Is progresive TFF or BFF?

[Mole]

Is progressive supposed to be TFF or BFF?

I know technically because it's progressive you can't set it "wrong" like with interlaced material.

For some reason in my head, I always remembers that interlaced are supposed to be TFF, except DV, which are BFF.

Progressive are also BFF.

But then in the CCE FAQ, it says Progressive material is always top field first

However, in HCEnc FAQ it says TFF + progressive is not allowed.
In other words, progressive must be BFF

If I'm creating a progressive video at 23.976 which I'll use pulldown to get 29.97, should I encode the video as TFF or BFF?
What about 24 pulldown to 25?

Then I should also specify the field order used when encoding in pulldown as well, right?

[Lyris]

When I encode commercial DVDs with CCE SP3, I always use TFF by leaving the "Output top field first stream" checked.

[Mole]

Yeah, I always do that too, and offset line to 0.

But why then won't HCEnc allow TFF progressive?

[Ghitulescu]

Progressive has no fields, thus BFF or TFF does not exist. That's why TMPGenc does not allow it. What CCE says for TFF refers strictly to the interlaced source.

[mp3dom]

Progressive + TFF flag is allowed when Progressive Sequence is OFF (this also allows to switch from progressive to interlaced - and vice versa - encoding in the same stream), it's not allowed when Progressive Sequence is ON (in that case it should be Progressive + BFF and switch from progressive to interlaced - and vice versa - is not possible)

[Mole]

ahh... I see, thanks for the clarification!

[Guest]

Originally Posted by mp3dom

Progressive + TFF flag is allowed when Progressive Sequence is OFF (this also allows to switch from progressive to interlaced - and vice versa - encoding in the same stream), it's not allowed when Progressive Sequence is ON (in that case it should be Progressive + BFF and switch from progressive to interlaced - and vice versa - is not possible)

Strictly speaking, the MPEG2 spec allows TFF=1 with progressive_sequence=1 but it then signals frame pulldown (in conjunction with RFF=1).

[Mole]

So, if I want to make a progressive stream and then use pulldown say from 24fps to 25fps, is it OK to enable progressive sequence, then set it as BFF?

In DGPulldown, I then also tell it to set as BFF (I think default is Top fiel first, which means I just uncheck that, right?)

What about "Set drop frames"? There is 3 modes I can set it as. Ticked, empty, or grayed out ticked.

[Guest]

[You are not concise in your statements. E.g., a "progressive stream" can mean the content is progressive or the progressive_sequence flag is set; they are not the same.]

It depends on whether you want to make frame pulldown or field pulldown. DGPulldown does not do frame pulldown.

Frame pulldown: Use progressive sequence=1, RFF=1. Then TFF signals number of frame repeats.

Field pulldown: Use progressive sequence=0, use RFF and TFF in the standard way.

A 24 to 25 conversion will look better with field pulldown.

Please read the DGPulldown documentation for clarification on its usage.

[Mole]

Yes, of course I want field pulldown.

So, if I want to field pulldown a progressive content from 23.976 to 29.97 or 24 to 25, I should not enable the progressive sequence in the MPEG encoder, and use TFF, is that correct?

[Mole]

Oh, also, for 24fps which will be field pulldown to 25, would GOP size 15 be too big?

Should I set it to 12 like for 23.976?

[Guest]

Originally Posted by Mole

So, if I want to field pulldown a progressive content from 23.976 to 29.97 or 24 to 25, I should not enable the progressive sequence in the MPEG encoder, and use TFF, is that correct?

You can use BFF too, it doesn't matter (coordinate it with the setting in DGPulldown).

For considerations on GOP size, please read the file GOPNote.txt included in the DGPulldown distribution.

[Mole]

Yes, I already read that, but it's a very confusing document.

Also I could not find info about 24->25 only about 23.976->29.97

[Guest]

Originally Posted by Mole

Yes, I already read that, but it's a very confusing document.

What are you confused about?

Also I could not find info about 24->25 only about 23.976->29.97

You need to apply the same principles to your desired conversion. I'm sorry that I don't have extra time right now to do that for you in the case of creating a PAL DVD, and in any case I do not have access to the PAL DVD requirements. If you are not technically equipped to do that, then just use 12 frames per GOP or do some experiments.

[Mole]

That's OK. Thanks so far.

I guess too small GOP is better than too big.

[mp3dom]

15 frames GOP for euro pulldown is too much. Scenarist will refuse it. Stay at 12 frames.

[TheSkiller]

Originally Posted by Ghitulescu

Progressive has no fields, thus BFF or TFF does not exist.

Yes, but the flag that signals TFF/BFF is always inside every MPEG2 video (it has to be), so one has to decide for either TFF or BFF even with a progressive video as weird as it sounds.

Actually, there is only one flag: TFF=true/false.

So, looking at it from that point of view it makes sense not to set this flag for something that is not TFF due to being progressive, but leaving it false which means BFF so to say.


TFF can be set even for progressive video if you do not set any of the two progressive flags, in other words if it's flagged like interlaced video. If you want to flag it properly as progressive by making use of both progressive flags ("frametype progressive" and "progressive sequence"), TFF has to be false otherwise you have an illegal combination of flags for DVD.
You can also set only frametype progressive, which, afaik, is not illegal to use with TFF=true but only as long as progressive sequence is false.

And "progressive sequence" has to be set in conjunction with "frametype progressive" (and therefore with TFF=false).
So, in a nutshell, if you encode progressive and flag progressive properly using both flags, the TFF flag has to be false.



Euro-Pulldown (24 or 23.976 -> 25) will give a stutter twice a second which, depending on the nature of the video, can be annoying.

If you use soft-pulldown the output video will be interlaced so in that case you have to flag the video like interlaced (and afaik pulldown.exe will unset any progressive flags automatically so you don't have to worry about it, this also means that TFF=true/false doesn't matter as it's plain interlaced video generated from a progressive video).


Yes, 15 GOP is too long for such pulldown.

[mp3dom]

For euro-pulldown it's much better to encode as PAL progressive 23.98 (or 24) and then add the pulldown later with DGPulldown. In this way you can gain some quality due to progressive encoding. The only drawback of DGPulldown is that you can have the last frame flagged as 'repeated' and this creates some problem when muxing with Scenarist (basically, you can't join two videos if the last frame of the first video is flagged as repeated).

[Mole]

OK, so from now on I'll encode anything which needs to be pulldown as progressive sequence=false and TFF=true.

But true 25fps progressive videos, I'll encode as progressive sequence=true and TFF=false.

I think I understand the logic now.

[TheSkiller]

Originally Posted by Mole

But true 25fps progressive videos, I'll encode as progressive sequence=true and TFF=false.

Yep, that's it. But you might want to double-check in case of "progressive sequence=true" if you have "frametype progressive=true" as well because progressive sequence alone is not allowed. Restream allows checking and changing these flags.

However, if you encode strictly as progressive in HCEnc or CCE (any version) then frametype progressive=true automatically (there's no option for it in HCEnc or CCE), but note that CCE never sets the progressive sequence flag. In such case you have to set it yourself using Restream.