HMC 150 and 30P at DVinfo.net

Denny Kyser · July 25th, 2009, 10:58 PM

Does the HMC 150 record 1080 in 30P mode?

I see it says over 60i, and I am not sure what that means.

Denny Kyser · July 26th, 2009, 10:35 AM

Can someone explain what this means "1080/30p (over 60i)"

I am considering this camera, but need it to shoot 1080 30P and mix on a timeline with my EX1 and HV30

Simon Zimmer · July 27th, 2009, 03:21 PM

Not sure what it means either but I have the HMC-150 and shoot in 30p (1080) and it works great.

Simon

John Wiley · July 27th, 2009, 09:53 PM

Each frame is captured as a progressive image but then split into fields before it is recorded to the card as a 60i stream. When the footage is de-interlaced by your TV or in your NLE it plays back exactly the same as if it was recorded 30p.

Barry Green · July 28th, 2009, 11:10 AM

Progressive footage should never be de-interlaced. De-interlacing progressive footage really just means that you're throwing away half your resolution.

NLEs will recognize the "progressive" flag and will be able to use the footage exactly as if it had been recorded in a progressive data stream in the first place. In other words, if it's shot 30p "over 60i", then the NLE will know exactly what to do with it and will treat it as 30p, as you intended.

John Wiley · July 29th, 2009, 07:16 AM

Barry, can you please explain how de-interlacing throws away half your resolution? I was under the impression that when you de-interlace, then both the fields are displayed at the same time. Temporal resolution would be decreased but spatial resolution would be higher, wouldn't it? Or does de-interlacing simply mean the NLE only plays the 'a' fields and ignores all the 'b' fields?

Barry Green · July 29th, 2009, 09:36 AM

Pretty much yes -- it ignores one field and duplicates the other to fill in the gaps.

Or, if you're using an advanced de-interlacing technique such as blended fields, it'll try to synthesize a new field by blending the "A" and "B" fields together.

In any case, you DON'T want that to happen to your progressive footage. Progressive footage has full information detail in each field and that should be preserved as-is.

Graham Hickling · July 29th, 2009, 10:02 AM

I don't think that "1080/30p (over 60i)" has the full information in each field.

Each field more likely has half the information, so that you need to combine the two fields to restore full resolution, at 30 frames per second.

But that's speculation - I'm open to be corrected.

Barry Green · July 31st, 2009, 09:34 AM

You are correct, that's exactly how it works, and that's exactly why you wouldn't want to "de-interlace". De-interlacing would destroy the valid information in one or the other field.

Jeremy Dallek · August 1st, 2009, 06:45 PM

Basically the footage will play back properly on a 60i timeline, just make sure you don't apply any deinterlacing processing to the clip. (i.e. deinterlace method: interpolate, blend, none. choose "none")

Barry Green · August 2nd, 2009, 07:30 PM

Yes, but there's another complication which is that if you use rendered graphics or titles on a 60i timeline, but you were using 30p footage, the graphics will be split across the fields.

Whereas if you use a 30p timeline, the graphics will be rendered as 30p, frame for frame.

So if you're using 30p footage, it's usually best to use a 30p timeline to edit it.

July 25th, 2009, 10:58 PM	#1
Denny Kyser Major Player Join Date: Aug 2007 Location: Warren, Pa Posts: 785	HMC 150 and 30P Does the HMC 150 record 1080 in 30P mode? I see it says over 60i, and I am not sure what that means. __________________ 2 Canon XF305's Kyser Photography www.kyserphoto.com

July 26th, 2009, 10:35 AM	#2
Denny Kyser Major Player Join Date: Aug 2007 Location: Warren, Pa Posts: 785	Can someone explain what this means "1080/30p (over 60i)" I am considering this camera, but need it to shoot 1080 30P and mix on a timeline with my EX1 and HV30 __________________ 2 Canon XF305's Kyser Photography www.kyserphoto.com

July 27th, 2009, 03:21 PM	#3
Simon Zimmer Major Player Join Date: May 2008 Location: Easton, Maryland Posts: 497	Not sure what it means either but I have the HMC-150 and shoot in 30p (1080) and it works great. Simon

July 27th, 2009, 09:53 PM	#4
John Wiley Trustee Join Date: Oct 2008 Location: Byron Bay, Australia Posts: 1,155	Each frame is captured as a progressive image but then split into fields before it is recorded to the card as a 60i stream. When the footage is de-interlaced by your TV or in your NLE it plays back exactly the same as if it was recorded 30p.

July 28th, 2009, 11:10 AM	#5
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	Progressive footage should never be de-interlaced. De-interlacing progressive footage really just means that you're throwing away half your resolution. NLEs will recognize the "progressive" flag and will be able to use the footage exactly as if it had been recorded in a progressive data stream in the first place. In other words, if it's shot 30p "over 60i", then the NLE will know exactly what to do with it and will treat it as 30p, as you intended.

July 29th, 2009, 07:16 AM	#6
John Wiley Trustee Join Date: Oct 2008 Location: Byron Bay, Australia Posts: 1,155	Barry, can you please explain how de-interlacing throws away half your resolution? I was under the impression that when you de-interlace, then both the fields are displayed at the same time. Temporal resolution would be decreased but spatial resolution would be higher, wouldn't it? Or does de-interlacing simply mean the NLE only plays the 'a' fields and ignores all the 'b' fields?

July 29th, 2009, 09:36 AM	#7
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	Pretty much yes -- it ignores one field and duplicates the other to fill in the gaps. Or, if you're using an advanced de-interlacing technique such as blended fields, it'll try to synthesize a new field by blending the "A" and "B" fields together. In any case, you DON'T want that to happen to your progressive footage. Progressive footage has full information detail in each field and that should be preserved as-is.

July 29th, 2009, 10:02 AM	#8
Graham Hickling Trustee Join Date: May 2004 Location: Knoxville, Tennessee Posts: 1,669	I don't think that "1080/30p (over 60i)" has the full information in each field. Each field more likely has half the information, so that you need to combine the two fields to restore full resolution, at 30 frames per second. But that's speculation - I'm open to be corrected.

July 31st, 2009, 09:34 AM	#9
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	You are correct, that's exactly how it works, and that's exactly why you wouldn't want to "de-interlace". De-interlacing would destroy the valid information in one or the other field.

August 1st, 2009, 06:45 PM	#10
Jeremy Dallek Regular Crew Join Date: May 2009 Location: Minneapolis MN Posts: 40	Basically the footage will play back properly on a 60i timeline, just make sure you don't apply any deinterlacing processing to the clip. (i.e. deinterlace method: interpolate, blend, none. choose "none")

August 2nd, 2009, 07:30 PM	#11
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	Yes, but there's another complication which is that if you use rendered graphics or titles on a 60i timeline, but you were using 30p footage, the graphics will be split across the fields. Whereas if you use a 30p timeline, the graphics will be rendered as 30p, frame for frame. So if you're using 30p footage, it's usually best to use a 30p timeline to edit it.