Add album/track releases with audio analysis, AnalyzeAlbumRelease RPC, Docker path auto-resolution, release parsing decision tree

internal/audio/mp3.go

@@ -0,0 +1,54 @@
+package audio
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/tcolgate/mp3"
+)
+
+func analyzeMP3(filePath string) (*TrackInfo, error) {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("opening MP3: %w", err)
+	}
+	defer f.Close()
+
+	decoder := mp3.NewDecoder(f)
+	var frame mp3.Frame
+	var skipped int
+	var totalDuration time.Duration
+	var sampleRate, channels, bitrate int
+	var frameCount int
+
+	for {
+		err := decoder.Decode(&frame, &skipped)
+		if err != nil {
+			break
+		}
+		if frameCount == 0 {
+			sampleRate = int(frame.Header().SampleRate())
+			channels = channelCount(frame.Header().ChannelMode())
+			bitrate = int(frame.Header().BitRate()) / 1000
+		}
+		totalDuration += frame.Duration()
+		frameCount++
+	}
+
+	return &TrackInfo{
+		Format:      "MP3",
+		SampleRate:  sampleRate,
+		Channels:    channels,
+		DurationMs:  int(totalDuration.Milliseconds()),
+		BitrateKbps: bitrate,
+		IsLossless:  false,
+	}, nil
+}
+
+func channelCount(mode mp3.FrameChannelMode) int {
+	if mode == mp3.SingleChannel {
+		return 1
+	}
+	return 2
+}