HMC150 720p vs. 1080 resized to 720

[mcsmooth]

Whether that argument holds in the general spatial-offset discussion or not, recognize that it's pretty irrelevant in the discussion here because the 1080 mode of AVCHD stores 960x540 chroma anyway, so you should certainly be getting maximum advantage of the chips' resolution by recording in 1080 mode.

Absolutely. I guess I had concluded that despite that argument, there is still extra room to be gained in 1080. While writing that... I may have forgotten to relate that the chip resolution was in fact the same amount of chroma that 1080 can provide. How convenient Being technical, you could argue AGAINST the hvx/hpx having any advantage with 4:2:2 in 1080 (ignoring other codec differences).

AVC is designed specifically to do that; instead of using big macroblocks like MPEG-2, it uses scalable blocks that range from, I believe, 16x16 on down to 4x4, so it can have much smoother transitions without the big blockiness.

On paper, that feature read to me as an explanation on how it is able to be more efficient in encoding. I am seeing a softness instead of jaggy macroblocks in the roughest spots. Not sure if this is simply a feature of the cameras encoder, my decoder or the magic of the codec.

I'm sure that's the case. I'm actually interested in trying out the new HMR10 AVCCAM HD-SDI recorder; I would love to put PH mode up against XDCAM-EX from the same source to see if my prediction (21mbps PH ~= 35mbps MPEG-2) is accurate.

Its too bad these cameras can't pull HDMI in like DV cameras would pull in an analog signal. I would put money on your prediction.

No idea, but the pieces are there; an HMC200 or 250 or whatever, with the HPX300's chipset, would give you the sensor resolution to fully tax the codec. No idea whether something like that is forthcoming, but if it was, it'd push AVCHD harder. Of course, then you'd have cmos issues to deal with, but there's no free lunch.

Well, I'm guessing you would be of the first to find out... but now we know they have put money into that game, I'd bet it is only a matter of time. With the biggest "disadvantage" of the Panny cams being sharpness, they would close that gap and be able to provide both options. With a pair of Panny CCD and CMOS cams, both would be A and B cams depending on the shot :thumbup:

Agreed on 720/60, still evaluating on the 1080/24p vs. 720/24p, but if it holds up in torture testing then yeah, I'd agree that 1080 would be the only way to go.

Can't say I've done in depth tests, but believe that you really cannot break the codec at 1080 in a controlled environment. I think the test would come down to if it can hold up in unstabilized mobile shots or with strobing lights. From what I have tested so far, it surpassed my expectations.

 

[aalleexx]

if shooting for slow motion in post, why is 1080 60i a bad idea?

 

[seven.b]

if shooting for slow motion in post, why is 1080 60i a bad idea?

Because shooting in 720/60p and then conforming to 24p will hold much more resolution/detail over deinterlaced then slowed down 60i footage. Plus, the 60p workflow is just way easier.

 

[Everts]

if shooting for slow motion in post, why is 1080 60i a bad idea?

you get whole frames and not half interlaced frames . slowing 60i down to 24 frames will get you jittery playback.
I shot some footage at night the other day on the lower setting ,HE right ?,

Just some Headshots it came out really clean .

 

[DavidNJ]

Barry's find is absolutely the case for chroma information. However, a test would be needed for spatial information.

Why? Because that chroma information didn't come for free. There was a fixed bandwidth, and now you are saving total fabricated spatial information.

In AVC Intra, 1080p24 taxes twice the storage of 720p24. In AVCHD it is the same.

The answer is implementation dependent. There is also a little more spatial information in the bigger stream. So a test is necessary.

But great info for any camera with selectable frame sizes, chroma subsampling (all unless raw), and fixed output bitrate. The undersampled sensor in this most cost effective prosumer camera make it more obvious. Even in an HMC200 (my WAG at presumably a full HD version announced maybe next month?) this same issue would occur.

I created a thread on the topic generically in a different section: http://www.dvxuser.com/V6/showthread.php?goto=newpost&t=165102

 

[Denwa]

I would unquestionably always shoot 1080p for greenscreen. But I wouldn't shoot 1080i for greenscreen.

