Normalize audio frame rate in AudioMixer output #1271
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WalkthroughBuffer timestamping now uses each source's configured rate when buffering incoming frames; separately, the mixer enforces its fixed output rate on filtered frames and computes elapsed time using that mixer output rate for downstream timing. Changes
Sequence DiagramsequenceDiagram
participant Source as Upstream Source
participant Mixer as AudioMixer
participant Buffer as Per-Source Buffer
participant Timing as Downstream Timing
rect rgb(240,250,255)
Note over Source,Buffer: Incoming frame arrives (may report various rates)
Source->>Buffer: push frame (frame.rate() = variable)
end
rect rgb(245,240,255)
Note over Buffer,Mixer: Buffer timestamping uses source-configured rate
Buffer->>Buffer: update buffer_last using source.rate (per-source)
end
rect rgb(245,255,240)
Note over Mixer: Mixer normalizes output rate
Mixer->>Mixer: set filtered_frame.rate = AudioMixer::INFO.rate()
Mixer->>Timing: compute elapsed using AudioMixer::INFO.rate()
end
rect rgb(255,245,245)
Note over Mixer: Downstream receives frames with consistent mixer rate
Mixer->>Timing: emit frame with fixed output timestamps
end
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Actionable comments posted: 0
🧹 Nitpick comments (2)
crates/recording/src/sources/audio_mixer.rs (2)
134-141: Avoid long‑run/32‑bit overflow in sample counter.
samples_out: usizecan overflow on 32‑bit or extremely long runs. Preferu64and cast at use sites.Apply:
@@ - samples_out: usize, + samples_out: u64, @@ - samples_out: 0, + samples_out: 0u64, @@ - let elapsed = Duration::from_secs_f64(self.samples_out as f64 / output_rate); + let elapsed = Duration::from_secs_f64(self.samples_out as f64 / output_rate); @@ - self.samples_out += filtered.samples(); + self.samples_out += filtered.samples() as u64;Also applies to: 206-220, 411-415
297-315: Use existing helpers for silence math (readability/consistency).You already have
samples_for_timeoutandduration_from_samples. Using them here reduces duplication and keeps rounding consistent.- let silence_samples_needed = (gap.as_secs_f64()) * rate as f64; - let silence_samples_count = silence_samples_needed.ceil() as usize; + let silence_samples_count = samples_for_timeout(rate, gap); @@ - let silence_duration = Duration::from_secs_f64( - silence_samples_count as f64 / rate as f64, - ); + let silence_duration = duration_from_samples(silence_samples_count, rate);
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**/*.rs
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Rust modules should be named with snake_case, and crate directories should be in kebab-case.
Files:
crates/recording/src/sources/audio_mixer.rs
crates/*/src/**/*
📄 CodeRabbit inference engine (AGENTS.md)
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Files:
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🧬 Code graph analysis (1)
crates/recording/src/sources/audio_mixer.rs (1)
crates/media-info/src/lib.rs (1)
rate(125-127)
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🔇 Additional comments (2)
crates/recording/src/sources/audio_mixer.rs (2)
403-411: Output rate normalization + elapsed at mixer rate — correct and necessary.Setting
filteredtoAudioMixer::INFO.rate()and computingelapsedfrom that fixed rate prevents downstream from inheriting bad upstream sample-rate metadata and keeps timestamps monotonic at 48 kHz. Nice.
323-326: Buffered-frame duration now uses source rate — fix verified and consistent.The change at line 325 correctly switches to
rate(per-source rate) for buffered-frame duration, keeping it aligned with silence generation at line 312 which already uses the sameratevariable. Verified no other Duration calculations depend onframe.rate(). Output elapsed time at line 411 correctly usesoutput_rate(mixer rate) for downstream encoders. No additional fixes needed.
1 participant
Ensures that the audio frames output by AudioMixer have their rate set to AudioMixer::INFO.rate(), preventing downstream encoders from inheriting incorrect rates from upstream sources such as CoreAudio devices. This change also updates the elapsed time calculation to use the normalized output rate
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