[Ffmpeg-devel] [BUG] Error: 2pass curve failed to converge

Corey Hickey bugfood-ml
Tue Jul 18 07:38:01 CEST 2006


This bug is a bit elusive; it only happens with some source videos with
some parameters, and is not always the same between amd64 and i386. In
each case, the second pass fails immediately with the error:

[mpeg4 @ 0xc840d0]Error: 2pass curve failed to converge

I can reproduce this with mencoder r18679 and with ffmpeg
r5780--both from today. I have attached the full output of ffmpeg, but I
think this is easy to reproduce. Here are the steps:

$ wget http://samples.mplayerhq.hu/MPEG1/zelda%20first%20commercial.mpeg

$ for i in 1 2 ; do /usr/local/src/ffmpeg/ffmpeg -acodec copy -i zelda\
first\ commercial.mpeg -b 817 -pass $i -y test.avi ; done


$ for i in 1 2 ; do mencoder -ovc lavc -lavcopts vbitrate=817:vpass=$i
-o /dev/null -nosound "zelda first commercial.mpeg" ; done

The bitrate in the above commands is significant; 817 fails for me on
both amd64 and i386 (Pentium 4).

These particular problems only started occurring after ffmpeg r5422;
reverting that commit makes them go away. I reported the error in the
5422 commit thread.


Apparently that change isn't really causing the bug, but merely flushing
it out. Nevertheless, the problem still remains. A few users have
reported it again recently:


Also, in that thread, Loren Merritt provided some information that may
be helpful:


Hopefully I've reported enough information. If there's anything more I
can do, let me know.

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