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

Nathan Lutchansky lutchann-mythtvusers at litech.org
Sat May 14 00:14:54 UTC 2005


On Thu, May 12, 2005 at 10:31:41PM -0400, Tim Sailer wrote:
> On Thu, May 12, 2005 at 08:15:20PM -0400, Nathan Lutchansky wrote:
> > 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?

The audio is compressed on the host, just like when using a standard sound
card.  Check the recording profile settings for the compression
parameters.

> > 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).

I thought I ironed out all the corruption bugs (except for overruns with
too-high bitrates, anyway).  It could be a buffer overrun, hardware error,
cable problem, or a bug in the stream parser in the driver.  Can you try
and take a screenshot to send me?  Since it doesn't look like you're able
to convert the NUV files to anything exportable, it doesn't sound like 
you'd be able to send me an example AVI or anything.

> > 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".

This one's the kicker.  I've thought about this a lot and I can't imagine
how this could be caused by anything in the driver, so I suspect it might
be a hardware issue.  Do your logs show that the device is connecting and
disconnecting spontaneously?  In /var/log/messages or /var/log/syslog do
you see more USB "new device" and "disconnect" messages than you would
expect?  If not, I don't really have any other ideas.  Maybe there's some
other process messing with your device nodes?  -Nathan
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
Url : http://mythtv.org/pipermail/mythtv-users/attachments/20050513/ed518178/attachment.pgp


More information about the mythtv-users mailing list