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

[Tom Dexter]

On Wed, Mar 18, 2009 at 10:33 PM, Mark Kendall <mark.kendall at gmail.com> wrote:
> 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
>

Hey Mark...I was curious as to whether or not you made any progress
with this.  I have a 1080i RP CRT display and have been testing Paul
Gardiner's patch that adds a field-order deinterlacer in my 0.21-fixes
install:

 http://www.gossamer-threads.com/lists/mythtv/dev/376690#376690

So far it appears to be perfect for my situation.  The only problem is
that these types of stations cause problems with that deinterlacer
unless I manually set the display to interlaced.

I actually don't use the internal player for DVDs...I was thinking
that might make a simple hack for my own purposes quite a bit easier.

Thanks in advance.

Tom