View Full Version : a little resolution question


Andzei Matsukevits
February 19th, 2007, 09:02 AM
Im confused, i have a 50hz HVX, what is the resolution when i film in 720p/25pn? 1440x1280? I was trying to use raylight for editing and tutorial says that i supposed to set on 1280x1080, but i thought its for 60hz cameras, not european ones...Im i right?

thanks

Jeff Kilgroe
February 19th, 2007, 01:10 PM
I'm not using Raylight so I can't comment there... But when you shoot 720 25pn, it's encoded as 960x720.

The HVX (and DVCPROHD spec) encode 720p formats as 960x720 and they encode 1080i at 1280x1080 for NTSC modes, 1440x1080 for PAL. When you shoot 1080p with the HVX, it gets encoded over 1080i since DVCPROHD does not officially support 1080p and your NLE software must perform the proper pull-down to re-assemble the progressive frames.

Andzei Matsukevits
February 20th, 2007, 12:35 AM
thanks Jeff, now i know.

Please someone comment on Raylight question!

Marcus van Bavel
February 20th, 2007, 04:28 PM
thanks Jeff, now i know.

Please someone comment on Raylight question!


Did you know that there is a readMe file that comes with Raylight?
The settings are in there.

You can also find them at http://dvfilm.com/help, click on Raylight.

Normally Raylight frame sizes are 1920 x 1080 or 1280 x 720
regardless of the frame rate.

You can also use native frame sizes like in FCP but those are not recommended for new users, since many PC editing systems do
not automatically know the correct pixel aspect ratio.

John Bosco Jr.
February 25th, 2007, 05:58 AM
This camera is suppose to scan 1080p 4:4:4; therefore it should produce full HD even though using dvcprohd codec, which produces true HD with just a bit of compression. Thus, in NTSC that would mean 1280 x 720p or 1920 x 1080i. HDV takes a hit on the horizontal resolution by producing a 1440 x 1080i, using a pixel aspect of 1.33 (like widescreen SD) instead of 1 to achieve HD aspect.

John

David Heath
February 25th, 2007, 09:16 AM
This camera is suppose to scan 1080p 4:4:4; therefore it should produce full HD even though using dvcprohd codec, which produces true HD with just a bit of compression. Thus, in NTSC that would mean 1280 x 720p or 1920 x 1080i.
Not true - the front end of the camera features 3 960x540 chips, with horizontal and vertical pixel shift to improve the luminance resolution to more than the pixel specs would have you think. From that 1080p is derived, but the native chip resolutions mean that it cannot be full HD 4:4:4 - by definition that means 1920x1080 resolution for luminance AND chrominance.

"True HD" or "full HD" are tending to be used nowadays by manufacturers to refer to 1920x1080 resolution, so talking of "True HD 720" is a bit of a contradiction. For 1080, DVCPro HD doesn't have the necessary resolution to qualify, any more than HDV - or HDCAM for that matter - and as Jeff says, at 1080 DVCProHD is 1440x1080 at 50Hz, 1280x1080 at 60Hz. At the moment, only the top end solutions really manage "Full HD", though the coming JPEG2000 (Infinity) and AVC (Panasonic) products should change that.

Chris Hurd
February 25th, 2007, 10:07 AM
HDV takes a hit on the horizontal resolution by producing a 1440 x 1080iHDCAM works *exactly* the same way, yet nobody complains about it.

There is no hit on the horizontal resolution when a native 1440 sensor is boosted by Pixel Shift.

John Bosco Jr.
March 20th, 2007, 07:13 PM
Not true - the front end of the camera features 3 960x540 chips, with horizontal and vertical pixel shift to improve the luminance resolution to more than the pixel specs would have you think. From that 1080p is derived, but the native chip resolutions mean that it cannot be full HD 4:4:4 - by definition that means 1920x1080 resolution for luminance AND chrominance.

"True HD" or "full HD" are tending to be used nowadays by manufacturers to refer to 1920x1080 resolution, so talking of "True HD 720" is a bit of a contradiction. For 1080, DVCPro HD doesn't have the necessary resolution to qualify, any more than HDV - or HDCAM for that matter - and as Jeff says, at 1080 DVCProHD is 1440x1080 at 50Hz, 1280x1080 at 60Hz. At the moment, only the top end solutions really manage "Full HD", though the coming JPEG2000 (Infinity) and AVC (Panasonic) products should change that.

I think I understand. I guess you have to be careful of slick marketing from manufacturers. I guess that also explains why the canon is sharper than the HVX 200.

AVC-Intra and jpeg2000 are reported to be full hd. What about AVCHD? I heard JVC is out with a full hd, not hdv but some sort of MPEG 2 compression. It's called the hd 7, but it has the same resolution chips as the HVX only 1/5th inch instead of 1/3rd inch sensors.

Anyway, I'm drifting off the subject. What I would like to know, if any body knows, is Panasonic's claim it was forced to use the lower resolution chips, so it can achieve a decent low light performance. Well, then why are the other cameras with higher resolution chips, like the canon XHA1, just as good or better in low light?