[FFmpeg-devel] MPEG4 Decoding Optimization with VFP on i.MX31

Måns Rullgård mans
Mon Nov 10 17:02:53 CET 2008

Gilles Curchod wrote:
> Hi,
> As part of my diploma project, I work on an i.MX31 development board.
> I want to use the VFP co-processor in order to optimize decoding an
> MPEG4 video.

VFP is a floating-point processor, and video decoding uses integer
arithmetic exclusively.  I very much doubt you'd be able to use VFP
to speed up MPEG4 (or any other video) decoding.

> I'd like to know if you can help me find where the MPEG4 decoding part is.
> I figured that it should be in the libavcodec directory, but I'm blocked
> here...
> I can see the mpeg1/2 or h263/4 files but not the mpeg4 one...

MPEG4 part 2 is more or less h263.

The i.MX31 has an ARMv6 core (ARM1136), which has some SIMD capability,
which can be used to accelerate certain operations.  See dsputil.[ch] for

If you want to use the VFP for something, I'd suggest optimising the FFT
used by most lossy audio codecs, e.g. AAC, AC-3, DTS, and Vorbis.

M?ns Rullg?rd
mans at mansr.com

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