Re: [pygame] Pygame Mixer Crackle noise not an SDL_Mixer problem

["René Dudfield" <renesd@xxxxxxxxx>]

ah,

feel free to change that back... I mistakenly added the extra
brackets, thinking I was cleaning it up - when I was adding the bug
fix for reverse stereo in 8bit.  I should have just left that part
alone.

...

But strangely we were having the crackling sound problem way before I
made that change (about one month ago).




On Thu, Apr 24, 2008 at 12:24 PM, Lenard Lindstrom <len-l@xxxxxxxxx> wrote:
> Beat Nicholas. It is revision 1143 (need 1146 to compile) that breaks things.
>  It deals with an SDL_mixer bug where the stereo channels are reversed for 8 bit
>  sound. I wonder if this is our culprit:
>
>  ==== From around line 160 in mixer.c ===============
>      /*make chunk a power of 2*/
>      for (i = 0; 1 << i < chunk; ++i); //yes, semicolon on for loop
>      chunk = MAX (1 << i, 256);
>  ==== To around line 167 ============================
>      /*make chunk a power of 2*/
>      for (i = 0; 1 << i < chunk; ++i) {
>      chunk = MAX (1 << i, 256);
>      }
>
>  Lenard
>
>
>
>
>  Quoting René Dudfield <renesd@xxxxxxxxx>:
>
>  > This would be a good script to add to pygame for the google testing
>  > project by Nicholas...
>  >
>  > test_between_revisions.py r990 r1175 run_tests.py
>  >
>  > Then it could to a bisect build, and test between the revisions.  It
>  > could take a file name to run between revisions.  So you could pass it
>  > a file to run tests for you.
>  >
>  > eg. for this bug it could be:
>  > test_between_revisions.py r990 r1175 tests/manual/music.py
>  >
>  > It would download, and build them all, then run the tests.
>  >
>  >
>  > cu,
>  >
>  >
>  > On Thu, Apr 24, 2008 at 11:13 AM, Brian Fisher
>  > <brian@xxxxxxxxxxxxxxxxxxx> wrote:
>  > > sweet, you rock. with 185 revisions between, then it only takes 8 more
>  > > get-build-test cycles to narrow it down to a single change :)
>  > >
>  > >
>  > >
>  > > On Wed, Apr 23, 2008 at 4:22 PM, Lenard Lindstrom <len-l@xxxxxxxxx> wrote:
>  > >
>  > > > I have been going through SVN. I have narrowed the problem to between
>  > > revisions 990 (1.0.0 rc 0) and 1175 (1.8.0release). SDL may be involved
>  > only
>  > > indirectly. Simple C programs using it don't have the problem. It could be
>  > > Pygame doing something it shouldn't. Of course Pygame could be exposing an
>  > > SDL problem that has remained dormant until now.
>  > > >
>  > > > Lenard
>  > > >
>  > > >
>  > > > Brian Fisher wrote:
>  > > >
>  > > > >
>  > > > > Your test demonstrates that 1.8 changes are required to cause the
>  > > problem, but clearly SDL is involved, otherwise why would waveout solve
>  > the
>  > > problem as well? If possible, a test of pygame 1.8 against the 1.7 SDL
>  > > versions could still help solve the case.
>  > > > >
>  > > > > maybe in order to figure out what pygame 1.8 change made the crackling
>  > > start happen, you could binary search against svn revisions? i.e. if
>  > pygame
>  > > 1.8 was rev. 1200 and 1.7 was rev 600 (made up numbers) then try rev. 900?
>  > > > >
>  > > > >
>  > > > > On Wed, Apr 23, 2008 at 8:42 AM, Lenard Lindstrom <len-l@xxxxxxxxx
>  > > <mailto:len-l@xxxxxxxxx>> wrote:
>  > > > >
>  > > > >    I have narrowed the problem some. It has something to do with
>  > > > >    Pygame 1.8, not
>  > > > >    SDL. I built Pygame 1.7 and linked against the 1.8 prebuilts. The
>  > > > >    crackling
>  > > > >    went away. I don't know if anyone else thought to move the 1.8
>  > > > >    dependencies to
>  > > > >    1.7. And it definitely involves the SDL DirectX audio driver.
>  > > > >    Changes to that
>  > > > >    driver improved sound quality for 1.8, though it did not
>  > > > >    completely eliminate
>  > > > >    the noise. I fear it is another memory access problem. Let's hope
>  > > > >    it was
>  > > > >    introduced with Pygame 1.8. That should be easier to track down.
>  > > > >
>
>
>