1000;
     Json(serde_json::json!({
         "name": user.name, "admin": user.is_admin, "sign_out": sign_out, "blocked": blocked,
+        "deadair_saved": saved,
     }))
 }
 
@@ -760,6 +773,8 @@ struct FeedRow {
     keywords: Vec<String>,
     /// Your words that hide an item of this feed, beside your list for every feed.
     blocked: Vec<String>,
+    /// Played from DeadAir's copies: on for this feed or its group, off until you turn it on.
+    deadair: bool,
     allow_explicit: bool,
     auto_download: bool,
     max_new_per_check: Option<usize>,
@@ -824,6 +839,8 @@ async fn feed_rows(state: &WebState, user: &crate::db::User, only: Option<&str>)
         .collect();
     let counts = state.ctx.db.subscriber_counts().instrument(step("subscriber_counts")).await?;
     let pinned = state.ctx.db.pinned_feeds(user.id).instrument(step("pinned")).await?;
+    let deadair: std::collections::HashMap<String, bool> =
+        state.ctx.db.deadair_prefs(Some(user.id)).await?.into_iter().map(|(_, f, w)| (f, w)).collect();
     let mut listed = state.ctx.db.feed_list(user.id, only).instrument(step("feed_list")).await?;
     let mut out = Vec::with_capacity(mine.len());
     for sub in subs.iter().filter(|s| only.is_none_or(|o| o == s.id)) {
@@ -848,6 +865,7 @@ async fn feed_rows(state: &WebState, user: &crate::db::User, only: Option<&str>)
                 .or_else(|| up.and_then(|u| u.keywords.clone()))
                 .unwrap_or_else(|| feed.keywords.clone()),
             blocked,
+            deadair: deadair.get(id).or_else(|| feed.group.as_deref().and_then(|g| deadair.get(g))).copied().unwrap_or(false),
             allow_explicit: mine
                 .allow_explicit
                 .or(up.and_then(|u| u.allow_explicit))
@@ -1436,10 +1454,30 @@ async fn entry_page(
             row.description = Some(clean_description(&mut sanitizer, d, row.link.as_deref()));
         }
     }
+    crate::deadair::for_reader(&state.ctx, user_id, &mut rows).await?;
     let total = db.count_in(user_id, feed, filter, search).await?;
     Ok(Json(EntryPage { total, entries: rows }))
 }
 
+/// One entry, in the clock of the file this person will play (`deadair::for_reader`).
+async fn one_entry(
+    State(state): State<WebState>,
+    Path((feed_id, guid)): Path<(String, String)>,
+    user: crate::db::User,
+) -> Result<Json<crate::db::EntryRow>, ApiError> {
+    subscribed(&state, &user, &feed_id).await?;
+    let Some(row) = state.ctx.db.entry(user.id, &feed_id, &guid).await? else {
+        return Err(ApiError::not_found("no such entry"));
+    };
+    let mut rows = [row];
+    crate::deadair::for_reader(&state.ctx, user.id, &mut rows).await?;
+    let [mut row] = rows;
+    if let Some(d) = &row.description {
+        row.description = Some(clean_description(&mut feed_sanitizer(), d, row.link.as_deref()));
+    }
+    Ok(Json(row))
+}
+
 /// Feed HTML is untrusted: it reaches the page only after ammonia has been through it.
 fn feed_sanitizer() -> ammonia::Builder<'static> {
     let mut b = ammonia::Builder::new();
@@ -1539,6 +1577,10 @@ struct FeedPatch {
     #[serde(default, deserialize_with = "double_option")]
     max_new_per_check: Option<Option<usize>>,
     pinned: Option<bool>,
+    /// True plays the feed from DeadAir's copies, false keeps it out (of its group's too), null
+    /// follows its group again (#171).
+    #[serde(default, deserialize_with = "double_option")]
+    deadair: Option<Option<bool>>,
 }
 
