Bump mp3 encoding to 320kbps, attach album cover and artist/album/title metadata to the file, handle file collision gracefully (useful for syncing playlists - download only missing files)

Cargo.toml

@@ -28,6 +28,9 @@ dirs = "5.0"
 mp3lame-encoder = { version = "0.1.5", optional = true }
 futures = "0.3"
 rayon = "1.10"
+hex = "0.4"
+reqwest = { version = "0.11", features = ["blocking", "json"] }
+id3 = "0.6"
 
 [features]
 default = ["mp3"]

src/channel_sink.rs

@@ -19,14 +19,14 @@ pub struct ChannelSink {
 
 impl ChannelSink {
 
-    pub fn new(track: TrackMetadata) -> (Self, SinkEventChannel) {
+    pub fn new(track: &TrackMetadata) -> (Self, SinkEventChannel) {
         let (tx, rx) = tokio::sync::mpsc::unbounded_channel();
 
         (
             ChannelSink {
                 sender: tx,
                 bytes_sent: 0,
-                bytes_total: Self::convert_track_duration_to_size(&track),
+                bytes_total: Self::convert_track_duration_to_size(track),
             },
             rx,
         )

src/download.rs

@@ -77,7 +77,7 @@ impl Downloader {
     #[tracing::instrument(name = "download_track", skip(self))]
     async fn download_track(&self, track: Track, options: &DownloadOptions) -> Result<()> {
         let metadata = track.metadata(&self.session).await?;
-        tracing::info!("Downloading track: {:?}", metadata);
+        tracing::info!("Downloading track: {:?}", metadata.track_name);
 
         let file_name = self.get_file_name(&metadata);
         let path = options
@@ -88,7 +88,12 @@ impl Downloader {
             .ok_or(anyhow::anyhow!("Could not set the output path"))?
             .to_string();
 
-        let (sink, mut sink_channel) = ChannelSink::new(metadata);
+        if std::path::Path::new(&path).exists() {
+            println!("File already exists, skipping: {}", path);
+            return Ok(());
+        }
+
+        let (sink, mut sink_channel) = ChannelSink::new(&metadata);
 
         let file_size = sink.get_approximate_size();
 
@@ -129,15 +134,12 @@ impl Downloader {
             }
         }
 
-        tracing::info!("Encoding track: {:?}", file_name);
+        tracing::info!("Encoding and writing track: {:?}", file_name);
-        pb.set_message(format!("Encoding {}", &file_name));
+        pb.set_message(format!("Encoding and writing {}", &file_name));
         let samples = Samples::new(samples, 44100, 2, 16);
         let encoder = crate::encoder::get_encoder(options.format);
-        let stream = encoder.encode(samples).await?;
+        let output_path = &path;
-
+        encoder.encode(&samples, &metadata, output_path).await?;
-        pb.set_message(format!("Writing {}", &file_name));
-        tracing::info!("Writing track: {:?} to file: {}", file_name, &path);
-        stream.write_to_file(&path).await?;
 
         pb.finish_with_message(format!("Downloaded {}", &file_name));
         Ok(())

src/encoder/flac.rs

@@ -1,9 +1,6 @@
-use flacenc::bitsink::ByteSink;
 use flacenc::component::BitRepr;
 use flacenc::error::Verify;
 
-use super::execute_with_result;
-use super::EncodedStream;
 use super::Encoder;
 use super::Samples;
 
@@ -12,7 +9,9 @@ pub struct FlacEncoder;
 
 #[async_trait::async_trait]
 impl Encoder for FlacEncoder {
-    async fn encode(&self, samples: Samples) -> anyhow::Result<EncodedStream> {
+    async fn encode(&self, samples: &Samples, metadata: &crate::track::TrackMetadata, output_path: &str) -> anyhow::Result<()> {
+        let file_name = &metadata.track_name;
+        tracing::info!("Writing track: {:?} to file: {}", file_name, output_path);
         let source = flacenc::source::MemSource::from_samples(
             &samples.samples,
             samples.channels as usize,
@@ -26,7 +25,7 @@ impl Encoder for FlacEncoder {
 
         let (tx, rx) = tokio::sync::oneshot::channel();
 
-        rayon::spawn(execute_with_result(
+        rayon::spawn(super::execute_with_result(
             move || {
                 let flac_stream = flacenc::encode_with_fixed_block_size(
                     &config,
@@ -35,7 +34,7 @@ impl Encoder for FlacEncoder {
                 )
                 .map_err(|e| anyhow::anyhow!("Failed to encode flac: {:?}", e))?;
 
-                let mut byte_sink = ByteSink::new();
+                let mut byte_sink = flacenc::bitsink::ByteSink::new();
                 flac_stream
                     .write(&mut byte_sink)
                     .map_err(|e| anyhow::anyhow!("Failed to write flac stream: {:?}", e))?;
@@ -47,6 +46,7 @@ impl Encoder for FlacEncoder {
 
         let byte_sink: Vec<u8> = rx.await??;
 
-        Ok(EncodedStream::new(byte_sink))
+        let stream = super::EncodedStream::new(byte_sink);
+        stream.write_to_file(output_path).await
     }
 }

src/encoder/mod.rs

@@ -54,8 +54,8 @@ pub fn get_encoder(format: Format) -> &'static dyn Encoder {
 }
 
