[linux-dvb] Re: Bug in mpegtools

[Marcus O.C. Metzler <mocm@convergence.de>]

Klaus Schmidinger writes:
 > "Marcus O.C. Metzler" wrote:
 > > 
 > > I would like to stress once again, that TS is the natural format of
 > > DVB and that the DVB API is mainly concerned with this format. So that
 > > in the future we will mainly concentrate on programs that use TS
 > > and/or transform other formats from/to TS. I might add that TS is also
 > > the best format for streaming MPEG.
 > 
 > Does this mean that it would be best if VDR stored the data as "TS"?
 > 
That depends, you could also insert a ts2pes if you want to, or use
PES filters. But you have to remember that the muxing of the TS is
usally better than that of the transformed PES stream, unless you use a
more sophisticated ts->pes with remuxing. If you can get the original
TS, it is also possible to save tele(video)text information and EPG in
the recording.


 > Didn't you say in an earlier message that it is not possible to get
 > the "original" TS from the Siemens card?

Yes, that's true, but there are other cards out there and there will
probably come some better ones. The budget cards already give you the
original TS.

 > 
 > Will the TS delivered by the driver be free of the video and audio
 > glitches we see when replaying a recording made in the default PES
 > format of the 0.8.2 driver? In that case I could drop the implementation
 > of a remultiplexer in VDR.
 > 

No, probably not. We still have to work on that.


 > Can the NAPI deliver and replay video and audio in _one_ TS (not
 > separate video and audio streams)? This would make it easier for VDR.
 > 

If you use the /dev/ost/dvr you can record and playyback the TS via
that device. In theory, you can feed any TS into that and it will
be handled as if it were coming from satellite. You can set pes
filters, section filters etc.

 > And finally: is "TS" that which is generally referred to as MPEG2?

See the FAQ for that. In short, what usually is refered to as MPEG2 is
an MPEG2 program stream (PS), which is not a TS (transport stream).
 
> Apparently there is some irritation amoung the various tools that
 > process MPEG2 files (from what I've heard not all tools are able to
 > process the files recorded with VDR). So would storing the files
 > in TS format solve this problem? In that case it might make sense
 > to change the name of those files from "001.vdr" to "001.mpg".
 > 
I don't know if there is a special .xxx file ending for TS, but in
general it wouldn't be .mpg.
Problems with replaying .vdr files could arise if the first video PES
doesn't start with a sequence header (00 00 01 b3) as the first data
in the video ES and the audio PES with a audio sync (FFF).
That is because they are not expecting a streamed format, where you
don't have a beginning or an end.


So, in conclusion, you don't have to switch to TS. The DVB API allows
you to get PES from the PES filters and feed PES into the
/dev/ost/audio and /dev/ost/video devices (or muxed into
/dev/ost/video). I think that TS has some advantages, though. It is
better for streaming. You can include EPG and tele(video)text
information and it doesn't have to be reformated (if you can get it
from the hardware).


Marcus

---------------------------------------------------------------------
Dr. Marcus Metzler                             
mocm@netcologne.de                     http://www.metzlerbros.de
mocm@convergence.de                    http://www.convergence.de

Convergence Integrated Media GmbH          
Rosenthaler Str. 51                   
D-10178 Berlin                             
---------------------------------------------------------------------




--- 
Info:
To unsubscribe send a mail to listar@linuxtv.org with "unsubscribe linux-dvb" as subject.