[mythtv] distorted sound with wintv pvr-350

Justin justin at sandershosting.com
Wed Dec 17 00:16:17 EST 2003

I'm having an issue with my mythtv box where sometimes the sound that is
recorded with the program will be distorted.  I saved a mp3 clip of the
sound at http://sandershosting.com/badsound.mp3 so you can see what I
mean.  This only happens sometimes, I would say 1 out of 5 times.  I've
never experienced it when watching live tv but one time when I viewed a
current recording doing this I canceled it went to live tv and the live tv
had garbled sound.  So I went to the epg and reloaded the same channel and
it came up fine.

As background, I'm running Debian unstable, mythtv-0.13 compiled from
source.  My motherboard is Asus P4S533-MX with SiS 651 + SiS 962L chipset.
 I have a wintv-pvr 350 card that is handling the recording and playback
using the axboe ivtv-031125A drivers.  I know this could be an ivtv issue
but I've only experienced the problem in Mythtv so I figured I'd try here

My mythbackend log appears fine, here is the log from the recording that
is sampled in the mp3:

2003-12-16 20:00:02 Started recording "That '70s Show" on channel: 1013 on
cardid: 1, sourceid 1
2003-12-16 20:00:02 Changing from None to RecordingOnly
2003-12-16 20:30:00 Changing from RecordingOnly to None
2003-12-16 20:30:05 Found changes in the todo list.
Input #0, mpeg, from
  Stream #0.0: Video: mpeg1video, 480x480, 29.97 fps
  Stream #0.1: Audio: mp2, 48000 Hz, stereo, 384 kb/s

No errors or anything were logged.

The /var/log/messages shows DMA problems.  I've gotten these messages
multiple times however in normally recorded programs so I'm not sure if
that where the problem is:

Dec 16 19:55:34 MythTV kernel: ivtv: ivtv_dec_timeout: lost IRQ; resetting...
Dec 16 20:00:02 MythTV kernel: saa7115[0]: decoder set size
Dec 16 20:00:02 MythTV kernel: Hpsc: 0x00001, Hfsc: 0x00600
Dec 16 20:00:02 MythTV kernel: Setting full NTSC height
Dec 16 20:00:05 MythTV kernel: ivtv: DMA read error. Result=0x00000002
Dec 16 20:00:30 MythTV kernel: ivtv: DMA read error. Result=0x00000002
Dec 16 20:01:17 MythTV last message repeated 2 times
Dec 16 20:02:00 MythTV kernel: ivtv: DMA read error. Result=0x00000002

These go on to repeat every minute or so till the program is done.  It
seems to be fairly random, like just now I set 10 programs to record on
various channels canceling them as I checked the sound and they were all
ok, so maybe the machine needs to be in some special state for this to
occur.  Again though it seems that changing the channel fixes it when it
does happen.  If anyone can give me some pointers on how to track this
down I'd appreciate it.

Justin <justin at sandershosting.com>

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