 /// A block list as sent: trimmed, blanks and repeats dropped, and bounded, since each word is
@@ -1576,6 +1618,10 @@ async fn patch_feed(
     {
         return Err(ApiError::not_found("you do not subscribe to that feed"));
     }
+    if let Some(wanted) = body.deadair {
+        state.ctx.db.set_deadair(user.id, &id, wanted).await?;
+        state.ctx.deadair.notify_one();
+    }
     // What one person wants -- which items, whether to fetch them, how many at a time --
     // is theirs. It goes on their subscription and nobody else sees the change.
     if let Some(mut mine) = state.ctx.db.subscription(user.id, &id).await? {
@@ -1869,15 +1915,42 @@ async fn media(
     user: crate::db::User,
     req: Request,
 ) -> Response {
+    serve_media(state, id, user, req, false).await
+}
+
+/// DeadAir's copy of a file (#171), at an address of its own: a player that had part of one
+/// version cached and asked the same address for more would stitch the two together.
+async fn media_deadair(
+    State(state): State<WebState>,
+    Path(id): Path<i64>,
+    user: crate::db::User,
+    req: Request,
+) -> Response {
+    serve_media(state, id, user, req, true).await
+}
+
+async fn serve_media(state: WebState, id: i64, user: crate::db::User, req: Request, copy: bool) -> Response {
     let Ok(Some(enc)) = state.ctx.db.enclosure(id).await else {
         return (StatusCode::NOT_FOUND, "no such enclosure").into_response();
     };
     if let Err(e) = subscribed(&state, &user, &enc.feed_id).await {
         return e.into_response();
     }
-    let Some(path) = enc.path else {
+    let Some(mut path) = enc.path else {
         return (StatusCode::NOT_FOUND, "not downloaded").into_response();
     };
+    // Which version this person is playing, so the positions their player saves are read in its
+    // clock (`deadair::on_save`).
+    let key = (user.id, enc.feed_id.clone(), enc.guid.clone());
+    if copy {
+        let Some(c) = state.ctx.db.copies(&[id]).await.ok().and_then(|c| c.into_iter().next()) else {
+            return (StatusCode::NOT_FOUND, "no DeadAir copy").into_response();
+        };
+        path = c.path.clone();
+        state.playing.lock().unwrap().insert(key, Arc::new(c));
+    } else {
+        state.playing.lock().unwrap().remove(&key);
+    }
     match ServeFile::new(crate::download::playable(std::path::Path::new(&path))).oneshot(req).await {
         Ok(r) => r.into_response(),
         Err(e) => (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()).into_response(),
@@ -1893,10 +1966,11 @@ struct ArtQuery {
 /// time it is fetched from the publisher and kept on disk (`art`, up to `art_cache_mb`), so
 /// later it is fast, the publisher is not asked on every visit, and it outlives the publisher's
 /// server. Only an address some feed or item names as its artwork, and only an image up to
-/// 5 MB, so the route cannot be pointed at anything else. It began as a way round http-only
+/// 20 MB, so the route cannot be pointed at anything else. It began as a way round http-only
 /// artwork on the https page (#90).
 async fn art(State(state): State<WebState>, Query(q): Query<ArtQuery>) -> Response {
-    const MAX: usize = 5 << 20;
+    // 5 MB turned away the Glass Cannon Network's covers, 7 MB PNGs (#169).
+    const MAX: usize = 20 << 20;
     let web = q.u.starts_with("http://") || q.u.starts_with("https://");
     if !web || !state.ctx.db.names_image(&q.u).await.unwrap_or(false) {
         return (StatusCode::NOT_FOUND, "no feed names that artwork").into_response();
@@ -1906,6 +1980,9 @@ async fn art(State(state): State<WebState>, Query(q): Query<ArtQuery>) -> Respon
     if keep && let Some((kind, body)) = crate::art::read(&file) {
         return art_response(kind, body);
     }
+    if let Some(why) = crate::art::failed(&q.u) {
+        return (StatusCode::BAD_GATEWAY, why).into_response();
+    }
     let got = async {
         let mut r = state.ctx.client.get(&q.u).timeout(crate::feed::FEED_TIMEOUT).send().await?.error_for_status()?;
         let kind = r.headers().get(header::CONTENT_TYPE).and_then(|v| v.to_str().ok()).unwrap_or("").to_owned();
@@ -1924,7 +2001,13 @@ async fn art(State(state): State<WebState>, Query(q): Query<ArtQuery>) -> Respon
             }
             art_response(kind, body)
         }
-        Err(e) => (StatusCode::BAD_GATEWAY, format!("{e:#}")).into_response(),
+        Err(e) => {
+            let why = format!("{e:#}");
+            // The access line says only that it failed, not which image or why (#169).
+            tracing::warn!(url = %q.u, error = %why, "could not fetch artwork");
+            crate::art::fail(&q.u, &why);
+            (StatusCode::BAD_GATEWAY, why).into_response()
+        }
     }
 }
 
