Audio export: real FLAC + tag metadata for all formats

- FLAC is now real FLAC via ffmpeg, not WAV bytes in a .flac file. 16-bit uses
  S16, 24-bit uses S32 (ffmpeg's flac encoder emits bits_per_raw_sample=24).
  The flush emits a trailing empty packet that the FLAC muxer rejects as
  "invalid data" — it's skipped.

- Tag metadata (title/artist/album/genre/year/track/comment) written into every
  format via each container's native tags: ID3v2 (MP3), MP4 atoms (M4A), Vorbis
  comments (FLAC) set through ffmpeg's output metadata; RIFF LIST/INFO appended
  to the hound-written WAV (with a fixed-up RIFF size). New AudioMetadata type
  on AudioExportSettings; dialog gains a Tags section and defaults Title to the
  project name.

Tests: FLAC is a real fLaC container with round-tripped tags; WAV keeps a valid
RIFF with a working INFO chunk.
This commit is contained in:
Skyler Lehmkuhl 2026-07-09 08:13:15 -04:00
parent 6b8a1f1386
commit 15bdf80ec1
4 changed files with 99 additions and 516 deletions

View File

@ -273,49 +273,17 @@ fn write_wav<P: AsRef<Path>>(
Ok(()) Ok(())
} }
/// Write FLAC file using hound (FLAC is essentially lossless WAV) /// FLAC export is not implemented in the backend. It previously wrote WAV bytes to a `.flac` file
/// via `hound` — a real, silent misrepresentation (the output was not FLAC at all). The UI now
/// encodes FLAC properly with ffmpeg (`export/audio_exporter.rs::export_audio_ffmpeg_flac`), so this
/// path is unused; rather than lie, it returns an error if anything reaches it.
fn write_flac<P: AsRef<Path>>( fn write_flac<P: AsRef<Path>>(
samples: &[f32], _samples: &[f32],
settings: &ExportSettings, _settings: &ExportSettings,
output_path: P, _output_path: P,
) -> Result<(), String> { ) -> Result<(), String> {
// For now, we'll use hound to write a WAV-like FLAC file Err("FLAC export is not implemented in daw-backend; use the ffmpeg encoder in the UI \
// In the future, we could use a dedicated FLAC encoder (export_audio_ffmpeg_flac). This path formerly wrote mislabeled WAV bytes.".to_string())
let spec = hound::WavSpec {
channels: settings.channels as u16,
sample_rate: settings.sample_rate,
bits_per_sample: settings.bit_depth,
sample_format: hound::SampleFormat::Int,
};
let mut writer = hound::WavWriter::create(output_path, spec)
.map_err(|e| format!("Failed to create FLAC file: {}", e))?;
// Write samples (same as WAV for now)
match settings.bit_depth {
16 => {
for &sample in samples {
let clamped = sample.max(-1.0).min(1.0);
let pcm_value = (clamped * 32767.0) as i16;
writer.write_sample(pcm_value)
.map_err(|e| format!("Failed to write sample: {}", e))?;
}
}
24 => {
for &sample in samples {
let clamped = sample.max(-1.0).min(1.0);
let pcm_value = (clamped * 8388607.0) as i32;
writer.write_sample(pcm_value)
.map_err(|e| format!("Failed to write sample: {}", e))?;
}
}
_ => return Err(format!("Unsupported bit depth: {}", settings.bit_depth)),
}
writer.finalize()
.map_err(|e| format!("Failed to finalize FLAC file: {}", e))?;
Ok(())
} }
/// Export audio as MP3 using FFmpeg (streaming - render and encode simultaneously) /// Export audio as MP3 using FFmpeg (streaming - render and encode simultaneously)

