[linux-dvb] Re: One tough question with sound disapearing

[Benjamin Harling <benjamin.harling@web.de>]

Carsten Koch <Carsten.Koch@icem.de> schrieb am 07.03.01:
> Benjamin Harling wrote:
> ....
> > Yesterday all recordings (whether instant or timed) a showing the same
> > thing: after it first has a few dropouts, the sound goes completely away
> > within the first minute or shortly after it.
> 
> I have seen similar symptoms in some recordings, but not all:
> The picture is perfect, but the sound has a lot of dropouts
> or goes away entirely sometimes. I have not yet figured out
> a system behind it, because I have a lot of recordings and I
> sometimes watch them weeks after recording them.
> 
> Klaus has reported a while ago that he was experiencing sound 
> dropouts on channels with high bit rates, such as ARD.
> 
> It may have to do with the temperature of the card. Have you tried
> cooling it? It may have something to do with your disk throughput. 
> Did you see any changes in the sound dropouts when you changed 
> hdparm settings? Or with the signal quality of your dish. Are you
> seeing perfect quality with an anlog receiver? It may also be a 
> firmware or driver problem that is triggered by certain data or 
> at certain data rates.
> 
Hi Carsten,

thank you for your thoughts. Here are the answers to your questions:

Yes, I do see perfect signal quality with an analog receiver. I even do see perfect quality (that goes all for picture and sound) when just watching TV with the DVB-s-card and seems so strange to me. Just the recordings have dropouts and fading sound. So the signal quality of the dish should be ok. And remember, all went well a few days ago.

For the certain data rates. I observed the problem while recording different channels, like ARD and VIVA or Pro7. I even calculated the approximate average data rate. I was almost always below 500 kByte/s, just VIVA went up to 600 kByte/s. But thats average. Should be a meaningful value, though.

There we are at the trouhput off the disk subsystem. hdparm is reporting an unbuffered transfer of approx. 12 MByte/s and buffered around 60 MByte/s after optimizing the parameters. Even with this disk unoptimized (unbuffered transfer of around 2 MByte/s) I was able to make perfect recordings a few days ago.

That leaves the temperature and that could very well be. I'll check into that and let you know. Alas, I can't leave the case open because my little children are around.

So, we'll see. Thanks again for your thoughts and to all who created and contributed to this project.

One more piece of information:

My system is...

350 MHz AMD K6-2
128 MB RAM
6 GB HDD
40 GB HDD (Quantum Ict, very silent)
WinTV DVB-s Hauppauge


Benjamin

PS.: How can I tell the bit rate of a channel???
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