mp3 and aac export

daw-backend/Cargo.toml

@@ -18,8 +18,7 @@ pathdiff = "0.2"
 
 # Audio export
 hound = "3.5"
-# TODO: Add MP3 support with a different crate
-# mp3lame-encoder API is too complex, need to find a better option
+ffmpeg-next = "8.0"  # For MP3/AAC encoding
 
 # Node-based audio graph dependencies
 dasp_graph = "0.11"

daw-backend/src/audio/export.rs

@@ -10,7 +10,8 @@ use std::path::Path;
 pub enum ExportFormat {
     Wav,
     Flac,
-    // TODO: Add MP3 support
+    Mp3,
+    Aac,
 }
 
 impl ExportFormat {
@@ -19,6 +20,8 @@ impl ExportFormat {
         match self {
             ExportFormat::Wav => "wav",
             ExportFormat::Flac => "flac",
+            ExportFormat::Mp3 => "mp3",
+            ExportFormat::Aac => "m4a",
         }
     }
 }
@@ -72,13 +75,23 @@ pub fn export_audio<P: AsRef<Path>>(
     mut event_tx: Option<&mut rtrb::Producer<AudioEvent>>,
 ) -> Result<(), String>
 {
-    // Render the project to memory
+    // Route to appropriate export implementation based on format
+    match settings.format {
+        ExportFormat::Wav | ExportFormat::Flac => {
+            // Render to memory then write (existing path)
             let samples = render_to_memory(project, pool, midi_pool, settings, event_tx)?;
-
-    // Write to file based on format
             match settings.format {
                 ExportFormat::Wav => write_wav(&samples, settings, output_path)?,
                 ExportFormat::Flac => write_flac(&samples, settings, output_path)?,
+                _ => unreachable!(),
+            }
+        }
+        ExportFormat::Mp3 => {
+            export_mp3(project, pool, midi_pool, settings, output_path, event_tx)?;
+        }
+        ExportFormat::Aac => {
+            export_aac(project, pool, midi_pool, settings, output_path, event_tx)?;
+        }
     }
 
     Ok(())
@@ -270,7 +283,319 @@ fn write_flac<P: AsRef<Path>>(
     Ok(())
 }
 
-// TODO: Add MP3 export support with a better library
+/// Export audio as MP3 using FFmpeg
+fn export_mp3<P: AsRef<Path>>(
+    project: &mut Project,
+    pool: &AudioPool,
+    midi_pool: &MidiClipPool,
+    settings: &ExportSettings,
+    output_path: P,
+    mut event_tx: Option<&mut rtrb::Producer<AudioEvent>>,
+) -> Result<(), String> {
+    use std::sync::atomic::{AtomicBool, Ordering};
+    use std::sync::Arc;
+
+    // FFmpeg encoding doesn't support cancellation in this implementation
+    let cancel_flag = Arc::new(AtomicBool::new(false));
+
+    // Initialize FFmpeg
+    ffmpeg_next::init().map_err(|e| format!("Failed to initialize FFmpeg: {}", e))?;
+
+    // Step 1: Render audio to memory
+    let pcm_samples = render_to_memory(project, pool, midi_pool, settings, event_tx)?;
+
+    // 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_next::encoder::find(ffmpeg_next::codec::Id::MP3)
+        .ok_or("MP3 encoder (libmp3lame) not found")?;
+
+    // Create output file
+    let mut output = ffmpeg_next::format::output(&output_path)
+        .map_err(|e| format!("Failed to create output file: {}", e))?;
+
+    // Create encoder
+    let mut encoder = ffmpeg_next::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_next::channel_layout::ChannelLayout::MONO,
+        2 => ffmpeg_next::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_next::format::Sample::I16(ffmpeg_next::format::sample::Type::Planar));
+    encoder.set_bit_rate((settings.mp3_bitrate * 1000) as usize);
+    encoder.set_time_base(ffmpeg_next::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);
+    }
+
+    // Write header
+    output.write_header()
+        .map_err(|e| format!("Failed to write header: {}", e))?;
+
+    // Step 3: Encode frames and write to output
+    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_next::frame::Audio::new(
+            ffmpeg_next::format::Sample::I16(ffmpeg_next::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::<i16>(),
+                );
+            }
+        }
+
+        // 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(())
+}
+
+/// Export audio as AAC using FFmpeg
+fn export_aac<P: AsRef<Path>>(
+    project: &mut Project,
+    pool: &AudioPool,
+    midi_pool: &MidiClipPool,
+    settings: &ExportSettings,
+    output_path: P,
+    mut event_tx: Option<&mut rtrb::Producer<AudioEvent>>,
+) -> Result<(), String> {
+    use std::sync::atomic::{AtomicBool, Ordering};
+    use std::sync::Arc;
+
+    let cancel_flag = Arc::new(AtomicBool::new(false));
+
+    // Initialize FFmpeg
+    ffmpeg_next::init().map_err(|e| format!("Failed to initialize FFmpeg: {}", e))?;
+
+    // Step 1: Render audio to memory
+    let pcm_samples = render_to_memory(project, pool, midi_pool, settings, event_tx)?;
+
+    // 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_next::encoder::find(ffmpeg_next::codec::Id::AAC)
+        .ok_or("AAC encoder not found")?;
+
+    // Create output file
+    let mut output = ffmpeg_next::format::output(&output_path)
+        .map_err(|e| format!("Failed to create output file: {}", e))?;
+
+    // Create encoder
+    let mut encoder = ffmpeg_next::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_next::channel_layout::ChannelLayout::MONO,
+        2 => ffmpeg_next::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_next::format::Sample::F32(ffmpeg_next::format::sample::Type::Planar));
+    encoder.set_bit_rate((settings.mp3_bitrate * 1000) as usize);
+    encoder.set_time_base(ffmpeg_next::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);
+    }
+
+    // Write header
+    output.write_header()
+        .map_err(|e| format!("Failed to write header: {}", e))?;
+
+    // Step 3: Encode frames and write to output
+    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_next::frame::Audio::new(
+            ffmpeg_next::format::Sample::F32(ffmpeg_next::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(())
+}
+
+/// 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() {
+            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(())
+}
 
