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awayand

Member

Registered: 2009-09-25

Posts: 398

ffmpeg screen recording filesize

Pardon me for opening several questions about ffmpeg, but I don't want to mix several questions into one post as it may get really hard to keep track of the answers.

I have noticed that recording my screen with the following command:

ffmpeg -f alsa -i hw:0 -f x11grab -s wxga -r 25 -i :0.0 -qscale 31 /tmp/out.mpg

which I assume is the worst quality I can get, I still record at about 1MB/s which is kind of large. Can I further reduce this filesize, and if so, how do I do this?

Thanks a lot!

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: ffmpeg screen recording filesize

I'm not a A/V compression guru, but maybe you can compress the output file with e.g. mp4?

ffmpeg -i source_video.avi input -acodec aac -ab 128kb -vcodec mpeg4 -b 1200kb -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 320x180 -title X final_video.mp4

These settings are for iPod / iPhone, but you can keep the original resolution if you want to.

DrZaius

Member

Registered: 2008-01-02

Posts: 193

Re: ffmpeg screen recording filesize

A common practice is to use a fast, and often lossless, encoder to initially capture your screen and then re-encode this to something more manageable. The two-step method allows you to take advantage of a fast encoder so your screencast looks smooth, and also achieve an output that isn't morbidly obese in file size.

FFcast is a good screencast tool. Also see HOWTO: Proper Screencasting on Linux.