Changes between Version 13 and Version 14 of Capture/Desktop


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Timestamp:
Jan 29, 2015, 7:14:58 PM (3 years ago)
Author:
fratti
Comment:

Added notes about lossless recording

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  • Capture/Desktop

    v13 v14  
    9292ffmpeg -i output.flv -acodec ... -vcodec ... final.flv 
    9393}}} 
     94 
     95== Lossless recording == 
     96 
     97If you want a perfect recording of your desktop, x264 can help. Use lossless encoding, e.g.: 
     98 
     99{{{ 
     100ffmpeg -video_size 1920x1080 -framerate 30 -f x11grab -i :0.0 -c:v libx264 -qp 0 -preset ultrafast -profile:v high444 capture.mkv 
     101}}} 
     102 
     103The high444 profile is used to ensure a lossless RGB to YUV transformation. Otherwise, the capture will not be lossless, and text will look blurry. {{{-qp 0}}} tells x264 to encode in lossless mode, {{{-preset ultrafast}}} advises it to do so fast. 
     104 
     105The encoder should be fast enough on most modern hardware to record without any framedrop, and even leave enough CPU headroom for other applications. 
     106 
     107If most of your screen will be static, it may be useful to use the {{{-tune stillimage}}} parameter, i.e.: 
     108 
     109{{{ 
     110ffmpeg -video_size 1920x1080 -framerate 30 -f x11grab -i :0.0 -c:v libx264 -qp 0 -tune stillimage -preset ultrafast -profile:v high444 capture.mkv 
     111}}} 
     112 
     113If you're going to archive the recording or are concerned about file size, re-encode it losslessly again but with a slower preset. Note that since the initial recording was lossless, and the re-encode is lossless too, no quality loss is introduced in this process in any way. 
     114 
     115{{{ 
     116ffmpeg -i capture.mkv -c:v libx264 -qp 0 -tune stillimage -preset veryslow -profile:v high444 capture_smaller.mkv 
     117}}}