[MEncoder-users] x264 [error] requested bitrate is too low when using 2-pass encoding

[John Ratliff]

I saw some posts on this earlier, but I don't think anything got resolved.

Quoting from
http://archives.free.net.ph/message/20100412.084556.7d862f71.en.html

>>
>> Looks like an libx264 issue but I may be wrong - mencoder just parses
>> stuff from libx264 so if there's the problem, better ask on the
>> x264-devel list
>>

> You may be right.
> The error disappered after I switch to an older revision of libx264.
> I have post in the x264-devel list, and I'm waiting for the reply.

I was on the x264 IRC channel last night, and they told me that mencoder
sends incorrect timestamp information, and this is the cause of this error.

Adding force-cfr to the x264encopt parameter will tell x264 to ignore
the broken timestamps.

I don't know exactly when this started. The windows binaries linked from
the mplayer homepage are here:

http://sourceforge.net/projects/mplayer-win32/files/MPlayer%20and%20MEncoder/

rev 30945 works without the force-cfr. This was put up on March 22.
rev 31027 demonstrates this problem. This binary was put up on April 8.

I'm not sure which versions of libx264 were linked in each of these
binaries. I'm assuming they used the same day's x264 snapshot as the
mplayer snapshot.

On my home system running Mac OS X Snow Leopard, I cannot compile svn
30945. I am using the mplayer daily source tarball from April 17
(r31044) and the libx264 package from April 16.

Something appears to have changed between March 22 and April 8.

I don't really understand what the guy meant by "incorrect timestamp
information" nor do I know what the force-cfr option does to x264. I
only know what he told me. Is this a bug in mencoder?

--John Ratliff