[mythtv-users] mythTV, Kaffeine and Twinhan DVB-T

[Nicklas Bergfeldt]

Nicklas Bergfeldt wrote:
> Hi,
>
> I'm using the following system:
> Linux 2.6.15-gentoo-r1 #9 SMP PREEMPT Wed Mar 8 00:50:22 CET 2006 i686 
> AMD Athlon(TM) XP 1800+ AuthenticAMD GNU/Linux
> with 1 GB RAM and 2 Twinhan DVB-T cards.
>
> Software:
> *  media-tv/mythtv
>       Latest version available: 0.19_p9163-r1
>       Latest version installed: 0.19_p9163-r1
>
> *  media-video/kaffeine
>       Latest version available: 0.7.1
>       Latest version installed: 0.7.1


I have made more tests and come up with what seems to be the 
explanation: The two Twinhan cards cannot function properly at the same 
time in the same computer.
 - Basic test: Both cards are working good in mythTV on their own (i.e. 
being the only TV card in the machine)...

More tests reviled that: As long as only one card is opened the picture 
is good...
 - But as soon as the other card is accessed as well the "jerking" starts.

This applies to all combinations of single and simultaneous access:
 - It works ok if only one card is available to mythTV, then only one 
card is opened and the picture is good (even if there are two cards in 
the machine!).
 - It works ok if both cards are available to mythTV but opened on 
demand, as long as only one card is opened... as soon as both cards are 
opened (e.g. during record and LiveTV) the "jerking" starts...
 - It do not work ok when both cards are available to mythTV (always) 
but only one should be active (e.g. only watching LiveTV, second card 
should not do anything) - this I find kind of strange... but perhaps one 
must access the cards somehow...

I have tried both separate IRQs and as long as possible physical 
distance between the cards in the computer (PCI slots) but nothing 
helped the "jerking"...

Btw, this (seems to) apply to Kaffeine as well... since Kaffeine did not 
open the second card until that was necessary (e.g. recording one 
program while watching another mux) the picture was "better" in Kaffeine...
 - But as it turned out it was equally good in mythTV when only one card 
was used!
 - And Kaffeine started "jerking" once several cards were accessed at 
the same time!

Btw, I measured the CPU usage during recording on one channel and 
watching LiveTV on another and there were still approx 65% idle...
 - I also measured the "hdparm -tT /dev/hda" and that resulted in 
45MByte per second... Even though that is not a very fast HD, I find 
that to be fast enough for streaming two channels :-)

Anyhow, just though I should mention this...
 - Now I'll try to get rid of these cards and buy some more expensive 
ones :-/

/Nicklas