Fallback extracting tags using ffmpeg

core/ffmpeg/ffmpeg.go

@@ -0,0 +1,103 @@
+package ffmpeg
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+
+	"github.com/navidrome/navidrome/log"
+)
+
+type FFmpeg interface {
+	Transcode(ctx context.Context, command, path string, maxBitRate int) (io.ReadCloser, error)
+	ExtractImage(ctx context.Context, path string) (io.ReadCloser, error)
+	// TODO Move scanner ffmpeg probe to here
+}
+
+func New() FFmpeg {
+	return &ffmpeg{}
+}
+
+const extractImageCmd = "ffmpeg -i %s -an -vcodec copy -f image2pipe -"
+
+type ffmpeg struct{}
+
+func (e *ffmpeg) Transcode(ctx context.Context, command, path string, maxBitRate int) (io.ReadCloser, error) {
+	args := createFFmpegCommand(command, path, maxBitRate)
+	return e.start(ctx, args)
+}
+
+func (e *ffmpeg) ExtractImage(ctx context.Context, path string) (io.ReadCloser, error) {
+	args := createFFmpegCommand(extractImageCmd, path, 0)
+	return e.start(ctx, args)
+}
+
+func (e *ffmpeg) start(ctx context.Context, args []string) (io.ReadCloser, error) {
+	log.Trace(ctx, "Executing ffmpeg command", "cmd", args)
+	j := &Cmd{ctx: ctx, args: args}
+	j.PipeReader, j.out = io.Pipe()
+	err := j.start()
+	if err != nil {
+		return nil, err
+	}
+	go j.wait()
+	return j, nil
+}
+
+type Cmd struct {
+	*io.PipeReader
+	out  *io.PipeWriter
+	ctx  context.Context
+	args []string
+	cmd  *exec.Cmd
+}
+
+func (j *Cmd) start() error {
+	cmd := exec.CommandContext(j.ctx, j.args[0], j.args[1:]...) // #nosec
+	cmd.Stdout = j.out
+	if log.CurrentLevel() >= log.LevelTrace {
+		cmd.Stderr = os.Stderr
+	} else {
+		cmd.Stderr = io.Discard
+	}
+	j.cmd = cmd
+
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("starting cmd: %w", err)
+	}
+	return nil
+}
+
+func (j *Cmd) wait() {
+	if err := j.cmd.Wait(); err != nil {
+		var exitErr *exec.ExitError
+		if errors.As(err, &exitErr) {
+			_ = j.out.CloseWithError(fmt.Errorf("%s exited with non-zero status code: %d", j.args[0], exitErr.ExitCode()))
+		} else {
+			_ = j.out.CloseWithError(fmt.Errorf("waiting %s cmd: %w", j.args[0], err))
+		}
+		return
+	}
+	if j.ctx.Err() != nil {
+		_ = j.out.CloseWithError(j.ctx.Err())
+		return
+	}
+	_ = j.out.Close()
+}
+
+// Path will always be an absolute path
+func createFFmpegCommand(cmd, path string, maxBitRate int) []string {
+	split := strings.Split(cmd, " ")
+	for i, s := range split {
+		s = strings.ReplaceAll(s, "%s", path)
+		s = strings.ReplaceAll(s, "%b", strconv.Itoa(maxBitRate))
+		split[i] = s
+	}
+
+	return split
+}