quick Q re de-interlacing PAL and field dominance?

Hi there Pals-

Just need to check in re de-interlacing PAL DV in terms of field dominance -

-if DV PAL has a LOWER (even) Field Dominance, then does that mean I should select Lower in the de-flicker video filter effect as well (ie, does that filter SKIP the first field or REMOVE the first field)?

-or is it better to select the OPPOSITE, ie UPPER (odd) in this case?

Thanks!

Marla-still-editing-the-TED-talks-in-snowy-New-York....

Hey Marla

What are you trying to achieve?

Use Blended fields if you want a "Progressive look" - use Too Much Too Soon's Blend Fields Filter.


[www.mattias.nu]


If you are trying to use DV PAL on an Upper Field Dominant format like 1080i HD or PAL Digibeta then use the FCP Shift Fields -1



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Hey Ben,

Thanks for gettin' back -

We experimented with various DV de-interlacing options and recently found, to our surprise, that the FCP de-interlace filter actually looks good on our recent DV-PAL material. We have a long pipeline at TED, ie one person digitizes a talk, then I edit it, and then I add titles in a nested sequence and export the talk with no compression, and then someone else does myriad compression versions from that for TED's various players and partner's-players. many sizes, many resolutions, but all for the web.

we have lots of NTSC DV talks from the olden days which are not de-interlaced and which look fine, but we had some issues with our recent PAL footage that made de-interlacing before getting on the website very desirable.

So just recently we started de-interlacing in the "just after editing and just before uncompressed exporting" phase, via the FCP de-interlacing video filter. We put out 5 videos a week, so time is always crucial around here.

Again, this is only for our recent Global conference material, that was all shot DV-PAL. Our main conference is always shot in HD, so no de-interlacing needed there.

The de-interlace video filter is fine, I just need to understand how it interprets field-dominance - ie if the settings of my sequence and media are DV-PAL, Lower (even), then when I use the de-flicker filter, should it match the Lower (even) material, or should it be set at the opposite?

Any wisdom on this (or other) matter(s) would be apreciated!

Thanks,

M A R L A

My preferred route which will give you the best quality "Progressive look" from interlaced.


? Add the TMTS Blend fields to all the clips in your 576i DV PAL sequence.

? Then drop the 576i DV PAL Sequence onto a ProRes PAL timeline with fields set to none.

? Output a Progressive ProRes Quicktime.


If you use the de-interlace filter you will be discarding half the picture information as it throws away the upper or lower field and duplicates the remaining one. Or at best it tries to interpolate and blurs.

Try my method - the TMTS filters are free and the Blend Fields will be your new best friend.

It is especially noticeable on fine details and graphics

See below look closely at the text:

With FCP De-interlace filter




With TMTS Blend Fields then Nested on Progressive Sequence



Also the motion will be smoother using TMTS Blend Fields as it produces what would be akin to the captured motion blur on a progressive camera from the separate fields.



Read more about fields here: [lurkertech.com]



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Thanks for the tip - I will try it - but can you please explain the field dominance issue anyway?

I'd like to know: matching settings or opposite - which is it (ie which field gets removed)?

Marla

Here download this test file: [loudandfast.co.uk]

It is a 1 second ProRes 422 video with Black lines for each Upper Field and White lines for each Lower Field

Test it:

If you apply the De-interlace filter it in any interlaced Upper/Lower sequence.


? Set the De-interlace filter to Upper

You get an all White clip (indicating it is discarding the Upper Field and duplicating the Lower)


? Set the De-interlace filter to Lower

You get an all Black clip (indicating it is discarding the Lower Field and duplicating the Upper)


It won't matter what the sequence settings or clip field dominance is.

Fields are the same for both upper and lower field dominant footage - its simply the order that they record and play back that matters.

---

How to spot field order issues.

If you record an object movement on Lower Field Dominant DV

For 1 frame you record field 1 then field 2

and in that time the object(s) moves.

Looking at the fields separately its like a very thin "Venetian blind" effect of two pictures with the object(s) in slightly different places.

Now play that back in a Upper Field Dominant

You play back f2 then f1

Looking at the "Venetian blind" pictures - the object(s) will look like the motion is in reverse.

so extrapolate that.

10 frames LFD: 12 12 12 12 12 12 12 12 12 12

10 frames LFD played on UFD: 21 21 21 21 21 21 21 21 21 21


So the resultant movement will look juddery because its playing the movement over 1 frame backwards but the movement over all frames forwards.

This is why people - you MUST have an interlaced display - either CRT TV or CRT Broadcast Monitor to cut and online SD or interlaced HD video!

~~~~~~~~~~~~~~~~~~~~~~~

Interestingly if you load that fields clip into Quicktime 7 you see the fields - but in Quicktime X on Snow Leopard you see blended fields, but thats for another post!



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

if DV PAL has a LOWER (even) Field Dominance, then does that mean I should select Lower in the de-flicker video filter effect ... or is it better to select the OPPOSITE, ie UPPER (odd) in this case?


Hey Marla

For your raw DV PAL footage, if you intend to deinterlace by discarding a field, it does't matter which field you keep/discard, so there is really no "better". However, if you'd really like a definitive answer then please go ahead and set the filter to "Lower" (ie discard the lower field).

Best
Andy

...but don't discard either and use the Blended Fields as you will get a superior picture!



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You are A W E S O ME - that was the clear and detailed, thanks so much!

But just to nit-pick, why wouldn't it "matter?" if you had say, a close-up of a hand-clap, wouldn't one field contain the point at which the hands meet and the other might not?

M A R L A

Nope

They contain completely separate lines of information.

If you remove half of the lines and double up the remaining line you get exactly half the vertical resolution.

Essentially you will have a 720x288 resolution picture stretched out on a 720x576 canvas.



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yes, the fields do contain separate images taken at different times,
so yes, one would have the hand clap, the other wouldn't.
but it's such a fine point it doesn't matter much.

Ben likes blending fields,
it gives you the most resolution,
but i find the motion artifacts terribly disturbing,
giving the image a "smeared" look.
on your hand clap, for instance, you would see both images blended together in the one frame.

ok for locked off talking heads,
but looks bad on anything with a bit of movement.


nick

But just to nit-pick, why wouldn't it "matter?" if you had say, a close-up of a hand-clap, wouldn't one field contain the point at which the hands meet and the other might not?


Hey Marla

It doesn't matter because no one actually watching the programme will look at any single frame (except the poster frame), what they are looking at is 25 frames per second ... and in your example the hand claps look every bit as good regardless of which field you choose.

For what its worth, I suggested to lose the lower field solely because FCP by default displays only the upper field in the Canvas window, so if you ever find yourself monitoring your edit from the Canvas window (rather than an external interlaced monitor) then what you're looking at is generally Upper field only ... so if you throw the Deinterlace filter on and remove the lower field, then what you get is what you've been seeing all along.

Hope that makes sense
Andy

You can see both fields if you resize the canvas window to exactly 100%



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>>what you're looking at is generally upper field only

>You can see both fields if you resize the canvas window to exactly 100%


Hehe ... not too busy today then Ben? :-)

Very busy but keep getting these weird email alerts trying to knock my Blend Loveliness off the last spot! Lucky then I'm-a-rendering-a-DooV-Dee!




BLENDED FIELDS FTW!!!



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]