[linux-dvb] Re: V4 API proposal

[Marcus Metzler <mocm@metzlerbros.de>]

Johannes Stezenbach writes:
 > same as for A/V PES (the PSD even is in PES format). Also, if I'm not
 > mistaken (plese correct me if I'm wrong), the MPEG-2 PS syntax is the
 > same as the MPEG-1 System Stream syntax, so there are no additional
 > requirements for the demux to process MPEG-1.

Unfortunately, you are wrong. MPEG-1 PES are quite different from
MPEG-2 PES starting with the 7th byte. The MPEG-2 PES structure is
much nicer. You need a different demux for that or one demux for both
which can handle the difference. It depends on your hardware. Some
hardware understands PES, other only handles the ES. E.g. Margi, em8400 and
av7110 can't handle it, so that you have to handle PTS/DTS extraction
depending on MPEG-1 or MPEG-2.

 > 
 > My hardware manual tells me that it is also possible to filter PS
 > on the sub_stream_id, which implies that the stream_id is 0xbd
 > (private_stream_1). I can't find any more documentation on that,
 > but I guess it's handy for DVD stuff.
 > 

The substream IDs are only defined for DVD private audio streams
(e.g. PCM or AC3). For AC3 via TS (in ATSC) you don't have a substream
ID and the private stream PES has a different structure
(i.e. different private header) than a DVD AC3 PES.


Marcus
-- 
/--------------------------------------------------------------------\
| Dr. Marcus O.C. Metzler        |                                   |
|--------------------------------|-----------------------------------|
| mocm@metzlerbros.de            | http://www.metzlerbros.de/        |
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