@@ -1956,7 +2039,9 @@ async fn set_position(
     user: crate::db::User,
     Json(body): Json<Position>,
 ) -> Result<StatusCode, ApiError> {
-    state.ctx.db.set_position(user.id, &feed_id, &guid, body.secs, body.duration).await?;
+    let (secs, duration) =
+        crate::deadair::on_save(&state.ctx, &state.playing, user.id, &feed_id, &guid, body.secs, body.duration).await?;
+    state.ctx.db.set_position(user.id, &feed_id, &guid, secs, duration).await?;
     Ok(StatusCode::NO_CONTENT)
 }
 

tests/ui/app.spec.js

@@ -1750,3 +1750,45 @@ test('a feed\'s settings say what downloads, take words as chips, and keep what
   await expect(page.locator('#skw .chip, #sblock .chip')).toHaveCount(0);
   await page.keyboard.press('Escape');
 });
+
+test('DeadAir is off until turned on for a show, then plays its shortened copy and switches back', async ({ page }) => {
+  // #171/#172. A show of its own, with real audio, added here and left at the end.
+  const { id } = await (await page.request.post('/api/feeds', { data: { url: 'http://127.0.0.1:8792/quiet.xml' } })).json();
+  const entry = async () => {
+    const r = await page.request.get(`/api/feeds/${encodeURIComponent(id)}/entries`);
+    return (await r.json()).entries?.[0];
+  };
+  await expect.poll(async () => (await entry())?.guid, { timeout: 15_000 }).toBe('quiet-1');
+  await page.request.post(`/api/feeds/${encodeURIComponent(id)}/download-latest`, { data: { count: 1 } });
+  await expect.poll(async () => !!(await entry())?.enclosures[0]?.path, { timeout: 15_000 }).toBe(true);
+  // Off for a show until someone turns it on: no copy is made.
+  expect((await entry()).enclosures[0].deadair).toBeUndefined();
+  await page.reload();
+
+  // On, in the show's settings.
+  await page.locator('#feedlist .feed', { hasText: 'Quiet Show' }).first().click();
+  await page.locator('#content .acts [data-a="settings"]').click();
+  const sw = page.locator('#sdead');
+  await expect(sw).not.toBeChecked();
+  await sw.locator('xpath=..').click();
+  await page.locator('#ssave').click();
+  // Made at once, not at the next pass: about 1.8 s off each of four 2 s silences.
+  await expect.poll(async () => (await entry()).enclosures[0].deadair ?? 0, { timeout: 20_000 }).toBeGreaterThan(5);
+  await page.reload();
+  await page.locator('#feedlist .feed', { hasText: 'Quiet Show' }).first().click();
+  const row = page.locator('.ep', { hasText: 'Pauses Between' });
+  await expect(row).toContainText('s shorter');
+
+  // Played from the copy, with the switch beside the speed pressed.
+  await row.locator('[data-a=play]').click();
+  await expect.poll(() => page.evaluate(() => document.querySelector('#audio').getAttribute('src'))).toMatch(/\/deadair$/);
+  await expect(page.locator('#pdead')).toHaveAttribute('aria-pressed', 'true');
+  // Off from the player: the original, from the same place.
+  await page.locator('#pdead').click();
+  await expect(page.locator('#pdead')).toHaveAttribute('aria-pressed', 'false');
+  await expect.poll(() => page.evaluate(() => document.querySelector('#audio').getAttribute('src'))).toMatch(/\/media\/\d+$/);
+  expect((await entry()).enclosures[0].deadair).toBeUndefined();
+
+  await page.locator('#pclose').click();
+  await page.request.delete(`/api/feeds/${encodeURIComponent(id)}`);
+});

tests/ui/fixtures/quiet.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0"?>
+<rss version="2.0" xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd">
+<channel><title>Quiet Show</title><link>http://127.0.0.1:8792/</link><description>Real audio with long silences, for DeadAir.</description>
+<item><title>Pauses Between</title><guid>quiet-1</guid>
+  <pubDate>Mon, 15 Sep 2026 10:00:00 +0000</pubDate>
+  <description>A second of tone, then two of silence, five times.</description>
+  <enclosure url="http://127.0.0.1:8792/quiet.mp3" length="60518" type="audio/mpeg"/></item>
+</channel></rss>

