[mythtv-users] Slight Pauses in Playback/Live TV

[Tim Sawyer]

Thanks for your thoughts everyone, keep 'em coming.

On Thursday 20 Dec 2007, David Watkins wrote:
> I don't know much about this but I see similar effects and, from what
> I've been reading, it may have something to do with 50Hz vs 60Hz
> refresh rates on the video output which particularly affects us in the
> UK.  Does that Jetway have component output, or are you using S-Video?
>  Are you using a digital or analog TV?  What graphics driver are you
> using.

That's interesting.  

I'm using svideo (motherboard has composite video out too).  I have an old 
(six years old?) analog CRT TV.  I'm using the "via" driver in xorg.conf, I 
think it's the openchrome one.  When I first installed mythbuntu it used the 
vesa driver, I had to change xorg.conf manually.  The vesa driver gave me 
about one frame of TV a second - it was unwatchable.

What's interesting is that on my cheap sony portable TV, via scart, the 
picture is black and white.  On the big panasonic widescreen downstairs it's 
also in black and white on AV2 (using svideo), but I have the option for AV2S 
which makes it colour.  (Think this might have something to do with NTSC 
playback?  Dunno.)

On Thursday 20 Dec 2007, Erik wrote:
> Is the system that you mentioned a backend/frontend combo? If so, your
> VIA chip may not be fast enough to handle all that video. Hauppauge's
> site says that you need a 1.7 GHz processor.

But that's for windows, surely! ;-)  Yes, it's a combined front and back end.

Here's the output from top whilst it's recording one programme and watching 
live TV:

top - 17:07:55 up 20 min,  2 users,  load average: 1.65, 0.76, 0.40
Tasks: 115 total,   1 running, 114 sleeping,   0 stopped,   0 zombie
Cpu(s): 27.8%us,  3.0%sy,  0.3%ni, 67.9%id,  0.3%wa,  0.7%hi,  0.0%si,  0.0%st
Mem:    969524k total,   549844k used,   419680k free,    12416k buffers
Swap:  1951888k total,        0k used,  1951888k free,   319420k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 5287 tjs       15   0  197m  79m  39m S 27.6  8.4   0:59.97 mythfrontend.re
 4848 mythtv    18   0  278m  31m  10m S  2.0  3.4   0:34.26 mythbackend
 5062 root      15   0  143m  35m  19m S  0.7  3.7   0:37.89 Xorg

Hmmm.  Anyone know if this is normal?  I do have a spare mini-itx board of the 
same kind, so I can try using a separate front end if that's likely to be 
part of the problem.

On Thursday 20 Dec 2007, Joe Ripley wrote:
> I've noticed this in some DVDs that I've transcoded.

This is live tv/recording playback, not ripped DVDs.  I tried messing with the 
Video Scan option but it didn't seem to help.

More info:

The drop outs in frames, where noticable, might coincide with hard drive 
access, I can hear it chirping.  hdparm gives:

/dev/hdb:
 Timing cached reads:   462 MB in  2.00 seconds = 230.48 MB/sec
 Timing buffered disk reads:  226 MB in  3.07 seconds =  73.56 MB/sec

Thanks one and all,

Tim.