As the title suggests, I am asking a lot.

We've been trying to generate some screencasts on my eeepc. recordmydesktop is doing the job decently, but only if allowed time to "compile" the video afterwards. If we ask it to do "on the fly", video and audio get out of sync.

Now, we are creating many screencasts as practice (and like to watch them after, to criticize). Reducing quality is undesirable, because eventually a good practice run becomes the one we'll release.

So we'd like a way to do screencasts "on the fly", with decent quality, on the low end machine. As nothing is ever free, we are willing to sacrifice: we don't care too much about compression: 20GB for a 15min video is acceptable

  • 1)I would not mind using other software instead of recordmydesktop. 2) Maybe a good approach would be to have recordmydesktop produce bad quality output on a first run (just for us to check the video out) and a better output later (if the video is good enough). That would require keeping the raw files, and using the --rescue option. I am trying to figure out if this is possible, with not much success (have not been able to --rescue a single video so far) – josinalvo Jun 17 '12 at 2:40

I've found a satisfatory way:

It seems that mkv(**) allows for many levels of compression. By using a low compression for video, I am able to record in real time and with quality on my lowly eeepc.

To achieve that, I had to use ffmpeg. It is available in Ubuntu, but I used a version from a ppa(*):

To install:

sudo add-apt-repository ppa:jon-severinsson/ffmpeg
sudo apt-get update
sudo apt-get install ffmpeg

To record:

ffmpeg -f x11grab -r 25 -s 800x450 -i :0.0+0,60 -f alsa  -i plughw:1,0 -vcodec libx264 -crf 0 -preset ultrafast -acodec pcm_s16le file.mkv

The important part is this "preset ultrafast" that tells the encoder not to compress the video too much.

(*) apparently, Ubuntu is using a fork of ffmpeg that is not the most common in use. I tried that line with Ubuntu's ffmpeg and it did not work. However, one should note that I am still using 11.10

(**) probably mkv is a container, and this libx264 is the codec that allows different compressions ...

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I've had only great experiences with Kazam Screencaster so far. I don't know how it would behave on a low end PC, but on mine it produces high quality recordings that can be saved instantly after the recording is stopped.

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Here's how I solved the issues


but I need to try Kazam now!

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  • I'd be nice to have a summary of that post in here. – josinalvo Aug 17 '12 at 13:51
  • The heart of the matter seems to be this "zero compression". How do you achieve that ? What is the command you use in the command line ? – josinalvo Aug 17 '12 at 13:53
  • Welcome to Ask Ubuntu! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. – Peachy Sep 27 '12 at 11:51

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