View Full Version : Interlaced 30f


Mitch Hunt
September 23rd, 2009, 05:29 PM
I normally shoot in HD 30f but I'm having troubles with my editing system (here's the thread: http://www.dvinfo.net/forum/attend-world-premiere/408893-cs4-instability.html). So I have decided to shoot in SD 30f for the time being, but guess what, Another problem! The supposedly progressive 30f mode captures as interlaced 60i in Premiere Pro. The final output will be for web.

Which leads to another question, is there a difference in quality between shooting in progressive on the A1 to begin with and deinterlacing 60i in post?

Any Ideas?

Danny Winn
September 23rd, 2009, 07:13 PM
You can capture at HDV 1080p 30. When you're setting up your project and it asks you to select your "new sequence" settings, select "HDV" under the available presets, then select "HDV 1080p 30. I've been using this setting since i got my XH A1s, it's beautiful!

If you have to use SD, just make sure your export settings are set to progressive, that's all I've ever used, I never use interlaced.

Michael Hutson
September 23rd, 2009, 07:17 PM
I agree, I think it is your nle.....not the camera.

Refer to page 40 of xha1 manual.

Michael Galvan
September 23rd, 2009, 07:17 PM
Well remember, in SD modes, it is recording to the DV standard. So both 24F and 30F progressive modes will be laid down on tape as an interlaced stream.

In 30F, both fields will be comprised of the same frame, so in essence, it is still progressive. 24F will have a pulldown added.

The modes will stay fully progressive in HD mode, no laying on tape as interlaced.

Mitch Hunt
September 23rd, 2009, 08:01 PM
The 30f videos really are interlaced. It's apparent just by watching them. In both Premiere and AE they are identified as interlaced in the interpret footage dialog box. Why?

Mitch Hunt
October 8th, 2009, 06:00 PM
Here's a sample clip shot in 24f, but is still interlaced. What's going on?

http://www.archive.org/download/River_30/interlaced_24f.avi

Brian Ford
October 8th, 2009, 06:54 PM
That interlacing has to be coming from your editing workflow. The .avi you provided is 720x480 at 29.97fps. Your NLE must be set up to render as NTSC interlaced. I use vegas, not premiere, but there must be some way for you to set the project as progressive..

Mitch Hunt
October 8th, 2009, 07:38 PM
That is the RAW untranscoded video from the A1 shot in 24f DV 16/9. Premiere interprets it as 720x480 23.976 Lower Field First. It was captured in a DV 24p project.

Michael Galvan
October 8th, 2009, 09:31 PM
I just looked at y our clip, and it seems fine.

Remember, 24F in SD is exactly how the DVX dealt with 24P. There is a 3:2 pulldown added to conform it to 60i (29.97). I just took your clip and did a reverse 3:2 pulldown removal, and extracted the 24F just fine.

24F is only laid to tape in as native 24 frames if shot in HDV mode.

Mitch Hunt
October 8th, 2009, 10:52 PM
How would I do a reverse 3:2 pulldown removal in Premiere? In the interpret footage dialogue box there is a check mark next to: "Remove 24p DV pulldown". This is the first time I've ever dealt with 24p video, so if you could explain it to me I would appreciate it.

Mitch Hunt
October 9th, 2009, 03:16 PM
Well remember, in SD modes, it is recording to the DV standard. So both 24F and 30F progressive modes will be laid down on tape as an interlaced stream.

So Michael, are you saying that the A1 cannot shoot in SD progressively, only HD? If that is true what is the difference between 30i and 30f in SD? Thanks

Michael Galvan
October 9th, 2009, 04:22 PM
Mitch,

Yes, it totally shoots and lays as progressive in SD as well as HD.

The difference is in HD, it lays it at 24 discrete frames per second to tape and that's it. You can capture it into your editing system 1:1.

In SD, if you shot 24F, it lays it to tape as 60i by introducing a 3:2 pulldown (or 3:2:2:3 pulldown - you can choose which method in camera). Every DV camera that shoots 24 progressive does a pulldown as the minidV standard is 60i.

So in order to reclaim the 24F which has been embedded in the stream, is to remove it, either upon capture, or after capturing to 60i, and thus bringing it back to true 24 frames.

in 30P(F), you can capture as 60i and leave it because both fields will be the same, hence it essentially being progressive.

Sorry, I only edit mainly with Final Cut Pro and Avid, so I don't know the workings of premiere.

Hope this helps.

Mitch Hunt
October 10th, 2009, 02:51 PM
So what is the best way to remove pulldown? Is pulldown removal necessary for both 24f and 30f in SD? Premiere sees the 24f and 30f videos as interlaced and deinterlaces them; will this degrade the image quality? The deinterlacing also uses more system resources, slowing the whole editing process down.

Peter Manojlovic
October 10th, 2009, 06:58 PM
Mitch, although i don't shoot in 30FPS, i believe the trick in Premiere, is to work on a 29.97fps timeline (interlaced), but upon export, choose the progressive output. Internally, PPro treats it as interlaced....
Although, i'm not working with CS4 currently, take it with a grain of salt...

Mitch Hunt
October 12th, 2009, 04:09 PM
Peter, won't Premiere deinterlace the video? If so, what is the advantage of shooting in 30f over 60i?

Peter Manojlovic
October 13th, 2009, 10:46 PM
I don't believe Premiere should deinterlace, but rather reconstruct the frames to their original progression...
One clue would be the output speed once you save the file...
Deinterlacing usually takes more time, as there's calculation involved.

As far as the difference between 30F and 60i go, usually your final delivery is the answer to that question.
30F is preffered for web, or progressive outputs. It compresses better, and is sort of in the middle of 24F and 60i...
60i gives the video look, but it also focuses quicker, needs less light, and is the output format for DVD video....

Lots of info. kicking around about Film, NTSC, and other framerates...

Good luck!!!

Mitch Hunt
October 17th, 2009, 10:37 AM
Premiere deinterlaces it alright, take a look at this:

http://huntnriggs.com/images/deinterlace.gif

Any other ideas?

Mitch Hunt
October 23rd, 2009, 07:15 PM
in 30P(F), you can capture as 60i and leave it because both fields will be the same, hence it essentially being progressive.


Premiere sees the 30f footage as interlaced, so in a progressive project it is automatically deinterlaced. Consequently, the video looses much detail and the editing is much more processor intensive. So the key here is keep Premiere from deinterlacing the videos. How is this done?

Pete Bauer
October 23rd, 2009, 09:39 PM
Mitch started a new thread on the same subject in the Premiere Pro forum, so I'll close this thread and point further discussion on the topic there:

http://www.dvinfo.net/forum/attend-world-premiere/466356-canon-30f-premiere-pro-cs4.html

Mitch: the gif images from 17 Oct don't really help as you didn't describe the workflow and settings used to produce the "after" picture. It doesn't really look like interlace artifact to me, though.