[linux-dvb] dvb-kernel TS continuity errors

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

I'm currently testing VDR under kernel 2.6 with the dvb-kernel
driver (version from linuxtv.org CVS as of 2004-09-10).

When I run 5 parallel recordings on the same transponder
(RTL, RTL 2, Super RTL, VOX and RTL Shop) it works just fine on a full
featured DVB card, while I get TS continuity errors when I
do the same thing on a WinTV NOVA-S budget card.

What makes this so strange is that normally it is said that
a _budget_ card can deliver the full TS, while a full featured
card is limited in what it can deliver. In this scenario it would
appear that the FF card works better than a budget card.

Could it be that there is a bug in the budget card driver
that causes problems with multiple recordings from the same
transponder (which means high data transfer rate)?

Note that with two recordings on the budget card (RTL and RTL 2)
I don't get these problems. The more recordings I run on the same
budget card, the more TS continuity errors I get. On the FF card
with 5 recordings I don't get a single continuity error. Needless
to say that the recordings where the continuity errors happened are
broken (video and audio artefacts), while those made with the FF card
are perfectly fine.

Also, during all these tests there were no buffer overflows in VDR,
and also none in the driver (at least none that were reported by the
read() call).

One observation is that with 5 recordings the FF card typically returns
some 30KB in one read(), while the budget card delivers around 4KB per
read(). So with the budget card there are apparently a lot more read()
calls. Don't know whether this constitues a problem, though.

Any ideas what could be causing this?

Klaus