[mythtv-users] Internal DVD player incorrectly detects video scan (interlacing)

Matt Doran matt.doran at papercut.biz
Mon May 28 10:54:54 UTC 2007


Matt Doran wrote:
> stanley kamithi wrote:
>   
>> add  inverse telecine filter (ivtc) to your custom filter list.
>> sounds like some of your  dvds has telecined output.
>>
>>     
> Hi Stanley,
>
> I don't know anything about telecined output.  If I add this to the 
> custom filter, will this impact TV at all?   My TV output is now very 
> good, and would not want to affect that if possible.
>
> Can I apply the filter to DVD only?
>
> I'll give it a try tonight.
>
>
>   
Hi Stanley,

I don't think this is a telecine issue.  I'm in Australia, so my DVDs 
are mostly PAL.   However, one DVD I can reproduce the problem on is a 
"West Wing" import ... so I'm not sure of the standard it's using.  The 
other was a DVD I rented and have returned ... but would have been PAL.

I've added "ivtc" to my custom filters, but it hasn't had any effect.  I 
haven't seen the line "turning on inverse telecine filter" on stderr 
(which I can see in the code) so I don't think it's switched on.  Any 
way that I can confirm?

I've attached the output of 2 -v playback for two different examples.  
They both show interlacing is used in the startup sequence, the first 
one switches to progressive when I press play, the second switches to 
progressive when I go to the "Episodes" submenu even though it has no 
video content and nothing is playing.

Time sequence for frontend-play1.log

    * 20:1 7:40 - start dvd, playing startup sequence.  Startup sequence
      is interlaced, and plays fine.
    * 20:18:21 - pressed play once startup completed.  Changes to
      progressive, and looks awful
    * 20:18:50 - Manually change video sync to "Interlaced".  Looks
      fine  again


Time sequence for frontend-play2.log

    * 20:23:35 - start dvd, playing startup sequence.  Startup sequence
      is interlaced, and plays fine.
    * 20:24:16 - selected the "Episode" menu.  Changes to progressive,
      even though there is no video content.
    * 20:18:21 - select an episode to play.  Still in progressive mode,
      looks awful
    * 20:18:50 - Manually change video sync to "Interlaced".  Looks fine
      again


What do you think?  It definitely seems to be detecting the progressive 
frames incorrectly.   I'm happy to help in anyway and provide any info 
that could be of assistance.

(I'm running trunk r13509, and can easily test patches and/or recompile 
if necessary.)

Thanks,
Matt


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