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

[Johannes Stezenbach <js@convergence.de>]

On Thu, Oct 31, 2002 at 05:28:21PM +0200, Dennis Noordsij wrote:
> 
> > capability... As far as I understand Ralph's work here he found a way
> > to grab the TS data by directly reaching into the data stream at an earlier
> > stage, before the PES packets are generated. maybe I'm misunderstanding
> > something here, but the bottom line is: the driver should _always_ provide
> > TS data - IMHO...
> 
> If the TS data CAN be directly grabbed (can someone confirm this?) I agree, 
> but otherwise, maybe not :)

That's what I mean. If the hardware won't give you TS packets, the
driver should not try to emulate this. Likewise, if the hardware
only gives you TS packets, the driver should not repack them into
PES packets. That's better done in userspace.

I'm not shure about Ralph's last work for the AV7110 firmware, so maybe
my knowledge is out of date. I don't know what the firmware does
for DATA_TS_RECORD.
Look in av7110.c for pes_to_ts(). AFAIK the does AV7110 not give you
the TS packets, at least not if the data is also going to the
MPEG decoder (i.e. maybe it works for DMX_PES_OTHER).

It would be nice if Ralph or Marcus could enlighten us with their
opnion on that.

> If it is not strictly necessary to multiplex a TS stream in software in the 
> driver and then demux it immediately after in the application it 
> significantly lowers the performance requirements for STB controller 
> hardware. While the cheapest available hardware today has no problem doing 
> this anyway, I am also sure that nobody would mind having extra cycles to do 
> other things with, if only to save some power.

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.

Regards,
Johannes


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