Field order question

[dyanglp]

Hello, I want to thank this site and people here for so much information and great help they provide. I have gone through many threads about field order recently but still not 100% certain about the following conclusions from my reading, any inputs are greatly appreciated.

1. DV is always BFF, analog always TFF, no matter NTSC or PAL
2. NTSC TV use BFF, PAL TV use TFF (what does it really mean ?)
3. Both TFF and BFF DVD will be fine when playback on either NTSC TV or PAL TV, DVD player will handle it correctly
4. Field order can NEVER be changed after captured if you don't use a specific program (like Restream) to do so on purpose
5. Encoder software, such as TMPGEnc, only set a flag (TFF=0 or <>0) for the output mpeg file, they don' t physically change field order of the video data stream
6. You can not change the field order flag without reencoding the whole file

Than you in advance.

[adam]

As far as I know, most of those conclusions are correct. I don't know anything about the field order of broadcasts though. I assumed the field order varied. A couple of caveats though...

(4). One way to change field order is to crop a scan line. So if in your editing/pre-encoding process, you were to crop an odd number of scan lines, I believe this would effectively reverse your field order. I could see this happening unintentionally.

(5) For most encoders this is true, but I know that Cinema Craft Encoder at least does not work like this. CCE always outputs tff footage (tff flag enabled). If your source is tff then you needn't do anything. If your source is bff then you have to enable the tff setting. This will then crop the first scan line to change the field order and give you tff output. So yes, CCE at least does physically change the field order not just set the appropriate flag.

(6) I'm assuming this is a typo and you meant that you cannot change field order without re-encoding? If so then yes I believe that is true. If you want to just change the field order flag then you don't necessarily have to re-encode. The flag can be changed in an mpeg2 video stream using either restream or pulldown.exe.

[jdw]

Good questions I think and brings up a question to me

1. DV is always BFF, analog always TFF, no matter NTSC or PAL

I didn't realize analog was TFF.

So I assume then when you run analog footage thru an NTSC AV/DV convertor, such as a Canopus ADVC100, it is converting TFF to BFF. Is this a correct assumption?

[BJ_M]

1. DV is always BFF, analog always TFF, no matter NTSC or PAL

FALSE - there is some (rare) DV that is TFF , though you can assume alwasy that it willbe BFF most of the time ..

Analog is not always TFF (analog what ?)




2. NTSC TV use BFF, PAL TV use TFF (what does it really mean ?)

FALSE

Pal in fact uses a lot of BFF and anyway goes against your #1 above doesnt it?




3. Both TFF and BFF DVD will be fine when playback on either NTSC TV or PAL TV, DVD player will handle it correctly

TRUE



4. Field order can NEVER be changed after captured if you don't use a specific program (like Restream) to do so on purpose

FALSE , just cropping can change the field order as an example ... every NLE can also do so ... so can many encoders ..





5. Encoder software, such as TMPGEnc, only set a flag (TFF=0 or <>0) for the output mpeg file, they don' t physically change field order of the video data stream

FALSE - Procoder will change the field order physically , so does CCE in a way ..

others (a few) can also -- some can not ...



6. You can not change the field order flag without reencoding the whole file


FALSE

[junkmalle]

Broadcast TV doesn't have a field order. It's simply a constant stream of fields -- there are no frames.

When computers capture these fields they pair them up to fully fill frames. So the field order depends on how the capture device decides to capture the fields. If it starts with a top field you get TFF, if it starts with a bottom field you get BFF.

[sacajaweeda]

When in dount, author a test clip.

edit: I don't recall ever visiting dount. Perhaps I was just passing through on my way to doubt?

[lenti_75]

1. DV is always BFF, analog always TFF, no matter NTSC or PAL
2. NTSC TV use BFF, PAL TV use TFF (what does it really mean ?)
3. Both TFF and BFF DVD will be fine when playback on either NTSC TV or PAL TV, DVD player will handle it correctly
4. Field order can NEVER be changed after captured if you don't use a specific program (like Restream) to do so on purpose
5. Encoder software, such as TMPGEnc, only set a flag (TFF=0 or <>0) for the output mpeg file, they don' t physically change field order of the video data stream
6. You can not change the field order flag without reencoding the whole file

1. False, not always true, usually this way, but not always
2. false, they use either BFF or TFF
3. true
4. false, you can change it, but it should remain the same
5. false, procoder can change it
6. false, you can use pulldown without reencoding

the main ideea is that you should not change the field order, unless you really have to.

[BJ_M]

1. DV is always BFF, analog always TFF, no matter NTSC or PAL
2. NTSC TV use BFF, PAL TV use TFF (what does it really mean ?)
3. Both TFF and BFF DVD will be fine when playback on either NTSC TV or PAL TV, DVD player will handle it correctly
4. Field order can NEVER be changed after captured if you don't use a specific program (like Restream) to do so on purpose
5. Encoder software, such as TMPGEnc, only set a flag (TFF=0 or <>0) for the output mpeg file, they don' t physically change field order of the video data stream
6. You can not change the field order flag without reencoding the whole file

1. False, not always true, usually this way, but not always
2. false, they use either BFF or TFF
3. true
4. false, you can change it, but it should remain the same
5. false, procoder can change it
6. false, you can use pulldown without reencoding

the main ideea is that you should not change the field order, unless you really have to.

isnt this exactly what i just said above ?

[dyanglp]

Thanks everyone! I changed the first post based on the replies and hope this one looks better.

1. Usually, DV is BFF, field order from an analog source is determined by the capture card or capture program. This applies to both NTSC and PAL systems.

Q: Surprising enough, my PCI capture card (V-stream) gave "non-interlace" captured avi files for the TV tuner and Composite connections with different capture programs. Is anything wrong ?

2. NTSC TV uses BFF, PAL TV uses both TFF and BFF.

Q: Are they refering to certain standards built in TV sets or broadcast standards or both ?

3. TFF DVD,BFF DVD and Progressive DVD will all be fine when playback on either NTSC TV or PAL TV, DVD player will handle it correctly

Q: What about mixing TFF,BFF and Progressive on the same DVD ?

4. Field order could be reversed intentionally or unintentionally after the capturing process, cropping a scan line during editing is an example. The rule is that you should not change it.

Q: How can I simulate such a "cropping" ?

5. Some encoders only set a flag (TFF=0 or <>0) for the output mpeg file, some others not only set the flag, but also physically change the field order of the video data stream.

6. Field order flag can be changed without re-encoding the whole file,eg. using Pulldown.

[BJ_M]

1. TRUE

an image under a certain size will always be progressive (should) also

2. FALSE - not correct - see my reply above ..

3. TRUE - though you can get jerky playback in some situations .

you can mix on smae dvd -- i do it all the time ..

4. TRUE -- but nothing wrong in changing it - as long as you know you did .

crop one line at top will change it ...


5 and 6 - TRUE

though if you just "change it" you can also reverse the field oreder which is really nasty ... but i see a lot of that .. the fields get out of order

[dyanglp]

MJ_M, thank you for the quick reply.

an image under a certain size will always be progressive (should) also

So, capturing from an analog source reults in a progressive video file is actualy a sequence of images which is fine, in another word, the interlaced source gets de-interlaced ?

2. NTSC TV uses BFF, PAL TV uses both TFF and BFF.

2. FALSE - not correct - see my reply above

and

Pal in fact uses a lot of BFF and anyway goes against your #1 above doesnt it?

Change "both" to "either" ? I get a bit lost.

crop one line at top will change it ...

Sorry, I still don't know how to do.