Autor Thema: Low signal quality  (Gelesen 9327 mal)

theswitch

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Low signal quality
« am: Dezember 23, 2009, 11:03:41 Nachmittag »
The new driver does not crash my mediasrv anymore :)

But I have a problem with my signal quality. The 2 DVB-C PCI cards I'm using are giving perfect streams. But when I try to capture from the dvb input, I get a very distored screen. I've disconnected the other cards and using the same input cables as for those cards, so the quality of the line signal must be OK. Czap reports:

status 1b | signal ffdc | snr 0000 | ber 00007fa9 | unc 0308cf08 | FE_HAS_LOCK

when I'm using lower signal quality cables, the signal ffdc lowers to e000 or b000, but in all cases the ber is still above 0.

mplayer reports:
...
[mpeg2video @ 0x7fc86012ca80]ac-tex damaged at 21 23
[mpeg2video @ 0x7fc86012ca80]skipped MB in I frame at 42 28
[mpeg2video @ 0x7fc86012ca80]ac-tex damaged at 8 29
[mpeg2video @ 0x7fc86012ca80]ac-tex damaged at 26 33
[mpeg2video @ 0x7fc86012ca80]concealing 405 DC, 405 AC, 405 MV errors
[mpeg2video @ 0x7fc86012ca80]ac-tex damaged at 26 20  1% 199.5% 52 0
[mpeg2video @ 0x7fc86012ca80]invalid mb type in B Frame at 17 21
[mpeg2video @ 0x7fc86012ca80]ac-tex damaged at 11 32
[mpeg2video @ 0x7fc86012ca80]concealing 135 DC, 135 AC, 135 MV errors
...

See the attached screenshow of the best quality I can get..

Any ideas how to improve the quality?

« Letzte Änderung: Dezember 23, 2009, 11:05:50 Nachmittag von theswitch »

Sundtek

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Re:Low signal quality
« Antwort #1 am: Dezember 24, 2009, 12:24:03 Vormittag »
According to the czap output your signal strength is 99%

is there any other process running in the background and taking all the CPU time?

Can you upload the content of /var/log/mediasrv.log?

Does this happen with all channels?
« Letzte Änderung: Dezember 24, 2009, 12:38:29 Vormittag von Sundtek »
Failure is a good thing! I'll fix it

theswitch

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Re:Low signal quality
« Antwort #2 am: Dezember 24, 2009, 08:54:22 Vormittag »
I closed down mythtv, the cpu was about idle when I tried this.

I attached the requested logfile, it is a bit boring ;-)

I have only tried this channel, due to the fact that it is the only one which is unencrypted. But tuning to other channels give around the same numbers with czap.


Sundtek

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Re:Low signal quality
« Antwort #3 am: Dezember 24, 2009, 09:11:36 Vormittag »
Do you have another PC for testing? The signal quality seems to be ok.

TS Sync byte not aligned, realigning stream

The driver is trying to resync a corrupted MPEG Stream, the reason for that I cannot tell it is a topic for one of our engineers but they won't be available until 28th Dec. Another option which could be tried would be to switch the mpeg transfer mode - but it also needs to wait until 28th.

Do you have any other USB 2.0 devices attached which might interfere?

What Linux system do you have?

It seems like a problem on USB level actually, unrelated to the signal quality, since it is working here it also seems to be related to your system. Best is to check back with our engineer

If the problem still happens with the latest driver let us know, also what PC Board you have (AMD SB600 is known to have some problems!).
« Letzte Änderung: Januar 26, 2010, 06:19:55 Nachmittag von Sundtek »
Failure is a good thing! I'll fix it