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Weblog:   H.264 is Amazing
Subject:   H.264, Compression & Multi-threading
Date:   2005-05-02 14:31:23
From:   DRayMIS
I was playing with H.264 at an Apple Store this weekend, and found a couple of amazing features:
- I created a slideshow in Keynote, exported to QT w/ JPEG200, then opened it in QT 7 & exported to H.264. The original file was 500MB, exported as:
- High: about 18MB @ 800x600
- Med: about 12MB @ 800x600
- Low: 2.3MB @ 800x600
I honestly couldn't tell the diff. b/w 'high' & 'med', both looked awesome. The 'low' looked too blocky, and had trouble with the transitions. However, if I had reduced to 400x300 during export, it would have looked great. All settings used auto-keyframes (makes a big. difference on file size) and 30fps.


Even using 3ivx I've never gotten such small files & 800x600!


2nd, QT now makes an export funtion a seperate thread (viewable in activiy monitor)!! This means you can do multiple exports running at the same time!


For example, on a DP 2.3ghz G5, I was exporting the same source as three different export files (high, med. & low quality settings) - at the same time!! (with three seperate threads showing up in activity monitor!)


Encode times seemed a bit slow, so I tried it again only peforming one export, but it didn't speed up the process. So... you can do multiple exports simultanously, without any major performance hit!
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  • Derrick Story photo RE: H.264, Compression & Multi-threading
    2005-05-03 07:34:29  Derrick Story | O'Reilly AuthorO'Reilly Blogger [View]

    This is really interesting and helpful information... thanks!
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