[FFmpeg-user] audio is out of sync and "ALSA buffer xrun"

YuGiOhJCJ Mailing-List yugiohjcj-mailinglist at laposte.net
Tue Feb 11 18:24:36 CET 2014

OK. I found a nice way to stop having this "ALSA buffer xrun" message:
$ ffmpeg -y -f alsa -i default -f x11grab -r 10 -s 640x480 -async 1 -i :0.0 -strict -2 -c:a aac -c:v libx264 -pix_fmt yuv420p -preset ultrafast -s 640x480 -threads 0 -ar 44100 -b:a 64k -b:v 64k -bufsize 64k -f flv out.flv

The command is not the only thing I have changed.
As I am on a network folder (shared with NFS), the read/write access is slower (I don't know how to find the exact speed value) than a normal directory.
So, I go in the /tmp normal directory.
If I stay in my /home directory shared over the network I still have these "ALSA buffer xrun" messages.

Also, if I replace "out.flv" by a stream like "rtmp://live-fra.twitch.tv/app/live_xxxxxxxx_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", then I got the "ALSA buffer xrun" messages.

So, the only way I found to avoid this "ALSA buffer xrun" message (and so the audio out of sync) is to write to a local file (I mean not over the network) and to use the command line above.

Do you know how I can avoid this "ALSA buffer xrun" message when I am over the network ? (e.g., NFS or twitch)

Thank you.
Best regards.

On Fri, 7 Feb 2014 14:47:57 +0100
YuGiOhJCJ Mailing-List <yugiohjcj-mailinglist at laposte.net> wrote:

> OK. I have upgrade from ffmpeg version 1.2 to ffmpeg version 2.1.git (474db7a696a34582ee655c07e5073a6702236be0).
> Also, you can find attached to this mail the complete console output of this command:
> ffmpeg -y -f x11grab -r 15 -s 640x480 -i :0.0 -f alsa -i default out.mkv 1>&2 2>ffmpeg_stdout_stderr.txt
> Any suggestion for my problem?
> On Thu, 6 Feb 2014 19:22:09 +0000 (UTC)
> Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> > YuGiOhJCJ Mailing-List <yugiohjcj-mailinglist <at> laposte.net> writes:
> > 
> > > I am using ffmpeg version 1.2.
> > 
> > Please test current git head before reporting problems.
> > 
> > > To record (audio/video) my desktop with ffmpeg, I use this command:
> > > $ ffmpeg -f x11grab -r 15 -s 640x480 -i :0.0 -f alsa -i default out.mkv
> > 
> > Please add the complete, uncut console output.
> > 
> > Carl Eugen
> > 
> > _______________________________________________
> > ffmpeg-user mailing list
> > ffmpeg-user at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-user

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