[vdr] AW: Another question about conversion

["Bläser, Lars" <LBlaeser@hofheim.de>]

> Von: Luca Merega [mailto:lmerega@email.it]
> Gesendet am: Mittwoch, 18. September 2002 10:53
> An: vdr@linuxtv.org
> Betreff: [vdr] Another question about conversion
> 
> I know this has been a very discussed argument, but there is still
> something I cannot understand.
> VDR produces .vdr files which are in Mpeg-Pes file format.
> When I use PVAStrumento to produce a Mpeg-Ps file I cannot 
> reproduce it
> with a good audio.

no probs here with pvas, using it for longer time
are there errors in the stream when you convert a record (pvas will log this)

> Sometimes it's crappy, sometimes it's really fast, sometimes it's mute
> (it seems to depend from the player?!?).

maybe you tried with a hardwareplayer as a SVCD?
the muxed ps is not very good, better have mpv and mpa and mux it with tmpeg or bbmpeg

> Now, If I right understand Mpeg-Pes is an MPEG2 file format so there
> must be a tool to convert it witouth resampling it to Mpeg-PS format

thats what pvas does (with a very good error compasation), but without "resampling", its more a repackatizing with error correction, the mpeg2 picture and mp2 sound streams are not realy changed (picture size size, datarate, ... will be the same as before)

> (standard DVD file format, right?) so that I can burn it to a CD or a
> DVD and make it played by any "normal" player.

no, DVB streams can have very different picture size (704x576, 720x576, 512x576, 480x576, ...) and sound (48kHz, or 44.1 kHz)

DVD complient will be 720,704,352x576 with 48kHz sound
i.e. german paytv pw transmits usualy in 480x576 with 48Khz or german Pro7 will has 
720x576 with 48kHz mp2 and DD (2.0 or 5.1)
also the datarates (kbit/s) are very different

i.e. you have a 480x576 MPEG2 picture with datarate from 500-3500 kbit/s and sound 48kHz mp2 with 192 kbit and you want to have a standard comlient disk (DVD, SVCD, VCD)
-as DVD: the sound is DVD complient but the picture resolution is wrong
-as SVCD: the picture resolution is ok but the datarate is to high (should be max. 2550 kbit/s, sound should have 44.1kHz to be complient (even if a lot of standalone players will tollerate this)
-as VCD: no way is a MPEG1

beside this its very important how the streams are muxed (svcd is usualy a good example for this)

> I cannot find the right way to obtain a compliant Mpeg2 file.
> Any of you could do it?

there a lot of defined MPEG2 formats, PES is one of this
the "universal" solution would be a automatic transcoder where PES will  be read and a destination profile gives the compliens to the desired format (mencoder)

my way looks like this:
-with vdr cut all pieces to a new file, if more then 2GB (more then 1 dest. file) i copy them to a big one (i.e. 3.5GB file for a movie, its importent because of the folowing step)
-convert to mpv/mpa or PS with pvastumento (batch/joblist)
-with a hardware mpeg2-transcoder (only windows soft) i convert it to the format i need (realtime or faster, joblist)
-demux file to mpv/mpa and remux with bbmpeg or dvd-autoring software
-writing to standard complient DVD, SVCD or VCD

most timeconsuming is the video-trancoding, so its possible to let the picture decide wich type of dest. suits best (and spare the svcd datarate complience)

-480x576 with 48kHz sound would become a SVCD where only the sound is converted to 44.1 (or left at 48kHz, less work means less compatibility), a movie would take 3 CD´s
-720x576 with 48kHz sound would become a DVD

the "best" solution would be a realtime conversion to DVD compliente material when the movie is recorded and the result could be directly or after cutting written to DVD - that would need a 4 GHz CPU with software based encoding or a plugin for a hardware-transcoder card, thats the way the comercial DVD-recorder at the moment works, it gets a analog picture, a mpeg2 chip gives a dvd-complient stream wich is written to dvd (realtime)