On Mon, Nov 9, 2015 at 5:14 PM, Michael Niedermayer <mich...@niedermayer.cc> wrote: > On Mon, Nov 09, 2015 at 09:38:43AM -0500, Ganesh Ajjanagadde wrote: >> When upsampling, factor is set to 1 and sines need to be evaluated only >> once for each phase, and the complexity should not depend on the number >> of filter taps. This does the desired precomputation, yielding >> significant speedups. Hard guarantees on the gain are not possible, but gains >> themselves are obvious and are illustrated below. >> >> Sample benchmark (x86-64, Haswell, GNU/Linux) >> test: fate-swr-resample-dblp-2626-44100 >> old: >> 29161085 decicycles in build_filter (loop 1000), 256 runs, 0 skips >> 28821467 decicycles in build_filter (loop 1000), 512 runs, 0 skips >> 28668201 decicycles in build_filter (loop 1000), 1000 runs, 24 skips >> >> new: >> 14351936 decicycles in build_filter (loop 1000), 256 runs, 0 skips >> 14306652 decicycles in build_filter (loop 1000), 512 runs, 0 skips >> 14299923 decicycles in build_filter (loop 1000), 1000 runs, 24 skips >> >> Note that this does not statically allocate the sin lookup table. This >> may be done for the default 1024 phases, yielding a 512*8 = 4kB array >> which should be small enough. >> This should yield a small improvement. Nevertheless, this is separate from >> this patch, is more ambiguous due to the binary increase, and requires a >> lut to be generated offline. >> >> Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com> >> --- >> libswresample/resample.c | 21 +++++++++++++++++---- >> 1 file changed, 17 insertions(+), 4 deletions(-) > > LGTM > > thanks
pushed, thanks. On the note of a lut: any suggestions? In particular, one could for instance create the lut for 2048 phases yielding an 8kB array, etc. > > [...] > -- > Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB > > it is not once nor twice but times without number that the same ideas make > their appearance in the world. -- Aristotle > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
