Re: Tcrequant breakthrough!

John Pilkington wrote:
> Otto J. Makela wrote:
>> I just got confirmation from our friends at Metakine that their 
>> M2VRequantiser
>> also produces garbage on my original test data, so the conclusion is 
>> that the
>> equivalent of:
>>
>>     tcdemux -i videofile-dvd.mpg -x mpeg2 > sample.m2v
>>
>> will produce video content to sample.m2v which (though it will play with
>> programs like xine) cannot be handled by tcrequant or mplex.
>>
>> What is your suggestion, what can be done to fix this?
> 
> 
> In view of this question about tcdemux it might be useful for me to 
> clarify both my experience of successfully using tcrequant in the past 
> and what I meant by .vob files when describing my experiments with vamps.
> 
> I have been using MythArchive to create dvds from dvb-t recordings.  All 
> recordings have been stripped, in mencoder, of all except one audio 
> channel before lossless mpeg2 transcoding with a cutlist by 
> mythtranscode. Output is (probably) mpeg2 PS.
> 
> MythArchive then uses
> 
> mythreplex --demux --fix_sync -o outfiles_prefix -v 224 -a 192 "infile"
> 
> the code for which is replex.c within the mythtranscode package; I don't 
> know what its history is or how it may be related to tcdemux.  tcrequant 
> is called if needed to shrink the video file before mplex -M -f 8  and 
> dvdauthor.
> 
> I saw artefacts here in fc10, none in CentOS.  Target shrinkage was 
> rarely more than a few percent.
> 
> The experiments I have done with vamps in fc10 have used the output of 
> the mplex -M -f 8 stage with target shrinkage up to 2.0 - and no prior 
> passage through tcrequant.  I haven't seen  artefacts although obviously 
> the quality is reduced.  These files are what I referred to as .vob 
> files.  vamps may report an error on reaching EOF, and the MythArchive 
> code sometimes reports fatal buffer underflow in mplex, and exits, after 
> creating an output file although I don't think it reacts similarly when 
> using a FIFO.  I think I can avoid this by mplex  -M -f 8 -b 500 -r 
> 15000 but have only tried this once.
> 
> Code for use in the real world ought to be robust, but are there 
> definitive examples of standard-compliant input for testing tcdemux?
> 
> HTH,
> 
> John P
> 
> 
I just tried your posted example.  I had no problems with:

$ mplex -M -f 8 -o am-dvd.mpg am.m2v am.mp2

$ vamps -e 1.5 -a 1 -p -i xx < am-dvd.mpg > out.vob

and out.vob played like any normal .mpg file.

$ ls -l
total 21828
-rw-rw-r-- 1 John John 9172992 2009-02-12 16:51 am-dvd.mpg
-rw-rw-r-- 1 John John 8375981 2009-02-10 23:37 am.m2v
-rw-rw-r-- 1 John John  561792 2009-02-10 23:37 am.mp2
-rw-rw-r-- 1 John John 4194304 2009-02-12 16:59 out.vob
-rw-rw-r-- 1 John John     363 2009-02-11 00:08 requant-sample2.txt

so maybe you should try different mplex options :-)

John P