[MEncoder-users] New quality problem with low contrast images
michaelni at gmx.at
Sun Oct 1 13:46:18 CEST 2006
On Sat, Sep 30, 2006 at 07:44:41PM +0200, Pepe wrote:
> I'm having again a problem to get a quality image. I recorded a movie with my
> dvd-recorder from a satellite channel.
> Now I'm trying to pass to divx. I'm having problems with some scenes. Scenes
> well illuminated (outside, with sun) look very good. But the movie has a lot
> of scenes with very low light. They are dark but not very dark, maybe they
> have low contrast.
> The problem is that those scenes look very bad in my xvid, a lot of blocks,
> very annoying. In the original video, image looks much better.
> This is the command I used:
> mencoder -noodml -o temp/video2.avi \
> -oac mp3lame -lameopts vol=0:mode=3:cbr:br=64 \
> -ovc xvid \
> -vf-add crop=688:560:20:8 \
> -vf-add pp=l5 \
> -vf-add scale=576:432 -zoom \
> -vf-add harddup \
> -force-avi-aspect 4:3 \
> -sws 9 \
> I tried everything. I used max_iquant=4:max_pquant=4. I tried different values
> for -sws, also tried yadif instead of l5. I raised the bitrate up to 4000. I
> used b-frames. I used libavcodec instead of xvid. But nothing improved the
> quality, it always remained the same. Removing the filters (crop,
> deinterlace, scale) may improve a little bit, but there's still very visible
> blocks. And anyway I don't want to make a video with such a high resolution
> (720x576) because I would need a bigger bitrate.
> I also tried quant_type=mpeg. With that option the image is very different,
> the blocks are smaller but there are even more, all over the whole image
> and are even more annoying.
> If I use hqdn3d after the other filters, yes it removes most of the blocks,
> but image loses a lot of details.
> Any idea of how to improve the image?
with libavcodec vqmin=1 lmin=1 and a sufficiently high bitrate should make
all blocks dissapear
alternatively cmp=10 subcmp=10 mbcmp=10 might also help (try various values
and of course dont forget v4mv mbd=2 trell ...
and using -vf spp or -vf noise when viewing the final video will also
remove all blocks pretty effectively or change the gamma of your
(and dont use a TFT based one if you can, TFTs suck for displaying
dark colors correctly)
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 MEncoder-users