[mythtv-users] Any Plextor PX-TV402U-NA users?

Tim Sailer tps at buoy.com
Fri May 13 02:31:41 UTC 2005


On Thu, May 12, 2005 at 08:15:20PM -0400, Nathan Lutchansky wrote:
> File size: try setting your frame size to 640x480 and your bitrate to 

That's what I have.

> 2000 or 2500.  Anything above 1500kbps will be comparable to software 

I was using 2200, which seems to be the builtin default.

> MPEG4 codecs.  If you push it much lower, the bitrate control in the 
> hardware has trouble maintaining consistency and the quality will suck.  
> Don't expect to run at 800kbps like when transcoding DVDs; anything other 
> than a pristine film transfer has too much noise to compress well at those 
> bitrates, and even then it requires two-pass encoding which is impossible 
> with a live source.

What about the audio part of the recording? MP3 or uncompressed wav?
What rate?

> Mangled frames: could you explain this a bit more?  Myth seems to have 
> some issues finding a keyframe when seeking, but playback should be fine.  
> If you push the bitrate up around 6000 kbps, you'll probably see some 
> buffer overruns during periods of high action which will cause dropped 
> frames and weird artifacts.  The other possibility is that you have the 
> device connected to a USB 1.1 port, which will cause similar behavior.

I bought a USB2.0 board just to rule this out. I can be watching a show,
and all of a sudden, the screed turns to a burst of strange pixelated
squares. Hitting pause, backing it up frame by frame, I see 1-3 frames
that are garbage. The machine is lightly loaded, nothing else running.
No apparent timing similarities, nor anything in the scenes that are close
(like quick action, bright sections, etc).

> Viewing the recordings: I can't help with this one since I don't export 
> anything from my Myth system.  But the hardware produces MPEG4 as standard 
> as standard can be, so converting from the Myth NUV files shouldn't be 
> hard for external tools since it's just a container format change.

One would think... I'll have to do some more digging.

> Random failures opening /dev/video0: I've not seen this with Myth, but it
> sounds pretty serious.  What is the error message you're getting?  -Nathan

It's been alternating between "Permission denied" and "no device /dev/video0".

Tim

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