[linux-dvb] Re: hdtv scanning

Wolfgang Wegner wolfgang at leila.ping.de
Mon Nov 6 16:45:54 CET 2006


On Mon, Nov 06, 2006 at 04:07:13PM +0100, Marco Masotti wrote:
> > ==========================
> > Date: Mon, 6 Nov 2006 15:25:05 +0100
> > From: wolfgang at leila.ping.de (Wolfgang Wegner)
> > To: linux-dvb at linuxtv.org
> > Subject: Re: [linux-dvb] Re: hdtv scanning
> > ==========================
> [...]
> > *dreaming* a graphics card giving the possibility of adjusting 
> > the master
> > clock from the TSC and having on-board audio capability, also 
> > synchronized
> > from the same clock, would be perfect IMO.
> > 
> > 
> 
> Yes, got the point, sticking to such beaconing data could alleviate software hassles. In a windowish - and simplistic, as far as I'm concerned -  view, the stream of data would be input in the DVB source filter of a Directx model, where one ouput pin of the filter could be dedicated to provide the TSC data, if any. Could that be feasible in a linux implementation too, or, as you might have meant,  just the TSC data is not available out of the DVB card available so far? 

The TSC data is available, and (if necessary) with slight driver modifications
the receive timestamps are accurate enough to build a SC PLL in software.
But you have to do this part at the receiver side (i.e. the DVB card, in
this case probably the budget cards are even easier to handle).
The more difficult part is to synchronize the playback part (audio sample
clock and video clock (frame rate)) to this new system clock - this is simply
not possible with any of the PC hardware I currently know about. (Except
the FF DVB cards, which do it internally.)

Regards,
Wolfgang




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