[Ffmpeg-devel] MPEG 2 Quality Issues

[Brian Brice]

Hello.

A while back I had emailed about bitrate issues regarding MPEG 2
encoding, and now I'm back for quality issues!  I have a DV clip
that contains some fast motion and I'm getting some horrible blocking
when trying to encode to MPEG 2.  I am trying to find the right options
to pass to ffmpeg that make a huge different in the quality of the
encoding.  I've used TMPGEnc and it produced *great* results, and I wish
I could get ffmpeg up to the same standard.  At this point I'm just
passing numbers without knowing what they do.

I have tried setting lmin to 0 and lmax to 1*QP2LAMBDA.  This video
smooth like I would expect, but the bitrate ended up averaging around
13.7 Mbps even though I tried to aim for CBR 7 Mbps.

Here's a sample screenshot of how TMPGEnc looks to ffmpeg:
TMPGEnc: http://heapify.org/etc/ffm/tmpgenc.png
ffmpeg:  http://heapify.org/etc/ffm/ffmpeg.png
Major blocky-ness with ffmpeg :-(

Here is the original clip:
http://heapify.org/etc/ffm/TestforMPG-Short.avi

Encoded with ffmpeg without lmin/lmax settings:
http://heapify.org/etc/ffm/YuckNolminlmax.mpg

Encoded with TMPGEnc, looks *great* as I want ffmpeg's to :-(
http://heapify.org/etc/ffm/TMPGEnc.mpg

Here is how I used ffmpeg:
ffmpeg -i TestforMPG-Short.avi -y -f vob -vcodec mpeg2video -acodec mp2
-ab 384k -ar 48000 -ac 2 -aspect 4:3 -b 7000k -minrate 7000k -maxrate
7000k -bufsize 1835008 -g 12 -bf 2 -flags ildct+trell -mbd 2
LooksGoodBadBitrate.mpg

I know ffmpeg is capable of having decent quality at 7 Mbps, but how can
I achieve this?  TMPGEnc does it, how can ffmpeg?  Any advice,
recommendations, information is greatly needed and appreciated.  Thank
you guys.

-- 
Brian Brice