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wwdv  
#1 Posted : Wednesday, September 7, 2016 5:27:23 AM(UTC)
wwdv

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Just a basic SD question.

Because I can't see any difference in the streamed picture quality I am wondering what the best solution is in theory:

Camera composite video output (PAL) -> capture card (without deinterlacing) -> vMix 768x576 50i (deinterlacing enabled)
Camera composite video output (PAL) -> capture card (without deinterlacing) -> vMix 384x288 25p

vMix outputs are in both cases 768x576 25p because of desktop capture and photo inputs.

There are a lot of different opinions about deinterlacing.
Some say use the highest camera resolution and others say avoid deinterlacing because it creates artefacts when encoded.

Peter B  
#2 Posted : Wednesday, September 14, 2016 6:59:49 AM(UTC)
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If you need `P' output then you would have to de-interlace otherwise you will get combing
artefacts when the image moves. If you only need `i' output then don't de-interlace and
leave the signal as is.
NiBTour  
#3 Posted : Wednesday, September 14, 2016 7:49:54 AM(UTC)
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Peter B wrote:
If you need `P' output then you would have to de-interlace otherwise you will get combing
artefacts when the image moves. If you only need `i' output then don't de-interlace and
leave the signal as is.


Peter i think he was asking if you have the choice which shall it be? I run into this all the time and always opt to be P so all my inputs are coming in that way but if you have the option which is best? I'm guessing P so you don't have to deinterlace?

or does it really even matter as long as you know what setting to have? Maybe more CPU with I?

-King
Peter B  
#4 Posted : Thursday, September 15, 2016 11:55:31 AM(UTC)
Peter B

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NiB,

Well P is the best but `I' still has one advantage, greater fluidity of motion as you are shooting 50 half frames /sec. If this was a cine forum I'd get flamed saying that. Almost all broadcasting in Aust is 1080i50 that can carry a P source without any real damage, it's then called PsF, but I into P is not as simple and for streaming I don't think you have a choice.

When a broadcaster here got their new HD truck they shot the football in 1080p25. After the game they switched it all back to I. 1080p50 and 720p50 will make `I' obsolete.

The UHD TX spec will support up to 120fps, NHK were proposing something like 250.

Interestingly temporal or H264, Mpeg2 compression of 50fps only requires about 20% more bandwidth as the changes between the frames are less and easy to compress. I do digress.
thanks 1 user thanked Peter B for this useful post.
umek on 9/18/2016(UTC)
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