[PD] trying to configure hammerfall + asio..

[kristof lauwers]

hello list,

i just bought a hammerfall DIGI96/8 card, and now i'm trying to configure 
pd to get the lowest possible latency out of it. i first tried with 
pd-0.36, then with  pd-0.37. with both some strange things happened. 
(<ashamed to admit> using win ME</> on a DELL pentium III 64meg RAM)

pd0.36 seems to change the number of audio buffers i ask for, sometimes 
lowering them to 1!

the details:

when i try: "pd -asio -listdev -blocksize 32 -audiobuf 4:

pd first says "4 audio buffers", then "bufs 8" in stead

quoting the console:
    Number of devices = 1
    ---------------------------------------------- #1 DefaultInput 
DefaultOutput
    Name         = ASIO DIGI96 Serie
    Max Inputs   = 16, Max Outputs = 16
    Sample Rates = 44100.00, 48000.00, 88200.00, 96000.00,
    Native Sample Formats = paInt32,
    ----------------------------------------------
 >  4 audio buffers
    not using MIDI input (use 'pd -midiindev 1' to override)
    using default input device number: 0
    using default output device number: 0
 >  nchan 2, flags 3, bufs 8, framesperbuf 32



as pd seems to prefer 8 buffers: " pd -asio -listdev -blocksize 32 -audiobuf 8"

now the console first says "4 audio buffers", then changes it to "bufs 16"
latency (measured with the patch from the doc files) is +- 27ms - this 
works fine, but i'd expect about 12ms here - (32 * 16 / 44100 = .0116")?

(snipped the beginning as it stays the same..)
    4 audio buffers
    nchan 2, flags 3, bufs 16, framesperbuf 32



another try: "pd -asio -listdev -blocksize 64 -audiobuf 4"

pd doesn't change the params here - latency 16ms (but the audio is fucked 
up, so i can't use this setting)

    4 audio buffers
    nchan 2, flags 3, bufs 4, framesperbuf 64



"pd -asio -listdev -blocksize 128 -audiobuf 4"

even weirder - pd sets bufs to 1, than says it's less than recommended..

    4 audio buffers
    nchan 2, flags 3, bufs 1, framesperbuf 128
    warning: number of buffers 1 less than recommended minimum 2


(tried some other settings also, getting similar results as above..)



with 0.37 i first tried "pd -asio -listdev -blocksize 32 -audiobuf 8"

choosing media from the menu: everything seems ok. the delay (i suppose 
this the same as latency?) field is set to 8 ms, but the actual latency is 
about 25 ms

next i tried with a higher sampling rate, as according to the hammerfal 
docs this should allow for lower latency..:
"pd -asio -r 96000 -listdev -blocksize 32 -audiobuf 8"

the displayed delay is again 8ms, the actual delay is 17.3ms (without jitter!?)
but now metro works at about half speed and the osc~ freq is about two 
times (probably 2.18 times) too low, so somewhere something goes wrong with 
the samplerate..
when i set delay to 4 msec in the media window i get a latency of 12 
ms.  (with no -r 96000 flag this doesn't work, as the audio then is 
completely fucked up when i try to set delay to 4)

the 12ms seems to be the lowest i can get.. is there any chance i can get 
lower if i'd try it on linux with ALSA? i need to put real time effects 
on  sharp-attack-no-sustain-instruments such as harpsichord and lute, so i 
really want the latency to be as low as possible..


thanx for reading this far - now i hope someone can answer my questions..

kind regards,

kristof




____________________________________

kristof.lauwers at logosfoundation.org

http://kristoflauwers.de.vu
____________________________________