[SATLUG] screen recording tool

Borries Demeler demeler at biochem.uthscsa.edu
Tue Dec 3 08:53:16 CST 2013


So, after much looking around, testing, compiling and upgrading,
I finally found an excellent solution that seems to work better than
any other: ffmpeg. The latest version (2.1) has support for x11grab,
and hence can record directly from the X11 screen.  Needless to say,
it produces excellent quality video without frameloss or compression,
and supports virtually any format I could ever need. The best part is
that audio is properly recorded alongside with the video and multiplexed
with the video on the fly for perfect synchronization for my voice-over
needs. Oh, and ffmpeg is multithreaded in case a single core is not
fast enough. Here is an example commandline that works just fine:

ffmpeg -video_size 800x600 -framerate 25 -f x11grab -i :0.0 -f alsa -ac 2 -i hw:0,0 output.mkv

The KDE 4 plasma desktop supports a mouse cursor for magnification in
the vicinity of the mouse cursor, this way I can scale the video down
and the important part is still perfectly readable.

All set now to make my instructional videos :-)

-b.

On Sat, Jul 20, 2013 at 12:56:31PM -0500, Borries Demeler wrote:
> On Sat, Jul 20, 2013 at 12:50:49PM -0500, Don Davis wrote:
> > I don't know off hand - but I know it works better with some obscure
> > formats than one might expect. But aside of that - converting the
> > video with ffmpeg would be trivial. (Given all the work you're doing
> > with vnc and the specificity of your requests - adding and moving
> > audio with openshot will improve overall quality with higher return on
> > time than the other bits.)
> 
> Thanks for the suggestion, I think I'll try openshot - looks like a neat project,
> I was not aware of it before.
> 
> -b.
> > 
> > On Sat, Jul 20, 2013 at 12:38 PM, Borries Demeler
> > <demeler at biochem.uthscsa.edu> wrote:
> > > On Sat, Jul 20, 2013 at 12:24:38PM -0500, Don Davis wrote:
> > >> Can you just combine audio and video with openshot?
> > >
> > > Probably, haven't tried openshot. I have compiled kino on my slackware box, it
> > > may be able to do it as well. I was just hoping for a solution where I do not
> > > have to do any multiplexing/audio combining at all, and have both audio and video
> > > be recorded in realtime. The less time I have to expend with this, the better.
> > > Can Openshot work with flash video format?
> > >
> > > -b.
> > >>
> > >>
> > >> On Sat, Jul 20, 2013 at 10:07 AM, Borries Demeler
> > >> <demeler at biochem.uthscsa.edu> wrote:
> > >> > On Thu, Jul 18, 2013 at 03:09:47PM -0500, Austin Lowery wrote:
> > >> >> I have played around with Recordmydesktop and Kazam from the Ubuntu 13.04
> > >> >> software center and with my set up Kazam is a winner for sure.
> > >> >> Recordmydesktop is great for videos about 30 seconds long, and then for
> > >> >> some reason it just stops recording. Its probably just my set up though.  I
> > >> >> can take long high resolution viedos with Kazam.
> > >> >>
> > >> >> I am running an Intel® Core? i5-3470 CPU @ 3.20GHz × 4 with 8 gigs of ram.
> > >> >
> > >> > I tried both of these without success. Recordmydesktop basically failed to
> > >> > record fast enough, and the -fps setting seemed to be without effect. And
> > >> > that was on an 8-core I7 with ssd drive and 8GB RAM, certainly enough
> > >> > horsepower. Kazam requires Python 3.2, Slackware comes with 2.7.3 in
> > >> > the latest version so it refuses to run under Slackware. I don't have
> > >> > an Ubuntu box to try it.
> > >> >
> > >> > I think I may have found something that would work: a combination of
> > >> > vnctoflv, x11vnc and the KDE plasma desktop effects. I can run x11vnc
> > >> > on my linux :0 desktop on my second screen and record that screen with
> > >> > vnctoflv. The recorded flash video is smooth and very high quality. I can
> > >> > resize the resolution of the second screen easily with desktop setting
> > >> > app in KDE to whatever I need and with the plasma desktop in KDE I can
> > >> > use various magnification effects to highlight and magnify a rectangle
