Files
oak-editor/crates/oak-render/examples/render_audio_wav.rs
T
Mike-Solar 9dab9efc38 codec: carry codec-frame overflow across audio chunk boundaries
retrieve_audio_to decodes whole codec frames but copies only the part
inside the requested chunk; the tail of the frame crossing the chunk end
(up to 1023 samples for AAC) was consumed by the decoder and lost, so
the next chunk started with a hole. On the playback grid (1920 samples
at 25fps/48kHz) the hole cycles 128..896 samples and hits 7 of 8 chunk
starts -- the heavy stutter/noise heard during playback.

Keep the overflow (decode and resampler-flush tails) in a per-session
carry buffer and serve it at the start of the next contiguous chunk;
clear it on seek, format change and chunk failure. Also make seek()
actually drop the cached resampler as its comment claimed.

Verified sample-exact: chunked decode of a 440Hz tone now matches a
one-shot decode bit for bit, and chunked renders of real media line up
with the ffmpeg CLI reference at correlation 1.0 / drift 0.

Adds a regression test (playback_sized_chunks_match_oneshot_sample_exact)
with a new tone fixture -- demo.mp4's audio is -90dB digital silence and
cannot expose the holes -- plus a render_audio_wav example used to
diagnose chunk-boundary artifacts offline.
2026-08-29 19:51:59 +08:00

93 lines
3.0 KiB
Rust

// Temporary diagnostic: render a media file's audio exactly like the
// playback prefetch does (one sequence frame per chunk through
// `eval::render_audio_samples`) and write the result as a PCM s16 WAV,
// so render-side artifacts can be analyzed offline.
//
// Usage: render_audio_wav <media> <stream_index> <start_sec> <end_sec> <out.wav> [fps]
use oak_core::{Rational, TimeRange};
use oak_render::eval::render_audio_samples;
use oak_render::ticket::{AudioTicketParams, MontageClip, TicketPayload};
fn main() {
let args: Vec<String> = std::env::args().collect();
if args.len() < 6 {
eprintln!("usage: render_audio_wav <media> <stream_index> <start_sec> <end_sec> <out.wav> [fps]");
std::process::exit(64);
}
let media = &args[1];
let stream_index: i32 = args[2].parse().unwrap();
let start_sec: f64 = args[3].parse().unwrap();
let end_sec: f64 = args[4].parse().unwrap();
let out_path = &args[5];
let fps: i64 = if args.len() > 6 { args[6].parse().unwrap() } else { 25 };
let sample_rate = 48000i32;
let channel_layout = 0x3u64; // stereo
let channels = 2usize;
let start_frame = (start_sec * fps as f64).round() as i64;
let end_frame = (end_sec * fps as f64).round() as i64;
let montage = vec![MontageClip {
filename: media.clone(),
stream_index,
in_time: Rational::new(start_frame, fps),
out_time: Rational::new(end_frame, fps),
media_in: Rational::new(0, 1),
gain: 1.0,
effects: Vec::new(),
}];
let mut pcm: Vec<i16> = Vec::new();
for f in start_frame..end_frame {
let range = TimeRange::new(Rational::new(f, fps), Rational::new(f + 1, fps));
let params = AudioTicketParams {
viewer: 1,
range,
sample_rate,
channel_layout,
montage: montage.clone(),
};
match render_audio_samples(&params) {
Ok(TicketPayload::Audio(samples)) => {
for s in &samples.samples {
pcm.push((s.clamp(-1.0, 1.0) * 32767.0) as i16);
}
}
other => {
eprintln!("frame {f}: render failed: {:?}", other.is_err());
let frames = ((sample_rate as f64) / fps as f64).round() as usize;
pcm.extend(std::iter::repeat(0i16).take(frames * channels));
}
}
}
// Minimal 16-bit PCM WAV.
let data_len = (pcm.len() * 2) as u32;
let mut w = Vec::with_capacity(44 + data_len as usize);
w.extend_from_slice(b"RIFF");
w.extend_from_slice(&(36 + data_len).to_le_bytes());
w.extend_from_slice(b"WAVEfmt ");
w.extend_from_slice(&16u32.to_le_bytes());
w.extend_from_slice(&1u16.to_le_bytes()); // PCM
w.extend_from_slice(&(channels as u16).to_le_bytes());
w.extend_from_slice(&(sample_rate as u32).to_le_bytes());
w.extend_from_slice(&(sample_rate as u32 * channels as u32 * 2).to_le_bytes());
w.extend_from_slice(&(channels as u16 * 2).to_le_bytes());
w.extend_from_slice(&16u16.to_le_bytes());
w.extend_from_slice(b"data");
w.extend_from_slice(&data_len.to_le_bytes());
for s in &pcm {
w.extend_from_slice(&s.to_le_bytes());
}
std::fs::write(out_path, &w).expect("write wav");
println!(
"wrote {} samples ({} ch @ {} Hz) to {}",
pcm.len() / channels,
channels,
sample_rate,
out_path
);
}