web/index.html

@@ -66,6 +66,7 @@
     </div>
   </div>
   <div id="pright">
+    <button class="iconbtn" id="pdead" aria-pressed="false" aria-label="DeadAir" hidden></button>
     <select id="rate" title="Speed">
       <option value="0.8">0.8×</option><option value="1" selected>1×</option>
       <option value="1.25">1.25×</option><option value="1.5">1.5×</option>

web/src/dialogs.ts

@@ -363,7 +363,15 @@ function due(ts){
 /// Your settings: the theme, your subscriptions as OPML, and, to read, what the server does
 /// with feeds. The server's own settings, the accounts and the log are on /admin, which only an
 /// admin is sent (issue #19); this used to hold them too, shown to admins only.
+function deadSavedText(me){
+  const s=me&&me.deadair_saved||0;
+  return s?`It has saved you ${spanText(s)} of dead air, on episodes you heard three quarters of or more.`
+    :'Turn it on in a show\'s settings, or beside the speed while it plays, to cut the dead air from it.';
+}
+
 async function prefsModal(){
+  // Fresh, so the time saved counts what was heard since the page loaded.
+  api('/api/me').then(u=>{ S.me=u; const h=$('#sdeadsaved'); if(h) h.textContent=deadSavedText(u); }).catch(()=>{});
   const g = await api('/api/settings');
   const admin = !!(S.me&&S.me.admin);
   openModal(`<button class="iconbtn cardx" onclick="closeModal()" title="Close" aria-label="Close">${ICON.close}</button><h3>Settings</h3>
@@ -374,6 +382,8 @@ async function prefsModal(){
       <select id="smode">${Object.entries(MODES).map(([k,t])=>
         `<option value="${k}"${theme.mode===k?' selected':''}>${esc(t)}</option>`).join('')}</select>
       <span class="hint">Auto follows your system's light/dark setting.</span></div>
+    <div class="field"><label>DeadAir</label>
+      <span class="hint" id="sdeadsaved">${deadSavedText(S.me)}</span></div>
     <div class="field"><label>Subscriptions</label>
       <div class="inline">
         <!-- Words as well as icons: a floppy disk and a plus mean nothing on their own here. -->
@@ -517,6 +527,10 @@ function settingsModal(f, newUrl?: string){
         <p class="cap">Any one of these will do, and a phrase needs all its words. Empty takes everything.</p></div>
       ${sw(`<input type="checkbox" role="switch" id="sexp"${f.allow_explicit?' checked':''}>`,'Include explicit items')}
     </div></div></div></div>
+    <div class="ffield">${sw(`<input type="checkbox" role="switch" id="sdead"${f.deadair?' checked':''}>`,'DeadAir',' lead')}
+      <p class="cap">Cuts the dead air: long silences in ${isGroup?'these shows':'this show'} shrink to a beat, so
+      episodes finish sooner and every voice keeps its own pace. Leave it off for stories whose pauses
+      are part of the telling.</p></div>
     ${isGroup?'':`<div class="ffield"><label class="flabel" for="sblockin">Hide items that mention</label>
       <div class="chips" id="sblock">${chipsHTML(f.blocked||[],'sblockin')}</div>
       <p class="cap">Whole words or phrases. Hidden from your list and not downloaded for you, along
@@ -600,7 +614,7 @@ function settingsModal(f, newUrl?: string){
       const patch: Record<string, unknown>={
         keywords:chipWords($('#skw')),
         max_new_per_check:mode==='default'?null:mode==='all'?0:newest,
-        auto_download:$('#sauto').checked, allow_explicit:$('#sexp').checked};
+        auto_download:$('#sauto').checked, allow_explicit:$('#sexp').checked, deadair:$('#sdead').checked};
       if($('#sblock')) patch.blocked=chipWords($('#sblock'));
       // The address is the same for everyone: an admin's to change, for a feed that moved, and the
       // API refuses it from anyone else. The folder and category are not this dialog's at all.