 #[async_trait::async_trait]
-pub trait Encoder {
+pub trait Encoder: Sync {
-    async fn encode(&self, samples: Samples) -> Result<EncodedStream>;
+    async fn encode(&self, samples: &Samples, metadata: &crate::track::TrackMetadata, output_path: &str) -> Result<()>;
 }
 
 pub struct Samples {

src/encoder/mp3.rs

@@ -3,6 +3,7 @@ use anyhow::Ok;
 use mp3lame_encoder::Builder;
 use mp3lame_encoder::FlushNoGap;
 use mp3lame_encoder::InterleavedPcm;
+use id3::{Version, frame::{Picture, PictureType, Frame, Content}};
 
 use super::execute_with_result;
 use super::EncodedStream;
@@ -11,6 +12,8 @@ use super::Samples;
 
 pub struct Mp3Encoder;
 
+unsafe impl Sync for Mp3Encoder {}
+
 impl Mp3Encoder {
     fn build_encoder(
         &self,
@@ -26,7 +29,7 @@ impl Mp3Encoder {
             anyhow::anyhow!("Failed to set number of channels for mp3 encoder: {}", e)
         })?;
         builder
-            .set_brate(mp3lame_encoder::Birtate::Kbps160)
+            .set_brate(mp3lame_encoder::Birtate::Kbps320)
             .map_err(|e| anyhow::anyhow!("Failed to set bitrate for mp3 encoder: {}", e))?;
 
         builder
@@ -37,14 +40,46 @@ impl Mp3Encoder {
 
 #[async_trait::async_trait]
 impl Encoder for Mp3Encoder {
-    async fn encode(&self, samples: Samples) -> anyhow::Result<EncodedStream> {
+    async fn encode(&self, samples: &Samples, metadata: &crate::track::TrackMetadata, output_path: &str) -> anyhow::Result<()> {
+        let file_name = &metadata.track_name;
+        tracing::info!("Writing track: {:?} to file: {}", file_name, output_path);
+        let stream = self.encode_raw(samples).await?;
+        stream.write_to_file(output_path).await?;
+
+        // Embed tags using id3 crate
+        let mut tag = id3::Tag::read_from_path(output_path).unwrap_or_else(|_| id3::Tag::new());
+        tag.set_title(file_name);
+        tag.set_album(&metadata.album.name);
+        let artists = metadata.artists.iter().map(|a| a.name.as_str()).collect::<Vec<_>>().join("\0");
+        tag.set_artist(&artists);
+
+        // Embed cover image
+        if let Some(image_bytes) = metadata.cover_image.as_deref() {
+            let picture = Picture {
+                mime_type: "image/jpeg".to_string(),
+                picture_type: PictureType::CoverFront,
+                description: "cover".to_string(),
+                data: image_bytes.to_vec(),
+            };
+            let frame = Frame::with_content("APIC", Content::Picture(picture));
+            tag.add_frame(frame);
+        }
+        tag.write_to_path(output_path, Version::Id3v24)?;
+        Ok(())
+    }
+}
+
+impl Mp3Encoder {
+    async fn encode_raw(&self, samples: &Samples) -> anyhow::Result<EncodedStream> {
         let mut mp3_encoder = self.build_encoder(samples.sample_rate, samples.channels)?;
 
         let (tx, rx) = tokio::sync::oneshot::channel();
 
+        let samples_vec = samples.samples.clone();
+
         rayon::spawn(execute_with_result(
             move || {
-                let samples: Vec<i16> = samples.samples.iter().map(|&x| x as i16).collect();
+                let samples: Vec<i16> = samples_vec.iter().map(|&x| x as i16).collect();
                 let input = InterleavedPcm(samples.as_slice());
                 let mut mp3_out_buffer = Vec::with_capacity(mp3lame_encoder::max_required_buffer_size(samples.len()));
                 let encoded_size = mp3_encoder

src/track.rs

@@ -93,7 +93,24 @@ impl Track {
             .await
             .map_err(|_| anyhow::anyhow!("Failed to get album"))?;
 
-        Ok(TrackMetadata::from(metadata, artists, album))
+        // Fetch cover image bytes if available
+        let cover_image = if let Some(cover) = album.covers.first() {
+            let file_id_hex = hex::encode(cover.0);
+            let url = format!("https://i.scdn.co/image/{}", file_id_hex);
+            match reqwest::get(&url).await {
+                Ok(response) if response.status().is_success() => {
+                    match response.bytes().await {
+                        Ok(bytes) => Some(bytes.to_vec()),
+                        Err(_) => None,
+                    }
+                }
+                _ => None,
+            }
+        } else {
+            None
+        };
+
+        Ok(TrackMetadata::from(metadata, artists, album, cover_image))
     }
 }
 
@@ -178,6 +195,7 @@ pub struct TrackMetadata {
     pub track_name: String,
     pub album: AlbumMetadata,
     pub duration: i32,
+    pub cover_image: Option<Vec<u8>>,
 }
 
 impl TrackMetadata {
@@ -185,11 +203,13 @@ impl TrackMetadata {
         track: librespot::metadata::Track,
         artists: Vec<librespot::metadata::Artist>,
         album: librespot::metadata::Album,
+        cover_image: Option<Vec<u8>>,
     ) -> Self {
         let artists = artists
             .iter()
             .map(|artist| ArtistMetadata::from(artist.clone()))
             .collect();
+
         let album = AlbumMetadata::from(album);
 
         TrackMetadata {
@@ -197,6 +217,7 @@ impl TrackMetadata {
             track_name: track.name.clone(),
             album,
             duration: track.duration,
+            cover_image,
         }
     }
 }