Re: [pygame] noise added on OGG playback

[David Tweet <davidtweet@xxxxxxxxx>]

This is what I am running (I'm really curious whether anyone can
reproduce it on their (different) system using the screensaw demo):

Python 2.4
Pygame 1.7.1
SDL version 1.2.8
Windows XP SP2
M-Audio MobilePre sound card with ASIO driver

I tried playing a WAV with pygame.mixer.music, but it doesn't accept
WAV as a format.

Something else strange:  I was testing with my laptop's built-in
soundcard, and all the audio was distorted--had to take out the entire
pre-init line and then it was fine.

-david.


On 9/24/05, Rene Dudfield <renesd@xxxxxxxxx> wrote:
> ah, I guess this is something for sdl_mixer to fix then.
>
> Or pygames use of sdl_mixer.
>
> Out of interest... does this happen with wavs?  What os, pygame
> version, sdl version, do you use?
>
> Cheer.
>
>
>
> On 9/25/05, David Tweet <davidtweet@xxxxxxxxx> wrote:
> > Thanks very much for the suggestion, I hadn't tried it yet.
> > It has some effect--when I increase the buffer size to something very
> > large, say 1024 * 10, the crackling noise is reduced but not
> > eliminated.  Of course something like that would create much too long
> > of a delay.
> >
> > I also tried increasing the quality of the OGG file (less compressed)
> > but that has no effect at all.
> >
> > I've attached a modified version of the Screensaw demo from the PyGame
> > website.  It calls my song at 0 seconds for Critter, and then again at
> > 4.3 seconds for Ant.
> >
> > I uploaded the song in question to
> > http://davidtweet.com/noise_test_polka.ogg
> >
> >
> > -david.
> >
> >
> > On 9/24/05, Rene Dudfield <renesd@xxxxxxxxx> wrote:
> > > Hey,
> > > try using the pre_init line below to increase the buffer size.  It
> > > works for reducing noise on other systems.
> > >
> > > pygame.mixer.pre_init(44100,-16,2, 1024 * 3)
> > > pygame.init()
> > >
> > >
> > > Cheers,
> > >
> > >
> > >
> > > On 9/25/05, David Tweet <davidtweet@xxxxxxxxx> wrote:
> > > > I have a problem playing some OGG files with pygame.mixer.music.play():
> > > > When I pass a start position that's not zero into this function, on
> > > > playback of some files (not all), I get noise mixed in with the
> > > > playback of the file for as long as that file continues to play.  The
> > > > noise resembles loud crackle from a vinyl record.
> > > >
> > > > The WAV files were originally 16-bit/44.1kHz, I converted to OGG using
> > > > the same consistent settings in Audacity, and I have called
> > > > pygame.mixer.init(44100).  All the files sound fine played back from a
> > > > zero start position, and some even sound fine with a non-zero start
> > > > position, but others consistently have this problem with a non-zero
> > > > start position.
> > > >
> > > > I've considered that it might have to do with whether the music at the
> > > > specified start position is at a zero crossing (all nearby samples at
> > > > least close to zero amplitude), but no amount of modification of the
> > > > file at the chosen time point was able to remove the noise.  Plus, it
> > > > seems like the worst that ought to happen is that you would hear an
> > > > isolated clipping sound at the beginning of the file (if the
> > > > zero-crossing issue were it).
> > > >
> > > > Can anyone enlighten me somewhat on this?  Has anyone had a similar experience?
> > > >
> > > > Thank you,
> > > > David Tweet.
> > > >
> > >
> >
> >
> > --
> > David Tweet
> > __________________
> > http://davidtweet.com
> >
> >
> >
>


--
David Tweet
__________________
http://davidtweet.com