[MPlayer-users] Eagles - Hell Freezes over DVD

[Vladimir Mosgalin]

Hi Ni Bo!

 On 2006.07.12 at 12:42:35 +0000, Ni Bo wrote next:

> I'm only blaming the DVD because the second DVD I tried (Desperado, if it 
> matters?) is of excellent quality overall.  I'm not expecting perfection at 
> this stage as I haven't explored all the options of mencoder, but Desperado 
> I would say is at least a 100% improvement on Hell Freezes Over...

Don't own any of them, however some movies hardly require bitrate over
1mbps to look great (e.g. Equilibrium compresses that well), while for
some of the others 3mpbs won't be enough to look exactly as on dvd (I've
seen this on Ameli). If you want to roughly guess how much bitrate this
particular movie needs to look nice, just try encoding some parts with
qscale=2 or 3. It isn't exactly the bitrate you should use for the whole
movie, but after trying this on several movies you'll understand how to
use this.

> The command line I used is below (called from a script, hence the '$1', 
> '$2' etc)
> Video issues with Hell Freezes Over are 'blocky' video, particularly scenes 
> with dark backgrounds, people with dark clothing etc. Also the 'fog' 
> generated on stage appears blocky. (This is one of the reasons I chose 
> Desperado as my second attempt - there's a few smoking scenes)

Fog/smoke scenes are really hard to encode. Both lavc and xvid can't
deal with them on medium bitrate.

If you have a lot of these effects, first thing you should try is xvid.
When given enough bitrate, xvid can deal with them pretty well, at least
better than lavc with qscale=2. Usually, this is enough.
However, on some scenes, xvid won't be able to produce a nice picture.
In that case, you have to use lavc with qscale=1. It will use insane
bitrates, however. On the other case, usually it guesses these kind of
scenes pretty well, and won't encode anything else with such small qscale.
If it still doesn't look good on the bitrate you can afford, you should
try zones feature. I don't know if they work in lavc right now, but at
least they do in xvid. You can manually give more bitrate to bad-looking
scenes.

> A second problem was that fast-moving scenes tend to appear 'streaky'.

I don't understand that.. You sure you are not talking about interlacing
effects?

I see that you don't crop your video. That's not good, are you sure you
don't need cropping? Uncropped sides of the picture eat your precious
bitrate.

Also you don't do any ivtc. Unless you have PAL source, you should use
either -ofps 24000/1001 or both that and some kind of ivtc filter
(pullup is usually the best). Encoding a telecined movie is a VERY bad
idea.

> Thanks for your help! Let me know if you need any more info.

Yes I do. Do you watch videos afterwards with or without postprocessing?
Why do you use vqmin,vqmax,mbqmin and mbqmax if you specify vqscale
parameter? What bitrate the movie ends with when encoded with vqscale=2?
Have you tried denoising video before encoding? Can you post all details
about encoded video (fps, resolution etc)?

> mencoder dvd://1 -aid 128 -ffourcc DX50 -sws 2 -vf scale -zoom -xy $1 -ovc 
> lavc -lavcopts 
> vcodec=mpeg4:mbd=1:lumi_mask=0.5:scplx_mask=0.1:vqscale=2:cmp=256:vqmin=2:vqmax=6:mbqmin=2:mbqmax=10:vpass=1 
> -oac copy -o /dev/null

IMHO you should use -vf scale=$1:-2 and ditch -xy -zoom. I'm not sure
whether scaling takes part on that scale or in the end of the chain.

> I've also tried the xvid codec, but get a 'jerky' picture...

What do you mean by that?
Also note that due to the way xvid works, only results from second pass
are useable.

Try the following options:
-xvidencopts
pass=1:bitrate=2100:min_iquant=1:max_iquant=4:min_pquant=1:max_pquant=6:min_bquant=2:
max_bquant=9:me_quality=6:quant_type=mpeg:keyframe_boost=15:trellis:chroma_me:
chroma_opt:max_bframes=2:hq_ac:vhq=1:autoaspect:bvhq=1

Put it on one line, use desired bitrate instead of 2100 and don't use
bvhq=1 if you have old xvid (quality would be worse though). Use
two-pass encoding. In case of good results, you can try decreasing the
bitrate.

For lavc, try these options for a change (not optimal, but should work
better than yours):

codec=mpeg4:vbitrate=2100:vqmin=1:lmin=1:v4mv:mbd=2:trell:subcmp=2:cmp=2:precmp=2:
mv0:autoaspect:vpass=1:mpeg_quant:vqcomp=0.7:vqblur=0.3

The quality would be overally worse than with xvid, however difference
wouldn't be all that big on high bitrate, and you'll have to use lavc if
xvid won't be able to encode smoke scenes nicely enough. However, I
suggest you to play with xvid options first.

-- 

Vladimir