Re: [LAU] Desktop recorders - was "Another Reality" LP

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To: <linux-audio-user@...>
Date: Friday, June 7, 2013 - 8:14 pm

On 06/05/2013 10:42 AM, Atte André Jensen wrote:

Recently, the only effective way I've found to do screen recording with
jack is using ffmpeg - yet this must be the 'original' ffmpeg not libav
which is now packaged e.g. in Debian, which I couldn't get to work with
jack - And this needs to be compiled by hand on debian [1]

This is the script I use (adapted from someone else (TM) I found online):

ffmpeg -f jack -ac 2 -i ffmpeg -f x11grab -r 30 -s 1280x800 -i :0.0
-acodec pcm_s16le -vcodec libx264 -preset ultrafast -threads 0 output.avi

Advantages:
- it works well (with jack)
- very good quality
- good audio/video sync
Disadvantages:
- you have to manually calculate the screen size and rectangle (-s and
-i switches)
- you need to connect your jack output(s) to the ffmpeg jack input
after you've started recording
- fairly big output file

For the last 'drawback' you can convert to a compressed video format
such as webm. Recently I am use (again stolen, ehm, inspired from some
online forum [2]):

ffmpeg -y -i "$INFILE" -threads 8 -f webm -vcodec libvpx -g 120 -level
216 -profile 0 -qmax 42 -qmin 10 -rc_buf_aggressivity 0.95 -vb 2M
-acodec libvorbis -aq 90 -ac 2 $OUTFILE

This will give a nice webm video which is about 20% the filesize of the
original avi

Here is a quick short example of the final output:
http://gnufunk.org/~lorenzosu/temp/ffmpeg_grab_test.webm

Hope this helps
Lorenzo.
PS This (longer) was also created with the same technique:
http://vimeo.com/36609964

[1] I succeed on Debian wheezy amd64 following this:
https://ffmpeg.org/trac/ffmpeg/wiki/UbuntuCompilationGuide
[2] I actually found the source for this:
http://ubuntuforums.org/showthread.php?t=1522381&p=9539218#post9539218 -
thanks demizer
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Messages in current thread:
Re: [LAU] Desktop recorders - was "Another Reality" LP, Atte André Jensen, (Wed Jun 5, 8:42 am)
Re: [LAU] Desktop recorders - was "Another Reality" LP, Lorenzo Sutton, (Fri Jun 7, 8:14 pm)
Re: [LAU] Desktop recorders - was "Another Reality" LP, Atte André Jensen, (Fri Jun 21, 11:12 am)
Re: [LAU] Desktop recorders - was "Another Reality" LP, Johannes Kroll, (Wed May 29, 10:39 am)
Re: [LAU] Desktop recorders - was "Another Reality" LP, Louigi Verona, (Tue May 28, 9:06 pm)