[mythtv-users] How I got great quality TV-out on my nVidia MX4000

[Brian J. Murrell]

On Mon, 2005-03-07 at 23:20 +0100, Jeroen Brosens wrote:
> 
> You probably don't know how bob works too well. Using bobdeint is the
> *only* way to achieve the original field rate of the broadcast, as played
> on a TV. Just outputting frames that are captured by the MPEG2 encoder
> (which are a combination of the even and odd fields!) 1:1 using an
> interlaced modeline leaves you with a setup that plays back at 30
> f(rames)ps, whereas TV signal is 60 f(ields)ps (replace with 25 and 50
> respectively for PAL).

If that is how your video card is dealing with frames sent to it.  It
was explained to me that the G400 will, when programmed into proper
TV-Out mode, take a "frame" (i.e. the odd and even fields together in
one frame @29.97/s as you explain above) and first display one field and
then the other, each at the proper interval of 59.94 _fields_ per
second.

I don't know what your card does but it sounds like it's wanting a
"field" per "transaction" rather than a frame of two fields (which it
will then separate and display one after the other) which is what the
"Bob/(Progressive Scan)" filter explanation on the below reference page
shows.

I guess this is just another way to skin the same cat.  Whether you send
two fields at once and have the card display them separately or send
them indvidually is pretty much six of one, half dozen of the other I
guess, video card transfer overhead not-withstanding.

> Therefore, using bob is paramount for a smooth video playback. All other
> deinterlacers as well as no deinterlacing (!) can't provide this.

It can, as long as the video card understands it is getting an
interlaced frame and that it is to show the frame's two fields
separately.

> Please do read this: http://www.100fps.com/, it offers excellent
> explanations!

b.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: This is a digitally signed message part
Url : http://mythtv.org/pipermail/mythtv-users/attachments/20050307/f23e1277/attachment-0001.pgp