Fix truncated rips on dual-layer discs, propagate read errors

Use UDF file_extents() to read actual allocation descriptors instead
of assuming m2ts files are contiguous from file_start_lba. Dual-layer
UHD discs split large files across 70+ extents (~1 GB each) — the old
code created one extent from packet count which only covered the first
chunk, causing silent truncation at ~37%.

Also changed fill_extents() to return io::Result<bool> so read errors
propagate instead of being silently treated as EOF.

src/disc/bluray.rs

@@ -66,20 +66,21 @@ impl Disc {
                     pkt_count = clip_info.source_packet_count;
                     total_size += pkt_count as u64 * 192;
 
-                    // Get m2ts file start LBA and compute extent from packet count.
-                    // BD-ROM m2ts files are contiguous on disc (mastering requirement).
+                    // Get m2ts file extents from UDF allocation descriptors.
+                    // Dual-layer discs split files across layers — UDF knows the real layout.
                     let m2ts_path = format!("/BDMV/STREAM/{}.m2ts", play_item.clip_id);
-                    let file_lba = udf_fs.file_start_lba(reader, &m2ts_path).unwrap_or(0);
-                    let total_bytes = pkt_count as u64 * 192;
-                    let total_sectors = total_bytes.div_ceil(2048) as u32;
-                    if total_sectors > 0 && file_lba > 0 {
+                    if let Ok(file_exts) = udf_fs.file_extents(reader, &m2ts_path) {
+                        for (lba, sectors) in file_exts {
+                            if sectors > 0 && lba > 0 {
                                 extents.push(Extent {
-                            start_lba: file_lba,
-                            sector_count: total_sectors,
+                                    start_lba: lba,
+                                    sector_count: sectors,
                                 });
                             }
                         }
                     }
+                }
+            }
 
             clips.push(Clip {
                 clip_id: play_item.clip_id.clone(),

src/mux/disc.rs

@@ -117,9 +117,9 @@ impl DiscStream {
         self.disc.as_ref()
     }
 
-    fn fill_extents(&mut self) -> bool {
+    fn fill_extents(&mut self) -> io::Result<bool> {
         if self.current_extent >= self.extents.len() {
-            return false;
+            return Ok(false);
         }
         let ext_start = self.extents[self.current_extent].start_lba;
         let ext_sectors = self.extents[self.current_extent].sector_count;
@@ -137,21 +137,15 @@ impl DiscStream {
         let bytes = sectors as usize * 2048;
         self.read_buf.resize(bytes, 0);
 
-        match self
-            .reader
-            .read_sectors(lba, sectors, &mut self.read_buf[..bytes])
-        {
-            Ok(_) => {
+        self.reader
+            .read_sectors(lba, sectors, &mut self.read_buf[..bytes])?;
         self.buf_valid = bytes;
         self.current_offset += sectors as u32;
         if self.current_offset >= ext_sectors {
             self.current_extent += 1;
             self.current_offset = 0;
         }
-                true
-            }
-            Err(_) => false,
-        }
+        Ok(true)
     }
 }
 
@@ -166,7 +160,7 @@ impl crate::pes::Stream for DiscStream {
         }
 
         loop {
-            if !self.fill_extents() {
+            if !self.fill_extents()? {
                 self.eof = true;
                 // Flush demuxer — last PES packet may still be in the assembler
                 if let Some(ref mut demuxer) = self.ts_demuxer {