[mythtv] [mythtv-commits] Ticket #6343: Problem with VDPAU and Temporal 2X deinterlacing

[Mark Kendall]

2009/3/15 Yeechang Lee <ylee at pobox.com>:
> Mark Kendall <mark.kendall at gmail.com> says:
>> Of that 1%, a certain amount is genuinely mixed
>> progressive/interlaced.
>
> Such content actually exists?!? My understanding, from reading
> previous threads on the subject, was that no one had actually seen
> genuinely mixed progressive/interlaced content in the wild.

I've done a little digging around and I think you're probably right.
Most references seem to suggest that interlaced material sometimes
uses progressive frames for compression savings but they are still
interlaced frames.

>> The balance of the 1% is genuinely interlaced material that has a
>> mix of progressive and interlaced flags (I'm going to ignore for the
>> time being telecined material). I have one dvb-t channel here that
>> seems to flip between the 2 almost randomly. I know it's interlaced
>> material (it's a news channel - the scrolling text is an easy
>> giveaway) yet it sometimes flips 3 or 4 times a second and sometimes
>> doesn't change for a couple of minutes.
>
> Same here in the US; one OTA (the NBC affiliate) and several cable are
> notorious for this. It even varies by program; for example, on NBC the
> half hour-long _30 Rock_ and the hour-long _Chuck_ don't do this but
> the hour-long _Friday Night Lights_ does. (_30 Rock_ used to do so,
> but changed at some point.) The difference is visible in the displayed
> recording times (yes, that longstanding cosmetic issue again); _30
> Rock_ and _Chuck_'s recorded times are more or less accurate but
> _Friday Night Lights_ displays ~53 minutes. These are all 1080i
> broadcasts, by the way.

I'm going to a put together a small patch that locks playback to
interlaced once it has seen interlaced frames (i.e. start progressive
and switch as soon as we see non-progressive). I'd be willing to bet
that that will cure most of the problems seen. The eternal fly in the
ointment is probably dvd material. While locking onto interlaced
should still get dvd playback correct for ivtc/pulldown etc (as long
as you're using the correct deinterlacer), the constant switching
between stream types on all those menus etc will probably be an issue.

Regards

Mark