I need some clarification on this gy-100u 19 megabits per sec please! at DVinfo.net

Laurence Maher · March 19th, 2005, 03:31 AM

I know that everone was saying it that transfer/data rate needs to be around 50 Mbps or 100 Mbps for good HD. Are they talking mega bits or mega bytes? What is larger transfer rate, bits or bytes. Please elaborate about the whole bit/byte thing. . . . ya, I know, laymens are annoying.

From all I can gather, a 19 Mbs image would be pretty unusable blown up to a big screen, am I right? And I'm assuming it won't be very great color separation like 4:2:2 or anything.

Thanks!

Chris Hurd · March 19th, 2005, 09:50 AM

MPEG compression and a long GOP provides the relatively low data rate. Image quality cannot be assessed "sight unseen" just based on the data rate. We'll have to see it first in order to evaluate how good it is.

Tom Roper · March 19th, 2005, 01:49 PM

8 bits = 1 byte

mbps = mega bits per second

Most broadcast HDTV is 10-19 mbps

D-Theater tapes can go up to 50 mbps in theory, though rarely do.

Barry Green · March 19th, 2005, 03:09 PM

You can't equate bits across different compression schemes. As Chris said, MPEG-2 relies on groups of pictures, rather than individual frames, and this can lead to very efficient compression. 19 megabits of MPEG-2 may look an awful lot better than 100 megabits of MJPG (or may not).

The JVC records at 19 megabits, which is about two, two and a half times as much as a DVD records at. Whether that's good enough for theatrical blowup quality remains to be seen. However, what is known is that the JVC records in HDV-compatible format, which means 4:2:0, not 4:2:2.

Lawrence Bansbach · March 20th, 2005, 11:35 AM

<<<-- Originally posted by Barry Green : . . . The JVC records at 19 megabits, which is about two, two and a half times as much as a DVD records at. Whether that's good enough for theatrical blowup quality remains to be seen. However, what is known is that the JVC records in HDV-compatible format, which means 4:2:0, not 4:2:2. -->>>

Has it been confirmed that the "ProHD" format is, at this point, essentially 19-Mbps, 720p HDV, with the only major difference being the addition of 24p? Is it official -- no higher data rates or 4:2:2 sampling?

Bill Pryor · March 20th, 2005, 12:42 PM

From all that I've read, it is HDV only, although not 1080i, only 720p.

Kevin Dooley · March 20th, 2005, 01:32 PM

Well, nothing confirmed at this point of course, but from what I can gather, the ProHD is essentially 720p standard for HDV + 24p +a total of 4 channels of audio (2 of which may or may not be uncompressed)

Joe Carney · March 21st, 2005, 09:46 AM

I think JVC is simply adding a 24p option while still supporting HDV spec in other modes. When I posted on the Cineform section, they said they could easily adopt the cineform codec to handle HDV at 720 24p. This is good news as far as I'm concerned. Capture/Edit at 24p shouldn't be a problem for anyone. As far as output? I guess you could do what they've been doing for decades. From a film based perspective, 24p is a universal format that can be easily converted to NTSC or PAL HD with current technology.

The new Pana notwithstanding, I'm hoping the JVC is the camera I've been waiting for, for so long. If JVC does with HDV color what they did with DV25, they should rival the new pana in video quality.

As far as being able to change lenses? Do what the big guys do, rent what you need for the current project. Thats how Panavision stays in business (not saying you would use Panavision lenses on this camera).

right now in pre nab mode, all the manufacturers are posturing to get their product noticed. Nothing wrong with that at all, just keep all that in mind. I plan on waiting till there are some good reviews.

My only question is...
If the JVC is really outstanding....will 'duhsonymen' get upset and start trashing it (lying about it) like they did with the gy-dv300?

