[Ffmpeg-devel] MPEG 2 Quality Issues

Michael Niedermayer michaelni
Thu Nov 30 11:40:26 CET 2006


Hi

On Wed, Nov 29, 2006 at 07:21:17PM -0600, Brian Brice wrote:
> 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

one thing missing here is -flags ilme

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is




More information about the ffmpeg-devel mailing list