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Author Topic: Pitch-Down for PAL  (Read 1090 times)

squeedle

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Pitch-Down for PAL
« on: December 18, 2018, 12:28:42 am »

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lepa

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Re: Pitch-Down for PAL
« Reply #1 on: December 18, 2018, 05:14:29 am »

For a workaround. Wouldn't you be able to make zone "Pitch-Down" where you have set rate slower using DSP and which will be activated when starting to play such videos?

EDIT: I guess not... MC's video clock seems to "fix" the changes made by DSP..
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RD James

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Re: Pitch-Down for PAL
« Reply #2 on: December 18, 2018, 06:37:06 am »

+1
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blgentry

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Re: Pitch-Down for PAL
« Reply #3 on: December 18, 2018, 10:06:11 am »

I read most of the thread, but find it extremely confusing. 

Is the intended use for this, to play back media that was originally at 24 fps, then converted to 25, and then MC is converting it *back* to 24?  If so, that seems bizarre.  If you have a 24 fps playback device, why are you not playing content intended for it?  Why would you have a 25fps version of a 24fps movie or tv show to start with?

Or perhaps I have missed the point entirely.

Brian.
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lepa

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Re: Pitch-Down for PAL
« Reply #4 on: December 18, 2018, 01:04:46 pm »

Some of the FILM PAL DVDs are sped up to 25fps and audio is not converted to maintain original pitch.

So feature request I guess is to be able to play these videos at 24fps (23,976) and not "correcting" the pitch as it is too high in the source
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RD James

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Re: Pitch-Down for PAL
« Reply #5 on: December 19, 2018, 02:35:10 am »

I read most of the thread, but find it extremely confusing. 

Is the intended use for this, to play back media that was originally at 24 fps, then converted to 25, and then MC is converting it *back* to 24?  If so, that seems bizarre.  If you have a 24 fps playback device, why are you not playing content intended for it?  Why would you have a 25fps version of a 24fps movie or tv show to start with?

Or perhaps I have missed the point entirely.

Brian.
This is a somewhat simplified explanation, but:
 
In America, and other NTSC regions, film (24 FPS) was encoded to NTSC DVD (60i) using 2:3 pulldown for playback on 60Hz displays.
This meant that films were played back at an uneven cadence, causing the video to stutter every other frame, but it played back at the correct speed and audio was untouched.
With modern displays that now support 24Hz, you can cut out the repeated field, turning that into 2:2, and weave the two fields together to get two film frames at 24 FPS.
 
In Europe and other PAL regions, film (24 FPS) was encoded to PAL DVD (50i) by speeding up the video slightly and encoding it using 2:2 for playback on 50Hz displays.
This meant that films played perfectly smooth, but everything was slightly faster than intended.
With modern displays that now support 24Hz, you can slow down the video from 25 FPS to 24 FPS and play it at the correct speed.
 
The issue is that some PAL releases were pitch-corrected, while others were not. And some content was natively shot as PAL and should be played back at 50Hz.
Media Center currently preserves the original pitch, which means that even if you slow down the video to the correct speed, the audio still sounds higher-pitch in releases that were not pitch-corrected. Part of the issue is that this would have to be set using a per-file tag, rather than a global option.
And for what it's worth, I still have a dozen or so Blu-rays that are encoded at 25 FPS (and some which are 60i for that matter) so the problem is not exclusive to DVDs and other PAL sources.
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blgentry

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Re: Pitch-Down for PAL
« Reply #6 on: December 19, 2018, 09:32:23 am »

With those details I understand a lot more now.

I was going to type a lot about goofy sources here, but I realize that it doesn't matter what I say about that.

Thank you for taking the time to explain the technical issues to me.  :)

Brian.
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