Lower field first/upper field first/progressive/de-interlaced?

[John Nada]

Hello people,

First of all, please bear with me as I am a relative newcomer to video editing and DVD authoring.

Over the last few months I have been editing/compiling a video montage using many different video clips from many different sources. Most of these clips were originally AVI (Divx) files which I then converted into DV-AVI (NTSC) for editing in Premiere Pro. Some of these I converted using Windows Movie Maker (Gasp) but the majority were converted by importing AVISynth scripts (.avs files - Created with MeGui Media Encoder) into Premiere, exporting into DV-AVI (NTSC) format and then re-importing the newly created DV-AVI files.

Even though my project is made up entirely of NTSC DV-AVI files, I ultimately intend to author these into both NTSC and PAL format DVD's for viewing at home on TV.

The thing that is really confusing me is the whole lower field/upper field/progressive/de-interlaced issue. I know that TV's come in two main display methods - Progressive scan and interlaced, although I'm still yet to fully grasp how both of these work.

Are progressive scan TV's able to play interlaced footage without combing?

Are interlaced TV's able to play de-interlaced/progressive footage without any distortion?

How do I optimize settings for each format so that the finished DVD's play properly on both progressive scan and interlaced TV's?

Do the settings need to be different for PAL and NTSC?

Thanks in advance...

John

[jman98]

I would suggest that you not worry about interlaced playback as within 10 years it will probably become impossible to buy TVs that aren't progressive.
Continuing to support interlaced TV sets will very soon be the equivalent of making a cassette tape for some friend who doesn't own a PC and is too cheap to buy a CD player.

PAL and NTSC require different resolutions and frame rates for DVD, but the whole interlaced/progressive/etc. question is the same for PAL and NTSC. Since you live in Europe, there really is nothing to be gained by converting NTSC video to PAL as almost all DVD players and TVs sold in Europe are capable of displaying NTSC video.

Good progressive scan TVs can correctly play interlaced footage and good interlaced TVs can play progessive footage with no problems.

[jagabo]

The thing that is really confusing me is the whole lower field/upper field/progressive/de-interlaced issue. I know that TV's come in two main display methods - Progressive scan and interlaced, although I'm still yet to fully grasp how both of these work.

A progressive transmission sends all the scanlines that make up the frame in order. It starts with the top-most scanline, then sends the next scanline down, then the next, etc. Progressive displays show all the scanlines at once. So a progressive computer monitor running at 60 Hz over a VGA cable displays 60 different whole pictures every second.

Interlaced analog TV signals are transmitted one field at a time. A field is every other scanline of the picture. If you number the scanlines from top to bottom (0 to 479 NTSC, 0 to 575 PAL) one field contains all the even numbered scanlines. The other field contains all the odd numbered scanlines. So scanline 0 is sent the the TV, then scanline 2, then scanline 4, etc. Then the next field is then sent, scanline 1, scanline 3, scanline 5, etc. When watched on an interlaced TV you see one field at a time, 59.94 different fields per second on an NTSC TV, 50 different fields per second on a PAL TV.

Are progressive scan TV's able to play interlaced footage without combing?

Yes. They will somehow deinterlace the incoming fields to produce full frames. Quality of deinterlacing varies.

Are interlaced TV's able to play de-interlaced/progressive footage without any distortion?

Yes and no. Interlaced displays typically can't accept progressive signals. The device which is sending the signal to the interlaced display is responsible for producing the interlaced frames. For example, a DVD can contain progressive frames. But the DVD player has to peel the frames apart to send one field at a time to the interlaced TV.

[jman98]

jagabo is 100% correct about interlaced displays. I forgot that every time I've ever seen this some device other than the TV converted the image to interlaced from progressive. Thanks for the correction/better explanation.

[interlaced]

@jman98
"I would suggest that you not worry about interlaced playback as within 10 years it will probably become impossible to buy TVs that aren't progressive."