web/src/items.ts

@@ -78,6 +78,7 @@ function epEl(e){
         num&&`<span>${num}</span>`,
         left&&`<span>${left}</span>`,
         others>0&&`<span>+${others} more file${others===1?'':'s'}</span>`,
+        enc&&enc.deadair>0&&`<span title="DeadAir cut its dead air">${shorter(enc.deadair)}</span>`,
         enc&&enc.last_error&&enc.state==='error'&&`<span style="color:var(--bad)">${esc(enc.last_error)}</span>`,
       ].filter(Boolean).join('<span class="dot"></span>')}</div>
     </div>

web/src/player.ts

@@ -1,8 +1,12 @@
 /* ---------------- player ---------------- */
 const audio=$('#audio');
-const player: {guid: string|null, feed: string|null, entry: any, enc?: number, moved?: boolean,
+const player: {guid: string|null, feed: string|null, entry: any, enc?: number, src?: string, moved?: boolean,
   saveAt: number, marked: boolean}={guid:null,feed:null,entry:null,saveAt:0,marked:false};
 
+/// Where a file plays from: DeadAir's copy when the server says this person plays it (#171),
+/// whose times the entry is already given in, else the file itself.
+const mediaSrc=enc=>enc.deadair!=null?`/media/${enc.id}/deadair`:`/media/${enc.id}`;
+
 // Marked read when an item has actually been listened to -- at the end, or past 90%.
 // NOT on play: doing that made the item vanish from the Unread list the instant
 // you pressed play, which looks exactly like it went missing.
@@ -20,14 +24,15 @@ function play(e,enc=e.enclosures.find(isPlayable)){
     toast(e.enclosures.some(x=>x.path) ? 'That file is not audio or video' : 'Not downloaded yet', true);
     return;
   }
-  // The same file carries on where it was; another of the item's files starts from its top.
-  const resuming = player.guid===e.guid && player.enc===enc.id;
+  // The same file carries on where it was; another of the item's files starts from its top. So
+  // does the other version of the same file, from the place the entry gives in its clock.
+  const resuming = player.guid===e.guid && player.enc===enc.id && player.src===mediaSrc(enc);
   // Every play button is a pause button for what is playing, as the player bar's is.
   if(resuming && !audio.paused){ audio.pause(); return; }
   if(!resuming){
     player.guid=e.guid; player.feed=e.feed_id; player.entry=e; player.enc=enc.id; player.moved=false;
     document.body.classList.toggle('has-video', kindOf(enc)==='video');
-    audio.src=`/media/${enc.id}`;
+    audio.src=player.src=mediaSrc(enc);
     audio.currentTime=0;
     if(e.position>5) audio.addEventListener('loadedmetadata',()=>{audio.currentTime=e.position},{once:true});
     // Initials, if it comes to that, are the feed's: the episode's read as "SE" beside the feed's art.
@@ -38,6 +43,7 @@ function play(e,enc=e.enclosures.find(isPlayable)){
     $('#player').classList.add('on');
     mediaSession(e,f);
     player.marked=false;
+    paintDead();
   }
   audio.play().catch(err=>toast('Playback failed: '+err.message,true));
   renderEntries();
@@ -110,6 +116,48 @@ $('#pfwd').onclick=()=>audio.currentTime+=30;
 $('#seek').oninput=e=>{const d=audio.duration;if(d)audio.currentTime=d*e.target.value/1000};
 $('#rate').onchange=e=>{audio.playbackRate=+e.target.value;localStorage.setItem('ipx.rate',e.target.value)};
 $('#vol').oninput=e=>{audio.volume=e.target.value/100;localStorage.setItem('ipx.vol',e.target.value)};
+/// DeadAir's switch beside the speed: on or off for the show that is playing. The state is in the
+/// icon's shape and aria-pressed, never a colour.
+function paintDead(){
+  const b=$('#pdead'), f=S.feeds.find(x=>x.id===player.feed);
+  b.hidden=!f||document.body.classList.contains('has-video');
+  if(b.hidden) return;
+  b.setAttribute('aria-pressed',String(!!f.deadair));
+  b.innerHTML=f.deadair?ICON.deadairOn:ICON.deadair;
+  b.title=f.deadair?'DeadAir is cutting the dead air from this show':'DeadAir: cut the dead air from this show';
+}
+$('#pdead').onclick=async()=>{
+  const f=S.feeds.find(x=>x.id===player.feed); if(!f) return;
+  const on=!f.deadair;
+  try{ await api(`/api/feeds/${encodeURIComponent(f.id)}`,{method:'PATCH',body:JSON.stringify({deadair:on})}); }
+  catch(err){ toast(err.message,true); return; }
+  f.deadair=on; paintDead();
+  const switched=await switchVersion();
+  toast(!on?'DeadAir is off for this show':switched?'DeadAir is cutting the dead air from this show'
+    :'DeadAir is on for this show. Episodes lose their dead air a few minutes after they download.');
+  renderEntries();
+};
+/// Carries on at the same place in the other version of what is playing, once DeadAir has been
+/// turned on or off for its show. True if it changed version: a copy not made yet plays next time.
+async function switchVersion(){
+  if(!player.guid) return false;
+  const [feed,guid]=[player.feed,player.guid].map(encodeURIComponent);
+  // Saved and waited for, not beaconed, so the entry asked for next has this place in it.
+  if(audio.readyState){
+    await api(`/api/entries/${feed}/${guid}/position`,{method:'POST',body:JSON.stringify({
+      secs:Math.floor(audio.currentTime),duration:isFinite(audio.duration)?Math.floor(audio.duration):null})}).catch(()=>{});
+    player.moved=false;
+  }
+  const e=await api(`/api/entries/${feed}/${guid}`).catch(()=>null);
+  const enc=e&&e.enclosures.find(x=>x.id===player.enc);
+  if(!enc||mediaSrc(enc)===player.src) return false;
+  const was=!audio.paused;
+  player.entry=e; player.src=mediaSrc(enc); player.saveAt=e.position;
+  audio.src=player.src;
+  audio.addEventListener('loadedmetadata',()=>{audio.currentTime=e.position},{once:true});
+  if(was) audio.play().catch(()=>{});
+  return true;
+}
 $('#pclose').onclick=()=>{savePos();audio.pause();audio.removeAttribute('src');player.guid=null;$('#player').classList.remove('on');document.body.classList.remove('has-video');renderEntries();
   // Called here, not left to the pause event: closing a player already paused fires none.
   syncListening()};

