[mythtv-users] DVB problems after system update

Lachlan McIntosh lachlan at directions.com.au
Wed Dec 27 09:53:26 UTC 2006

I upgraded to the latest SVN today and am experiencing similar issues.

2006-12-27 19:34:31.356 RingBuf(/myth/tv/1002_20061227190000.mpg):
Waited 1.0 seconds for data to become available...
2006-12-27 19:34:32.387 RingBuf(/myth/tv/1002_20061227190000.mpg):
Waited 2.0 seconds for data to become available...

Seems to be a lot more noise and corruption in the video stream and
sound dropouts in the audio stream during play back.

This affects current as well as older recordings.

MPEG4 type files with the internal player do not seem to be affected.

Did anything turn up for you?



-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Johan Reinalda
Sent: Saturday, 23 December 2006 2:27 AM
To: mythtv-users at mythtv.org
Subject: [mythtv-users] DVB problems after system update


I just updated my FC6-x86_64 system to the latest patches and the latest
myth rpms (0.20-148). (I am now running kernel 2.6.18-1.2868, on
AMD64/2800, with 768MB)

I am now experiencing a number of problems with my DVB-S, but NOT with
my PVR-150!

- I get "hickups" while watching live Sat. TV; the picture freezes
momentarily, then continues.
- on Sat. recordings, I get lots of jumps, where the recording simply
misses several seconds

In the backend log, I see the following lines
     DevRdB(0) Error: Driver buffers overflowed

and the front end log show things like:
NVP: prebuffering pause
RingBuf(/mnt/store/recordings/2153_20061221210417.mpg): Taking too long
to be allowed to read..
RingBuf(/mnt/store/recordings/2153_20061221210417.mpg): Waited 1.0
seconds for data to become available...

This seems to mean disk access issues? However, my disk and its
partitions are running on a 3Ware 8006 raid1 controller with dual
SATA150 drives, and hdparm testing show performace as expected.
(mythfrontend is also running as suid root)

I did some other testing, to see if I can eliminate the base system.
When I run the following in three different shells, basically simulating
what myth live tv does, the picture is just fine:

szap   #tune the DVB card

cat /dev/dbv/adapter0/dvr0 > /mnt/store/FILE.mpg      #record from dvb-s

card to file

mplayer /mnt/store/FILE.mpg  #play file while being 'recorded'

Cpu utilization with the above 3 is about 10%, with Myth Livetv it's
about 15-20%

I've notived that vmstat shows virtually no disk waits (WA value) when I
run things in the 3 shells, but with Mythtv I see this jump from 1 to as
high as
6 at times.

I have backed down to the original kernel, build 2798, and to myth
0.20.-147.1 with the same results; the szap/cat/mplayer test works fine
under 2.6.18-2798. Nvidia 5200 drivers are v8776

Now I am starting to expect something else, like QT libraries, or some
other piece that got upgraded?

Any suggestions?



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