Dienstag, 17. September 2002 at 12:08 Felix Domke wrote: >> Do you really think, this is a problem? Normally, SAT-providers state >> their bandwidth in kBit/s and not MByte/s. So I believe you won't hardly >> be able to exploit the bandwidth within your card with IP-Networking. >> The bottelneck of SAT-IP-Networking is the shared bandwidth on the >> transponder and not the hardware on the DVB-card. > But these 1.5MB/s are the *theoretical* bandwidth. I think the card doesn't > offer any busmastering (correct me if i'm wrong), so when you read from the > card, say, 200kb, you need > 200k/1.5M = ~130ms. In these 130ms you cannot do anything else, so you have > a VERY HIGH cpu load with higher bandwiths. It get's critical if you want to > do timeshifting and stuff (ok, that's not your concern). It's like an IDE > harddisk which does about 2MB/s without DMA. Are you willing to use this to > record movies? Movies are ~500kb/s. But it won't work very well.
Interesting view. I didn't take this into account. But, let's see it from a different point. To receive the 200kB you mentioned with - let's say "normal" DSL-speed of 768kBit/s, you need (200kByte * 8) / 768 kBit ~= 2.1 seconds. So this is much more time than the card needs to transfer this data, means: Most of the time, the card will be waiting for data and not do anything. Am I right? So as long as we are talking about IP-Networking, there should be no problem. For video, I fully aggree with you. > Some multicasts on EON (or other) have bandwidths of up to 8MBit/s, and then > it really gets hot. I know that some PCI-cards (not the Siemens ones) had a > problem here and thus couldn't be used for this. Ok, but even with 8MBit/s you only get 1 MByte/s from the transponder and this is still below the mentioned 1,5 MB/s. >> I have no personal experience with the full featured cards, but I know >> people using T-DSL via Satellite from Deutsche Telekom with such cards >> and they are getting equal transmission rates like I have with my budget >> card. > Off course. It *WILL* work. But for myself, i'd like to experiment with all > streams i find on the transponders, especially the multicast stuff. And, as > said, for this, the bandwidth provided by some cards isn't just enough. In > contrast, the bandwidth provided by the Nova is always enough. So i strongly > recommend these Cards for everyone who doesn't want to watch TV. > (Additionally, the delivery of the full, unmodified, unfiltered TS is an > unique feature of this cards.) And they are cheaper. FULL ACK. If you only want to do SAT-IP-networking, the budget-cards are the right choice and even if you want to do DTV and IP over Satellite, I'd prefer using a full featured DVB for DTV and an additional budget-card for IP (should be affordable due to it's small price). So we're not so far from each other ;-) -- Best regards Wolfgang Wershofen mailto:[EMAIL PROTECTED] -- Info: To unsubscribe send a mail to [EMAIL PROTECTED] with "unsubscribe linux-dvb" as subject.
