24F vs 30F in A1 vs HV20

[Dino Leone]

After reading several threads in the HV20 subforum about 2-3 pulldown removal being necessary in order to get good-looking 24F, I'm confused as to what exactly the 24F mode is in both HV20 and A1.

Am I correct in the assumption that the HV20 will always output 29.97fps (60i), even when 24F is selected (thus the pulldown necessary - in order to be compatible with consumer NTSC format)? I assume the 24fps get 3-2 "pulldowned" internally, resulting in 60i?

On the A1, on the other hand, having 24F selected will indeed output 24F (23.976 in fact) over firewire, correct? (That being the reason why on the Mac, FCP is necessary since FCE is not supporting 24F).

Not sure if I should have posted this in the HV20 forum as it seems more relevant to that cam?
Thanks in advance,
Dino

[Pete Bauer]

Yup, you've got it. 24F will go to tape as 23.976 progressive. If you send an F Mode signal out by SDI or analog component, though, it'll be pulled down in-camera to 60i to maintain NTSC compatibility.

[Tom Roper]

Maybe 24F goes to tape as 23.976 but it goes from the tape out the firewire as 60i with pulldown.

[Eric Weiss]

now im confused! what if you want to deliver something as 24P?
will the encoding back to 23.976 look the same?

[Brian Brown]

Hmmm... now I'm confused,. too!

24F footage shot on my A1 shows up as "non-interlaced" in my ProCoder Express encoder.

Is the HV20 different... or is ProCoder wrong (or both)??

I was hoping to get an HV20 to use as a deck and for occasional b-roll. But if it does capturing differently on 24F... I might have to pass.

Brian Brown

[Tom Roper]

Non-interlaced yes, but progressive frames carried inside a 60i stream with pulldown added.

[Bill Pryor]

Now you've got me confused. I shoot HDV at 24P (F), capture it in FCP's 1080P24 mode and edit in a 24P timeline. It all stays 24 fps progressive all the way. No pulldown.

[Dino Leone]

Originally Posted by Bill Pryor

Now you've got me confused. I shoot HDV at 24P (F), capture it in FCP's 1080P24 mode and edit in a 24P timeline. It all stays 24 fps progressive all the way. No pulldown.

Cool. Now I get everybody confused. :-)
I did some more reading in the meantime - with the following results:
- the A1 is true 24fps (records to tape and outputs 24f)
- HV20 is always(*) 60i. If one captures as 24p, it gets stored to tape (and outputs through firewire and HDMI) as 60i using pulldown (for compatibility with consumer equipment).

(*) one exception: if a 24f-recorded tape from the A1 is played back on the HV20, it actually outputs true 24f on its firewire port! This is according to page 101 in the HV20 user's manual (specifications at the very end - well hidden).

Sorry for the confusion.
Dino

[Salah Baker]

HV20 Records 24p not PsF
Plays Back 24PsF,30PsF ..etc from other Canon cameras
A-1 does 24PsF

[Piotr Wozniacki]

Originally Posted by Salah Baker

HV20 Records 24p not PsF
Plays Back 24PsF,30PsF ..etc from other Canon cameras
A-1 does 24PsF

Wrong and misleading.

[Bill Pryor]

24PsF...what's that?

[Tom Roper]

Use something else besides your NLE to capture with and you'll see. The XH-A1 firewire is exporting 24F as 29.97fps, pulldown added. CapDVHS works well for this with PCs.

Working with a native m2t stream, not with an intermediate codec, and because pulldown is added, I put 24F on the same timeline with 60i, not *re-encoding it* . It mixes because pulldown is already added to the 24F. If it wasn't, it wouldn't playback on the Tohsiba HD-DVD player, which doesn't support 24 fps mpeg, just VC1.

I think what's happening is the NLEs some of you are using is making the pulldown transparent when you import into a 24p timeline, so you just edit frame by frame. And I think you print to tape so you don't see just what the output format really is. I could be wrong.

[Justin Avery]

Originally Posted by Piotr Wozniacki

Wrong and misleading.

Which part is wrong Piotr? Can you set this thread straight?

[Salah Baker]

Originally Posted by Piotr Wozniacki

Wrong and misleading.

OK Im wrong fix it in post(IE tell me why?)

[Pete Bauer]

Dino's got it right. Unfortunately, the guessing has led to some misinformation in this thread.

F-mode is recorded to tape as progressive, not interlaced. The XL H1 and the XH cameras record and play F-mode.

The HV20 records 24p to tape with 3:2 pulldown as 60i...sometimes called "Progessive Segemented Frame." The HV20 can PLAYBACK F-Mode tapes as F-Mode, just can't record F-Mode. That makes it a good VTR for someone who doesn't want to use an XL or XH for capture and other playback purposes.

Firewire (1394) is simply a protocol for transferring digital data. The bits come out one end just the same as they went in the other end; it doesn't do any kind of conversions. What a NLE does once it receives a video clip is up to the coding of the NLE and the choices the editor makes with the NLE's features. For instance, when the XL H1 came out, presets needed to be released for PPro so it could work with F-Mode. Various NLEs can mix n match different kinds of clips and export in a wide variety of formats, frame rates and resolutions. So with most current NLEs, you can import a progressive clip and export 60i to DVD if you wish, or even vice versa.