Testing quad precision in resampling DSD to PCM about resampler

[jniemann66]

Hi Klassikmann - I'm impressed that you tried the quad-precision version - you Mad lad !!
Unfortunately, the speed of quad-precision is never going to be great unless one day we have a CPU that does quad precision in hardware - until then, the 128-bit quad-precision operations need to be "simulated" in software.

Nevertheless, there might be some things that can be done to speed it up a bit. I haven't really tested DSD with quad-precision much - I didn't think there would be much interest in doing so, but you appear to have contradicted that little assumption :-) , so maybe there are some optimization opportunities lurking in the shadows.

I'll have a look into it when I get a chance - absolutely flat-out atm. Can't promise anything, but who knows ? might be able to squeeze some more out of it - should be able to do better than 0.1x at any rate.

Cheers
Judd

[klassikmann]

Hi Judd,

thank you for your immediate feedback.

You're right, I'm testing quadruple-precision out of pure curiosity. Double-precision is more than enough for real life. The slowness of quad-precision seems to be appear in DSD->PCM conversion only.

Here a test result resampling PCM 16/44.1 (46'44") to 24/48:
Single-Precision (-r 48000 -b 24 --mt --multistage):
Time=101819 ms [27.5x]

Double-Precision (-r 48000 --doubleprecision -b 24 --mt --multistage):
Time=104067 ms [26.9x]

Quad-Precison (-r 48000 -b 24 --mt --multistage):
Time=91972 ms [30.5x]

Quad-precision seemed to be the fastest.

Regards
Herbert

[jniemann66]

Ok - Thanks for that. There might be something going wrong with DSD conversion in Quad precision - I'll try to check it out on the Weekend