[FFmpeg-devel] MULL()/MULH() & MPEGAUDIO_HP 0

ami_stuff ami_stuff
Sun Jul 19 13:12:24 CEST 2009


It looks for me that mpeg audio decoder uses 32x32->64 even with "normal"
quality (MPEGAUDIO_HP 0) mode. Is there any way to eliminate theses 32x32->64
at least for "normal" quality mode? I think that after change like this it would
be possible to play MP3 files with FFplay on the 68060 in the real time,
just like it is possible with libMAD's player.

BTW. There is a asm code for 32x32->64 (68060) in the longlong.h file,
but GCC don't know how to use it correctly with functions used by FFmpeg.

Here are some speed results (MPEGAUDIO_HP 1) with binar originally generated by GCC
and with manually added asm inlines for all functions (MULL/MUL64/MULH/MAC64/MLS64).
All tests done on the 68060 at 50MHz:

ffmpeg -i test.mp3 test.wav (1 min. long)

04:06 min.
02:48 min. 


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