[mythtv-users] bob deinterlacing and animated shows

[Robert Denier]

You can convert from 29.97 to 24 and with a great deal of success. 
Take a look at virtualdub.org.  It runs on windows, but the code is 
available for
most of the add ons.  In particular look for things like

3:2 pulldown
inverse telecine

Basically its a method of constructing the original frames from the 
29.97 frames.
In general, these are not 100% perfect, but they are fairly good.

I've yet to look at the transcode options in myth, but if one was going 
to put those
features in, it makes more sense to do it then, since its somewhat cpu 
intensive.

In theory you might be able to eventually have the option automagically 
selected
live, but the time required for an algorithm to notice and be reasonably 
sure the
original material was 24fps might be a few seconds worth of frames and 
then you
have the mess of changing back and forth + the fact that comercials 
might confuse
it even more.  Yes this would definitely be something worth porting to 
transcode
options, if it isn't already there, but doing it live would be messy.  I 
suppose you
could have a manual switch for live though.  It would likely require 
restarting however
live  programs are timeshifted so that the entire stream is  24 fps.  It 
might also
require a slight additional delay to allow the algorithm time to work.

I really should look at whats possible with transcoding one day soon...


Brad Templeton wrote:

>On Tue, Jan 25, 2005 at 11:44:08PM -0500, toad six wrote:
>  
>
>>The lines are ugly, and I want to get rid of them, so I'm trying to
>>use Bob deinterlacing.  (If somebody has suggestions on how to get rid
>>of the lines without using deinterlacing, please let me know!!)
>>    
>>
>
>Well, in theory since your TV is interlaced if you do things just right,
>you would not get them any more than watching regular TV.  But it's hard
>to get things just right.
>  
>
>>It looks pretty good on "live" shows (as in, those that are recorded
>>with a camera) - for some reason, live shows seem to have the least
>>occurences of the interlacing artifacts on screen, possibly because
>>they are natively recorded in 29.97fps???
>>But when I'm watching an animated show (natively 24fps) like The
>>    
>>
>
>Yup.  The software that converts 24fps animation to 60 half-frame-per-
>second interlaced video tends to create these intersitial frames by blending
>existing frames.  I heard of some folks doing software to specifically
>remove the artifacts for progressive displays but don't know if you can
>get it in free software.   The goal is to extract the original frames
>that came at 24fps.    But you have a TV, presumably not progressive.
>
>Are you driving the TV at 640x480?  How much are you overscanning?
>  
>
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