[mythtv-users] MX440/Radeon wars (Was: Hardware ideas)
jcw at wilsonet.com
Fri Jun 25 13:25:27 EDT 2004
On Friday 25 June 2004 06:20, Clyde Stubbs wrote:
> On Fri, Jun 25, 2004 at 01:22:41AM -0700, Jarod Wilson wrote:
> > You select a progressive-scan resolution, like 640x480, 800x600 or
> > 1024x768, then the TV encoder scales and interlaces the signal to match
> > the specs you give in XF86Config (such as NTSC & SVideo). You don't
> > specify an interlaced mode to X.
> HAve you actually tried this?
Yes. And ran it on a 27" analog, interlaced-only television for several
> And how could the tv-encoder (which
> is a relatively minor bit of logic and analog circuitry) convert
> progressive scan into interlaced? Surely in order to do that it would
> have to buffer half frames.
Dunno the specifics of it, I just know it works.
> Also, if you don't specify an interlaced mode to X (by which I
> presume you mean that XF86Config contains a progressive scan
> modeline or equivalent)
> then how do you tell the
> TV encoder you want interlacing?
By setting the TV-out options to NTSC (in my case). The NTSC spec is 720x480,
interlaced. The TV-out encoder then knows to interlace the signal.
> Can you provide an example
> of how you've done this?
Its been on my web site for ages now, used by quite a few people:
> I'm more than happy to test your
> claims if you can be a little more specific.
I don't have a PAL-specific config on hand, but change the HorizSync and
VertRefresh values to match PAL and change the TVStandard to PAL-whichever,
and you should be in business.
> Simply setting
> up a 50Hz/31.5kHz 800x600 mode does not produce an interlaced
> signal - I've tried it. It ouputs 31.5kHz progressive scan (and yes,
> I scoped the signal to confirm this).
> This is certainly not how the Radeon TV encoder works, BTW - you
> definitely do specify an interlaced mode in XF86Config.
Didn't know that. Definitely not necessary with nVidia cards. (Though perhaps
if/when the nvidia driver supports interlaced modes, one could get an even
crisper picture with perfect interlaced frame timing and not have to use
> > No, I believe they just use the TV-out encoder the way its intended...
> Well, if you're right I'll take back every alternate half-frame of
> what I've said about the MX440 :-) Please tell me how.
Jarod C. Wilson, RHCE
jcw at wilsonet.com
Got a question? Read this first...
MythTV, Fedora Core & ATrpms documentation:
MythTV Searchable Mailing List Archive
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Size: 189 bytes
Url : http://mythtv.org/pipermail/mythtv-users/attachments/20040625/0ecd9c49/attachment.pgp
More information about the mythtv-users