[mythtv-users] New deinterlacer for perfect image quality when using an interlaced display, mode that matches the source

[Tom Dexter]

On Thu, Apr 9, 2009 at 6:24 AM, Paul Gardiner <lists at glidos.net> wrote:
> Tom Dexter wrote:
>>
>>
>> Believe it or not, I have an episode of Medium (NBC) from Monday night
>> that's not cooperating well with the deinterlacer (in this case the
>> mythtv-0.21-field-order.6.patch version).  It the same thing I saw on
>> that ER episode.  It's not so much tearing as odd, almost slightly
>> jerky motion...almost like when a show intensionally uses special
>> effects to create that sort of choppy/jumpy motion, but not that
>> pronounced.
>
> Why Medium?! If they are going to mess things up, at least pick some
> rubbishy program that no one will care about!! I've recently discovered
> Medium. Watching the first series and loving it.
>
>> This time my wife was able to see it for sure this time.  I can almost
>> guarantee these issues are related to the manner in which NBC mixes
>> progressive frames into their 1080i stuff.  If that's the case, I have
>> a feeling it will do the same with all versions of the
>> deinterlacer...unless for some reason, it only occurs only with that
>> OSD flicker fix.  I saved the show and will try it with both other
>> versions when I get a chance.  I'm unclear as to why it on;y seems to
>> happen with specific programs...perhaps it depends on the amount of
>> progressive frames.
>
> Could it be that the content is just hard enough to decode that MythTv
> is dropping a few frames. Interlaced x2 will look awful if frames are
> being dropped. You'll sometimes see motion taking backward steps. I
> guess another possibility is that the content truly has bad motion,
> and the better resolution you are getting with Interlaced x2 is making
> the problem show more than Bob does. Next episode, you could try your
> commercial decoder.
>
>> It's an elusive issue though.  You can see the odd motion plainly on
>> part of a show, but jump back to the same place and have it work
>> fine...really annoying.  I also noticed that the show in general just
>> doesn't look that good...not as good as my 720p recordings and nowhere
>> near the 1080i stuff like, for example, PBS, which looks perfect.
>
> That does sound like they've done a bad conversion.
>
> Cheers,
>        Paul.
>

An update on my ongoing testing.  Since it takes me over an hour to
compile, and the fact that I can't do it during evening TV watching
time :D, I'm a little limited as to when i can do this sort of stuff.

First of all, I noticed the same motion issues with my recording of
Law and Order: SVU from Tuesday...so I have more content to test with.

This morning I compiled with your original patch (the one without the
OSD flicker fix).  Believe it or not, both shows look fine with
that...no problems at all.  I even watched a good portion of Medium
over again to make sure.

Tomorrow morning I'm going to try again with the version of the
original patch that has to OSD flicker fix just to see if for some
reason that's related.  I don't know if this means anything, but I
noticed something interesting.  For me the OSD flickering (without the
fix for it) seems to primarily be an issue with content that has those
progressive frames mixed in...the same sort of content that tends to
cause the motion issues.  Tonight my wife is watching Survivor, which
is in 1080i on CBS...but those sorts of shows (unlike dramas on NBC
and CBS) never have the progressive frames from what I've seen.
Interestingly, while watching that there's almost no noticeable OSD
flicker, even in the playback menu.  That's still using the original
patch.

In any case this all would seem to rule out decoding or dropped frame
issues, as that's all been the same in both tests so far.

I'll post back tomorrow after more testing.

Tom