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

Nathan Lutchansky lutchann-mythtvusers at litech.org
Fri May 13 00:15:20 UTC 2005


On Thu, May 12, 2005 at 03:51:25PM -0400, Tim Sailer wrote:
> On Thu, May 12, 2005 at 02:31:49PM -0400, Nathan Lutchansky wrote:
> > On Thu, May 12, 2005 at 01:47:10PM -0400, Tim Sailer wrote:
> > > Are there any other people out there using the  Plextor PX-TV402U-NA?
> > > If so, I'd like to compare experiences, offline. I'm getting very fed
> > > up (already) with this device, and I hope I'm doing something wrong.
> > 
> > As of two days ago, it sounded like you were reasonably satisfied with it
> > and your only problem was exporting NUV files.  What issues are you having
> > with it now?  -Nathan
> 
> File size, mangled frames, the inablilty to use anything else but
> MythTV to view the recordings, random failures opening /dev/video0
> resulting in missed recordings.

Well, OK, let's see:

File size: try setting your frame size to 640x480 and your bitrate to 
2000 or 2500.  Anything above 1500kbps will be comparable to software 
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.

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.

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.

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
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