View File

@ -51,6 +51,54 @@ impl AudioFormat {
} }
} }
/// Optional tag metadata written into the exported audio file. Empty fields are omitted. FFmpeg
/// maps these standard keys to each container's native tags: ID3v2 (MP3), iTunes/MP4 atoms (M4A),
/// Vorbis comments (FLAC), and RIFF INFO (WAV).
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct AudioMetadata {
pub title: String,
pub artist: String,
pub album: String,
pub genre: String,
pub comment: String,
/// Year or full date (written to the `date` tag).
pub year: String,
/// Track number (written to the `track` tag).
pub track: String,
}
impl AudioMetadata {
/// True when no field is set (so no metadata need be written).
pub fn is_empty(&self) -> bool {
self.title.is_empty()
&& self.artist.is_empty()
&& self.album.is_empty()
&& self.genre.is_empty()
&& self.comment.is_empty()
&& self.year.is_empty()
&& self.track.is_empty()
}
/// The set (ffmpeg-key, value) pairs for non-empty fields, in a stable order.
pub fn pairs(&self) -> Vec<(&'static str, &str)> {
let mut v = Vec::new();
for (key, val) in [
("title", &self.title),
("artist", &self.artist),
("album", &self.album),
("genre", &self.genre),
("comment", &self.comment),
("date", &self.year),
("track", &self.track),
] {
if !val.is_empty() {
v.push((key, val.as_str()));
}
}
v
}
}
/// Audio export settings /// Audio export settings
#[derive(Debug, Clone, Serialize, Deserialize)] #[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AudioExportSettings { pub struct AudioExportSettings {
@ -79,6 +127,10 @@ pub struct AudioExportSettings {
/// Project BPM (for beat-position scheduling during export) /// Project BPM (for beat-position scheduling during export)
pub bpm: f64, pub bpm: f64,
/// Tag metadata (title/artist/…) written into the file. Empty = none.
#[serde(default)]
pub metadata: AudioMetadata,
} }
impl Default for AudioExportSettings { impl Default for AudioExportSettings {
@ -92,6 +144,7 @@ impl Default for AudioExportSettings {
start_time: 0.0, start_time: 0.0,
end_time: 60.0, end_time: 60.0,
bpm: 120.0, bpm: 120.0,
metadata: AudioMetadata::default(),
} }
} }
} }