Bill Pryor · March 21st, 2005, 09:59 AM

Yes, people doing big budget films rent lenses they need along with the cameras they need. But the concept is pretty much irrelevant for a 1/3" chip camera. Any available prime lens is way too long to do you any good in normal shooting situations unless you go to one of those adapters with the spinning ground glass...and if you're going to spend that kind of money anyway, you should just rent a better camera when you need it, or buy one, I think.

As far as the progressive scan thing, I want to see the cameras first. I'm not in the market at the moment, but if I were, I would go for the best quality image, featues, useability, reliability, etc., over whether the camera shoots progressive or interlaced. Unless I planned on transferring to film, and then I would prefer to shoot 24p (although most labs are quite good at transferring interlaced video, and most of the low budget video-to-film movies I've seen theatrically have been shot 60i).

I used several JVC cameras very successfully way back in the tube camera days and find that even today they manage to give you an image quality very close to other cameras at significantly less cost. They don't get much respect, and I'd guess that's for two reasons--their primary market in the past seems to have been corporate in-house production units and institutions, rather than broadcast, and they have had some well publicized problems with new cameras. However, if you don't buy the first version but wait till the bugs are worked out, and if you treat the camera with the care you should, then it could turn out to be the best value for the dollar on the market today...uh, well, maybe not today since it's not on the market yet. But soon.

Joe Carney · March 21st, 2005, 10:42 AM

Bill, I understand what you are saying. I don't think the high end glass makers will target this camera. But it might open opportunites for companies like Century Optics and others. But as you said, it will depend on the quality of the video coming out, and the reliability of the camera itself, and number of units sold. If there are enough sold, someone will make glass for it.

I'm both optimistic, and skepticle at the same time. Optimistic because 720 24p HDV won't require me to change from my current NLE setup. Skeptical because 'I've been there done that' too many times not to be.

March 19th, 2005, 03:31 AM	#1
Laurence Maher Join Date: May 2004 Location: denton, texas, usa Posts: 416	I need some clarification on this gy-100u 19 megabits per sec please! I know that everone was saying it that transfer/data rate needs to be around 50 Mbps or 100 Mbps for good HD. Are they talking mega bits or mega bytes? What is larger transfer rate, bits or bytes. Please elaborate about the whole bit/byte thing. . . . ya, I know, laymens are annoying. From all I can gather, a 19 Mbs image would be pretty unusable blown up to a big screen, am I right? And I'm assuming it won't be very great color separation like 4:2:2 or anything. Thanks!

March 19th, 2005, 09:50 AM	#2
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	MPEG compression and a long GOP provides the relatively low data rate. Image quality cannot be assessed "sight unseen" just based on the data rate. We'll have to see it first in order to evaluate how good it is. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

March 20th, 2005, 01:32 PM	#7
Kevin Dooley Major Player Join Date: Dec 2003 Location: Fort Worth, TX Posts: 414	ProHD Well, nothing confirmed at this point of course, but from what I can gather, the ProHD is essentially 720p standard for HDV + 24p +a total of 4 channels of audio (2 of which may or may not be uncompressed) __________________ Kevin Dooley Media Director, Pantego Bible Church

March 19th, 2005, 01:49 PM	#3
Tom Roper Trustee Join Date: Jun 2004 Location: Denver, Colorado Posts: 1,891	8 bits = 1 byte mbps = mega bits per second Most broadcast HDTV is 10-19 mbps D-Theater tapes can go up to 50 mbps in theory, though rarely do.

March 19th, 2005, 03:09 PM	#4
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	You can't equate bits across different compression schemes. As Chris said, MPEG-2 relies on groups of pictures, rather than individual frames, and this can lead to very efficient compression. 19 megabits of MPEG-2 may look an awful lot better than 100 megabits of MJPG (or may not). The JVC records at 19 megabits, which is about two, two and a half times as much as a DVD records at. Whether that's good enough for theatrical blowup quality remains to be seen. However, what is known is that the JVC records in HDV-compatible format, which means 4:2:0, not 4:2:2.

