[FFmpeg-user] Capturing audio with x11grab

Moritz Barsnick barsnick at gmx.net
Tue Nov 10 12:46:23 CET 2015

Hi Phil,

On Tue, Nov 10, 2015 at 22:39:24 +1100, Philip Rhoades wrote:
>    http://iview.abc.net.au
> - which I think are basically Flash videos, I have tried:

Have you tried downloading the actual video file with youtube-dl?
Capturing from screen sound so last-resort-hacky that I would avoid it
at any cost!

>    ffmpeg -f alsa -ac 2 -i hw:1 -f video4linux2 -f x11grab -framerate 25 
> -i :0.0 ./out.mpg
> which gets the video OK but only gets my heavy breathing into the mic on 
> my headset - I presume there is some way of capturing the audio that is 
> coming out of the computer?

Perhaps you shouldn't be breathing so heavily. ;-) Kidding aside: I
don't know whether alsa can even do that, that is to redirect the audio
output to a pseudo input. I know that pulseaudio can, if your system
happens to support that. It takes a bit of googling, but you can direct
even just one program's output to a pseudo-sink, and then grab that
sink directly with ffmpeg. I know it works - I have done it (to get
some really rare stuff off Spo**fy).


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