[pvrusb2] FAQ addendum for 4:3 recording resolutions

[roger]

Right. I'm recording with Mythtv.  Although recording at 720x480 on most
channels, just on a few I get a noticable black bar on the right side.

I finally found out lately via a brief search on google, 720x480 is not
a true 4x3 (or 1.33:1) compatible resolution.  640x480 is.

So I set Mythtv to record at a custom resolution at 640x480, and the
black bar on the right side is gone.  I'm guessing this has to do with
what kind of signal the broadcasting station is broadcasting and what
Comcast does to convert it to an analog cable signal.  Most other
channels such as Discovery don't appear to exhibit this except for maybe
a thing black border on either the right or left side.

Maybe you'll see this also on TVLand channel as well, because it's
broadcasting some older show formats as well.

Anyways, I can send Mike clippings, but I'm just going to kick back and
relax and see what my recordings look like this friday when the same
show is recorded at 640x480.. pretty sure it's providing a better
picture.


On Sun, 2007-03-11 at 12:35 -0500, Rod Smith wrote:
> On Sunday 11 March 2007 07:28, roger wrote:
> > On Sun, 2007-03-11 at 01:46 -0600, Mike Isely wrote:
> > > Try this: Use the sysfs interface to change the aspect ratio.  Don't
> > > change the resolution; there's a separate control for the aspect ratio
> > > (ctl_video_aspect).  Observe the results in mplayer...
> >
> > Yes.  Most times mplayer and other video players will correctly stretch
> > the video to fill the screen, but I'm noticing on some broadcasts,
> > especially on Channel 12 playing an oldie but favorite, I will get a
> > black bar on the right when recording 720x480.  Recording 640x480 gets
> > rid of the borders when playing with mplayer, etc.
> 
> Are you using MythTV? If so, have you by any chance set the option to use a 
> custom video resolution based on the recording resolution? If this is the 
> case, the black bar you're seeing could be caused by the playback video 
> resolution for 720x480 producing a slightly smaller image than the playback 
> resolution(s) you use for other recording resolutions.
> 
--
Roger
http://www.eskimo.com/~roger/index.html
Key fingerprint = 8977 A252 2623 F567 70CD 1261 640F C963 1005 1D61

Tue Mar 13 01:08:55 PDT 2007