March 20th, 2005, 11:35 AM	#5
Lawrence Bansbach Major Player Join Date: Dec 2004 Posts: 295	<<<-- Originally posted by Barry Green : . . . The JVC records at 19 megabits, which is about two, two and a half times as much as a DVD records at. Whether that's good enough for theatrical blowup quality remains to be seen. However, what is known is that the JVC records in HDV-compatible format, which means 4:2:0, not 4:2:2. -->>> Has it been confirmed that the "ProHD" format is, at this point, essentially 19-Mbps, 720p HDV, with the only major difference being the addition of 24p? Is it official -- no higher data rates or 4:2:2 sampling?

March 20th, 2005, 12:42 PM	#6
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	From all that I've read, it is HDV only, although not 1080i, only 720p.

March 21st, 2005, 09:46 AM	#8
Joe Carney Inner Circle Join Date: Jul 2002 Location: Centreville Va Posts: 1,828	I think JVC is simply adding a 24p option while still supporting HDV spec in other modes. When I posted on the Cineform section, they said they could easily adopt the cineform codec to handle HDV at 720 24p. This is good news as far as I'm concerned. Capture/Edit at 24p shouldn't be a problem for anyone. As far as output? I guess you could do what they've been doing for decades. From a film based perspective, 24p is a universal format that can be easily converted to NTSC or PAL HD with current technology. The new Pana notwithstanding, I'm hoping the JVC is the camera I've been waiting for, for so long. If JVC does with HDV color what they did with DV25, they should rival the new pana in video quality. As far as being able to change lenses? Do what the big guys do, rent what you need for the current project. Thats how Panavision stays in business (not saying you would use Panavision lenses on this camera). right now in pre nab mode, all the manufacturers are posturing to get their product noticed. Nothing wrong with that at all, just keep all that in mind. I plan on waiting till there are some good reviews. My only question is... If the JVC is really outstanding....will 'duhsonymen' get upset and start trashing it (lying about it) like they did with the gy-dv300?

March 21st, 2005, 09:59 AM	#9
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	Yes, people doing big budget films rent lenses they need along with the cameras they need. But the concept is pretty much irrelevant for a 1/3" chip camera. Any available prime lens is way too long to do you any good in normal shooting situations unless you go to one of those adapters with the spinning ground glass...and if you're going to spend that kind of money anyway, you should just rent a better camera when you need it, or buy one, I think. As far as the progressive scan thing, I want to see the cameras first. I'm not in the market at the moment, but if I were, I would go for the best quality image, featues, useability, reliability, etc., over whether the camera shoots progressive or interlaced. Unless I planned on transferring to film, and then I would prefer to shoot 24p (although most labs are quite good at transferring interlaced video, and most of the low budget video-to-film movies I've seen theatrically have been shot 60i). I used several JVC cameras very successfully way back in the tube camera days and find that even today they manage to give you an image quality very close to other cameras at significantly less cost. They don't get much respect, and I'd guess that's for two reasons--their primary market in the past seems to have been corporate in-house production units and institutions, rather than broadcast, and they have had some well publicized problems with new cameras. However, if you don't buy the first version but wait till the bugs are worked out, and if you treat the camera with the care you should, then it could turn out to be the best value for the dollar on the market today...uh, well, maybe not today since it's not on the market yet. But soon.

March 21st, 2005, 10:42 AM	#10
Joe Carney Inner Circle Join Date: Jul 2002 Location: Centreville Va Posts: 1,828	Bill, I understand what you are saying. I don't think the high end glass makers will target this camera. But it might open opportunites for companies like Century Optics and others. But as you said, it will depend on the quality of the video coming out, and the reliability of the camera itself, and number of units sold. If there are enough sold, someone will make glass for it. I'm both optimistic, and skepticle at the same time. Optimistic because 720 24p HDV won't require me to change from my current NLE setup. Skeptical because 'I've been there done that' too many times not to be.