[mythtv-users] Deinterlace stopped working in latest SVN trunk

Brad Templeton brad+myth at templetons.com
Fri Jun 1 04:45:58 UTC 2007


On Thu, May 31, 2007 at 09:17:25PM -0400, Boleslaw Ciesielski wrote:
> Brad Templeton wrote:
> > And while I don't have enough knowledge to decode the transport
> > streams, I still am curious if there are really progressive frames
> > in the stream.  I mean, is it legal to transmit a 1080 line progressive
> > frame (even at 30fps or less) in an over the air ATSC broadcast?
> 
> Yes, at 24fps or 30fps but not at 60fps. AFAIK, nobody does it though.
> 
> > Would the TVs out there handle it? 
> 
> They are supposed to, in theory (via the internal ATSC tuner, not 
> necessarily via component/DVI/whatever input). But since there are no 
> test cases, who knows.
> 
> > I mean it would be great if the networks transmitted moves at 1080p 30FrPS
> > or even 1080p 24FrPS rather than in 1080i 60 fields/second (30 frames/second)
> > as they normally do, but I didn't think it was even in the broadcast
> > HDTV spec.  Does anybody know?
> 
> Both 1080p24 and 1080p30 are (and have been) part of ATSC spec. 1080p60 
> is not.
> 

Got it.  However, I don't think this is what they are doing.  Stations actually
go too far the other way, staying in the same format no matter what, not
even switching to 720p for sports, or 480p for STDV broadcasts.  No
widescreen 480 line modes either, annoyingly -- if they have a letterbox show
they do it letterboxed 480i.

And in particular, with these broadcasts, when myth is detecting supposedly
progressive frames and turning off deinterlace, the result is I see all sorts
of comb aliasing, so something wrong is going on -- and I doubt the stations are
randomly switching between progressive and interlaced frames every second.


More information about the mythtv-users mailing list