[linux-dvb] DVB file formats

Johannes Stezenbach js at linuxtv.org
Fri Jun 17 11:04:17 CEST 2005


Andreas Oberritter wrote:
> On Fri, 2005-06-17 at 00:10 +0100, Andrew de Quincey wrote:
> > The first thing that springs to my mind is something like the following:
> > 
> > DVBS: ((frequency / (symbolrate/1000)) << 1) | polarisation
> > DVBT: (frequency / bandwidth)
> > DVBC: (frequency / symbolrate)
> 
> AFAIK there can not be more than one multiplex one frequency except if
> the polarization differs.

Not true for Japan / ARIB. They do funky stuff, below is a quote
from a private mail where someone explained this to me a while ago:

| In the ARIB-T, there is just one transport stream per frequency, so, as
| you said, transport_stream_id parameter is not needed for tuning
| purpose.
| 
| In the ARIB-S and ARIB-C, there are multiple transport streams mux-ed in
| a frequency. Bandwidth of a frequency is divided into 48 slots, each
| assigned to any of the transport streams. TMCC describes, for each slot,
| a transport_stream_id to which a slot belongs. This is explained in ARIB
| STD-B20. Regretably, there isn't english version.

Which means that *the frontend* needs to know the transport_stream_id
for tuning...

(I'm not implying that we should support this.)


Johannes




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