 #[cfg(test)]
 mod tests {

lightningbeam-ui/lightningbeam-core/Cargo.toml

@@ -24,7 +24,7 @@ uuid = { version = "1.0", features = ["v4", "serde"] }
 daw-backend = { path = "../../daw-backend" }
 
 # Video decoding
-ffmpeg-next = "7.0"
+ffmpeg-next = "8.0"
 lru = "0.12"
 
 # File I/O

lightningbeam-ui/lightningbeam-editor/Cargo.toml

@@ -8,7 +8,7 @@ lightningbeam-core = { path = "../lightningbeam-core" }
 daw-backend = { path = "../../daw-backend" }
 rtrb = "0.3"
 cpal = "0.15"
-ffmpeg-next = "7.0"
+ffmpeg-next = "8.0"
 
 # UI Framework
 eframe = { workspace = true }

lightningbeam-ui/lightningbeam-editor/examples/ffmpeg_test.rs

@@ -0,0 +1,413 @@
+/// Minimal test program to validate FFmpeg audio encoding workflow
+///
+/// This program tests encoding raw PCM samples to MP3 using ffmpeg-next.
+/// Run with: cargo run --example ffmpeg_test
+
+use std::path::Path;
+
+fn main() -> Result<(), String> {
+    println!("Testing FFmpeg audio encoding...");
+
+    // Initialize FFmpeg
+    ffmpeg_next::init().map_err(|e| format!("Failed to initialize FFmpeg: {}", e))?;
+
+    // Test 1: List available encoders
+    println!("\nAvailable MP3 encoders:");
+    if let Some(encoder) = ffmpeg_next::encoder::find(ffmpeg_next::codec::Id::MP3) {
+        println!("  - Found MP3 encoder: {}", encoder.name());
+    } else {
+        println!("  - No MP3 encoder found!");
+    }
+
+    println!("\nAvailable AAC encoders:");
+    if let Some(encoder) = ffmpeg_next::encoder::find(ffmpeg_next::codec::Id::AAC) {
+        println!("  - Found AAC encoder: {}", encoder.name());
+    } else {
+        println!("  - No AAC encoder found!");
+    }
+
+    // Test 2: Create a simple MP3 encoder and encode silence
+    test_mp3_encoding()?;
+
+    // Test 3: Create a simple AAC encoder and encode silence
+    test_aac_encoding()?;
+
+    println!("\n✅ All tests passed!");
+    Ok(())
+}
+
+fn test_mp3_encoding() -> Result<(), String> {
+    println!("\nTest: Encoding 1 second of silence to MP3...");
+
+    // Output file
+    let output_path = "/tmp/test_silence.mp3";
+
+    // Generate 1 second of stereo silence at 44.1 kHz
+    let sample_rate = 44100;
+    let channels = 2;
+    let duration_secs = 1.0;
+    let num_samples = (sample_rate as f64 * duration_secs * channels as f64) as usize;
+    let pcm_samples: Vec<f32> = vec![0.0; num_samples]; // Silence
+
+    println!("  Generated {} PCM samples ({}Hz, {} channels, {:.1}s)",
+             num_samples, sample_rate, channels, duration_secs);
+
+    // Encode to MP3
+    encode_pcm_to_mp3(&pcm_samples, sample_rate, channels, 320, output_path)?;
+
+    // Check output file exists
+    if Path::new(output_path).exists() {
+        let metadata = std::fs::metadata(output_path).unwrap();
+        println!("  ✅ Created MP3 file: {} ({} bytes)", output_path, metadata.len());
+    } else {
+        return Err("MP3 file was not created!".to_string());
+    }
+
+    Ok(())
+}
+
+fn test_aac_encoding() -> Result<(), String> {
+    println!("\nTest: Encoding 1 second of silence to AAC...");
+
+    // Output file
+    let output_path = "/tmp/test_silence.m4a";
+
+    // Generate 1 second of stereo silence at 44.1 kHz
+    let sample_rate = 44100;
+    let channels = 2;
+    let duration_secs = 1.0;
+    let num_samples = (sample_rate as f64 * duration_secs * channels as f64) as usize;
+    let pcm_samples: Vec<f32> = vec![0.0; num_samples]; // Silence
+
+    println!("  Generated {} PCM samples ({}Hz, {} channels, {:.1}s)",
+             num_samples, sample_rate, channels, duration_secs);
