[mythtv-users] pcHDTV with FX5200 TV-Out

Dan Lanciani ddl5 at danlan.com
Tue Oct 26 02:25:50 UTC 2004

Jarod Wilson <jcw at wilsonet.com> wrote:

|On Sunday 24 October 2004 01:01, Dan Lanciani wrote:
|> I've been playing with the TV-Out on an FX5200 to display ATSC content fr=
|> a pcHDTV.  I see a lot of motion artifacts in the form of short black lin=
|> around moving objects.  I'm not at all sure that these are (de)compression
|> artifacts as I have seen similar problems caused by color encoder or
|> interlace glitches.  In any case, the same program on the same TV sourced
|> from an old DTC-100 shows no problems, so it isn't intrinsic to the strea=
|>  Is there anything I should be tweaking or should I look for a different
|> TV-Out card?
|Try turning on deinterlacing in the frontend setup for playback.

Will do.

|> (And if a different card, which one?)
|nVidia is as good as it gets for HDTV playback in Myth. Not sure if anyone =
|tried much of anything else... The only other card I'd possibly consider is=
| a=20
|Radeon though.

I had tried a Radeon initially, but I was not able to get useful operation
even on the VGA screen.  (It would work for a few seconds and then start
stuttering.)  I tried a variety of drivers including ATI's own (which made
glxgears run very fast, but ran X out of resources for Myth).  I wasn't
thrilled with its TV-Out performance under Windows in any case.

|> There is something funny going on with aspect ratios and/or scaling.  Most
|> of the ATSC programming here is really 4:3 presented in 16:9 format with
|> black bars on the sides.  When I display this on the normal VGA monitor in
|> default 16:9 mode I see it letter boxed as expected such that the 4:3 ima=
|> is centered with black bars on all four sides.  If I use the W command to
|> select 16:9 Zoom mode I get approximately the right result with the 4:3
|> picture full-screen.
|That does sound like the expected behavior...
|> When I display in default 16:9 format on the TV I see the 4:3 image again=
|> the right side side of the screen with black on the left, top, and bottom.
|> (In spite of this, selecting 16:9 Zoom mode again does the right thing.)=
|> If I had real 16:9 material I think I would be missing a chunk on the
|> right. Thoughts?
|=2E..but that definitely doesn't...

Good, at least my understanding of what is expected seems on target. :)

|Do you have any real 16:9 material you =
|verify that with?

They show widescreen programs sometimes, but not, it seems, whenever I have
time to play with Myth. :(  However, I'm pretty sure they are sending a 16:9
stream, as confirmed by the DTC-100 (and for that matter Myth on the VGA).
I have the DTC-100 set to crop, which seems about the same as Myth's 16:9 Zoom.
By the way, what is 4:3 Zoom exactly?

|> Of course, none of this matters much if I can't get rid=20
|> of the motion artifacts...
|Definitely try the deint filters.

You know, I just though what else the artifacts remind me of.  Remember in
the bad old days when contention for the video memory caused "checking" unless
you synchronized CPU access with the VBI?  They look a bit like that.  It
couldn't be something that simple, could it?

				Dan Lanciani
				ddl at danlan.*com

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