Foundation: config, schema/migrations, auth, stable IDs, metadata probing

internal/metadata/ffprobe.go

@@ -0,0 +1,69 @@
+package metadata
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os/exec"
+)
+
+type ffprobeOutput struct {
+	Format  ffprobeFormat   `json:"format"`
+	Streams []ffprobeStream `json:"streams"`
+}
+
+type ffprobeFormat struct {
+	FormatName string            `json:"format_name"`
+	Duration   string            `json:"duration"`
+	BitRate    string            `json:"bit_rate"`
+	Tags       map[string]string `json:"tags"`
+}
+
+type ffprobeStream struct {
+	Index       int               `json:"index"`
+	CodecType   string            `json:"codec_type"` // "audio", "video", "subtitle", ...
+	CodecName   string            `json:"codec_name"`
+	SampleRate  string            `json:"sample_rate"`
+	Channels    int               `json:"channels"`
+	Duration    string            `json:"duration"`
+	BitRate     string            `json:"bit_rate"`
+	Disposition map[string]int    `json:"disposition"`
+	Tags        map[string]string `json:"tags"`
+}
+
+// Prober runs ffprobe to extract tags and technical properties from a
+// media file.
+type Prober struct {
+	FFprobePath string
+}
+
+// Probe reads metadata from the file at path. path must already be a
+// validated, absolute filesystem path within a configured music
+// folder — Probe does not perform any authorization or traversal checks
+// itself.
+func (p *Prober) Probe(ctx context.Context, path string) (*Tags, error) {
+	ffprobePath := p.FFprobePath
+	if ffprobePath == "" {
+		ffprobePath = "ffprobe"
+	}
+	cmd := exec.CommandContext(ctx, ffprobePath,
+		"-v", "error",
+		"-print_format", "json",
+		"-show_format",
+		"-show_streams",
+		"--", path,
+	)
+	out, err := cmd.Output()
+	if err != nil {
+		if ee, ok := err.(*exec.ExitError); ok {
+			return nil, fmt.Errorf("ffprobe: %w: %s", err, string(ee.Stderr))
+		}
+		return nil, fmt.Errorf("ffprobe: %w", err)
+	}
+
+	var raw ffprobeOutput
+	if err := json.Unmarshal(out, &raw); err != nil {
+		return nil, fmt.Errorf("parsing ffprobe output: %w", err)
+	}
+	return parseFFprobeOutput(raw), nil
+}