The patch Mark attached looks good and valgrind gives it a clean bill of health:
Mark.Howson@ntu.ac.uk 2010-12-15 07:45:25 PST
Reproducible here under Windows and Linux. Looking at the code for
SDL_Upsample_S16LSB_2c:
const int dstsize = (int) (((double)cvt->len_cvt) * cvt->rate_incr);
Sint16 *dst = ((Sint16 *) (cvt->buf + dstsize)) - 2;
const Sint16 *target = ((const Sint16 *) cvt->buf) - 2;
while (dst > target) {
dst[1] = ((Sint16) SDL_SwapLE16(sample1));
dst[0] = ((Sint16) SDL_SwapLE16(sample0));
dst -= 2;
...
if dstsize is odd (and therefore dst), it'll write to target[1] which is one
byte before the allocated buf.
The attached patch to sdlgenaudiocvt.pl changes dst > target to dst >= target,
and removes the - $channels for the upsample case. The patch is not fully
tested, but seems to work here.
I'm not confident this is a complete fix, but I'm not confident the current
resamplers are really worth keeping at all, either.
--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%404352
We should probably give options to drop resamplers by channels, too, for
developers that know they'll never need more than stereo, etc.
--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403481
Notable changes:
- Converters between types are autogenerated. Instead of making multiple
passes over the data with seperate filters for endianess, size, signedness,
etc, converting between data types is always one specialized filter. This
simplifies SDL_BuildAudioCVT(), which otherwise had a million edge cases
with the new types, and makes the actually conversions more CPU cache
friendly. Left a stub for adding specific optimized versions of these
routines (SSE/MMX/Altivec, assembler, etc)
- Autogenerated converters are built by SDL/src/audio/sdlgenaudiocvt.pl. This
does not need to be run unless tweaking the code, and thus doesn't need
integration into the build system.
- Went through all the drivers and tried to weed out all the "Uint16"
references that are better specified with the new SDL_AudioFormat typedef.
- Cleaned out a bunch of hardcoded bitwise magic numbers and replaced them
with new SDL_AUDIO_* macros.
- Added initial float32 and int32 support code. Theoretically, existing
drivers will push these through converters to get the data they want to
feed to the hardware.
Still TODO:
- Optimize and debug new converters.
- Update the CoreAudio backend to accept float32 data directly.
- Other backends, too?
- SDL_LoadWAV() needs to be updated to support int32 and float32 .wav files
(both of which exist and can be generated by 'sox' for testing purposes).
- Update the mixer to handle new datatypes.
- Optionally update SDL_sound and SDL_mixer, etc.
--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%402029