+
+    // Encode to AAC
+    encode_pcm_to_aac(&pcm_samples, sample_rate, channels, 192, output_path)?;
+
+    // Check output file exists
+    if Path::new(output_path).exists() {
+        let metadata = std::fs::metadata(output_path).unwrap();
+        println!("  ✅ Created AAC file: {} ({} bytes)", output_path, metadata.len());
+    } else {
+        return Err("AAC file was not created!".to_string());
+    }
+
+    Ok(())
+}
+
+/// Encode raw PCM samples to MP3 using ffmpeg-next
+fn encode_pcm_to_mp3(
+    samples: &[f32],
+    sample_rate: u32,
+    channels: u32,
+    bitrate_kbps: u32,
+    output_path: &str,
+) -> Result<(), String> {
+    use ffmpeg_next as ffmpeg;
+
+    // Find MP3 encoder
+    let encoder_codec = ffmpeg::encoder::find(ffmpeg::codec::Id::MP3)
+        .ok_or("MP3 encoder not found")?;
+
+    println!("  Using encoder: {}", encoder_codec.name());
+
+    // Create output format context FIRST (like transcode example)
+    let mut output = ffmpeg::format::output(&output_path)
+        .map_err(|e| format!("Failed to create output file: {}", e))?;
+
+    // Don't use stream parameters - create encoder directly
+    // The stream was just added but has no parameters set yet
+    let mut encoder = ffmpeg::codec::Context::new_with_codec(encoder_codec)
+        .encoder()
+        .audio()
+        .map_err(|e| format!("Failed to create encoder: {}", e))?;
+
+    println!("  Created encoder directly from codec");
+
+    // Determine channel layout first
+    let channel_layout = match channels {
+        1 => ffmpeg::channel_layout::ChannelLayout::MONO,
+        2 => ffmpeg::channel_layout::ChannelLayout::STEREO,
+        _ => return Err(format!("Unsupported channel count: {}", channels)),
+    };
+
+    // Configure encoder with explicit format (required in ffmpeg-next 8.0)
+    encoder.set_rate(sample_rate as i32);
+    encoder.set_channel_layout(channel_layout);
+
+    // Set format to S16 Planar (s16p) which libmp3lame supports
+    use ffmpeg_next::format::sample::Type;
+    use ffmpeg_next::format::Sample;
+    encoder.set_format(Sample::I16(Type::Planar));
+
+    encoder.set_bit_rate((bitrate_kbps * 1000) as usize);
+    encoder.set_time_base(ffmpeg::Rational(1, sample_rate as i32));
+
+    println!("  Encoder configured: {}Hz, {} channels, {} kbps",
+             sample_rate, channels, bitrate_kbps);
+    println!("  Format before open: {:?}", encoder.format());
+
+    // Open encoder (like transcode-audio example)
+    let mut encoder = encoder.open_as(encoder_codec)
+        .map_err(|e| format!("Failed to open encoder: {}", e))?;
+
+    println!("  ✅ Encoder opened successfully!");
+    println!("  Opened encoder format: {:?}", encoder.format());
+
+    // Now add stream and set its parameters from the opened encoder
+    let mut stream = output.add_stream(encoder_codec)
+        .map_err(|e| format!("Failed to add stream: {}", e))?;
+    stream.set_parameters(&encoder);
+
+    // Write header
+    output.write_header()
+        .map_err(|e| format!("Failed to write header: {}", e))?;
+
+    println!("  Encoding {} samples...", samples.len());
+
+    // Convert interleaved f32 to planar i16
+    let num_frames = samples.len() / channels as usize;
+    let planar_samples = convert_to_planar_i16(samples, 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
+    };
+
+    println!("  Frame size: {} samples", samples_per_frame);
+
+    // Encode in chunks
+    let mut samples_encoded = 0;
+    while samples_encoded < num_frames {
