[linux-dvb] Re: Fw: DVB audio/video decoder API

[Johannes Stezenbach <js@convergence.de>]

On Thu, Oct 31, 2002 at 05:37:44PM +0100, Klaus Schmidinger wrote:
> Johannes Stezenbach wrote:
> > 
> > I don't see why an application would request a TS from the driver if the
> > applicaton wants PES and the driver can deliver PES.
> > STB controllers that support recording can use any format they want,
> > as long as they support playback of the same format.
> 
> The entire recording and "Transfer Mode" mechanisms of VDR are based on the
> assumption that the driver can deliver TS packets, since that's the most
> basic form of data (AFAIK that's the way it is broadcast), and it is the
> easiest way to distribute the data to various receivers. This is what made,
> for instance, "overlapping recordings" possible in VDR. I also don't see
> how one would be able to record more than one programme (or one programme
> with several audio PIDs) if the driver delivers PES. As far as I understand
> things this is only possible if it delivers TS (but please correct me if I'm
> wrong here).

The API allows you to get multiple PES at the same time, just open
/dev/dvb/adapter0/dmx0  multiple times, set your
DMX_PES_OTHER/DMX_OUT_TAP filter, and read from /dev/dvb/adapter0/dmx0
(currently broken, see my other post today).

If the hardware can give you a filtered TS, the most natural way
is to get it via DMX_OUT_TS_TAP from /dev/dvb/adapter0/dvr0.

If the hardware does not give you TS packets, but PES (or the infamous
Technotrend AVPES) packets, the driver must try to recreate the
TS if you ask for DMX_OUT_TS_TAP. That's where all those "badly
mltiplexed TS" were coming from that we had until some months ago.



But to cut that discussion short, I just reviewed some of the
driver source, and there is much less code devoted to multiplexing
than I thought. Since what we have now seems to work pretty good,
maybe just forget what I wrote.


Regards,
Johannes


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