Hello all,
I’m porting an SDL game to a device with low CPU power.
I face a problem caused by the huge amount of CPU required to decode mod’s
files.
Using valgrind I investigate the problem and discovered that quite all
the time was spent inside the high quality version (virtch2.c) of
MixStereoNormal()
(example of cg_annotate output)
304,109,309 … MixStereoNormal
62,506,907 … Mix32To16_Stereo
4,035,756 … memset
1,016,320 … SL_LoadInternal
831,704 … getc
395,642 … ConvertNote
so I did a patch to enable the low quality version with a configure switch
(–disable-mod-hq-mixer) that reduce more than 10 times the CPU consumption,
obvioulsly at the price of lower quality
(example of cg_annotate output with low quality mixer)
20,365,031 … AddChannel
13,879,944 … Mix32To16
1,824,095 … memset
1,016,320 … SL_LoadInternal
831,704 … getc
395,642 … ConvertNote
324,006 … pt_UpdateVoices
…
the patch is here:
http://www.digital-and-dreams.net/patches/SDL_mixer/disable_mod_hq_mixer.patch
Gianni.