revid: using smarter startWebcam func as suggested by Dan

revid/revid.go

@@ -499,27 +499,66 @@ func (r *Revid) startRaspivid() error {
 }
 
 func (r *Revid) startWebcam() error {
-	r.config.Logger.Log(smartlogger.Info, pkg+"starting webcam")
-	r.cmd = exec.Command("ffmpeg", []string{
-		"-i", "/dev/video0",
-		"-r", "25",
-		"-f", "h264", "-",
-	}...)
+	r.config.Logger.Log(smartlogger.Info, pkg+"starting V4L2 camera")
+
+	// ffmpeg -f v4l2 -i /dev/video0 -crf 40 -c:v libx264 -b:v 200000 -maxrate 200000 -bufsize 100000 -g 100 -vf hflip,vflip -r 5 -s 320x240 -f flv -
+
+	args := []string{
+		"-f", "v4l2",
+		"-i", r.config.InputFileName,
+	}
+
+	switch r.config.InputCodec {
+	default:
+		return fmt.Errorf("revid: invalid input codec: %v", r.config.InputCodec)
+	case H264:
+		args = append(args,
+			"-c:v", "libx264",
+			"-g", r.config.IntraRefreshPeriod,
+		)
+		if r.config.QuantizationMode == QuantizationOn {
+			args = append(args, "-crf", r.config.Quantization)
+		}
+	case Mjpeg:
+		args = append(args, "-c:v", "mjpeg")
+	}
+
+	switch {
+	case r.config.FlipHorizontal == true && r.config.FlipVertical == true:
+		args = append(args, "-vf", "hflip,vflip")
+	case r.config.FlipHorizontal == true:
+		args = append(args, "-vf", "hflip")
+	case r.config.FlipVertical == true:
+		args = append(args, "-vf", "vflip")
+	}
+
+	br, err := strconv.Atoi(r.config.Bitrate)
+	if err != nil {
+		return err
+	}
+	args = append(args, "-b:v", r.config.Bitrate,
+		"-maxrate", r.config.Bitrate,
+		"-bufsize", fmt.Sprint(br/2),
+		"-r", r.config.FrameRate,
+		"-s", fmt.Sprintf("%sx%s", r.config.Width, r.config.Height),
+		"-f", "flv",
+		"-",
+	)
+
+	r.config.Logger.Log(smartlogger.Info, pkg+"ffmpeg args", "ffmpegArgs", strings.Join(args, " "))
+	r.cmd = exec.Command("ffmpeg", args...)
 
 	d, err := strconv.Atoi(r.config.FrameRate)
 	if err != nil {
 		return err
 	}
-
 	delay := time.Second / time.Duration(d)
 	stdout, err := r.cmd.StdoutPipe()
 	if err != nil {
 		return err
 	}
-
 	err = r.cmd.Start()
 	if err != nil {
-		r.config.Logger.Log(smartlogger.Fatal, pkg+"cannot start webcam", "error", err.Error())
 		return err
 	}