fix(encode): trust the decoded signal spec for rate and channels - #293
Merged
Merged
Conversation
The interleaved samples appended to `all_samples` come from `decoded.spec()`, but the returned `(sample_rate, channels)` come from the container header with `unwrap_or` fallbacks. These diverge for real files: symphonia's ADTS AAC reader only sets `params.with_channels(channels)` when `header.channels` is `Some` (symphonia-codec-aac-0.5.5/src/adts.rs:139-141) — an ADTS stream with `channel_config == 0` leaves `codec_params.channels == None`, so rustmotion assumes 2 while the decoder actually emits mono. `to_stereo(&samples, 2)` (line 205) then passes the mono buffer through untouched, so the track is half its real length and plays at double speed; `mix_audio_tracks_segment` sizes everything from that, and the muxed audio desyncs from video with no error anywhere. `audio_analysis.rs:143-149` divides by the same wrong `channels` for the waveform/spectrum envelope, so the on-screen visualisation agrees with the broken mix. Refs #220
LeadcodeDev
added a commit
that referenced
this pull request
Sep 22, 2026
The interleaved samples appended to `all_samples` come from `decoded.spec()`, but the returned `(sample_rate, channels)` come from the container header with `unwrap_or` fallbacks. These diverge for real files: symphonia's ADTS AAC reader only sets `params.with_channels(channels)` when `header.channels` is `Some` (symphonia-codec-aac-0.5.5/src/adts.rs:139-141) — an ADTS stream with `channel_config == 0` leaves `codec_params.channels == None`, so rustmotion assumes 2 while the decoder actually emits mono. `to_stereo(&samples, 2)` (line 205) then passes the mono buffer through untouched, so the track is half its real length and plays at double speed; `mix_audio_tracks_segment` sizes everything from that, and the muxed audio desyncs from video with no error anywhere. `audio_analysis.rs:143-149` divides by the same wrong `channels` for the waveform/spectrum envelope, so the on-screen visualisation agrees with the broken mix. Refs #220
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Audit finding carried by this chantier. Refs #220 (RM-34).