[vlc-devel] Re: V4L Stalling on one Linux machine

James MacLean macleajb at ednet.ns.ca
Sat Apr 2 04:45:42 CEST 2005

James MacLean wrote:

> Hi Folks,
> In modules/access/v4l/v4l.c in the function Demux I see
>    if( p_sys->fd_audio < 0 || !( p_block = GrabAudio( p_demux ) ) )
>    {
>        /* Try grabbing video frame */
>        p_es = p_sys->p_es_video;
>        if( p_sys->fd_video > 0 ) p_block = GrabVideo( p_demux );
>    } else {
> GrabVideo() is never getting called from here. I expect it because I 
> see GrabAudio is never returning 0.
> If I stick a GrabVideo in the else, I get my video fine, but there is 
> no audio....
> Any suggestions as to what I am doing wrong :)?
> thanks,

I must have some odd hardware interaction as I have not seen this _yet_ 
on 2 other V4L machines. Is there some reason why the audio would not be 
opened correctly in that it keeps returning data but that data does not 
seem to be coming out as sound :)? Almost as if my igain is at 0 which 
it is not. Mencoder continues to work as expected....

To sumerize, if I add, in the above else, to do a GrabVideo, I can 
finally see the video every time I start to stream. Problem remains, 
that even doing this, I get no sound...

As a sidebar, I was also able to freeze the video when it was started 
with something like :
vlc v4l:/dev/video0:channel=0:norm=ntsc:size=640x480
just by repositioning the video window a few times.

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