Fix Symphonia total_duration for video containers

CHANGELOG.md

@@ -51,7 +51,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed sources to correctly handle sample rate and channel count changes at span boundaries.
 - Fixed sources to detect parameter updates after mid-span seeks.
 - Fixed `Stoppable` and `Skippable` not signaling exhaustion.
-- Fixed `SpatialAudio` left and write channel swapping
+- Fixed `SpatialAudio` left and write channel swapping.
+- Fixed the Symphonia decoder reporting a wrong `total_duration` for containers whose default track is not the decoded audio track.
 
 ## Version [0.22.2] (2026-03-05)
 

assets/README.md

@@ -1,3 +1,6 @@
 ## License
 
 The `music.wav` and `music.ogg` files in this directory are under cc-by-sa.
+
+`video_with_audio.mp4` is synthetic, generated from ffmpeg's `testsrc` (video)
+and `sine` (audio) sources, and carries no third-party licensing.

src/decoder/symphonia.rs

@@ -107,10 +107,9 @@ impl SymphoniaDecoder {
         };
         let mut probed = get_probe().format(&hint, mss, &format_opts, &metadata_opts)?;
 
-        let stream = match probed.format.default_track() {
-            Some(stream) => stream,
-            None => return Ok(None),
-        };
+        if probed.format.default_track().is_none() {
+            return Ok(None);
+        }
 
         // Select the first supported track
         let track = probed
@@ -131,7 +130,7 @@ impl SymphoniaDecoder {
         let total_duration = track
             .codec_params
             .time_base
-            .zip(stream.codec_params.n_frames)
+            .zip(track.codec_params.n_frames)
             .map(|(base, spans)| base.calc_time(spans).into())
             .filter(|d: &Duration| !d.is_zero());
 

tests/video_container_test.rs

@@ -0,0 +1,40 @@
+//! Regression tests for decoding the audio track of a container whose
+//! *default* track is not the audio track — i.e. a video file.
+//!
+//! `assets/video_with_audio.mp4` holds a 2 s H.264 video track (the default,
+//! 60 frames) plus a 2 s mono AAC audio track.
+
+#![cfg(all(feature = "symphonia-aac", feature = "symphonia-isomp4"))]
+
+use rodio::{Decoder, Source};
+
+fn decode_video_asset() -> Decoder<std::fs::File> {
+    let file = std::fs::File::open("assets/video_with_audio.mp4").unwrap();
+    let len = file.metadata().unwrap().len();
+    Decoder::builder()
+        .with_data(file)
+        .with_byte_len(len)
+        .with_seekable(true)
+        .build()
+        .unwrap()
+}
+
+/// `total_duration` must come from the audio track (~2.02 s), not the video
+/// track. The buggy pairing reported ~0.7 s, so a generous lower bound alone
+/// distinguishes the two, and the tight check pins the correct value.
+#[test]
+fn reports_audio_track_duration_not_default_track() {
+    let duration = decode_video_asset()
+        .total_duration()
+        .expect("video container should report a total duration")
+        .as_secs_f64();
+    assert!(
+        duration > 1.5,
+        "duration {duration}s looks like the video track's frame count, not the audio track"
+    );
+    let expected = 2.023_219_954;
+    assert!(
+        (duration - expected).abs() < 0.01,
+        "got {duration}s, expected about {expected}s"
+    );
+}