[linux-dvb] Re: porting the DVB driver to sparc64

[<mocm@metzlerbros.de>]

Eddie C. Dost writes:
 > > Could you describe the problems you fixed and those that you still have?
 > 
 > One big point of interest to me is getting statistics and more information
 > from the MPEG TS, i.e. the DVB-SI info sent with the data, the datarates
 > of the video and audio ESs, and such.
 > 
 > A datasheet or programmer's guide for the MPEG decoder could help here
 > is something like that available?
 > 
 > I work in the Video over ATM (Broadcast Quality) business, so this is
 > why... I am very interested in seeing numbers about what the consumer
 > actually gets.

For those that don't already know. The firmware consist of two main
parts. The so-called RTSL, which is a library provided by TI and
handles most of the tasks from demuxing the TS to decoding the MPEG
streams, and the part that is written by us, which just calls the RTSL
routines in the correct order. In the latter, we never get to see the
full transport stream, not even the adaptation fields in the
audio/video packets. The section filters give you the section data, so
SI information is of course no problem. You can of course get the bit
rate from the audio/video ES which you can record, but those are
usually not accurate. Well, audio is, but video can be fake, meaning
it's just a value that tells the MPEG decoder how fast it should be.
If you look at the mplex code you will see that an accurate value for
the bitrates can only be determined by counting the bytes and dividing
by the time differences you get from the PTS.

For an entire transponder you can get the bit rate through easy
calculations using the signal rate and the FEC.

Marcus

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