fix ffmpeg output flags

Author: davidnewhall

encode.go

@@ -382,11 +382,16 @@ func (e *Encoder) getVideoHandle(ctx context.Context, input, output, title strin
 		"-v", "16", // log level
 		"-rtsp_transport", "tcp",
 		"-i", input,
-		"-f", "mov",
 		"-metadata", "title=" + title,
 		"-y", "-map", "0",
 	}
 
+	if output == "-" {
+		arg = append(arg, "-f", "mp4", "-movflags", "frag_keyframe+empty_moov")
+	} else {
+		arg = append(arg, "-f", "mov")
+	}
+
 	if e.config.Size > 0 {
 		arg = append(arg, "-fs", strconv.FormatInt(e.config.Size, base10))
 	}
@@ -400,12 +405,15 @@ func (e *Encoder) getVideoHandle(ctx context.Context, input, output, title strin
 			"-profile:v", e.config.Prof,
 			"-level", e.config.Level,
 			"-pix_fmt", "yuv420p",
-			"-movflags", "faststart",
 			"-s", strconv.Itoa(e.config.Width)+"x"+strconv.Itoa(e.config.Height),
 			"-preset", "superfast",
 			"-crf", strconv.Itoa(e.config.CRF),
 			"-r", strconv.Itoa(e.config.Rate),
 		)
+
+		if output != "-" {
+			arg = append(arg, "-movflags", "faststart")
+		}
 	} else {
 		arg = append(arg, "-c", "copy")
 	}

encode_test.go

@@ -59,6 +59,8 @@ func TestSaveVideo(t *testing.T) {
 	asert.Contains(cmd, "-metadata title=TITLE", "TITLE value appears to be missing.")
 	asert.Contains(cmd, fmt.Sprintf("-vcodec libx264 -profile:v %v -level %v", DefaultProfile, DefaultLevel),
 		"Level or Profile are missing or out of order.")
+	asert.Contains(cmd, "-f mov", "File output should use mov container.")
+	asert.Contains(cmd, "-movflags faststart", "File output should set faststart for mov.")
 	asert.Contains(cmd, fmt.Sprintf("-crf %d", DefaultEncodeCRF), "CRF value is missing or malformed.")
 	asert.Contains(cmd, fmt.Sprintf("-t %d", DefaultCaptureTime),
 		"Capture Time value is missing or malformed.")
@@ -119,6 +121,9 @@ func TestGetVideoStreamLifecycle(t *testing.T) {
 	require.NoError(t, readErr)
 	require.NotEmpty(t, data)
 	require.Contains(t, string(data), "-metadata title=TITLE")
+	require.Contains(t, string(data), "-f mp4")
+	require.Contains(t, string(data), "-movflags frag_keyframe+empty_moov")
+	require.NotContains(t, string(data), "-movflags faststart")
 	require.NoError(t, stream.Close())
 	require.Contains(t, cmd, "-metadata title=TITLE")
 }