[MPlayer-users] MPlayer-1.0pre4 bug with divx4 multipass filter

[Vladimir Mosgalin]

On Sat, 11 Sep 2004, D Richard Felker III wrote:

DRFI>then do double blind.

You must be joking.. I and my friends easily see the difference between
lavc & xvid.

DRFI>> You just haven't tried right xvid options or saw only very old xvid
DRFI>> versions, that's why you are saying so.  I encoded a lot with lavc
DRFI>> before, and now I can say for sure: lavc sucks a lot comparing with
DRFI>> xvid.
DRFI>i still maintain you're doing something wrong.

How about this. Let's bet. In some days, I'll upload some parts of vobs
and post xvid & lavc options that result in visible quality difference.
Then, you try to modify lavc options in order to make the quality the
same or better at the same bitrate. If you will succeed, I'll change my
mind and won't be saying that xvid is better anymore. If you won't, you
will stop saying that xvid is worse than lavc and admit that in some
cases (I already wrote them: high bitrate & no postprocessing) it gives
better quality.

DRFI>> But when making high-quality dvd-rips, you can't even compare lavc and
DRFI>> xvid. With postprocessing, hq rips look bad - all the details are
DRFI>i never use postproc. too slow anyway.

Hmm.. Imho pp filter isn't slow. It's faster than mpeg4 decoding in
twisted cases, like: xvid + qpel decoded by xvid (it can't be decoded by
lavc), which eats about 50% of my athlon 3200+ cpu on dvd resolution.

DRFI>> blurred away. So I always make rips that do not need postprocessing
DRFI>> (1700-2500kbit/s depending on material is enough to make very hq rip
DRFI>normal bitrate for a dvdrip is 1300-1500, at least for anime. i've

I only encode normal movies, not anime. The amount of anime titles
licensed in Russia on dvds is extremly small (probably 20 or so), the
only way to get anime is collect fansubs.

DRFI>been away from hollywood crap so long i don't even remember what
DRFI>you want for that... keep in mind anime is normally 4:3 or 16:9

Well, does it really matter if it is a "crap" or not when it comes to
codec comparison?

DRFI>rather than 64:27, so you have more pixels to encode.

64/27? Heh.. My personal preference is 2.3, not 2.35 or 64/27...

I always try to keep original dvd resolution, without rescaling, to keep
all the details. When width and height aren't multiplies of 8 (16 is too
harsh) and I don't want to crop too much, I scale, say, from 708 to 704
pixels - eye can't tell the difference.

My opinion is that you can afford to downscale on older anime titles,
bitrate matters more than resolution, but normal movies and modern
anime (and older high-budget anime movies, for the matter) contain a lot
of fine details and I can't afford to downscale when I need to keep the
quality.

I don't really care about bitrate, since I store my encoded movies as
avi files on dvd+rw media, so I just use whatever I need to keep the
picture just as it was on dvd in all scenes. 1300-1500 is too little to
keep the quality of dvd-sized video.

DRFI>btw is part of your idea of "hq" keeping all the noise and artifacts
DRFI>from the bad dvd encode? these should be removed before encoding...

I do denoising (which other artifacts are you talking about? Pixes near
cropped area? MPEG compression artifacts? It's hard to filter them
without removing the details, and they are rare.)
I use hqdn3d filter with default parameters for anime and 3:2:5 for
normal movies, since default strength makes a picture lifeless and
sometimes makes some compression artifacts more visible. For movies that
suffer from denosing too much, I use something like 2:2:4.

DRFI>> with the right settings). Sadly, on most types on content it's nearly
DRFI>> impossible with lavc. Scenes with qp=2 look extremly bad (and I don't
DRFI>> want to discuss my monitor, gamma, brightness and eyes - they are
DRFI>> perfectly well).
DRFI>scenes with q=2 will look perfectly good on either lavc or xvid.

Some scenes do. Some don't. With xvid, all scenes do.

DRFI>> In a lot of scenes, you can see blocks everywhere!
DRFI>> With xvid, qp=2 will lead to perfect result. The bitrate will be
DRFI>> ~1.3-1.5 times higher than with lavc, though; but with qp=3, the result
DRFI>> is still much better than lavc's and bitrate is smaller.
DRFI>rotfl... q=3??

What's so funny? Yes, xvid's encoding with qp 3 is better than lavc's
with qp 2.

DRFI>> That's where b-frames kick in and improve quality a lot. With the
DRFI>> "regular" xvid settings for the first pass, i/p frames with qp=2 and 2
DRFI>> b-frames with qp=4, the quality almost always is very good.  On the
DRFI>> second pass, bitrate can be reduced by 20-30% without visible quality
DRFI>i would recommend disabling b frames. they lower quality in most
DRFI>cases, and they're just a stupid hack.

Maybe in lavc. In xvid, they help. If the b-frames paramters are choosen
right; defaults are mostly fine. But even small incorrect tweak of
b-frames can lower quality.

DRFI>> loss. At the same bitrate, lavc produces only low-quality video
DRFI>> that can either be watched with postprocessing (thus with washed
DRFI>> out details), or with a lot of blocking.
DRFI>huh? i never watch with postproc and never have any blocks. maybe

If you are talking about dvds and high-bitrate rips, I can agree with
you. On all other content, pp is very helpful.

DRFI>i'll try using eq2 with gamma boosted to 5.0 or something like your
DRFI>monitor to see if they appear... :)

My gamma is fine, thanks ;)

So, how about that bet? I work at ISP now, so I can upload large parts
of dvds without problems..

-- 

Vladimir