[mythtv-users] Fox Chicago (WLFD) OTA HD - Nearly unwatchable

Wed Mar 21 13:20:51 UTC 2007

I'm trying to record over-the-air HD via a pchdtv-5500.  It
generally seems to work, except with Fox (WFLD).  In particular, my
girlfriend's "American Idol" recordings are almost too lousy to
watch.  The recordings will have a lot of "jumps" and studdering.
Immediately prior to and following one of these blips is a lot of
blocky pixelation and artifacting of the video.

During playback, my CPU is only at about 30%.  Also, the problem
areas are not random---i.e., if we rewind/rewatch the recording, the
problems are always the same and in the same location.

The first time we recorded this show, these problems only happened a
few times throughout the video.  The most recent recording, though,
had this problem every couple minutes or so.

As far as we can tell, we haven't had this problem with other
channels.  But even within Fox, we haven't had these problems with
the animated shows we record ("The Simpsons", "The Family Guy").

According to antennaweb.org, we're 17.5 miles from *all* broadcast
towers (I believe all stations are broadcast from atop the Sears
Tower).  Unless Fox's signal strength is lower than its peers, it
seems like we should have this problem with all channels.

Our antenna is a cheap "rabbit ears and circle thing" sitting on top
of a speaker.  I believe we have an older version of this:
http://tinyurl.com/2asujb

I'm not really sure where to start debugging this: new antenna,
mythtv, etc.  I'm hoping someone on this list has experience with
this and/or some more insight into Chicagoland Fox.

FWIW, below is the frontend log creating during playback of
"American Idol", somewhat edited for brevity (the original log is
700+ lines long!).

