julien.breval@tremplin-utc.net wrote:

hello

All this happens under Windows XP

I discovered there was a slight latency when I use [adc~] with my sound card, and it would be good to reduce it (I currently don't have any performance problems)

in the configuration panel of the HDSP card, "Buffer Size (latency)" is 128 samples (3 ms)

which command line should I use for launching Pure Data ?

the current one is :

pd.exe -r 44100 -inchannels 8 -outchannels 8 -audioindev 2 -audiooutdev 2 - asio -blocksize 128 ============================================================================ Therefore only the pd internal I/O audio buffer size is explicitely specified here, not the sound card I/O audio buffer size 128 is weak for "-blocksize", I should set it to 2 or 4

So maybe this one would be better :

C:\pd\bin\pd.exe -r 44100 -inchannels 8 -outchannels 8 -audioindev 2 - audiooutdev 2 -asio -audiobuf 3 -blocksize 4 ============================================================================

hi. the measurements i have done with the HDSP/winXP have not been very satisfying. the main problem used to be, that measurements tended to be not-reproducable under winXP (as they were under linux)

test system was an athlon-XP3200+ machine (winXP-pro).

as far as i remember i didn't use the "-blocksize" option (don't know why; probably it had no effect) the "-audiobuf" should be at least the corresponding value to the buffer-size you set at the control-panel (for a buffersize of 128, use 3ms of audiobuf)

i didn't get any reasonable results with a buffer-size below 256. the best result i got was about 2179 samples (which is 50ms @ 44.1kHz) but it was not very stable (at least at at CPU-load of 80%) (but it really performed quite erratically: e.g: with an rme-buffer of 2048 samples (which gave me a latency of 6019 samples) i didn't get *any* good signal, even at a virtual load of 0% !!)

that was the main reason, why we chose to use linux even more for latency-critical applications. (at least we could do 835 samples latency with a load of 50% on the same machine with alsa/jack; and without file-access (this does not mean writing to soundfiles, but rather saving big-files at once) during dsp-processing the system gave us a stable latency of 1603 samples at 80% cpu-load)

but really, for low latency the old rme-hammerfall cards (which are not sold anymore) with OSS drivers performed best: without filesystem-access it gave us latency of 193samples, even at high load (80%). with the need to read and write files during the processing at high load, we got 961 samples latency.

quite disappointing.

big tip: use your task-manager to prioritize the pd thread to "real-time" and the pdgui-thread (wish83) to "lowest".

mfg.as.r IOhannes