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

[Yoni Levy]

This is the configure line I'm using:

./configure --enable-cross-compile --target-os=darwin
--cc=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/arm-apple-darwin9-gcc-4.0.1
--extra-cflags="-arch armv6 -pipe -miphoneos-version-min=2.0 -isysroot
/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS2.1.sdk
-I/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS2.1.sdk/usr/include/gcc/darwin/4.0"
arch=armv6
--extra-ldflags="-L/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/IphoneOS2.1.sdk/usr/lib"
--prefix=build --disable-shared --enable-static --disable-mmx
--disable-iwmmxt --disable-neon --disable-armvfp --disable-armv5te
--enable-armv6 --disable-debug --disable-stripping --arch=arm
--disable-ffmpeg --disable-ffserver --disable-ffplay --disable-gpl
--disable-nonfree

I didn't use ffmpeg itself, I'm just using the libs to decode video. I'm
pretty sure though any attempt to use the generated ffmepg in a way it has
to decode MPEG will generate these results (since other people had the same
results <http://code.google.com/p/ffmpeg4iphone/issues/detail?id=9>). I
would have tested this myself but I have a problem running ffmpeg/ffplay on
my device.

Thanks for helping.

2009/9/30 M?ns Rullg?rd <mans at mansr.com>

> 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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