[mythtv-users] Prebuffering Pause every minute (PCTV Stereo + Pundit-r)

Graham Voce gravety at hotmail.com
Mon Mar 21 23:52:35 UTC 2005


Hi, 

I had posted this to the Knoppmyth forums but have since found that the problem 'seems' to be related to the DMA (PCI) audio and the saa7134 cards (so I have posted here in hopes of a wider audience and hopefully a solution!).  

When using the line out on one PCTV card I do not get the frequent 'prebuffering pauses' (only the occasional one I can live with!)

Additional Info:

modules.conf
video_buf
tda9887 qss=0 
saa7134 oss=1 dsp_nr=1,2 video_nr=1,2 mixer_nr=1,2 vbi_nr=1,2 oss_rate=32000
tuner

< I have tried using the latency=64 option for the saa7134 >

Frontend output:
2005-03-21 14:17:24.359 mythfrontend version: 0.17.20050130-1 www.mythtv.org
2005-03-21 14:17:24.360 Enabled verbose msgs : important general
2005-03-21 14:17:24.542 Switching to square mode (Iulius)
2005-03-21 14:17:24.899 Registering Internal as a media playback plugin.
mythtv: could not connect to socket
mythtv: Connection refused
lirc_init failed for mythtv, see preceding messages
2005-03-21 14:17:24.908 Joystick disabled.
2005-03-21 14:17:24.930 Registering MythDVD DVD Media Handler as a media handler
2005-03-21 14:17:24.931 Registering MythDVD VCD Media Handler as a media handler
2005-03-21 14:17:25.660 Registering MythMusic Media Handler as a media handler
2005-03-21 14:17:25.700 Mediamonitor: Adding /dev/cdrom
2005-03-21 14:17:25.700 Starting media monitor.
2005-03-21 14:17:40.319 Connecting to backend server: 127.0.0.1:6543 (try 1 of 5)
2005-03-21 14:17:40.328 Using protocol version 14
2005-03-21 14:17:40.362 Using protocol version 14
2005-03-21 14:17:41.123 Opening audio device 'default'.
2005-03-21 14:17:41.390 Using XV port 59
2005-03-21 14:17:41.562 Using realtime priority.
2005-03-21 14:17:41.604 Changing from None to WatchingLiveTV
2005-03-21 14:17:41.664 Video timing method: RTC
2005-03-21 14:20:42.068 prebuffering pause
2005-03-21 14:22:03.343 prebuffering pause
2005-03-21 14:22:29.042 prebuffering pause
2005-03-21 14:23:31.362 prebuffering pause
  < loads of these follow! >

I also sometimes get periods of:
2005-03-21 18:46:00.341 prebuffering pause
2005-03-21 18:46:01.126 WriteAudio: buffer underrun
2005-03-21 18:46:01.126 WriteAudio: buffer underrun
2005-03-21 18:46:01.126 WriteAudio: buffer underrun
with what looks like slow motion video and no audio....------------- Original Information:

I have finally managed to get everything working. However, every time I watch live tv I get those rather annoying 'prebuffering pause' messages. They occur every minute (approx it varies 20secs-2mins) and are accompanied by an AV pause. Playback in-between is smooth. 

I have tried the following: 

Setting audio device to ALSA:default and mixer to default 
Compiling latest ALSA CVS 
Swapping the on-board sound for an external SB MP3+ USB 
Turning on/off aggressive SC buffering and Use internal volume controls 
Turning on/off deinterlacing, realtime priority threads, XV picture controls 
Switching unused devices off in BIOS 
Switching ACPI on/off in BIOS 
Changing card priorities with setpci (for sound/gfx/tv cards) 
Compiling 2.6.11.4 kernel 
Compiling Myth CVS 

In addition: 
XV is working as I get the 'using XV port' message on the front end. 
CPU usage is 22% watching tv. 
Memory usage starts with 250MB free and works its way down to 2-5MB free. 
Xine DVD playback is fine and smooth. 
I have also scoured the mythtv-users lists... 

None of which has made any improvement! The only thing that has made a difference is taking out both tuners and putting in an old bttv card (I still get the pauses but they are more random and less frequent). 

Suggestions welcomed as I am unsure where to look! 

Hardware/Knoppmyth version info in sig. 

Many thanks for any help with this, Graham
_________________
Knoppmyth R5A10 
Pundit-r BIOS 1003 
Intel Celeron D320 2.4Ghz 
2x Pinnacle PCTV Stereo (saa7134) 
512MB PC3200 RAM 
ATI 9100IGP using ATI 3.12 with hex hack 
120 GB Western Digital Caviar 2MB Cache 7200rpm 
BTC DVD-ROM 
Sapphire (ATI) Remote Wonder
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