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

[Con Kolivas]

On Thu, 17 Apr 2008 03:14:01 Jason Garrett-Glaser wrote:
> >  I'm using a recent snapshot of your sensational x264 encoder
> >  (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:
>
> This error previously would have caused a crash; my recent commit
> changes this to have it swap to intra mode instead, which costs a few
> bits but lets x264 continue encoding without error.  However, in
> reality, its just coverup for what appears to be a bug in B-Direct and
> B-Skip motion vector handling in threaded mode.
>
> >  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)
>
> If you have an input stream and settings that consistently generates
> this error, please post it somewhere (Mediafire/Rapidshare/etc); we
> could potentially use this to debug the actual problem and eliminate
> it.

Excellent, excellent. Thanks everyone for your replies!

The important part to me was that it doesn't harm the stream. I'll try and 
find a stream that generates it regularly, but basically I get it all the 
time. This could be because I use 16 bframes and 16 frames of reference and 8 
threads and b_bias of 100. This is probably why I see it so often if it's a b 
frame issue. Oh and if you think I'm silly for using 16 b frames for the 
quality loss, I also use --ipratio 1 --pbratio .

Hope this helps to recreate the bug for you. Otherwise I'll try and find time 
to find a sequence that reliably generates it.

Regards,
Con Kolivas

-- 
-ck