[mythtv] Interlaced vs. Progressive

David Asher david.asher at caviumnetworks.com
Sat Mar 4 20:51:43 UTC 2006


Getting closer to a releasable patch.

I changed it so that the deinterlacer stuff is allocated at the 
beginning unconditionally, and then if the first frame is progressive 
immediately disabled.  All enabling and disabling of deinterlacing no 
longer allocates or deallocates things (except changing of the TYPE of 
deinterlacer).

Anyway, that didn't fix the problem.  "odd stutters" was a poor 
description.  What it really looked like was the picture flashed, with a 
portion of the frame allowing you to see the color key.

So I discovered that it was because I set needrepaint (in 
videoout_xv.cpp) whenever the deinterlacing state changed.  If comment 
that out the flash doesn't happen.  I can't decide if not setting it is 
ok or not.  SetupDeinterlacer() sets it (which is what I modeled my 
enable/disable functions on).

What's your opinion?

Also, I think I need to add a menu option/bindable key to toggle 
deinterlacing for the case where the video stream isn't accurate.  The 
broadcast video I have that is switching back and forth DEFINITELY looks 
better with deinterlacing on all the time.

David.

Isaac Richards wrote:
> On Thursday 02 March 2006 23:59, David Asher wrote:
>   
>> Ok, I pretty much got this to work...  Buuuutttt... (there's always a
>> but, isn't there?)
>>
>> One broadcaster here in the Boston area (WGBH) broadcasts a show on 2-1
>> (a SD subchannel, 2-2 is HD).  The shows I've recorded on 2-1 oscillate
>> between interlaced and progressive according to ffmpeg -- not good.
>> Creates stutters as my code tries to enable and disable interlacing (I'm
>> using bob).  I've already put a small (2 frame) hysteresis in to handle
>> DVD playback (the DVD I tested with often has 1 interlaced frame is a
>> sea progressive frames when wandering through the menus at the beginning).
>>
>> Any clever ideas how to deal with this type of issue?  By using the
>> interlaced_frame info from ffmpeg I made NVP a slave to its knowledge.
>> One thing that MIGHT work is I'm currently allocating and freeing the
>> deint filters each time the flag changes -- I could keep the
>> deinterlacer structures around after disabling -- maybe that could
>> reduce the hiccups to where they weren't noticeable.
>>     
>
> Yeah, there shouldn't be any reason to reallocate things when it changes.
>
>   
>> Anybody know how ffmpeg figures out whether a frame is interlaced?
>>     
>
> frame headers.
>
> Isaac
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