+        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(sample_rate);
+
+        // Copy planar samples to frame
+        unsafe {
+            for ch in 0..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::<i16>(),
+                );
+            }
+        }
+
+        // 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))?;
+
+    println!("  Encoding complete - {} frames encoded", num_frames);
+
+    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
+}
+
+/// 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(())
+}
+
+/// Encode raw PCM samples to AAC using ffmpeg-next
+fn encode_pcm_to_aac(
+    samples: &[f32],
+    sample_rate: u32,
+    channels: u32,
+    bitrate_kbps: u32,
+    output_path: &str,
+) -> Result<(), String> {
+    use ffmpeg_next as ffmpeg;
+
+    // Find AAC encoder
+    let encoder_codec = ffmpeg::encoder::find(ffmpeg::codec::Id::AAC)
+        .ok_or("AAC encoder not found")?;
+
+    println!("  Using encoder: {}", encoder_codec.name());
+
+    // Create output format context
+    let mut output = ffmpeg::format::output(&output_path)
+        .map_err(|e| format!("Failed to create output file: {}", e))?;
+
+    // Create encoder directly from codec
+    let mut encoder = ffmpeg::codec::Context::new_with_codec(encoder_codec)
+        .encoder()
+        .audio()
+        .map_err(|e| format!("Failed to create encoder: {}", e))?;
+
+    println!("  Created encoder directly from codec");
+
+    // Determine channel layout
+    let channel_layout = match channels {
+        1 => ffmpeg::channel_layout::ChannelLayout::MONO,
+        2 => ffmpeg::channel_layout::ChannelLayout::STEREO,
+        _ => return Err(format!("Unsupported channel count: {}", channels)),
+    };
+
+    // Configure encoder - AAC supports F32 Planar (fltp)
+    encoder.set_rate(sample_rate as i32);
+    encoder.set_channel_layout(channel_layout);
+    encoder.set_format(ffmpeg::format::Sample::F32(ffmpeg::format::sample::Type::Planar));
+    encoder.set_bit_rate((bitrate_kbps * 1000) as usize);
+    encoder.set_time_base(ffmpeg::Rational(1, sample_rate as i32));
+
+    println!("  Encoder configured: {}Hz, {} channels, {} kbps",
+             sample_rate, channels, bitrate_kbps);
+    println!("  Format before open: {:?}", encoder.format());
+
+    // Open encoder
+    let mut encoder = encoder.open_as(encoder_codec)
+        .map_err(|e| format!("Failed to open encoder: {}", e))?;
+
+    println!("  ✅ Encoder opened successfully!");
+    println!("  Opened encoder format: {:?}", encoder.format());
+
+    // 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);
+    }
+
+    // Write header
+    output.write_header()
+        .map_err(|e| format!("Failed to write header: {}", e))?;
+
+    println!("  Encoding {} samples...", samples.len());
+
+    // Convert interleaved f32 to planar f32
+    let num_frames = samples.len() / channels as usize;
+    let planar_samples = convert_to_planar_f32(samples, 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
+    };
+
+    println!("  Frame size: {} samples", samples_per_frame);
+
+    // Encode in chunks
+    let mut samples_encoded = 0;
+    while samples_encoded < num_frames {
+        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(sample_rate);
+
+        // Copy planar samples to frame
+        unsafe {
+            for ch in 0..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))?;
+
+    println!("  Encoding complete - {} frames encoded", num_frames);
+
+    Ok(())
+}
+
+/// 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
+}

