Re: [Mjpeg-users] Strange mplex problem

[Andrew S. <and...@mn...>]

Oh dear,

This looks like a rate controller problem in mpeg2enc.  
There were some changes made in this area to fix a problem with the old method 
predicting how large a frame was likely to be (which tended to be rather 
inaccurate and produce 'oscillating' quantisation).   It looks like your 
stream probably worked well with the old method (for some reason) but not 
with the newer one.

Can you try it again after recompiling with the following attached 
mpeg2enc/ratectl.cc (matches CVS mpeg2enc)? This should eliminate the problem 
(it starts throttling extra-hard when the decoder's buffer is becoming 
significantly empty...).  I can't easily replicate problems like yours 
because the video 'spikes' that cause them depend entirely on whats being 
encoded.
 

Aside, setting
--video-bitrate 1800

without an increasing the specified minimum decoder buffer size is really 
'torturing' mpeg2enc.   If you can play a non-standard VCD like this you can 
almost certainly increase the decoder buffer size assumed to be required.

--video-buffer 120 or even
--video-buffer 230

and still playback fine. You'll get better looking results too!

Of course you need to give mplex the same 

--video-buffer

specification.


cheers,

	Andrew