[FFmpeg-devel] FFMpeg on SH4 (STi7109)

Mike Melanson mike
Wed Nov 19 08:18:28 CET 2008

Reimar D?ffinger wrote:
> On Wed, Nov 19, 2008 at 12:54:55AM +0000, M?ns Rullg?rd wrote:
>> Could I ask you to run some simple benchmarks with and without the
>> functions from qpel.c and dsputil_align.c?  I have the feeling those
>> optimisations are not all that optimal when all comes around.  A
>> comment in qpel.c talks about *p++ vs. p[n] to access arrays, and most
>> functions in this file seem to be the plain C functions rewritten to
>> use *p++ access.  There is, however, very little difference in the
>> generated code.
> I have the feeling that might be because some (probably all) sh4
> compilers really suck(ed) very much.
> IIRC the last time SH4 came up here was because some compiler
> miscompiled half of FFmpeg...

There are at least some versions of gcc that are known to produce proper 
code. I remember gcc 3.0.3 and 3.4.something working reliably. Before 
3.0, there were some well-known problems.

     -Mike Melanson

More information about the ffmpeg-devel mailing list