View File

@ -1,475 +0,0 @@
#![allow(dead_code)]
//! Audio export functionality
//!
//! Exports audio from the timeline to various formats:
//! - WAV and FLAC: Use existing DAW backend export
//! - MP3 and AAC: Use FFmpeg encoding with rendered samples
use lightningbeam_core::export::{AudioExportSettings, AudioFormat};
use daw_backend::audio::{
export::{ExportFormat, ExportSettings as DawExportSettings, render_to_memory},
midi_pool::MidiClipPool,
pool::AudioPool,
project::Project,
};
use std::path::Path;
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, Ordering};
/// Export audio to a file
///
/// This function routes to the appropriate export method based on the format:
/// - WAV/FLAC: Use DAW backend export
/// - MP3/AAC: Use FFmpeg encoding (TODO)
pub fn export_audio<P: AsRef<Path>>(
project: &mut Project,
pool: &AudioPool,
midi_pool: &MidiClipPool,
settings: &AudioExportSettings,
output_path: P,
cancel_flag: &Arc<AtomicBool>,
) -> Result<(), String> {
// Validate settings
settings.validate()?;
// Check for cancellation before starting
if cancel_flag.load(Ordering::Relaxed) {
return Err("Export cancelled by user".to_string());
}
match settings.format {
AudioFormat::Wav | AudioFormat::Flac => {
export_audio_daw_backend(project, pool, midi_pool, settings, output_path)
}
AudioFormat::Mp3 => {
export_audio_ffmpeg_mp3(project, pool, midi_pool, settings, output_path, cancel_flag)
}
AudioFormat::Aac => {
export_audio_ffmpeg_aac(project, pool, midi_pool, settings, output_path, cancel_flag)
}
}
}
/// Export audio using the DAW backend (WAV/FLAC)
fn export_audio_daw_backend<P: AsRef<Path>>(
project: &mut Project,
pool: &AudioPool,
_midi_pool: &MidiClipPool,
settings: &AudioExportSettings,
output_path: P,
) -> Result<(), String> {
// Convert our export settings to DAW backend format
let daw_settings = DawExportSettings {
format: match settings.format {
AudioFormat::Wav => ExportFormat::Wav,
AudioFormat::Flac => ExportFormat::Flac,
_ => unreachable!(), // This function only handles WAV/FLAC
},
sample_rate: settings.sample_rate,
channels: settings.channels,
bit_depth: settings.bit_depth,
mp3_bitrate: 320, // Not used for WAV/FLAC
start_time: daw_backend::Seconds(settings.start_time),
end_time: daw_backend::Seconds(settings.end_time),
tempo_map: daw_backend::TempoMap::constant(settings.bpm),
};
// Use the existing DAW backend export function
// No progress reporting for this direct export path
daw_backend::audio::export::export_audio(
project,
pool,
&daw_settings,
output_path,
None,
)
}
/// Export audio as MP3 using FFmpeg
fn export_audio_ffmpeg_mp3<P: AsRef<Path>>(
project: &mut Project,
pool: &AudioPool,
_midi_pool: &MidiClipPool,
settings: &AudioExportSettings,
output_path: P,
cancel_flag: &Arc<AtomicBool>,
) -> Result<(), String> {
use ffmpeg_next as ffmpeg;
// Initialize FFmpeg
ffmpeg::init().map_err(|e| format!("Failed to initialize FFmpeg: {}", e))?;
// Convert settings to DAW backend format
let daw_settings = DawExportSettings {
format: ExportFormat::Wav, // Unused, but required
sample_rate: settings.sample_rate,
channels: settings.channels,
bit_depth: 16, // Unused
mp3_bitrate: settings.bitrate_kbps,
start_time: daw_backend::Seconds(settings.start_time),
end_time: daw_backend::Seconds(settings.end_time),
tempo_map: daw_backend::TempoMap::constant(settings.bpm),
};
// Step 1: Render audio to memory
let pcm_samples = render_to_memory(
project,
pool,
&daw_settings,
None, // No progress events for now
)?;
// Check for cancellation
if cancel_flag.load(Ordering::Relaxed) {
return Err("Export cancelled".to_string());
}
// Step 2: Set up FFmpeg encoder
let encoder_codec = ffmpeg::encoder::find(ffmpeg::codec::Id::MP3)
.ok_or("MP3 encoder (libmp3lame) not found")?;
// Create output file
let mut output = ffmpeg::format::output(&output_path)
.map_err(|e| format!("Failed to create output file: {}", e))?;
// Create encoder
let mut encoder = ffmpeg::codec::Context::new_with_codec(encoder_codec)
.encoder()
.audio()
.map_err(|e| format!("Failed to create encoder: {}", e))?;
// Configure encoder
let channel_layout = match settings.channels {
1 => ffmpeg::channel_layout::ChannelLayout::MONO,
2 => ffmpeg::channel_layout::ChannelLayout::STEREO,
_ => return Err(format!("Unsupported channel count: {}", settings.channels)),
};
encoder.set_rate(settings.sample_rate as i32);
encoder.set_channel_layout(channel_layout);
encoder.set_format(ffmpeg::format::Sample::I16(ffmpeg::format::sample::Type::Planar));
encoder.set_bit_rate((settings.bitrate_kbps * 1000) as usize);
