refactor: more stable transcoder, based on http.FileSystem

engine/ffmpeg/ffmpeg.go

@@ -0,0 +1,52 @@
+package ffmpeg
+
+import (
+	"context"
+	"io"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+
+	"github.com/deluan/navidrome/conf"
+	"github.com/deluan/navidrome/log"
+)
+
+type FFmpeg interface {
+	StartTranscoding(ctx context.Context, path string, maxBitRate int, format string) (f io.ReadCloser, err error)
+}
+
+func New() FFmpeg {
+	return &ffmpeg{}
+}
+
+type ffmpeg struct{}
+
+func (ff *ffmpeg) StartTranscoding(ctx context.Context, path string, maxBitRate int, format string) (f io.ReadCloser, err error) {
+	cmdLine, args := createTranscodeCommand(path, maxBitRate, format)
+
+	log.Trace(ctx, "Executing ffmpeg command", "arg0", cmdLine, "args", args)
+	cmd := exec.Command(cmdLine, args...)
+	cmd.Stderr = os.Stderr
+	if f, err = cmd.StdoutPipe(); err != nil {
+		return f, err
+	}
+	if err = cmd.Start(); err != nil {
+		return f, err
+	}
+	go cmd.Wait() // prevent zombies
+	return f, err
+}
+
+func createTranscodeCommand(path string, maxBitRate int, format string) (string, []string) {
+	cmd := conf.Server.DownsampleCommand
+
+	split := strings.Split(cmd, " ")
+	for i, s := range split {
+		s = strings.Replace(s, "%s", path, -1)
+		s = strings.Replace(s, "%b", strconv.Itoa(maxBitRate), -1)
+		split[i] = s
+	}
+
+	return split[0], split[1:]
+}