web/src/util.ts

@@ -21,6 +21,10 @@ const ICON={
   // for the outline's stroke, so the two draw the same size.
   pin:fa('-18 -18 420 548','<path fill="none" stroke="currentColor" stroke-width="36" stroke-linejoin="round" d="M32 32C32 14.3 46.3 0 64 0L320 0c17.7 0 32 14.3 32 32s-14.3 32-32 32l-29.5 0 11.4 148.2c36.7 19.9 65.7 53.2 79.5 94.7l1 3c3.3 9.8 1.6 20.5-4.4 28.8s-15.7 13.3-26 13.3L32 352c-10.3 0-19.9-4.9-26-13.3s-7.7-19.1-4.4-28.8l1-3c13.8-41.5 42.8-74.8 79.5-94.7L93.5 64 64 64C46.3 64 32 49.7 32 32zM160 384l64 0 0 96c0 17.7-14.3 32-32 32s-32-14.3-32-32l0-96z"/>'), // solid/thumbtack, outlined
   pinOn:fa('-18 -18 420 548','<path fill="currentColor" d="M32 32C32 14.3 46.3 0 64 0L320 0c17.7 0 32 14.3 32 32s-14.3 32-32 32l-29.5 0 11.4 148.2c36.7 19.9 65.7 53.2 79.5 94.7l1 3c3.3 9.8 1.6 20.5-4.4 28.8s-15.7 13.3-26 13.3L32 352c-10.3 0-19.9-4.9-26-13.3s-7.7-19.1-4.4-28.8l1-3c13.8-41.5 42.8-74.8 79.5-94.7L93.5 64 64 64C46.3 64 32 49.7 32 32zM160 384l64 0 0 96c0 17.7-14.3 32-32 32s-32-14.3-32-32l0-96z"/>'), // solid/thumbtack
+  // DeadAir (#171): a waveform. Off for this show, outlined with the silence still in its
+  // middle; on, solid with the gap closed up. Padded like pin for the outline's stroke.
+  deadair:fa('-16 -16 544 544','<g fill="none" stroke="currentColor" stroke-width="24"><rect x="14" y="200" width="44" height="112" rx="22"/><rect x="84" y="136" width="44" height="240" rx="22"/><rect x="154" y="96" width="44" height="320" rx="22"/><rect x="314" y="96" width="44" height="320" rx="22"/><rect x="384" y="136" width="44" height="240" rx="22"/><rect x="454" y="200" width="44" height="112" rx="22"/></g>'),
+  deadairOn:fa('-16 -16 544 544','<g fill="currentColor"><rect x="59" y="200" width="44" height="112" rx="22"/><rect x="129" y="136" width="44" height="240" rx="22"/><rect x="199" y="96" width="44" height="320" rx="22"/><rect x="269" y="96" width="44" height="320" rx="22"/><rect x="339" y="136" width="44" height="240" rx="22"/><rect x="409" y="200" width="44" height="112" rx="22"/></g>'),
