[linux-dvb] DVB file formats

Andrew de Quincey adq_dvb at lidskialf.net
Thu Jun 16 17:47:16 CEST 2005


On Thursday 16 June 2005 16:26, Felix Domke wrote:
> Andrew de Quincey wrote:
> > What do you think of the pmt_extra idea I've just added to the wiki page?
> > (BTW the URL is
> > http://www.linuxtv.org/wiki/index.php/File_Format_Comparison in case
> > anyone missed it the first time/has lost it in the meantime)
>
> I like the idea, though I have a comment to the zap_pids first:
> I don't like the special order of these, as for example, a service could
> use DTS (right now there are only test streams), and then we need to fix
> the file format, which we of course want to avoid.
>
> So why not use a pid:type there, like for pmt_extra?

Yeah - that is much more flexible - it leaves it up to the application 
developer what they cache (if anything).

> A problem i see for the pmt_extra is that it can never represent a full
> PMT entry (for example: CA descriptors). But i don't think we should
> want this, as i can't image something useful.

Yeah - I reckon leave stuff like that for the moment.. if we find we do need 
it, we have a version= tag at the start for a reason :)

> However, just using the PMT-type won't work. AC3 channels have the same
> type as Videotext ("private" iirc.), and for DTS you have a descriptor
> with an ascii ID.

I've extended the description of the <type> to say that it can also be 
non-ISO-PMT codes - specfically _ac3, _dts, _tt to fix this problem. Any 
others you can think of?

> We still need some per-service "flags", for example to disable PAT/PMT
> parsing (to rely only on the pmt_extra stuff).

I've added a flags= key for this to the wiki - currently it just has 
<ignorepmt>.




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