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 [...] -- 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
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