Music Pipeline Refactor

internal/music/metadata.go

@@ -0,0 +1,62 @@
+package music
+
+import (
+	"encoding/json"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+func ProbeMetadata(ffprobePath, sourcePath string) (Metadata, error) {
+	cmd := exec.Command(ffprobePath, "-v", "quiet", "-print_format", "json", "-show_format", sourcePath)
+	output, err := cmd.Output()
+	if err != nil {
+		return Metadata{}, err
+	}
+	var payload struct {
+		Format struct {
+			Tags map[string]string `json:"tags"`
+		} `json:"format"`
+	}
+	if err := json.Unmarshal(output, &payload); err != nil {
+		return Metadata{}, err
+	}
+	tags := make(map[string]string, len(payload.Format.Tags))
+	for key, value := range payload.Format.Tags {
+		tags[strings.ToLower(strings.TrimSpace(key))] = strings.TrimSpace(value)
+	}
+	return Metadata{
+		Title:     FirstNonEmpty(tags["title"]),
+		Artist:    FirstNonEmpty(tags["artist"], tags["album_artist"], tags["composer"]),
+		Album:     FirstNonEmpty(tags["album"]),
+		Date:      FirstNonEmpty(tags["date"], tags["year"]),
+		Comment:   FirstNonEmpty(tags["comment"], tags["description"]),
+		Copyright: FirstNonEmpty(tags["copyright"]),
+		License:   FirstNonEmpty(tags["license"], tags["license_url"]),
+	}, nil
+}
+
+func ConvertSource(ffmpegPath, sourcePath, outputPath string) error {
+	cmd := exec.Command(
+		ffmpegPath, "-y",
+		"-i", sourcePath,
+		"-vn",
+		"-map_metadata", "-1",
+		"-ar", "44100",
+		"-ac", "2",
+		"-b:a", "192k",
+		"-codec:a", "libmp3lame",
+		"-write_xing", "0",
+		"-f", "mp3",
+		outputPath,
+	)
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		message := strings.TrimSpace(string(output))
+		if message == "" {
+			message = err.Error()
+		}
+		return fmt.Errorf("%s", message)
+	}
+	return nil
+}