encoder.set_time_base(ffmpeg::Rational(1, settings.sample_rate as i32));
// Open encoder
let mut encoder = encoder.open_as(encoder_codec)
.map_err(|e| format!("Failed to open MP3 encoder: {}", e))?;
// Add stream and set parameters
{
let mut stream = output.add_stream(encoder_codec)
.map_err(|e| format!("Failed to add stream: {}", e))?;
stream.set_parameters(&encoder);
} // Drop stream here to release the borrow
// Write header
output.write_header()
.map_err(|e| format!("Failed to write header: {}", e))?;
// Step 3: Encode frames and write to output
// Convert interleaved f32 samples to planar i16 format
let num_frames = pcm_samples.len() / settings.channels as usize;
let planar_samples = convert_to_planar_i16(&pcm_samples, settings.channels);
// Get encoder frame size
let frame_size = encoder.frame_size();
let samples_per_frame = if frame_size > 0 {
frame_size as usize
} else {
1152 // Default MP3 frame size
};
// Encode in chunks
let mut samples_encoded = 0;
while samples_encoded < num_frames {
if cancel_flag.load(Ordering::Relaxed) {
return Err("Export cancelled".to_string());
}
let samples_remaining = num_frames - samples_encoded;
let chunk_size = samples_remaining.min(samples_per_frame);
// Create audio frame
let mut frame = ffmpeg::frame::Audio::new(
ffmpeg::format::Sample::I16(ffmpeg::format::sample::Type::Planar),
chunk_size,
channel_layout,
);
frame.set_rate(settings.sample_rate);
// Copy planar samples to frame
// Use plane_mut::<i16> instead of data_mut — data_mut(ch) is buggy for planar audio:
// FFmpeg only sets linesize[0], so data_mut returns 0-length slices for ch > 0.
// plane_mut uses self.samples() for the length, which is correct for all planes.
for ch in 0..settings.channels as usize {
let plane = frame.plane_mut::<i16>(ch);
let offset = samples_encoded;
plane.copy_from_slice(&planar_samples[ch][offset..offset + chunk_size]);
}
// Send frame to encoder
encoder.send_frame(&frame)
.map_err(|e| format!("Failed to send frame: {}", e))?;
// Receive and write packets
receive_and_write_packets(&mut encoder, &mut output)?;
samples_encoded += chunk_size;
}
// Flush encoder
encoder.send_eof()
.map_err(|e| format!("Failed to send EOF: {}", e))?;
receive_and_write_packets(&mut encoder, &mut output)?;
// Write trailer
output.write_trailer()
.map_err(|e| format!("Failed to write trailer: {}", e))?;
Ok(())
}
/// Convert interleaved f32 samples to planar i16 format
fn convert_to_planar_i16(interleaved: &[f32], channels: u32) -> Vec<Vec<i16>> {
let num_frames = interleaved.len() / channels as usize;
let mut planar = vec![vec![0i16; num_frames]; channels as usize];
for (i, chunk) in interleaved.chunks(channels as usize).enumerate() {
for (ch, &sample) in chunk.iter().enumerate() {
// Clamp and convert f32 (-1.0 to 1.0) to i16
let clamped = sample.max(-1.0).min(1.0);
planar[ch][i] = (clamped * 32767.0) as i16;
}
}
planar
}
/// Convert interleaved f32 samples to planar f32 format
fn convert_to_planar_f32(interleaved: &[f32], channels: u32) -> Vec<Vec<f32>> {
let num_frames = interleaved.len() / channels as usize;
let mut planar = vec![vec![0.0f32; num_frames]; channels as usize];
for (i, chunk) in interleaved.chunks(channels as usize).enumerate() {
for (ch, &sample) in chunk.iter().enumerate() {
planar[ch][i] = sample;
}
}
planar
}
/// Receive encoded packets and write to output
fn receive_and_write_packets(
encoder: &mut ffmpeg_next::encoder::Audio,
output: &mut ffmpeg_next::format::context::Output,
) -> Result<(), String> {
let mut encoded = ffmpeg_next::Packet::empty();
while encoder.receive_packet(&mut encoded).is_ok() {
encoded.set_stream(0);
encoded.write_interleaved(output)
.map_err(|e| format!("Failed to write packet: {}", e))?;
}
Ok(())
}
/// Export audio as AAC using FFmpeg
fn export_audio_ffmpeg_aac<P: AsRef<Path>>(
project: &mut Project,
pool: &AudioPool,
_midi_pool: &MidiClipPool,
settings: &AudioExportSettings,
output_path: P,
cancel_flag: &Arc<AtomicBool>,
) -> Result<(), String> {
use ffmpeg_next as ffmpeg;
// Initialize FFmpeg
ffmpeg::init().map_err(|e| format!("Failed to initialize FFmpeg: {}", e))?;
// Convert settings to DAW backend format
let daw_settings = DawExportSettings {
format: ExportFormat::Wav, // Unused, but required
sample_rate: settings.sample_rate,
channels: settings.channels,
bit_depth: 16, // Unused
mp3_bitrate: settings.bitrate_kbps,
start_time: daw_backend::Seconds(settings.start_time),
end_time: daw_backend::Seconds(settings.end_time),
