[FFmpeg-devel] [PATCH] make tiny_psnr work with 32-bit audio
Mon Nov 9 04:51:53 CET 2009
Michael Niedermayer wrote:
> On Sun, Nov 08, 2009 at 03:29:47PM -0500, Justin Ruggles wrote:
>> Justin Ruggles wrote:
>>> I was trying to do some comparisons with 32-bit audio, but tiny_psnr
>>> kept crashing with a float exception. Then I noticed it does not really
>>> support 32-bit integer comparisons. The attached patch seems to work.
>> Hmmm... Most of the regression tests fail with this patch because of:
>> - psnr= ((2*log16(max<<16) + log16(i) - log16(sse))*284619LL*F +
>> (1<<31)) / (1LL<<32);
>> + psnr= ((2*log16(max<<16) + log16(i) - log16(sse))*284619LL*F +
>> (1LL<<31)) / (1LL<<32);
>> Looking at an objdump of tiny_psnr.o, it appears that the compiler is
>> treating (1 << 31) as a 32-bit integer (with a negative value), then
>> sign extending it to 64-bit. Is that what is meant to happen?
> i think your LL addition fixes a rounding bug
well, here is a patch with just the LL addition and all the resulting
regression test changes.
-------------- next part --------------
A non-text attachment was scrubbed...
Size: 35625 bytes
Desc: not available
More information about the ffmpeg-devel