audio file info added, fixed right click selecting.

backend/metadata/duration.go

@@ -7,12 +7,15 @@ import (
 )
 
 // getTrackDuration returns the duration of an audio file in
-// milliseconds.  For MP3 files it uses a fast header-only parser
-// (Xing/VBRI/CBR); for other formats it falls back to a full
-// decode via beep which is already O(1) for FLAC, OGG, and WAV.
+// milliseconds together with its audio stream properties.  For MP3
+// files it uses a fast header-only parser (Xing/VBRI/CBR); for FLAC
+// it reads the StreamInfo block; for other formats it falls back to
+// beep which is already O(1) for OGG and WAV.
 //
 // The file position is undefined after this call.
-func getTrackDuration(f *os.File) (int64, error) {
+func getTrackDuration(
+	f *os.File,
+) (int64, *AudioProperties, error) {
 	ext := filepath.Ext(f.Name())
 
 	switch ext {
@@ -26,7 +29,9 @@ func getTrackDuration(f *os.File) (int64, error) {
 	// (reads headers/metadata only, no full audio decode).
 	streamer, format, err := DecodeFile(f)
 	if err != nil {
-		return 0, fmt.Errorf("error decoding file: %w", err)
+		return 0, nil, fmt.Errorf(
+			"error decoding file: %w", err,
+		)
 	}
 
 	lengthMillis := int64(
@@ -35,5 +40,11 @@ func getTrackDuration(f *os.File) (int64, error) {
 	)
 	_ = streamer.Close()
 
-	return lengthMillis, nil
+	props := &AudioProperties{
+		SampleRate: int(format.SampleRate),
+		BitDepth:   format.Precision * 8,
+		Channels:   format.NumChannels,
+	}
+
+	return lengthMillis, props, nil
 }