[pvrusb2] HVR-1950 - bad video quality

[Mike Isely]

On Mon, 30 Mar 2009, Mike Isely wrote:

> On Sun, 29 Mar 2009, stan schultz wrote:
> 
> > My first HVR-1950 was DOA.  went back to the store and got a new one.  It
> > works much better. On WIndows it captures video that looks as good as the
> > direct TV in analog mode.  But on my Linux box, the video is very bad
> > quality.  It looks like the problem is the synchronization of the start of
> > the scan lines.  They start at a random location between 0 and about 20
> > pixels from the left edge of the screen.  This happens both with Mythtv and
> > with mplayer (both at 720x480 resolution).  Do you have any ideas on what's
> > wrong?
> > 
> > Thanks,
> > 
> > Stan
> 
> Stan:
> 
> Can you capture a snippet and post it somewhere?
> 
>   -Mike

Stan:

When I said "post it somewhere", I was thinking about a web page or 
direct e-mail to me.  Large multi-megabyte posts to this list are not 
allowed - that would just annoy everyone here and likely lay waste to my 
net connection for an extended period (and probably anger a bunch of 
other MTAs).  So I'm going to reject that post.

However the moderation message I received also includes the snapshots 
you are trying to post and I had a look.  I'm glad I asked because this 
is not anything like I was imagining.  This looks like seriously messed 
up video capture timing - looks like the color modulation is messing 
things up.  I think you've probably got the device set to the wrong 
video standard.  MythTV should be handling that automatically (assuming 
of course that you've configured MythTV with the correct standard).  As 
for mplayer, it isn't going to set the standard; rather it will just use 
the device according to whatever standard is in effect.  The quickest 
way to diagnose this problem is to first read this:

http://www.isely.net/pvrusb2/usage.html#sysfs

Then take a look at ctl_video_standard/cur_val and see if it looks 
reasonable.  It's entirely possible that the default setting in the 
driver isn't what you want.  You can change it directly which will help 
mplayer, but for MythTV it needs itself to be configured with the 
correct video standard.  If you think MythTV is getting it right, then 
look again at ctl_video_standard *while* MythTV is running a capture - 
you'll be able to directly observe what standard is being used at the 
moment the capture is going on.

If the problem isn't the video standard, then you have a huge signal 
reception problem.  But that would not seem likely since you said that 
the same hardware setup is working fine in Windows.  I bet my money on 
this being a video standard configuration issue.

  -Mike


-- 

Mike Isely
isely @ pobox (dot) com
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