Hmm, maybe I'm missing something, but what about this:
rice_parameter = 0; k = partition_samples;
int n = mean - k;
if (n > 0) {
rice_parameter += n;
k <<= n;
}
I've not looked at this code in its context within stream_encoder.c,
so it's easily possible that I left out something.
Brian Willoughby
Sound Consulting
On Oct 9, 2013, at 08:54, lvqcl wrote:
> MSVS profiler shows that the following code in stream_encoder.c takes
> several percent of CPU time:
>
> for(rice_parameter = 0, k = partition_samples; k < mean;
> rice_parameter++, k <<= 1)
> ;
>
> this code is equivalent to:
>
> rice_parameter = 0; k = partition_samples;
> while(k < mean) {
> rice_parameter++; k <<= 1;
> }
>
> The idea was to accelerate it:
>
> rice_parameter = 0; k = partition_samples;
> while(k*2 < mean) {
> rice_parameter+=2; k <<= 2;
> }
> while(k < mean) {
> rice_parameter++; k <<= 1;
> }
>
> or:
> rice_parameter = 0; k = partition_samples;
> while(k*4 < mean) {
> rice_parameter+=3; k <<= 3;
> }
> while(k < mean) {
> rice_parameter++; k <<= 1;
> }
>
>
> After tuning the code for 16-/24-bit WAV and 32-/64-bit compiles
> I wrote more complex code (see attach). It doesn't look pretty but
> it's faster than the current version. For highest compression preset,
> 24-bit input and 32-bit exe the encoding speed increases by 6..7%.
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