Why EVER use interlaced?

[Tom Brooks]

[Bouke Vahl] “Now moving images shot interlaced look horrible on a progressive monitor, and especially when you freeze frame it. “

Does it really look so horrible? I watch it all the time on my LCD TV at home. True, almost all of it is pure garbage, and maybe I’m conditioned to accept it, but I don’t perceive artifacts (or call it crappy deinterlacing if you will) when I watch NBC. The TV, which displays progressive images, combines the fields in a way that is…acceptable. Does anyone watch TV on a CRT anymore?

Why do we have so many formats, anyway? If the US broadcasts in i59 or p59 and Europe broadcasts in i50 and movies are p24, why all these p30 variations? It’s interesting to see that some of you use them a lot, even for broadcast.

[John Heagy]

Absolutely correct, not arguing that… but understanding the difference between broadcast standards and file “proprietary” workflows and delivery are equally important. Meeting broadcast standards will become less important, over time, as people shift to “online” delivery.

Apple requires all HD to be 720p24 for iTunes – that’s not a broadcast standard – and no VTR or video card will output it. You’ll not find a single online video site that “broadcasts” 1080i60. If you see interlaced video online… they don’t know what they’re doing.

The below clip is an example of how not to do it, but is ironic, as the person who encoded it did know how to maintain interlacing when scaling video, something Compressor can’t do. In this case maintaing the 60i standard was the wrong thing to do… it needed to be de-interlaced to 30p.

https://www.comcast.net/video/-danica-patrick-and-amani-toomer-go-karting-/627075758/

We are arguing over semantics and context, but the devil is always in the details.

John Heagy

[Gary Adcock]

[John Heagy] “That’s not correct, we shoot 1080p30 (29.97psf) HDCam with our Sony F900s when called for. 1080p29.97 and 1080p30.00 are both part of the SMPTE HDTV standards. “

I am with Shane on this one.

1080 is always transported as an interlaced signal- as that is what PsF is – an interlaced transmission and distribution signal that can interpreted as either progressive or interlace depending on whether the receiver can understand progressive.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://blogs.creativecow.net/24640

[Bouke Vahl]

This is not correct.
ANY device understands progressive.
A progressive signal in an interlaced stream only means that there is no time difference between the fields.

Displaying Interlace correctly is the issue here.

Bouke

https://www.videotoolshed.com/
smart tools for video pros

[Gary Adcock]

[Bouke Vahl] “This is not correct. ANY device understands progressive. “

Sorry Brouke,
for the record you cannot send a “True P” signal to a CRT in any way shape or form.

I have fought this argument many times (even John said it was a bad example of what he was trying to say) SMPTE SPEC for delivery does include P vs PsF debate but in reality not too many people ran into the P vs PsF until RED came on the scene, until that time all cameras were delivering PsF and noone was the wiser.

Segmented frame was designed to deliver progressive content over the existing interlaced transmission system, however it is the receiving device that determines whether the processing will be interlaced or progressive for playback.

Displays for the most part are dumb devices and do not care about progressive or interlace for the most part Sony has always cheated the signal naming on their own displays whereas Panasonic as always showed the signal type.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://blogs.creativecow.net/24640

[Bouke Vahl]

Gary,
Please enlighten me about P vs PsF.

I think i know my stuff pretty well, this is new to me…
(and way beyond the OP’s question, but that is not important now)

The way i see it, you can put a full frame progressive signal in an interlaced stream. You cannot put an interlaced stream to an output device that is not interlaced.
(well, you can, but an interlaced frame will show both fields at the same time, wich causes the lines that some refer to as ‘artifacts’)

Bouke

https://www.videotoolshed.com/
smart tools for video pros

[John Heagy]

Ok.. let’s step back and define some things as terms are being used out of context. Basically file formats vs base band video. Let’s look at a typical 24p HD file to video path.

PsF is an HD-SDI base band video signal used to feed 24p VTRs and the like. If you have a FCP 24p ProRes seq, you will need to use a Kona3 24Psf video output preset to go to an HDCam deck set the same way. Now, since Psf is only a way to transport progressive frames split into 2 fields (segmented) there is no such thing as a FCP 24Psf seq preset, as 24fr progressive media is truly progressive, and not processed in field segments inside FCP.

So we have a FCP seg that is 24p and a video HD-SDI output that is 24Psf… agreed?

Now let’s take a 1080i60 timeline with media that has true field motion. That goes to tape with a 1080i 29.97 Kona 3 output setting. If I deinterlace this media, it will of course go to tape with the same preset, essentially 30p going to a 60i tape. Again no 1080Psf30 seq preset… that would be the same 1080i setting with field dom set to “None”

Now… Sony HDCam’s do have a 29.97 Psf system setting. I’ve never tried it… never needed it… but it’s there. On he FCP side… there is no 29.97Psf Kona3 output setting. My question is: What’s the difference between recording 1080p 29.97 media to an HDcam with a system setting of 1080i 29.97 (59.97 really) and one with 1080Psf 29.97? I don’t think there is any difference, just the lack of field 2 editing I would assume. In all practical purposes 1080i60 = 1080Psf30. This goes to Bouke’s point and is a question I’ve always wondered about.

John Heagy

[Gary Adcock]

[Bouke Vahl] “Please enlighten me about P vs PsF. “

Lets start with a simple wiki page

https://en.wikipedia.org/wiki/Progressive_segmented_frame

I quote:

With PsF, a progressive frame is divided into two segments, with the odd lines in one segment and the even lines in the other segment. Technically, the segments are equivalent to interlaced fields, but unlike native interlaced video, there is no motion between the two fields that make up the video frame: both fields represent the same instant in time. This technique allows for a progressive picture to be processed through the same electronic circuitry that is used to store, process and route interlaced video.

The PsF technique is similar to 2:2 pulldown, which is widely used in 50 Hz television systems to broadcast 25 frame/s progressive material, but is rarely employed in 60 Hz systems as there is very little content of progressive 30 frame/s material. The 2:2 pulldown scheme had originally been designed for interlaced displays, so fine vertical details are usually filtered out to minimize interline twitter. PsF has been designed for transporting progressive content and therefore has no such filtering.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://blogs.creativecow.net/24640

[Gary Adcock]

[John Heagy] “On he FCP side… there is no 29.97Psf Kona3 output setting.”

I have had this argument with AJA for years,
first response was that nobody shoots 30p, then the response- why does anyone shoot 30p?

But I do not have an answer.

IMHO is it like the reason that there has never been a 1080 25Psf setting either (as AJA lists the 1080 as 25i) The signal as defined over the pipe in the PAL world is at 25sf and is always interlaced whereas there are devices that playback 24p ( 24.0 and 23.98) as P not just as PsF.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://blogs.creativecow.net/24640

[Bouke Vahl]

well, yes. This is what i was saying…

What my question / our difference was:
You stated that not all displays can show progressive, while i stated that not all displays can show interlaced correctly…

Bouke

https://www.videotoolshed.com/
smart tools for video pros