[mythtv] HDTV patches

Daniel Thor Kristjansson danielk at cat.nyu.edu
Fri Apr 30 08:58:33 EDT 2004

On Fri, 30 Apr 2004, Isaac Richards wrote:
]For me to apply this, please:
]- Get rid of the tabs
]- Don't get the settings (ATSCCheckSignalWait, ATSCCheckSignalThreshold),
]unless it's going to use them.  Way it is now, that's 2 extra database hits
]per channel change for everyone, not just people who are going to use this.
No problem, I'll fix this.

]I've applied the xvmc parts, but left out all changes to NVP, as I couldn't
]tell what was a required change, what was a nasty hack, and what was
]irrelevant.  Please don't make changes that you don't have to, especially
]ones that don't really make sense (framesPlayed -> recorder_frames_played
]doesn't make _any_ sense whatsoever to me -- what's the recorder have to do
]with it?)
That change is required for frame skipping. You need to keep track of
both the frames actually shown on the screen vs the frames in the movie.
If you don't skipping backwards and forward doesn't work. The NVP
keeps a ticker of the frames shown, so if it had only shown 90% of the
frames after 20 minutes it's time in recorded frames would be 2 minutes

I will annotate all the changes in NVP so that you can see the logic in

]Actually, check that.  Just finished testing the xvmc parts, and, it doesn't
]seem to do so well -- picture quality doesn't look all that great (much more
]pixelated than previously), and it dies pretty horribly on one of my test
]clips (video size changes 4 times in a row, 10 or so seconds on each
]resolution).  So, not ready for CVS just yet, I'd say.  =)
Hmm, can you point me to that video clip?

The pixelation is because it tries to figure out if the frame might be
interlaced, and if thinks it is (such as for 640x480i clips) it only
displays half the rows. It's a poor man's deinterlacing. I've only
noticed the pixelation from this in the OSD, but I can disable this
feature for 640x480i so the behavior doesn't change for PVR-x50 users.
At 1080i I think the loss in vertical resolution is compensated by the lack
of interlacing artifacts, at 720p it doesn't do deinterlacing. So I
think 480i is the problem resolution. I have few 480i clips myself.

Thanks for the comments. I'll make the change to the signal check
patch and see what I can do for the playback patch.

-- Daniel

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