   scan:fa('0 0 512 512','<path fill="currentColor" d="M65.9 228.5c13.3-93 93.4-164.5 190.1-164.5 53 0 101 21.5 135.8 56.2 .2 .2 .4 .4 .6 .6l7.6 7.2-47.9 0c-17.7 0-32 14.3-32 32s14.3 32 32 32l128 0c17.7 0 32-14.3 32-32l0-128c0-17.7-14.3-32-32-32s-32 14.3-32 32l0 53.4-11.3-10.7C390.5 28.6 326.5 0 256 0 127 0 20.3 95.4 2.6 219.5 .1 237 12.2 253.2 29.7 255.7s33.7-9.7 36.2-27.1zm443.5 64c2.5-17.5-9.7-33.7-27.1-36.2s-33.7 9.7-36.2 27.1c-13.3 93-93.4 164.5-190.1 164.5-53 0-101-21.5-135.8-56.2-.2-.2-.4-.4-.6-.6l-7.6-7.2 47.9 0c17.7 0 32-14.3 32-32s-14.3-32-32-32L32 320c-8.5 0-16.7 3.4-22.7 9.5S-.1 343.7 0 352.3l1 127c.1 17.7 14.6 31.9 32.3 31.7S65.2 496.4 65 478.7l-.4-51.5 10.7 10.1c46.3 46.1 110.2 74.7 180.7 74.7 129 0 235.7-95.4 253.4-219.5z"/>'), // solid/arrows-rotate
   download:fa('0 0 448 512','<path fill="currentColor" d="M256 32c0-17.7-14.3-32-32-32s-32 14.3-32 32l0 210.7-41.4-41.4c-12.5-12.5-32.8-12.5-45.3 0s-12.5 32.8 0 45.3l96 96c12.5 12.5 32.8 12.5 45.3 0l96-96c12.5-12.5 12.5-32.8 0-45.3s-32.8-12.5-45.3 0L256 242.7 256 32zM64 320c-35.3 0-64 28.7-64 64l0 32c0 35.3 28.7 64 64 64l320 0c35.3 0 64-28.7 64-64l0-32c0-35.3-28.7-64-64-64l-46.9 0-56.6 56.6c-31.2 31.2-81.9 31.2-113.1 0L110.9 320 64 320zm304 56a24 24 0 1 1 0 48 24 24 0 1 1 0-48z"/>'), // solid/download
   save:fa('0 0 448 512','<path fill="currentColor" d="M64 32C28.7 32 0 60.7 0 96L0 416c0 35.3 28.7 64 64 64l320 0c35.3 0 64-28.7 64-64l0-242.7c0-17-6.7-33.3-18.7-45.3L352 50.7C340 38.7 323.7 32 306.7 32L64 32zm32 96c0-17.7 14.3-32 32-32l160 0c17.7 0 32 14.3 32 32l0 64c0 17.7-14.3 32-32 32l-160 0c-17.7 0-32-14.3-32-32l0-64zM224 288a64 64 0 1 1 0 128 64 64 0 1 1 0-128z"/>'), // solid/floppy-disk
@@ -56,6 +60,13 @@ const EQ='<span class="eq" aria-hidden="true"><i></i><i></i><i></i></span>';
 // The page's own buttons name their icon; this draws it in, ahead of any label they carry.
 for(const b of $$('[data-icon]')) b.insertAdjacentHTML('afterbegin',ICON[b.dataset.icon]);
 
+/// What DeadAir took off an episode, as the list says it.
+function shorter(secs){ return secs<60?`${secs} s shorter`:`${Math.round(secs/60)} min shorter`; }
+/// A total of time saved: "3 h 12 min", "12 min", "40 s".
+function spanText(secs){
+  const h=Math.floor(secs/3600), m=Math.floor(secs%3600/60);
+  return h?`${h} h ${m} min`:m?`${m} min`:`${secs} s`;
+}
 async function api(url: string, opts?: RequestInit): Promise<any>{
   const r = await fetch(url,{headers:{'Content-Type':'application/json'},...opts});
   if(r.status===401){ location.href='/login'; throw new Error('signed out'); }