lightningbeam-ui/lightningbeam-editor/src/export/audio_exporter.rs

@@ -86,32 +86,347 @@ fn export_audio_daw_backend<P: AsRef<Path>>(
 
 /// 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>,
+    project: &mut Project,
+    pool: &AudioPool,
+    midi_pool: &MidiClipPool,
+    settings: &AudioExportSettings,
+    output_path: P,
+    cancel_flag: &Arc<AtomicBool>,
 ) -> Result<(), String> {
-    // TODO: Implement MP3 export using FFmpeg
-    // The FFmpeg encoder API is complex and needs more investigation
-    // For now, users can export as WAV or FLAC (both fully working)
-    Err("MP3 export is not yet implemented. Please use WAV or FLAC format for now, or export as WAV and convert using an external tool.".to_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: settings.start_time,
+        end_time: settings.end_time,
+    };
+
+    // Step 1: Render audio to memory
+    let pcm_samples = render_to_memory(
+        project,
+        pool,
+        midi_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 mut 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
+        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::<i16>(),
+                );
+            }
+        }
+
+        // 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>,
+    project: &mut Project,
+    pool: &AudioPool,
+    midi_pool: &MidiClipPool,
+    settings: &AudioExportSettings,
+    output_path: P,
+    cancel_flag: &Arc<AtomicBool>,
 ) -> Result<(), String> {
-    // TODO: Implement AAC export using FFmpeg
-    // The FFmpeg encoder API is complex and needs more investigation
-    // For now, users can export as WAV or FLAC (both fully working)
-    Err("AAC export is not yet implemented. Please use WAV or FLAC format for now, or export as WAV and convert using an external tool.".to_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: settings.start_time,
+        end_time: settings.end_time,
+    };
+
+    // Step 1: Render audio to memory
+    let pcm_samples = render_to_memory(
+        project,
+        pool,
+        midi_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)]

lightningbeam-ui/lightningbeam-editor/src/export/mod.rs

@@ -142,79 +142,33 @@ impl ExportOrchestrator {
             return;
         }
 
+        println!("🧵 [EXPORT THREAD] Starting export for format: {:?}", settings.format);
+
         // Convert settings to DAW backend format
         let daw_settings = daw_backend::audio::ExportSettings {
             format: match settings.format {
                 lightningbeam_core::export::AudioFormat::Wav => daw_backend::audio::ExportFormat::Wav,
                 lightningbeam_core::export::AudioFormat::Flac => daw_backend::audio::ExportFormat::Flac,
-                lightningbeam_core::export::AudioFormat::Mp3 |
-                lightningbeam_core::export::AudioFormat::Aac => {
-                    // MP3/AAC not supported yet
-                    progress_tx
-                        .send(ExportProgress::Error {
-                            message: format!("{} export not yet implemented. Please use WAV or FLAC format.", settings.format.name()),
-                        })
-                        .ok();
-                    return;
-                }
+                lightningbeam_core::export::AudioFormat::Mp3 => daw_backend::audio::ExportFormat::Mp3,
+                lightningbeam_core::export::AudioFormat::Aac => daw_backend::audio::ExportFormat::Aac,
             },
             sample_rate: settings.sample_rate,
             channels: settings.channels,
             bit_depth: settings.bit_depth,
-            mp3_bitrate: 320, // Not used for WAV/FLAC
+            mp3_bitrate: settings.bitrate_kbps,
             start_time: settings.start_time,
             end_time: settings.end_time,
         };
 
