[vdr] Re: downsizing mpeg2 /article on heise

[Robert Michel <news@RobertMichel.de>]

Salve Steffen,

thank you for you mail - I had read only Heises headlines.

Am Freitag, 26. September 2003 00:34 schrieb Steffen Barszus:
> Just for the case it might be usefull for some people here (Sorry the
> article is in german):
>
> http://www.heise.de/newsticker/data/vza-25.09.03-000/

This article is about "DVDRemaster is a utility for Mac OS X to recompress 
large DVDs so that they fit on standard DVD5." by the company 
http://www.metakine.com/

"DVDRemaster uses a modular architecture to recompress the video. Two modules 
are currently provided:
M2VRequantizer:
 A module which simply requantizes the video leaving the motion vectors 
unchanged. This module is very fast and provides relatively good quality.
M2VDownsizer:
 A modules which recompresses the video stream completely (including motion 
vectors). This will usually yield slightly better quality, at the cost of 
time.
Both of these modules are based on libmpeg2 and mpeg2enc and released under 
the GNU General Public License (GPL). If you wish, you can download their 
source code."
Because M2VRequantizer and M2VDownsizer are under GPL and don`t need special 
libaries they can be compiled and used with GNU/Linux as well.

Download the source:
http://www.metakine.com/files/M2VRequantizer.tgz
http://www.metakine.com/files/M2VDownsizer.tgz

In these archives are only a unneeded path for Apples Developers Tools project 
builder and tree files (main.c, getvlc.h and putvlc.h) compile them:
(change in source "#define DEMO" to "undef DEMO" to avoid demo-restrictions)

gcc main.c -o requant -lm

(possible options: -funroll-loops -frename-registers -O3) (what does these 
do?)
The compiling result is an executable wich will take M2V (pure MPEG-2 
videostreams) from Stdin, convert it with a given constant factor for 
reducing the bitrate and put the result to Stdot:

cat video.m2v | ./requant Faktor > video_transcoded.m2v

Faktor should be for DVDs between 1.25 and 1.5 and then compareble in speed an 
qualtiy with the program DVD2one.

> I have tried it and it works really fast (some minutes for a whole
> movie).  The quality is what you would think (clearly visible artifacts
> on fast moving scenes very good quality on calm scenes with a factor 2
> (meaning 2 Gig => 1Gig shrunk)). Haven't played that much with it, but
> i guess for some tasks it might be very valuable (and more for people
> that authors dvds here).

I would think that this gives a good tool to requantize the DVB-S stream on 
the fly to have somthink like "longplay" on the fly.
Hope my draft translation is usefull, you are wellcome to make this info 
better - and to send it to this list ;)

> Have fun!
Yes,
rob
> Steffen




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