The VideoLAN Forums

Hi,

I've got an usb webcam with internal (hardware) h264 encoder and I managed to start the stream using: So far, so good, but... The default bitrate, at which the webcam's h264 encoder is encoding the video stream, is too high for me (around 3-4 mbps) and I'd like to lower it down by telling the webcam to encode the video with a different bitrate. I don't want to transcode the stream with vlc, because in that case, there is no purpose of webcam's internal encoder.

I've been told (at the #v4l irc channel) that this can be done using ioctl() in vlc's source code (more info here, if needed: https://ffmpeg.org/trac/ffmpeg/ticket/1389 ), so my question is: is there a way to tell the webcam to lower the encoding bitrate, using vlc?

Thanks in advance.

VLC can change the V4L2 controls via the command line or UI effects dialog. There is no support for UVC-specific functionality at this point in time.

So if the encoding parameters are not available as V4L2 controls, then it will not work as is.

Hi all.

I have almost the same issue. But I want to tune some video stream params.
First of all I want to set FPS and frequency of k-frames. Now I'm doing this so: But I this that doesn't work because of this string in the output: May be I'm doing something wrong?

"fps" and "keyint" are not currently implemented by the V4L2 input plugin. fps is not a V4L2 "control" anyway, so it would need special support. I don't know about "keyint".

Hi Rémi,

Is there any frame rate control available in V4L2 input plugin? Or there is some option like use v4l2-ctl to set parameters I need ahead of vlc use?

No, this never was implemented in VLC.