[FFmpeg-devel] MPEG decoding on the iPhone is buggy

Måns Rullgård mans
Wed Sep 30 21:58:37 CEST 2009

Yoni Levy <yonilevy at gmail.com> writes:

> Disclaimer: I've posted a mail regarding this issue to ffmpeg-user a few
> hours ago (
> http://lists.mplayerhq.hu/pipermail/ffmpeg-user/2009-September/022179.html)
> The reasons I'm re-posting here are: 1) I got a lot more specific with the
> problem and 2) Given (1), I've been told this listing is more appropriate.
> I've written a mock-up iPhone application that uses the latest ffmpeg (SVN
> version) in conjunction with ffmpeg4iphone patches to play video from a file
> on the iPhone device.
> When I play an MPEG encoded file, the results I get look something like
> this:
> http://img2.imageshack.us/img2/3325/frame477.png
> http://img8.imageshack.us/img8/290/frame726.png
> http://img2.imageshack.us/img2/7680/frame863.png
> This bug is only occuring when decoding MPEG videos (h264 and real media for
> example, work fine) and someone suggested it is a result of ARM
> optimizations (I believe these were applied by the ffmpeg4iphone patches but
> I'm not sure). Anyhow, a bug has been reported to the ffmpeg4iphone project
> regarding this a few months ago, but hasn't been resolved yet. The
> discussion can be found here:
> http://code.google.com/p/ffmpeg4iphone/issues/detail?id=9 (it starts off a
> bit unrelated with talk about the move from img_convert to sws_scale).
> To my understanding nobody is currently working on a fix for that, which is
> a shame because ffmpeg4iphone is now only half a solution.
> Can anyone here suggest a solution, or get me closer to the bug itself?

What exact configure line did you use?  What exact ffmpeg command line
will produce broken output?

M?ns Rullg?rd
mans at mansr.com

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