[linux-dvb] Re: HDTV and FF card

[Johannes Stezenbach <js@linuxtv.org>]

arvo wrote:
> I have made lot of tests in last couple months on viewing HDTV with FF 
> card (Siemens one).
> Driver and firmware are improved a lot. Now i can view Euro1080 and 
> Astra test program witdh no dropouts at all. But there are still 
> problems with HDForum on HotBird.
> There are some differences between firmware versions.  261d and 261d rc5 
> are similar dropouts no so frequently but bigger dropouts 261d rc3 small 
> dropouts , but more frequently.
> 
> I think dropouts come due little bigger bandwith on HDForum, 2 min 
> recording take 304 MB disc space versus 260 MB on Euro1080.

If you're in the mood for experiments you could try if the
realtime preempt patches buy you something. Lowering irq latency
would increase the throughput some.
http://people.redhat.com/mingo/realtime-preempt/

> Question to developers (driver and firmware) is, are all limits on FF 
> card reached or is possible made more improvements?

I'm not sure if the bottleneck is the slowness of the ARM core,
or the bandwidth limit of the ARM<->host communication. For the
second case an improvement could be made by changing the
communication protocol, but I won't do it because the fw
code is a maintenance nightmare and it is all too much work
for a little gain anyway.

Johannes