[mythtv-users] MythTV - PVR-250 - some newbie questions

Mark Knecht markknecht at gmail.com
Sat Apr 23 20:32:59 UTC 2005

   I'm in the process of setting up a PVR-250 to use MythTV. I've not
used the application before today but I must say I'm very impressed so
far. For the most part the info on the web to get things set up is
pretty good. I've made it a long ways with a bit of help from
Gentoo-Users. I have managed to record some video although so far I
cannot view any of it. (Big problem, 'eh?) ;-) Anyway, this is my
first post here and hopefully it will help me make some forward
progress. Thanks in advance.

   The PVR is installed and I am able to record video from the command
line using the following set of commands:

ivtvctl -u 0x3000
ivtvctl -p 4
ivtvctl -f width=720,height=480
ivtvctl -v input=3,output=1
cat /dev/video0 >test.mpg
mplayer test.mpg

The video and audio quality looks good when I do that. I haven't
figured out channel tuning though. File size is small and the output
does appear to be mpeg. mplayer is happy with the data.

   I have attempted to read through the guide here: (very good BTW)


as well as use the Gentoo docs here:


but didn't find answers to the questions that follow:

TODAY's GOAL: Record Saturday Night Live tonight. (About 10 hours from now.) ;-)

1) The system is using the PVR-250. I've set up a ZapIt account and I
seem to be getting good cable guide info. Right programs, right
channels, etc.

2) I've managed to record some video. It's currently going into a
private partition called /TVstorage. However when I try to watch this
recorded program MythTV first goes to a black screen and then pretty
immediately comes back to the main screen. I see no video.

3) If I record for 10 minutes I see this in /TVstorage:

mark at dragonfly /TVstorage $ ls -aCs
total 7435740
      4 .   7435728 1009_20050423124000_20050423125000.nuv        0
      4 ..        4 log
mark at dragonfly /TVstorage $

So 10 minutes of recording took up about 7.6GB. This seems to me that
I'm getting raw video data and not the output of the PVR-250's mpeg
encoder? Is this true?

4) If I am getting raw data how do I get the output of the encoder
instead? This amount of disk space will kill me and if it was an mpeg
file I could try watching it with other apps also.

5) Can this *.nuv file be converted to mpeg so that I can see if
there's real video/audio there?

6) I'm seeing some messages I don't like in the log file:

2005-04-23 12:49:55.299 IOBOUND - blocking in ThreadedFileWriter::Write()
2005-04-23 12:49:56.801 IOBOUND - blocking in ThreadedFileWriter::Write()
2005-04-23 12:49:57.168 IOBOUND - blocking in ThreadedFileWriter::Write()
2005-04-23 12:49:58.303 IOBOUND - blocking in ThreadedFileWriter::Write()
2005-04-23 12:49:59.738 IOBOUND - blocking in ThreadedFileWriter::Write()
2005-04-23 12:50:00.126 Finished recording first test (Manual Record)
on channel: 1009
2005-04-23 12:50:00.280 Changing from RecordingOnly to None

Two things concern me:

1)  IOBOUND - blocking in ThreadedFileWriter::Write() - What's this
message about. This is the only app I've seen do this so far. The
machine is a fairly new 3GHz Intel ox, but CPU usage was low at 10%
when recording. DMA on the hard drive is enabled and throughput is
pretty fast according to hdparm:

dragonfly ~ # hdparm -tT /dev/hda

 Timing cached reads:   2620 MB in  2.00 seconds = 1310.20 MB/sec
 Timing buffered disk reads:  142 MB in  3.04 seconds =  46.75 MB/sec
dragonfly ~ #

2) Did MythTV actually record in the correct channel? I was trying to
record channel 9 (KQED tv) in the Bay Area from Comcast Cable. Does
this message look correct?

2005-04-23 12:50:00.126 Finished recording first test (Manual Record)
on channel: 1009

   I'll stop there for now.

   Thanks in advance for any pointers you can give a new guy.


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