Thing I've noticed with frame rates... at DVinfo.net

Steve Lewis · August 19th, 2008, 03:47 PM

The following probably has no scientific or technical backing, but I have found that the quality of the images produced by the XHA1 in 24f mode is much better than when the cam is in 60i mode. The real test for me is when I compare the two after being exported as a MOV: the 24fps video looks much sharper and less "artifacted". Anyone else have this experience?
-Steve

Tripp Woelfel · August 19th, 2008, 06:42 PM

No... but it makes sense. You're recording the equivalent of both fields simultaneously, effectively doubling the simultaneous resolution.

You don't actually double the resolution of the video, but every 1/24th of a second you get both fields as opposed to one field every 1/60th. This may be as clear as mud as the description lends itself to visual aids, of which I have none.

I don't know this for certain, but since the data rate for DV/HDV is fixed, a frame of video at 1/24th of a second should contain more video than a full frame (both fields) of 1/30th. This contention gets quite muddy when you consider that Canon's 24f is not true 24p and wraps the 24 frames each second in a 30fps envelope. My brain hurts just trying to work it out.

Net result is if you like the way it looks and think the quality is better... run with it.

Robert M Wright · August 19th, 2008, 06:50 PM

I'm guessing you are simply noticing interlace artifacts in the interlaced video?

Jonathan Shaw · August 19th, 2008, 07:03 PM

I think that you will actually find that when in Frame mode the resolution decreases by about 20%.
I agree with Robert you are probably noticing the interlaced artifacts

Bill Pryor · August 19th, 2008, 08:06 PM

That's why I shoot 24 fps. While the resolution drops just a little over 60i, there are no interlace artifacts when exporting, so the end result is that it looks better.

Steve Lewis · August 19th, 2008, 10:34 PM

Quote:

Originally Posted by Robert M Wright

I'm guessing you are simply noticing interlace artifacts in the interlaced video?

No, I deinterlace religiously.... it is mainly blotchiness and banding that i get with the 60i footage, which I don't get nearly as much with 24f.

Robert M Wright · August 20th, 2008, 06:52 AM

Deinterlacing will result in lower effective resolution and/or artifacts (depends on how you do it). Frame modes on the A1 work very well for producing progressive images (better than deinterlacing interlaced footage from the A1 to get progressive images).

Philip Williams · August 20th, 2008, 08:37 AM

Quote:

Originally Posted by Steve Lewis

No, I deinterlace religiously.... it is mainly blotchiness and banding that i get with the 60i footage, which I don't get nearly as much with 24f.

That's certainly plausible. Progressive frames are easier for the encoder to process *plus* you've got more bits per frame in 24F.

Steve Lewis · August 20th, 2008, 03:06 PM

Quote:

Originally Posted by Robert M Wright

Deinterlacing will result in lower effective resolution and/or artifacts (depends on how you do it).

Thanks Robert, that's good to know! What is the preferred way to deinterlacing footage? During export or in the timeline?

Robert M Wright · August 21st, 2008, 08:37 AM

You might want to give this a read:

What is deinterlacing? The best method to deinterlace movies

August 19th, 2008, 03:47 PM	#1
Steve Lewis Major Player Join Date: Apr 2008 Location: Goleta, CA Posts: 233	Thing I've noticed with frame rates... The following probably has no scientific or technical backing, but I have found that the quality of the images produced by the XHA1 in 24f mode is much better than when the cam is in 60i mode. The real test for me is when I compare the two after being exported as a MOV: the 24fps video looks much sharper and less "artifacted". Anyone else have this experience? -Steve __________________ www.spreefilms.com - Give me a museum and I'll fill it!

August 19th, 2008, 07:03 PM	#4
Jonathan Shaw Major Player Join Date: Nov 2007 Location: Sydney Posts: 552	I think that you will actually find that when in Frame mode the resolution decreases by about 20%. I agree with Robert you are probably noticing the interlaced artifacts __________________ www.ginclearfilm.com www.facebook.com/ginclearfilm

August 19th, 2008, 06:42 PM	#2
Tripp Woelfel Trustee Join Date: Jan 2008 Location: North Conway, NH Posts: 1,745	No... but it makes sense. You're recording the equivalent of both fields simultaneously, effectively doubling the simultaneous resolution. You don't actually double the resolution of the video, but every 1/24th of a second you get both fields as opposed to one field every 1/60th. This may be as clear as mud as the description lends itself to visual aids, of which I have none. I don't know this for certain, but since the data rate for DV/HDV is fixed, a frame of video at 1/24th of a second should contain more video than a full frame (both fields) of 1/30th. This contention gets quite muddy when you consider that Canon's 24f is not true 24p and wraps the 24 frames each second in a 30fps envelope. My brain hurts just trying to work it out. Net result is if you like the way it looks and think the quality is better... run with it.

August 19th, 2008, 06:50 PM	#3
Robert M Wright Inner Circle Join Date: Jan 2006 Location: Minnesota (USA) Posts: 2,171	I'm guessing you are simply noticing interlace artifacts in the interlaced video?

August 19th, 2008, 08:06 PM	#5
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	That's why I shoot 24 fps. While the resolution drops just a little over 60i, there are no interlace artifacts when exporting, so the end result is that it looks better.

August 20th, 2008, 06:52 AM	#7
Robert M Wright Inner Circle Join Date: Jan 2006 Location: Minnesota (USA) Posts: 2,171	Deinterlacing will result in lower effective resolution and/or artifacts (depends on how you do it). Frame modes on the A1 work very well for producing progressive images (better than deinterlacing interlaced footage from the A1 to get progressive images).

August 21st, 2008, 08:37 AM	#10
Robert M Wright Inner Circle Join Date: Jan 2006 Location: Minnesota (USA) Posts: 2,171	You might want to give this a read: What is deinterlacing? The best method to deinterlace movies