[linux-dvb] datarates: any experiences?

[Ralph Metzler <rjkm@convergence.de>]

Bart De Gruyter writes:
 > I would like to know up to what udp receiving
 > data rates people on the list have used the hauppauge
 > dvb-s or the nova card...
 > 
 > I've been able to test data rates up to 25 Mbit/s
 > with the nova card. At higher speeds the socket
 > calls start to lose more and more data. The strange
 > thing is dat the statistics of the ifconfig command
 > indicate the exact amount of data. It's as if the
 > hardware of the card is able to get higher speeds
 > but for some reason the data does not get to the
 > socket calls of the OS.
 > 
 > I've also done some tests on a windows 2000 pro
 > machine and see similar resulsts...
 

If the statistics counted the data it must have reached the network
driver and been passed on to the TCP/IP stack.
So, I don't know what could go wrong there.
Is your test data all addressed to the same IP or are you including
other kinds of packets when increasing the data rate?
Maybe they are filtered out by the TCP/IP stack for some other reason?

 
 > We have also seen that the old dvb-s card is less performing
 > for udp data reception than the nova card. We've ordered a
 > new dvb-s card with the updated hardware to see if it works
 > better.

That won't change anything. The bottleneck here is the memory transfer
inside the AV7110 and from the AV7110 to the PC.
For high data rates you have to use the Nova card.


Ralph


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