[x264-devel] Bug: horizontal stripes on PPC with Altivec since snapshot 20081125

[Josef Drexler]

On Dec 13, 2008, at 2:56 PM, Guillaume POIRIER wrote:
> On Sat, Dec 13, 2008 at 12:03 AM, Josef Drexler <joe- 
> x264 at jdrexler.com> wrote:
>> The source is 1024x576 h.264 video which I'm transcoding to 720x576
>> with SAR=64/45 (16:9 at PAL resolution). I believe mencoder would do
>> the scaling, so the input to x264 is 720x576.
>>
>> I've now tried another sample, for which the problem doesn't appear
>> only as stripes but rather generally discolored areas too. In case it
>> helps for reproducing the problem, I've uploaded a small sample
>> together with the resulting good and broken encodes at http://
>> jdrexler.com/home/x264-ppc-regression/
>
> Thanks for the sample. I however can't reproduce the problem here  
> on Tiger.
>
> I used the commandline:
> mencoder ~/Desktop/input.mkv -nosound -ovc x264 -x264encopts
> bitrate=900:frameref=6:bframes=3:direct_pred=auto:b_pyramid:weight_b:m 
> e=umh:mixed_refs:subq=6:turbo=1:pass=2
> -o out.avi

With the unscaled 1024x576 sample, the problem doesn't happen here  
either. It does happen when scaling to PAL resolution (720x576)  
however. Please try this command line:

mencoder -vf scale=::::::pal:1 -ovc x264 -x264encopts  
bitrate=900:frameref=6:bframes=3:direct_pred=auto:b_pyramid:weight_b:me= 
umh:mixed_refs:subq=6 input.mkv -o out.avi

(I've removed the two-pass options I was using before since the bug  
shows up in single-pass mode too.)

If that still doesn't reproduce the problem, do you have a G5 or G4?  
It might only be an issue on a 32-bit G4 CPU (or specifically, the  
7450 that's in my Powerbook).