> > >> > around the mouse which nicely tracks on the vnc screen and gets recorded,
> > >> > so I have my magnification effect incorporated. One thing I would like to
> > >> > be able to do is panning under vnc (not scrolling), where the desktop
> > >> > dynamically expands by following the mouse. Haven't figure this one out
> > >> > yet.
> > >> >
> > >> > One thing that I also need to figure out is how to record a mp3 sound
> > >> > track and multiplex it synchronized to the flash movie. There is an app
> > >> > that comes with the vnctoflv program that is supposed to do that.
> > >> >
> > >> > Some more testing needed....
> > >> >
> > >> > Thanks for all the suggestions! -b.
> > >> >>
> > >> >>
> > >> >> On Wed, Jul 17, 2013 at 3:54 PM, Borries Demeler <
> > >> >> demeler at biochem.uthscsa.edu> wrote:
> > >> >>
> > >> >> > Thanks Don, tried wink, but it crashes on my install - looks like the
> > >> >> > wrong glibc ver...  I'll try it on another computer. Thanks for the tip
> > >> >> > though, will try some of the others on your list.
> > >> >> >
> > >> >> > -b.
> > >> >> >
> > >> >> >
> > >> >> > On Wed, Jul 17, 2013 at 03:40:02PM -0500, Don Davis wrote:
> > >> >> > > I was not (very) lucky with the top GNU/Linux candidates that people
> > >> >> > > most frequently mention e.g. recordmydesktop, Istanbul, etc. They
> > >> >> > > provided basic functionality but flaked out a bit.
> > >> >> > >
> > >> >> > > As far as making instructional videos with a screen capture tool in
> > >> >> > > Linux - I had the most luck with 'Wink' - it's free but not open source.
> > >> >> > > It makes editing and adding extras (e.g. arrows, stickies, etc.) quite
> > >> >> > easy.
> > >> >> > >
> > >> >> > > http://www.debugmode.com/
> > >> >> > >
> > >> >> > >
> > >> >> > > Most screen capture recommendations I saw with a quick Google search
> > >> >> > > were pretty basic. This one had Wink and some I hadn't seen before - so
> > >> >> > > it might be worthwhile:
> > >> >> > > http://ostatic.com/blog/six-top-screen-capture-tools-for-linux
> > >> >> > >
> > >> >> > >
> > >> >> > >
> > >> >> > > On 07/17/2013 03:30 PM, Borries Demeler wrote:
> > >> >> > > > Does anybody have any experience with using screen recording tools in
> > >> >> > > > Linux that can produce videos that can be uploaded to youtube or some
> > >> >> > > > other website in a generic video format? I want to create a series of
> > >> >> > > > instructional videos for our software. I have done this in the past by
> > >> >> > > > recording a statically sized VNC window big enough to capture the whole
> > >> >> > > > screen (and rather large/complex GUI elements) and converting the
> > >> >> > captured
> > >> >> > > > vnc session into a flash movie.
> > >> >> > > >
> > >> >> > > > The problem with this approach is that some screens and apps are so
> > >> >> > large
> > >> >> > > > that I need to make a very big vnc window (and hence a large sized
> > >> >> > video
> > >> >> > > > format) in order to capture the entire application. On youtube I have
> > >> >> > > > seen recordings where preset (smaller) sized screen segments follow the
> > >> >> > > > mouse, so that preset sized screen segment is not too large for small
> > >> >> > > > screens, but still everything is shown at high resolution, even if the
> > >> >> > > > entire screen can not be seen. I also need the ability to record sound
> > >> >> > > > and multiplex that with my screen video recording, it would be best if
> > >> >> > > > the recording can do this simultaneously.
> > >> >> > > >
> > >> >> > > > If you can offer a recommendation based on prior experience for
> > >> >> > something
> > >> >> > > > that is stable and has the needed features that would be great!  An
> > >> >> > open
> > >> >> > > > source solution I can compile without an endless list of dependencies
> > >> >> > > > under a recent version of Slackware would be preferred.
> > >> >> > > >
> > >> >> > > > Thanks for any tips!
> > >> >> > > >
> > >> >> > > > -borries
> > >> >> > > --
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