fix: resample short inputs when upsampling#23
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AudioFrame::resample failed for any input shorter than rubato's chunk size when upsampling (e.g. a 160-sample G.711 frame to 44.1 kHz) because the output buffer was sized by input-times-ratio while rubato sizes its output by chunk-times-ratio. Switch to rubato's process_all_needed_output_len helper and match the chunk size to short inputs. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Move resampled.len() into a local before the assert! so the value is evaluated on the happy path, not only inside the panic-message format args. Lets codecov see the new test lines as covered. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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## 🤖 New release * `wavekat-core`: 0.0.9 -> 0.0.10 (✓ API compatible changes) <details><summary><i><b>Changelog</b></i></summary><p> <blockquote> ## [0.0.10](v0.0.9...v0.0.10) - 2026-05-14 ### Fixed - resample short inputs when upsampling ([#23](#23)) </blockquote> </p></details> --- This PR was generated with [release-plz](https://github.com/release-plz/release-plz/). Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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## Summary Adds `StreamingResampler` — a stateful resampler for real-time pipelines that feed short frames in sequence. `AudioFrame::resample` is fine for one-shot conversions, but it constructs a fresh rubato per call. A consumer that calls it on every 20 ms G.711 packet pays the sinc reconstruction's edge cost on every chunk — the resampler sees an abrupt step from zero to the chunk's first sample and produces audible boundary artifacts at the frame rate (50 Hz for 20 ms packets). On a real playback path the user hears continuous noise/buzz over the voice. This bit `wavekat-voice`'s M1 media work after the short-input fix from #23 made `resample` itself succeed. `StreamingResampler::new(source_rate, target_rate, chunk_size)` builds rubato once. `process` accumulates input until it has `chunk_size`, runs one rubato step, and emits output. Internal filter state is preserved across calls. Also factors the sinc parameters + builder out into a private `build_sinc_resampler` helper shared with `AudioFrame::resample`, so the two paths can't drift on quality settings. ## API ```rust use wavekat_core::StreamingResampler; let mut r = StreamingResampler::new(8000, 44100, 160)?; // chunk = 1 G.711 frame let mut out = Vec::new(); for packet in incoming_rtp_packets { let samples: Vec<f32> = /* G.711 decode */; r.process(&samples, &mut out)?; // `out` now has device-rate samples ready for the audio sink } ``` Pass-through fast path when `source_rate == target_rate`: no resampler is built, `process` is a copy. ## Test plan - [x] `cargo test --features resample` — 53 unit tests + 5 doctests pass. - [x] 6 new `StreamingResampler` tests: - `same_rate_is_passthrough` — proves the no-op fast path doesn't go through rubato. - `short_input_chunked_calls` — 10× 160-sample inputs at 8 kHz → 44.1 kHz produce roughly 10 × 882 output samples (the exact RTP receive shape). - `buffers_across_partial_calls` — splitting an input across two `process` calls produces sample-for-sample-identical output to one big call. - `avoids_per_frame_edge_artifacts` — the regression guard: a smooth 600 Hz sine, resampled chunk-by-chunk with `StreamingResampler` vs `AudioFrame::resample`. The streaming output's max consecutive-sample delta stays inside the expected smooth bound (under 10 spikes in steady state); the stateless per-chunk output has 5×+ more spikes because of the chunk-boundary transients. - `rejects_zero_rate` / `rejects_zero_chunk_size` — input validation. - [x] `cargo clippy --workspace --all-features -- -D warnings` clean. - [x] `cargo fmt --all --check` clean. ## Downstream `wavekat-voice`'s `LocalDeviceSink` will switch from per-frame `AudioFrame::resample` to `StreamingResampler` once this lands and bumps to 0.0.11. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
AudioFrame::resamplereturnedInsufficientOutputBufferSizefor any input shorter than rubato's internal chunk size when upsampling — e.g. a 160-sample G.711 frame to 44.1 kHz, the exact casewavekat-voice's RTP receive path hits.process_all_needed_output_len()helper (input-times-ratio underestimates by a full chunk's worth of output) and matched the chunk size to short inputs so we don't pad a 160-sample frame up to 1024.docs/04-resample-short-input-bug.md(8 kHz → 44.1 kHz, 8 kHz → 16 kHz, 8 kHz → 48 kHz) plus the design doc itself.Test plan
cargo test --features resample— 47 passing, including the three new short-input cases and the pre-existing long-input regression guards.cargo fmt --all --checkcargo clippy --workspace --all-features -- -D warnings🤖 Generated with Claude Code