-        println!("🧵 [EXPORT THREAD] Starting non-blocking export...");
+        // Use DAW backend export for all formats
+        let result = Self::run_daw_backend_export(
+            &daw_settings,
+            &output_path,
+            &audio_controller,
+            &cancel_flag,
+        );
 
-        // Start the export (non-blocking - just sends the query)
-        {
-            let mut controller = audio_controller.lock().unwrap();
-            println!("🧵 [EXPORT THREAD] Sending export query...");
-            if let Err(e) = controller.start_export_audio(&daw_settings, &output_path) {
-                println!("🧵 [EXPORT THREAD] Failed to start export: {}", e);
-                progress_tx.send(ExportProgress::Error { message: e }).ok();
-                return;
-            }
-            println!("🧵 [EXPORT THREAD] Export query sent, lock released");
-        }
-
-        // Poll for completion without holding the lock for extended periods
-        let duration = settings.end_time - settings.start_time;
-        let start_time = std::time::Instant::now();
-        let result = loop {
-            if cancel_flag.load(Ordering::Relaxed) {
-                break Err("Export cancelled by user".to_string());
-            }
-
-            // Sleep before polling to avoid spinning
-            std::thread::sleep(std::time::Duration::from_millis(100));
-
-            // Brief lock to poll for completion
-            let poll_result = {
-                let mut controller = audio_controller.lock().unwrap();
-                controller.poll_export_completion()
-            };
-
-            match poll_result {
-                Ok(Some(result)) => {
-                    // Export completed
-                    println!("🧵 [EXPORT THREAD] Export completed: {:?}", result.is_ok());
-                    break result;
-                }
-                Ok(None) => {
-                    // Still in progress - actual progress comes via AudioEvent::ExportProgress
-                    // No need to send progress here
-                }
-                Err(e) => {
-                    // Polling error (shouldn't happen)
-                    println!("🧵 [EXPORT THREAD] Poll error: {}", e);
-                    break Err(e);
-                }
-            }
-        };
-        println!("🧵 [EXPORT THREAD] Export loop finished");
+        println!("🧵 [EXPORT THREAD] Export finished");
 
         // Send completion or error
         match result {
@@ -232,6 +186,54 @@ impl ExportOrchestrator {
             }
         }
     }
+
+    /// Run export using DAW backend (for all formats)
+    fn run_daw_backend_export(
+        settings: &daw_backend::audio::ExportSettings,
+        output_path: &PathBuf,
+        audio_controller: &Arc<std::sync::Mutex<daw_backend::EngineController>>,
+        cancel_flag: &Arc<AtomicBool>,
+    ) -> Result<(), String> {
+        println!("🧵 [EXPORT THREAD] Starting DAW backend export...");
+
+        // Start the export (non-blocking - just sends the query)
+        {
+            let mut controller = audio_controller.lock().unwrap();
+            println!("🧵 [EXPORT THREAD] Sending export query...");
+            controller.start_export_audio(settings, output_path)?;
+            println!("🧵 [EXPORT THREAD] Export query sent, lock released");
+        }
+
+        // Poll for completion without holding the lock for extended periods
+        loop {
+            if cancel_flag.load(Ordering::Relaxed) {
+                return Err("Export cancelled by user".to_string());
+            }
+
+            // Sleep before polling to avoid spinning
+            std::thread::sleep(std::time::Duration::from_millis(100));
+
+            // Brief lock to poll for completion
+            let poll_result = {
+                let mut controller = audio_controller.lock().unwrap();
+                controller.poll_export_completion()
+            };
+
+            match poll_result {
+                Ok(Some(result)) => {
+                    println!("🧵 [EXPORT THREAD] DAW backend export completed: {:?}", result.is_ok());
+                    return result;
+                }
+                Ok(None) => {
+                    // Still in progress
+                }
+                Err(e) => {
+                    println!("🧵 [EXPORT THREAD] Poll error: {}", e);
+                    return Err(e);
+                }
+            }
+        }
+    }
 }
 
 impl Default for ExportOrchestrator {