Add auto transcoding to JPEG snapshot

internal/ffmpeg/helpers.go

@@ -0,0 +1,12 @@
+package ffmpeg
+
+import (
+	"bytes"
+	"os/exec"
+)
+
+func TranscodeToJPEG(b []byte) ([]byte, error) {
+	cmd := exec.Command("ffmpeg", "-hide_banner", "-i", "-", "-f", "mjpeg", "-")
+	cmd.Stdin = bytes.NewBuffer(b)
+	return cmd.Output()
+}