Thanks for any help, suggestions or ideas!
Matt

2007-03-20 23:13:18.340 TV: Attempting to change from None to WatchingPreRecorded
0: start_time: 8566.145 duration: 658.585
1: start_time: 8566.108 duration: 658.587
2: start_time: 8566.106 duration: 658.591
stream: start_time: 95178.957 duration: 7318.038 bitrate=11494 kb/s
2007-03-20 23:13:18.366 AFD: Opened codec 0x4ede220, id(MPEG2VIDEO) type(Video)
2007-03-20 23:13:18.366 AFD: Opened codec 0x4ede5f0, id(AC3) type(Audio)
2007-03-20 23:13:18.367 AFD: Opened codec 0x4ef3f50, id(AC3) type(Audio)
2007-03-20 23:13:18.368 Opening ALSA audio device 'default'.
2007-03-20 23:13:18.450 DPMS Deactivated 
2007-03-20 23:13:18.570 VideoOutputXv: XvMCTex: Init failed
2007-03-20 23:13:18.570 VideoOutputXv: XVideo Adaptor Name: 'NV17 Video Texture'
X Error: BadMatch (invalid parameter attributes) 8
  Major opcode:  141
  Minor opcode:  14
  Resource id:  0x1c8
2007-03-20 23:13:18.846 TV: Changing from None to WatchingPreRecorded
2007-03-20 23:13:18.847 New DB connection, total: 3
2007-03-20 23:13:18.847 Connected to database 'mythconverg' at host: localhost
2007-03-20 23:13:18.848 Realtime priority would require SUID as root.
2007-03-20 23:13:19.116 Video timing method: SGI OpenGL
2007-03-20 23:13:19.165 AO: dropping back audio_buffer_unused
[ ... above repeated many times ... ]
2007-03-20 23:42:19.383 NVP: prebuffering pause
2007-03-20 23:42:19.532 NVP: prebuffering pause
2007-03-20 23:43:18.177 NVP: prebuffering pause
2007-03-20 23:43:41.147 AFD Error: Unknown decoding error
2007-03-20 23:43:49.464 NVP: prebuffering pause
2007-03-20 23:43:49.562 NVP: prebuffering pause
2007-03-20 23:43:50.870 NVP: prebuffering pause
2007-03-20 23:43:50.951 NVP: prebuffering pause
2007-03-20 23:45:36.962 NVP: prebuffering pause
2007-03-20 23:45:36.949 WriteAudio: buffer underrun
2007-03-20 23:45:37.094 NVP: prebuffering pause
[ ... more of the same ... ]
2007-03-21 00:46:29.624 audio stream changed
2007-03-21 00:46:29.647 Opening ALSA audio device 'default'.
2007-03-21 00:46:29.794 audio stream changed
2007-03-21 00:46:29.813 Opening ALSA audio device 'default'.
2007-03-21 00:46:29.858 NVP: prebuffering pause
2007-03-21 00:46:29.936 AO: dropping back audio_buffer_unused
2007-03-21 00:46:30.026 AO: dropping back audio_buffer_unused
2007-03-21 00:46:30.134 AO: dropping back audio_buffer_unused
[ ... lots of what has already been seen ... ]
2007-03-21 00:48:06.633 audio stream changed
2007-03-21 00:48:06.653 Opening ALSA audio device 'default'.
2007-03-21 00:48:06.654 AudioOutput Error: Rate doesn't match (requested 32000Hz, got 44100Hz)
2007-03-21 00:48:06.692 AudioOutput Error: Unable to set ALSA parameters
2007-03-21 00:48:06.705 audio stream changed
2007-03-21 00:48:06.705 Opening ALSA audio device 'default'.
2007-03-21 00:48:06.782 NVP: prebuffering pause
2007-03-21 00:48:06.854 AO: dropping back audio_buffer_unused
[ ... etc ... ]
2007-03-21 00:51:48.856 NVP: prebuffering pause
2007-03-21 00:51:50.116 WriteAudio: buffer underrun
2007-03-21 00:51:50.126 NVP: prebuffering pause
2007-03-21 00:51:57.226 TV: Attempting to change from WatchingPreRecorded to None
2007-03-21 00:51:57.295 TV: Changing from WatchingPreRecorded to None
2007-03-21 00:51:57.489 DPMS Reactivated.
0: start_time: 8566.145 duration: 658.585
1: start_time: 8566.108 duration: 658.587
2: start_time: 8566.106 duration: 658.591
stream: start_time: 95178.957 duration: 7318.038 bitrate=11494 kb/s
2007-03-21 00:51:58.086 AFD: Opened codec 0x4cfb4e0, id(MPEG2VIDEO) type(Video)
2007-03-21 00:51:58.087 AFD: Opened codec 0x4e47fd0, id(AC3) type(Audio)
2007-03-21 00:51:58.087 AFD: Opened codec 0x4e5c8f0, id(AC3) type(Audio)
0: start_time: 8566.145 duration: 658.585
1: start_time: 8566.108 duration: 658.587
2: start_time: 8566.106 duration: 658.591
stream: start_time: 95178.957 duration: 7318.038 bitrate=11494 kb/s
2007-03-21 00:51:59.043 AFD: Opened codec 0x158fc80, id(MPEG2VIDEO) type(Video)
2007-03-21 00:51:59.043 AFD: Opened codec 0x4cfb4e0, id(AC3) type(Audio)
2007-03-21 00:51:59.044 AFD: Opened codec 0x4e47fd0, id(AC3) type(Audio)
2007-03-21 01:22:13.464 AFD Error: Unknown decoding error
2007-03-21 01:26:22.640 AFD Error: Unknown decoding error
2007-03-21 01:38:38.027 AFD Error: Unknown decoding error
2007-03-21 01:41:58.474 AFD Error: Unknown decoding error
2007-03-21 01:45:42.593 AFD Error: Unknown decoding error
2007-03-21 01:47:07.275 AFD Error: Unknown decoding error
2007-03-21 02:03:42.500 AFD Error: Unknown decoding error
2007-03-21 02:26:03.713 AFD Error: Unknown decoding error
2007-03-21 02:27:10.796 AFD Error: Unknown decoding error
2007-03-21 02:28:28.321 AFD Error: Unknown decoding error
[ ... the block above repeats several times ... ]