Barry,

If shooting 1080P for maximum chroma, is that only relevant if you are outputting (downres) to 720P or is is this independent of output?

 

[Thomas Lew]

Barry,

If shooting 1080P for maximum chroma, is that only relevant if you are outputting (downres) to 720P or is is this independent of output?

If a girl got pregnant when people stopped posting on this thread.. that baby would be just about ready to be delivered by the time you made this reply Denwa lol. (9 months) How'd u manage to pull that off?

:bath:

 

[Barry_Green]

Well, that's an interesting question... the chroma is stored as a ratio, so technically it 720 or 1080 shouldn't matter, they're both 4:2:0...

but...

the 1080 doesn't have quite as much detail as a true native 1080p camera would, and so you have less detail spread across the larger frame. In that case, and for that case, I think the higher number of chroma samples actually results in a better, more-accurate picture, because the effective ratio climbs above 4:2:0 when you're talking about actual luminance detail to recorded chroma detail.

 

[Denwa]

If a girl got pregnant when people stopped posting on this thread.. that baby would be just about ready to be delivered by the time you made this reply Denwa lol. (9 months) How'd u manage to pull that off?

:bath:

So that's what that crying in the corner is?

Well, that's an interesting question... the chroma is stored as a ratio, so technically it 720 or 1080 shouldn't matter, they're both 4:2:0...

but...

the 1080 doesn't have quite as much detail as a true native 1080p camera would, and so you have less detail spread across the larger frame. In that case, and for that case, I think the higher number of chroma samples actually results in a better, more-accurate picture, because the effective ratio climbs above 4:2:0 when you're talking about actual luminance detail to recorded chroma detail.

Thanks,... I think. LOL. Not sure if I am less confused or more confused. rogar-BigGrin(DBG) Well "confused" is not the right term. More like "perplexed".

 

[Barry_Green]

I think 1080p is the best-looking mode on the HMC150, with the most color resolution and the most sharpness overall.

(does that unperplex?)

 

[Denwa]

Yes.

The reason I was perplexed is that i kept hearing about the 720P "Sweet spot" for the HMC150, often accredited to Barry Green.

 

[Barry_Green]

Right -- that was my original assessment. But after playing with it more and more, I started to favor 1080p...

 

[ARW]

I got back from shooting with my HMC 150 in Africa to find my footage ridden with artifacts (shooting 1080 24p)! I am viewing the footage on a Panasonic 40" LED HD tv directly from the camera and clean it is not. The conditions I shot in were tricky to say the least, but the level of noise/artifacts in the picture was a real shock. I guess because of being on the equator and also shooting on a island (it's very bright) the camera is overloading?! Has anyone got any suggestions/thoughts on what I might be doing wrong?

 

[Cranky]

I got back from shooting with my HMC 150 in Africa to find my footage ridden with artifacts (shooting 1080 24p)! I am viewing the footage on a Panasonic 40" LED HD tv directly from the camera and clean it is not. The conditions I shot in were tricky to say the least, but the level of noise/artifacts in the picture was a real shock. I guess because of being on the equator and also shooting on a island (it's very bright) the camera is overloading?! Has anyone got any suggestions/thoughts on what I might be doing wrong?

It would be really interesting to see an original MTS file. Maybe you have a short clip that you can share, which contains those artifacts?

 

[ARW]

How would I upload the original MTS file?

 

[ARW]

I have converted all the files to ProRes, using FCP 6.6. I originally thought that the issue could be the way that FCP was converting the files, but it seems that even when you view the footage out of the camera there are way too many artifacts.

Here is a link to download a 3 sec clip: https://download.yousendit.com/S1VERkJha0QyWGRMWEE9PQ

I tested the camera today in normal US conditions (in central park) at 1080 24P and the footage looked OK. I'm wondering if the 1080 24P mode is just not up to shooting in harsh conditions (hi contrast & lots of detail). Any thoughts?