[MEncoder-users] RGB => YV12 conversion

[RC]

On Mon, 26 Sep 2005 01:42:45 +0400
Vladimir Mosgalin <mosgalin at VM10124.spb.edu> wrote:

> If you don't downscale and don't use postprocessing, I don't really
> understand why you don't see artifacts.

I don't use Xvid ;-)

To be fair, I do see artifacts on occasion, but as I've said, Xvid is
worse at the same bitrates.  It's usually a case of the source DVD being
blocky (very low bitrates) anyhow, with lots and lots of noise that
helps cover the blocks.

> sometimes. If you've got enough bitrate, p-frames only sequence can
> produce nice looking fade in, but b-frames almost always make it
> worse. But really, it depends..

Well if you have a very high bitrate,  Lavc will just make every
frame of a fade a keyframe, so it will look perfect.  I've never seen a
good-looking fade in/out with p-frames.

> Out of curiosity, have you tried some of this new stuff, like snow,
> x264 or something else h264-based? I haven't really, but I've seen a
> few really good wmv3 samples.

Haven't gotten around to trying x264 yet.  Snow looks good, and I'm sure
it will be quite impressive as soon as it stabilizes.

I've looked at WMV3 samples, and I'm not impressed.  Pretty much on-par
with MPEG-4.  Most samples use strong denoising to squeeze the
bitrate down as much as possible and still look decent, but you can get
better results with lavc and nr=~500.

> While I need "the least possible bitrate for encode that my eye can't
> distinguish from dvd". 

I'm beginning to suspect you're someone who needs noise in the video. 
Leave out all other postprocessing, and just use -vf noise on a lavc
MPEG-4 video and see if that's the reason.  If so you can try lavc
encoding with nsse.  (I find sse in general to not be very good, but
that's the only lavc *cmp function that preserves noise)

 
> I haven't tried qns=3, and turning on b-frames never (at least I don't
> remember) helped me on animation when encoding with lavc, but I
> wouldn't say that it is that much better than xvid.. It is better in
> some cases, but not in the most of them.

I'd love to see a sample of good looking animation
with Xvid at 720x480/24fps with bitrates of ~200.