Generate audio track labels when disc doesn't provide them

src/mux/mkv.rs

@@ -5,9 +5,61 @@
 //! cues and seek head are finalized at the end.
 
 use super::ebml;
-use crate::disc::{AudioStream, Chapter, Codec, ColorSpace, HdrFormat, SubtitleStream, VideoStream};
+use crate::disc::{
+    AudioChannels, AudioStream, Chapter, Codec, ColorSpace, HdrFormat, SubtitleStream, VideoStream,
+};
 use std::io::{self, Seek, SeekFrom, Write};
 
+/// Generate a descriptive audio track label from codec and channel layout.
+/// Used when the disc doesn't provide BD-J/CLPI labels.
+fn generate_audio_label(codec: &Codec, channels: &AudioChannels, secondary: bool) -> String {
+    let codec_name = match codec {
+        Codec::TrueHd => match channels {
+            AudioChannels::Surround71 => "Dolby TrueHD Atmos 7.1",
+            AudioChannels::Surround51 => "Dolby TrueHD 5.1",
+            _ => "Dolby TrueHD",
+        },
+        Codec::Ac3 => "Dolby Digital",
+        Codec::Ac3Plus => "Dolby Digital Plus",
+        Codec::DtsHdMa => "DTS-HD Master Audio",
+        Codec::DtsHdHr => "DTS-HD High Resolution",
+        Codec::Dts => "DTS",
+        Codec::Lpcm => "LPCM",
+        Codec::Aac => "AAC",
+        Codec::Mp2 => "MPEG Audio",
+        Codec::Mp3 => "MP3",
+        Codec::Flac => "FLAC",
+        Codec::Opus => "Opus",
+        _ => return String::new(),
+    };
+
+    // TrueHD already includes channel info in its name for 7.1/5.1
+    let has_channels = matches!(
+        codec,
+        Codec::TrueHd if matches!(channels, AudioChannels::Surround71 | AudioChannels::Surround51)
+    );
+
+    let channel_str = if has_channels {
+        String::new()
+    } else {
+        match channels {
+            AudioChannels::Mono => " 1.0".into(),
+            AudioChannels::Stereo => " 2.0".into(),
+            AudioChannels::Stereo21 => " 2.1".into(),
+            AudioChannels::Quad => " 4.0".into(),
+            AudioChannels::Surround50 => " 5.0".into(),
+            AudioChannels::Surround51 => " 5.1".into(),
+            AudioChannels::Surround61 => " 6.1".into(),
+            AudioChannels::Surround71 => " 7.1".into(),
+            AudioChannels::Unknown => String::new(),
+        }
+    };
+
+    let suffix = if secondary { " (Secondary)" } else { "" };
+
+    format!("{}{}{}", codec_name, channel_str, suffix)
+}
+
 /// MKV track definition (built from disc stream metadata).
 pub struct MkvTrack {
     pub track_type: u64, // 1=video, 2=audio, 17=subtitle
@@ -95,11 +147,19 @@ impl MkvTrack {
         };
         let sr = a.sample_rate.hz();
         let ch = a.channels.count();
+
+        // Use disc label if available, otherwise generate from codec + channels
+        let name = if a.label.is_empty() {
+            generate_audio_label(&a.codec, &a.channels, a.secondary)
+        } else {
+            a.label.clone()
+        };
+
         Self {
             track_type: ebml::TRACK_TYPE_AUDIO,
             codec_id,
             language: a.language.clone(),
-            name: a.label.clone(),
+            name,
             codec_private: None,
             is_default: !a.secondary,
             is_forced: false,