[x264-devel] recovering by using intra mode on many threads

[Guillaume POIRIER]

Hi Con Kolivas!
Looks like this mailing list also hosts some kernel V.I.Ps ! :-)


On 4/16/08, Con Kolivas <kernel at kolivas.org> wrote:
> Hi all
>
>  I'm using a recent snapshot of your sensational x264 encoder

Your job on the kernel est much appreciated too :-)


>  (x264-snapshot-20080403-2245), and to keep a quad core optimally busy I need
>  to use more than 4 threads (8 seems about optimal). Unfortunately that ends
>  up giving me lots of errors like this:
>
>
>  mb type: 18
>  mv: l1r0 (0,116)
>  limit: 96
>  mb_xy: 34,4
>  completed: 88
>  x264 [warning]: recovering by using intra mode
>  x264 [warning]: internal error (MV out of thread range)
>  mb type: 7
>  mv: l1r0 (0,117)
>  limit: 96
>  mb_xy: 35,4
>  completed: 88
>  x264 [warning]: recovering by using intra mode
>  x264 [warning]: internal error (MV out of thread range)
>
>
>  I can make the error go away by using only 4 threads, but alas the speed
>  difference is substantial. The final video looks flawless as far as I can
>  tell.
>
>  Is this error harmless given the video appears fine, or is it costing me in
>  bitrate or something?
>
>  I hope this bug report can be helpful for you.

Well, I can safely say that it's a known bug, which has been "swept
under the carpet" by this recent commit:

http://git.videolan.org/gitweb.cgi?p=x264.git;a=commitdiff;h=09499759acc0adc246a63a72099fc85ca1746235;hp=1fc702f8fc5b7640c62f80a5574b15a9b01fdfb7

So far, there's no known fix for that bug :-(

Guillaume
-- 
I don't measure a man's success by how high he climbs but how high he
bounces when he hits bottom.
 -- George S. Patton