[FFmpeg-devel] ARMv4 Development

Siarhei Siamashka siarhei.siamashka
Wed Jul 30 14:53:56 CEST 2008

On Monday 28 July 2008, Asif Tasleem wrote:
> My team is working on a Windows Mobile 6 application that provides
> multimedia processing functions like trimming and joining video files.
> I have compiled FFMPEG successfully for ARMv4 Processor.
> Following is the status of the operations that we are trying to perform on
> windows Mobile.
> 1)      Trimming operation only trims the video data in a Video file.
> 2)   Changing -ab value to higher rates generates nothing in the output
> file
> 3)      Discarding Audio/Video generates the files but files are not
> playable.
> 4)      Conversion from AVI to MPEG is working 100%.
> 5)      Converting a sequence of images to a video crashes the application
> However these operations are working 100% on the i386 compilation.
> Would you please like to refer some resource who could help us in finding
> out the solution to these issues.

If you have testcases where i386 build works fine while Windows Mobile 6 build
does not, you can try to look for the place where things start to be wrong.
Enable the most verbose output, add some of the debugging output messages
yourself. Once you find the offending part(s) of code, you can try to fix it
and submit a patch or ask for further assistance.

Standard FFmpeg regression test used to pass fine on ARMv6 not so long ago 
with ALT_BITSTREAM_READER. I may re-run it again shortly just to be sure.

So while I'm basically only interested in audio/video decoding, encoding
should not be in a very bad shape either. One of the possibilities 
is that you might have screwed something when building FFmpeg for Windows
Mobile 6. Of course, bugs that are not caught by regression tests are also

As you are using an old ARM core, you may have some alignment problems not
detected in my runs of regression tests on ARMv6 device. This is probably
worth checking.

> We are aimed to improve the FFMPEG for ARMv4 and definitely we will make
> our efforts "open source" as well.

Yes, making you "efforts" open source is the only legal way to use FFmpeg.
That is if you add modifications to the code of course.

Best regards,
Siarhei Siamashka

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