Where did you get that information from?
Over-air digital TV is transmitted interlaced. They took this decision quite consciously. Reason: progressive transmission needs twice the bandwidth. Since the available bandwidth is limited for over-air transmission, interlaced TV - even in digital form - is here to stay for a loooong-looong time.

Unless you have a huge budget for a camera that can record in 50p, you are better off with 50i. This is what consumer cameras do without asking you.

Some semi-pro cameras support 25p. It's a horrific, stu-stu-stuttering image.
So, where do you get the 50p footage from?

You/we are stuck with interlaced. TVs do and will support it for the foreseeable future. Just work in interlaced and your VD will be fine.

PAL vs NTSC. Don't worry about that. Work in the format you did the filming. Most TVs outside the US are able to play NTSC signals. Although US TVs may have difficulty to play PAL signals. The problem here is that it is difficult to convert between these formats. Premiere does something but the quality is really bad.
There are professionals who can do the PAL-NTSC conversion. Expensive. Do you really need it?


Cheers,

Bill

[JVRaines]

The only reason to deinterlace is to keep control over the results. The quality of realtime hardware and software deinterlacers varies. The viewer may even have deinterlacing turned off. So if quality is critical and the video is heading toward an unknown progressive display, I deinterlace it.

[Cornucopia]

@jman98
"I would suggest that you not worry about interlaced playback as within 10 years it will probably become impossible to buy TVs that aren't progressive."

Where did you get that information from?
Over-air digital TV is transmitted interlaced. They took this decision quite consciously. Reason: progressive transmission needs twice the bandwidth. Since the available bandwidth is limited for over-air transmission, interlaced TV - even in digital form - is here to stay for a loooong-looong time.

Unless you have a huge budget for a camera that can record in 50p, you are better off with 50i. This is what consumer cameras do without asking you.

Some semi-pro cameras support 25p. It's a horrific, stu-stu-stuttering image.
So, where do you get the 50p footage from?

You/we are stuck with interlaced. TVs do and will support it for the foreseeable future. Just work in interlaced and your VD will be fine.

PAL vs NTSC. Don't worry about that. Work in the format you did the filming. Most TVs outside the US are able to play NTSC signals. Although US TVs may have difficulty to play PAL signals. The problem here is that it is difficult to convert between these formats. Premiere does something but the quality is really bad.
There are professionals who can do the PAL-NTSC conversion. Expensive. Do you really need it?


Cheers,

Bill

@interlaced,

what jman98 said was referring to DISPLAYS (edit: REGARDLESS of the source footage). Plasma, LCD/LED, OLED, etc. These, or newer technologies, are what will be available in 10 years. CRT will either die altogether or become a niche market for Pros who specifically require them. All those newer technologies are inherently PROGRESSIVE.

You are also incorrect about OTA DTV. Some is interlaced 480i or 1080i, some is progressive 720p. Depends on the station.

Yes, we are "stuck" with interlaced for the foreseeable future, but it's no longer omnipresent, and never will be again. It will dwindle.
Sooner or later, once a newer generation of AVC-compatible/Service-compatible/Firmware-upgradeable tuners and cable boxes become common, OTA/Sat/Cable will be able to reconfigure their broadcasts to be Progressive with little bandwidth pain. Then, Progressive will REALLY be the norm, with legacy sources being the only real source of Interlaced.

Also, many consumer cameras now record 30p/25p by default, particularly Digi-cameras that can also do video.

@John Nada,
Sounds like you've got a mix of sources there. Items that were DivX originally, had probably ALREADY been deinterlaced, so "re-interlacing" them to DV could get a little hairy down the road.
What JVRaines said is correct - only deinterlaced to "control" the method. But since hardware deinterlacing in settop boxes, DVD/BD players, NAS boxes, tuners & TVs are ONLY going to get BETTER, this worry is really not worth your while.
Therefore, I say, "If it's already interlaced, keep it that way through to the end (unless of course you can do a VALID ITVC), If it's progressive, keep it that way."

Scott

[Gavino]

@John Nada, ...

I doubt if he's reading. John's only post was that one, three years ago.
Since then, nada ...