[FFmpeg-devel] ffmpeg configure for ios - using asm options causes MPx (mp1, mp2, mp3) codecs sound problems

Michael Niedermayer michaelni at gmx.at
Wed Jan 29 04:53:55 CET 2014

On Sat, Apr 20, 2013 at 01:36:52PM +0300, Murat Sudan wrote:
> I've made many tests to get good performance for video decoding with ffmpeg
> on low cpu idevices such as iPad 1 and iPhone 3Gs, and see that using asm
> option when configuring ffmpeg for cross compiling for ios is very very
> important for performance..
> But when I configure with --enable-asm, the audio stream which using
> mpx(mp1,mp2,mp) codec sounds squeaky. If I configure with --disable-asm
> option, than mpx(mp1,mp2,mp) codec sounds well but then the performance is
> %50 percent of the previous one built with the --enable-asm option...
> I've also tested these with the ffmpeg versions that are 0.8, 0.9, 0.10,
> 0.11, 1.0,1.1,1.2 All of them produces same results...
> Can anyone have the same problem with me ? Also, any idea how can I fix
> this issue ? please advice me .. (I can not find any patch to fix this
> issue on the net or in ffmpeg forums.)

if this issue is still unfixed then to debug that you either have to
disable asm functions one by one (that is bisect which are enabled)
to find the faulty one and then find out why it fails


put lots of printfs in the code and compare the output of a good and
bad ffmpeg until you find out where the first differences occur

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Freedom in capitalist society always remains about the same as it was in
ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin
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