feat: re-encode cover images for rockbox compatibility

src-tauri/src/tagger.rs

@@ -2,8 +2,10 @@ use id3::{
     frame::{Picture, PictureType},
     Tag as ID3Tag, TagLike, Version,
 };
+use image::codecs::jpeg::JpegEncoder;
 use metaflac::Tag as FlacTag;
 use serde::{Deserialize, Serialize};
+use std::io::Cursor;
 use std::path::Path;
 
 /// Metadata structure for audio file tagging
@@ -356,3 +358,20 @@ fn detect_mime_type_str(data: &[u8]) -> &'static str {
         "image/jpeg"
     }
 }
+
+/// Re-encode image data as a baseline (non-progressive) JPEG in sRGB.
+/// This ensures compatibility with players like Rockbox that can't
+/// decode progressive JPEGs or non-sRGB colorspaces.
+pub fn reencode_cover_image(data: &[u8], quality: u8) -> Result<Vec<u8>, String> {
+    let img = image::load_from_memory(data)
+        .map_err(|e| format!("Failed to decode image: {}", e))?;
+
+    let rgb = img.to_rgb8();
+
+    let mut buf = Cursor::new(Vec::new());
+    let encoder = JpegEncoder::new_with_quality(&mut buf, quality);
+    rgb.write_with_encoder(encoder)
+        .map_err(|e| format!("Failed to encode JPEG: {}", e))?;
+
+    Ok(buf.into_inner())
+}