Re: [pygame] Mixer latency

["René Dudfield" <renesd@xxxxxxxxx>]

hey,

cool.  I'll try and test it later (in about 8 hours).

Sounds like an interesting project :)



On Mon, Mar 31, 2008 at 3:26 PM, Wyatt Olson <wyatt.olson@xxxxxxxxx> wrote:
> Yes, I have tried all sorts of buffer sizes (all the way down to 8).  I
>  can't see any difference in performance with any of these.  As for the
>  source, I tool a  look at mixer.c, but to be honest I am not as up to
>  date on my C as I would like - I have concentrated on higher level
>  languages for a bit too long, and have forgotten the details of these
>  older ones. 8-(
>
>  As for the program, you can access it at
>  http://drummaster.thecave.homeunix.org/files/DrumSlave_Minimal.zip .
>  This only has one sample (a snare drum) for testing, which is mapped to
>  port 0.  Other than that, it is exactly as I am using it.
>
>  To run, unzip and use the command:
>
>  python drum_slave.py --keyboard rock
>
>  It should run on python 2.4 or 2.5, with any semi-recent version of pygame.
>
>  The application is meant to be the slave for a hardware board I
>  developed, which talks to the computer via a serial port.  To allow
>  testing, I added the keyboard mode, in which you can manually type the
>  commands which otherwise would come over the serial port.
>
>  Once the application starts, type "0:1023" (without quotes), and hit
>  enter.  A drum sound will play.  I am measuring latency by recording the
>  whole thing in an audio recorder, and measuring the difference in time
>  between the sound of me hitting enter and the sound of the sample being
>  played.  In my tests, it seems to average to about 65 or 70 ms, with a
>  maximum of about 100ms.
>
>  As for program layout, the initialization is done in slave.py.
>  drum_slave.py is just the command line wrapper.  Pygame Sound objects
>  are played in hardware/sensor.py.  I don't think that anything else
>  would be relevant to this discussion, but it should be simple enough to
>  find your way around in, if you are interested - the program is not very
>  large.
>
>  All my testing so far has been done on OS X.  I am planning to try some
>  tests on Linux, once I can get a box put together.  If anyone does test
>  this on a different platform, I would be very interested in hearing the
>  results, and how they compare to mine.
>
>  Thanks for all your help!
>
>  Cheers
>
>
>
>  René Dudfield wrote:
>  > Hello,
>  >
>  > Do you have a link to your code?
>  >
>  > You've tried setting a really small buffer size?  Like 512 or something?
>  >
>  > Have a look at src/mixer.c to see how SDL is used.
>  >
>  > cheers,
>  >
>  >
>  >
>  > On Mon, Mar 31, 2008 at 2:50 PM, Wyatt Olson <wyatt.olson@xxxxxxxxx> wrote:
>  >
>  >>  Upgraded to pygame 1.8 / python 2.5 - still the same latency.
>  >>
>  >>  I am thinking that it may be related to SDL itself, and not the python
>  >> wrapper per se... I have seen some suggestions on lowering the chunk size in
>  >> SDL.  Does this map directly to the buffer size in pygame, or is there some
>  >> magic happining behind the scenes?
>  >>
>  >>  Thanks
>  >>
>  >>
>  >>
>  >>  Wayne Koorts wrote:
>  >>
>  >>  Does anyone have any suggestions on what I can try?
>  >>
>  >>  Wouldn't hurt to upgrade to Pygame 1.8 for a start.
>  >>
>  >> Regards,
>  >> Wayne
>  >>
>  >>
>  >>
>
>