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copied!<p>Instead of chosing fixed bit rates, with the H.264 codec, you can also chose a different preset as described at <a href="https://trac.ffmpeg.org/wiki/x264EncodingGuide" rel="noreferrer">https://trac.ffmpeg.org/wiki/x264EncodingGuide</a>. I also found <a href="http://keyj.emphy.de/video-encoder-comparison/" rel="noreferrer">Video encoder comparison at KeyJ's blog</a> (<a href="http://archive.is/Tldgp" rel="noreferrer">archived version</a>) an interesting read, it compares H.264 against Theora and others.</p> <p>Following is a comparison of various options I tried. The recorded video was originally 673M in size, taken on an iPad using <a href="https://github.com/coolstar/RecordMyScreen" rel="noreferrer">RecordMyScreen</a>. It has a duration of about 20 minutes with a resolution of 1024x768 (with half of the video being blank, so I cropped it to 768x768). In order to reduce size, I lowered the resolution to 480x480. There is no audio.</p> <p>The results, taking the same 1024x768 as base (and applying cropping, scaling and <a href="https://stackoverflow.com/a/20313722/427545">a filter</a>):</p> <ul> <li>With no special options: 95M (encoding time: 1m19s).</li> <li>With only <code>-b 512k</code> added, the size dropped to 77M (encoding time: 1m17s).</li> <li>With only <code>-preset veryslow</code> (and no <code>-b</code>), it became 70M (encoding time: 6m14s)</li> <li>With both <code>-b 512k</code> and <code>-preset veryslow</code>, the size becomes 77M (100K smaller than just <code>-b 512k</code>).</li> <li>With <code>-preset veryslow -crf 28</code>, I get a file of 39M which took 5m47s (with no visual quality difference to me).</li> </ul> <p>N=1, so take the results with a grain of salt and perform your own tests.</p>

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