9 Jun
2013
9 Jun
'13
8:48 p.m.
On 06/07/2013 11:07 PM, Len Ovens wrote:
Yes.. Ideally someone (tm) could hack up a script to select the screen
rectangle to capture, the jack outputs you want and then start ffmpeg
with the correct parameters and same for jack.plumbing
True... what I meant here was mostly related to uploading as you usually
want to share your screencast.
On Fri, June 7, 2013 1:14 pm, Lorenzo Sutton wrote:
I agree, and I think for clarity they should call it with its proper
name (libav or avconv or whatever) and not 'trick' user into installing
it when they think they are installing ffmpeg.
On 06/05/2013 10:42 AM, Atte André Jensen wrote:
Now if libav would just stop shipping with links from ffmpeg, debian could
ship both... On 05/28/2013 10:35 PM, Len Ovens 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] As a UbuntuStudio team member, I would be very
interested in your
findings. We would like to include a desktop recorder, but would prefer
the best we can ship. The xvidcap page says that xvidcap is an OSS
audio
application.
I wanna join the choir.
I tried the screen casters I know of xvidcap, kazam and recordmydesktop,
and non of them are really working (terribly loose description, I know). 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)
A script that runs xrandr could probably do that automatically. xrandr has
the screen sizes (the size of each monitor with position as well as the
size of combined screen size in the case of two monitors). I think there
are tools that will give a window size and position as well and most of
the screen capture tools allow "rubberbanding" a rectangle, so that should
not be hard either... I am pretty sure I could figure that out in
tk/tcl... my python is not that advanced yet.
- you need to connect your jack output(s)
to the ffmpeg jack input
after you've started recording
jack.plumbing from the jack-tools package might make that less painful.
Possibly some of the session managers too. - fairly big output file
Most of us have fairly big hard drives these days ;) maybe I just don't
do enough recording to make mine seem small.
There are enough scripting GUIs around (like tk/tcl and everything newer)
it would not be hard to create a GUI to wrap around all that and the
recoding below. The biggest stumbling block is a real ffmpeg. Did you have
to remove libav?
I never installed it. Just went straight to the mentioned 'Compile for
ubuntu' guide.
Lorenzo
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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