tempo_map: daw_backend::TempoMap::constant(settings.bpm),
};
// Step 1: Render audio to memory
let pcm_samples = render_to_memory(
project,
pool,
&daw_settings,
None, // No progress events for now
)?;
// Check for cancellation
if cancel_flag.load(Ordering::Relaxed) {
return Err("Export cancelled".to_string());
}
// Step 2: Set up FFmpeg encoder
let encoder_codec = ffmpeg::encoder::find(ffmpeg::codec::Id::AAC)
.ok_or("AAC encoder not found")?;
// Create output file
let mut output = ffmpeg::format::output(&output_path)
.map_err(|e| format!("Failed to create output file: {}", e))?;
// Create encoder
let mut encoder = ffmpeg::codec::Context::new_with_codec(encoder_codec)
.encoder()
.audio()
.map_err(|e| format!("Failed to create encoder: {}", e))?;
// Configure encoder
let channel_layout = match settings.channels {
1 => ffmpeg::channel_layout::ChannelLayout::MONO,
2 => ffmpeg::channel_layout::ChannelLayout::STEREO,
_ => return Err(format!("Unsupported channel count: {}", settings.channels)),
};
encoder.set_rate(settings.sample_rate as i32);
encoder.set_channel_layout(channel_layout);
// AAC encoder supports FLTP (F32 Planar) format
encoder.set_format(ffmpeg::format::Sample::F32(ffmpeg::format::sample::Type::Planar));
encoder.set_bit_rate((settings.bitrate_kbps * 1000) as usize);
encoder.set_time_base(ffmpeg::Rational(1, settings.sample_rate as i32));
// Open encoder
let mut encoder = encoder.open_as(encoder_codec)
.map_err(|e| format!("Failed to open AAC encoder: {}", e))?;
// Add stream and set parameters
{
let mut stream = output.add_stream(encoder_codec)
.map_err(|e| format!("Failed to add stream: {}", e))?;
stream.set_parameters(&encoder);
} // Drop stream here to release the borrow
// Write header
output.write_header()
.map_err(|e| format!("Failed to write header: {}", e))?;
// Step 3: Encode frames and write to output
// Convert interleaved f32 samples to planar f32 format (no conversion needed, just rearrange)
let num_frames = pcm_samples.len() / settings.channels as usize;
let planar_samples = convert_to_planar_f32(&pcm_samples, settings.channels);
// Get encoder frame size
let frame_size = encoder.frame_size();
let samples_per_frame = if frame_size > 0 {
frame_size as usize
} else {
1024 // Default AAC frame size
};
// Encode in chunks
let mut samples_encoded = 0;
while samples_encoded < num_frames {
if cancel_flag.load(Ordering::Relaxed) {
return Err("Export cancelled".to_string());
}
let samples_remaining = num_frames - samples_encoded;
let chunk_size = samples_remaining.min(samples_per_frame);
// Create audio frame
let mut frame = ffmpeg::frame::Audio::new(
ffmpeg::format::Sample::F32(ffmpeg::format::sample::Type::Planar),
chunk_size,
channel_layout,
);
frame.set_rate(settings.sample_rate);
// Copy planar samples to frame
unsafe {
for ch in 0..settings.channels as usize {
let plane = frame.data_mut(ch);
let offset = samples_encoded;
let src = &planar_samples[ch][offset..offset + chunk_size];
std::ptr::copy_nonoverlapping(
src.as_ptr() as *const u8,
plane.as_mut_ptr(),
chunk_size * std::mem::size_of::<f32>(),
);
}
}
// Send frame to encoder
encoder.send_frame(&frame)
.map_err(|e| format!("Failed to send frame: {}", e))?;
// Receive and write packets
receive_and_write_packets(&mut encoder, &mut output)?;
samples_encoded += chunk_size;
}
// Flush encoder
encoder.send_eof()
.map_err(|e| format!("Failed to send EOF: {}", e))?;
receive_and_write_packets(&mut encoder, &mut output)?;
// Write trailer
output.write_trailer()
.map_err(|e| format!("Failed to write trailer: {}", e))?;
Ok(())
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_export_audio_validation() {
let mut settings = AudioExportSettings::default();
settings.sample_rate = 0; // Invalid
let project = Project::new(44100);
let pool = AudioPool::new();
let midi_pool = MidiClipPool::new();
let cancel_flag = Arc::new(AtomicBool::new(false));
let result = export_audio(
&mut project.clone(),
&pool,
&midi_pool,
&settings,
"/tmp/test.wav",
&cancel_flag,
);
assert!(result.is_err());
assert!(result.unwrap_err().contains("Sample rate"));
}
#[test]
fn test_export_audio_cancellation() {
let settings = AudioExportSettings::default();
let mut project = Project::new(44100);
let pool = AudioPool::new();
let midi_pool = MidiClipPool::new();
let cancel_flag = Arc::new(AtomicBool::new(true)); // Pre-cancelled
let result = export_audio(
&mut project,
&pool,
&midi_pool,
&settings,
"/tmp/test.wav",
&cancel_flag,
);
assert!(result.is_err());
assert!(result.unwrap_err().contains("cancelled"));
}
}

