[linux-dvb] Re: Origin of datarate limitation?

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Sven Karlsson wrote:
> 
> Hi All,
> 
> I've read at numerous places that there is a datarate limitation on the
> parts of the TS that can be read from the AV711x via the PCI bus. I also
> understand that the Nova does not have that limitation and that the Nova
> does not have any hardware MPEG playback capabilities although it is based
> on the AV711x.
> 
> Could someone (possibly yet again ;-)) clarify the origins of the data rate
> limitation on MPEG capable cards? It appears to me that this could be a
> firmware issue. Is that so? Are there any efforts focusing on patching the
> firmware or otherwise remove the datarate limitation at the possible expense
> of the MPEG capabilities?
> 
> I, for one, would gladly skip all MPEG capabilities of the board if I
> instead could process and possibly record several channels at once. My DVB-C
> card is sitting in my firewall/network server and I intend to send the MPEG
> stream over my home lan to my other boxes which all of them are powerful
> enough to decode MPEG-II streams in realtime.

Incidently I'm currently working in that area.

What I found so far is that with a Siemens DVB-S (rev 1.3) I can record
several channels on the same transponder, as long as I don't turn on recording
the channel that is being viewed live. In particular this means that I have to
set all desired PIDs as DMX_PES_OTHER. So far I have tested recording 3 channels
in parallel (don't know if this is the limit yet, just haven't tried more than that).

However, this only works on transponder 12188, with channels RTL2, Super RTL
and VOX. If I do the same on transponder 12480 with Pro7, Kabel 1 and Neun Live
the resulting recordings show some heavy distortions.

I haven't tried this with other transponders yet. Maybe there is a group of
transponders where this is possible, and another where it isn't.
I already asked Ralph about this. He said that maybe the channels are
muxed differently on these two transponders, so that on the first one it
works, while on the second one it doesn't. Maybe it's just a small change
that would be necessary to make this work for any transponder, but currently
I can't see what should be changed - especially if this is in the (closed source)
firmware...

Klaus
-- 
_______________________________________________________________

Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
_______________________________________________________________


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