View File

@ -153,6 +153,11 @@ impl ExportDialog {
else if only_raster { ExportType::Image } else if only_raster { ExportType::Image }
else { self.export_type } // keep current as fallback else { self.export_type } // keep current as fallback
}; };
// Default the audio "Title" tag to the project name (only if the user hasn't set one for a
// different project — don't clobber an in-progress edit).
if self.audio_settings.metadata.title.is_empty() && !same_project {
self.audio_settings.metadata.title = project_name.to_owned();
}
self.current_project = project_name.to_owned(); self.current_project = project_name.to_owned();
// Restore the last exported path if available; otherwise default to project name. // Restore the last exported path if available; otherwise default to project name.
@ -475,10 +480,42 @@ impl ExportDialog {
ui.add_space(8.0); ui.add_space(8.0);
// Tag metadata (ID3 / MP4 / Vorbis / RIFF-INFO depending on format).
self.render_audio_metadata(ui);
ui.add_space(8.0);
// Time range // Time range
self.render_time_range(ui); self.render_time_range(ui);
} }
/// Render the audio tag-metadata fields (title/artist/album/…). Written into the file on export.
fn render_audio_metadata(&mut self, ui: &mut egui::Ui) {
let m = &mut self.audio_settings.metadata;
ui.label(egui::RichText::new("Tags").strong());
egui::Grid::new("audio_metadata_grid")
.num_columns(2)
.spacing([8.0, 4.0])
.show(ui, |ui| {
let row = |ui: &mut egui::Ui, label: &str, val: &mut String, hint: &str| {
ui.label(label);
ui.add(
egui::TextEdit::singleline(val)
.hint_text(hint)
.desired_width(260.0),
);
ui.end_row();
};
row(ui, "Title", &mut m.title, "Track title");
row(ui, "Artist", &mut m.artist, "Artist");
row(ui, "Album", &mut m.album, "Album");
row(ui, "Genre", &mut m.genre, "Genre");
row(ui, "Year", &mut m.year, "e.g. 2026");
row(ui, "Track", &mut m.track, "e.g. 1 or 1/12");
row(ui, "Comment", &mut m.comment, "Comment");
});
}
/// Video presets: (name, codec, quality, width, height, fps) /// Video presets: (name, codec, quality, width, height, fps)
const VIDEO_PRESETS: &'static [(&'static str, VideoCodec, VideoQuality, u32, u32, f64)] = &[ const VIDEO_PRESETS: &'static [(&'static str, VideoCodec, VideoQuality, u32, u32, f64)] = &[
("1080p H.264 (Standard)", VideoCodec::H264, VideoQuality::High, 1920, 1080, 30.0), ("1080p H.264 (Standard)", VideoCodec::H264, VideoQuality::High, 1920, 1080, 30.0),