Hdv50?

C

Chimpan-A

Member
I've been hearing rumors about an upcoming HDV50 format- as in HDV with twice the bitrate. Does anyone know anything about this? Will it rival the DVCPRO-HD of the HVX? etc etc Googling the term finds only the briefest of mentions of the term...
 
It will come some day, and first from JVC. At least two years away. Very expensive.
It will serve as a replacement for DigiBeta and Digital-S, not MiniDV. High end format, high price.
 
People have been speculating about a 50-megabit MPEG-2 variant since HDV was first announced. I don't think anyone's announced actual plans to implement such, although, as Wells alludes to, JVC has said that in their ProHD XE system they expect to be able to accomodate "higher bitrates". No specifications on what that potential higher bitrate would be though. Could be 50, could be 36, could be anything. And the only ProHD XE camera they've talked about is the $27,950 2/3" camera (plus lens, so figure at least $40,000).

Would HDV50 rival DVCPRO-HD? Certainly it would do better than HDV25 and HDV19 do. 50 megabits might be plenty of space to appropriately handle the high-def frame. If someone were to introduce a 50-megabit variant (and boost it up to 4:2:2 while they were at it) then it could potentially make for some very nice-looking pictures.
 
Can MPEG 2 handle 4:2:2? What are its limitations?

Aren't there newer, better codecs out there now, or are they too processor intensive?
 
mmm said:
Can MPEG 2 handle 4:2:2? What are its limitations?

Aren't there newer, better codecs out there now, or are they too processor intensive?
Click to expand...

Did ya know that DVCPro-HD is merely a series of JPEG's ? That has to be the MOST inefficient way of storing stills as there are much better codecs available (I imagine).

And, yes, MPEG2 can handle anything you throw at it, given enough bandwidth. In fact, the Sony 1080i HDV data can be extracted into a 480P 4:4:4 compressed signal... pretty interesting stuff.

Point is there is always a better codec and various ways of interpreting the same data. JPEG's vs. MPEG's makes little difference in the end as long as there is enough bandwidth there to handle the information without compressing the daylights out of it.
 
There are definitely better, newer codecs! MPEG-2 has been around for something like 12 years. Sony's new implementation of HDCAM SR uses MPEG-4, and I believe MPEG-4 is the basis for H.264.

But, if they wanted to stick with MPEG-2 for some reason, yes it should be able to support 4:2:2 (as well as theoretically 4:4:4). There's a 4:2:2 profile ("Studio Profile") already defined in the MPEG-2 documents.

As far as its limitations -- give MPEG-2 lots and lots of bandwidth, and it can do a stellar job. Choking it by shoving high-def video into 25 megabits will reveal artifacts in many cases, but with enough bandwidth it can do plenty fine.
 
Cheers guys!

So how come people aren't using the best codecs now?!

Surely a 25Mbit HD H.264 stream would look pretty sweet... Could that be implemented on a camera?
 
You need a 2Ghz dual G5 just to play back 1080 H.264! Somehow I doubt a camera can compress it on the fly like that.
 
FWIW,
Even Sony's new MPEG-IMX HD (due to ship by 2nd quarter 06) will not even be 50Mbit (at first)...it will be 35Mbit. Albeit at a Variable Bitrate MPEG2.

Brian
 
So what codec will the HVX use?
I know it has been talked about, but I figured since a more in depth conversation about codecs has evolved over here, then someone might want to refresh everybody's memory. Then we ( :huh: well... you guys anyway :laugh: ) could take it a step further and start stipulating about how that would affect the long term status of the HVX.
 
The HVX uses DVCPRO-HD, which is the same format that's used in the $70,000 VariCam and the $42,500 HDX400. It's a frame-based codec that's derived from DV, in essence it's four DV codecs ganged together. It provides for 4:2:2 color sampling, native support for 1080 and 720 resolutions, and no motion artifacts or variable-resolution artifacts ever.
 
Barry_Green said:
Sony's new implementation of HDCAM SR uses MPEG-4, and I believe MPEG-4 is the basis for H.264.
Click to expand...
MPEG-4 is indeed the basis for H.264 (H.264 is also known as MPEG-4 Part 10).

Barry_Green said:
But, if they wanted to stick with MPEG-2 for some reason, yes it should be able to support 4:2:2 (as well as theoretically 4:4:4). There's a 4:2:2 profile ("Studio Profile") already defined in the MPEG-2 documents.
Click to expand...
Steve Mullen's table of MPEG-2 profile-level combinations (here) seems to show that the "Studio Profile" (ie, the 4:2:2 Profile) at 50 Mbps (4:2:2 Profile @ Main Level) supports only 720 x 480, which, ironically, is the same combination of resolution and data rate as DVCPro 50. According to the table, the 4:2:2 Profile requires 80 Mbps for 4:2:2 1080i or 720p.

mmm said:
Surely a 25Mbit HD H.264 stream would look pretty sweet... Could that be implemented on a camera?
Click to expand...
From everything I've seen H.264 is about twice as efficient as MPEG-2 -- that is a 25-Mbps H.264 stream would be roughly equivalent to a 50-Mbps MPEG-2 stream of the same resolution, frame rate, and color sampling. But currently H.264 is computationally expensive.

evinsky said:
You need a 2Ghz dual G5 just to play back 1080 H.264! Somehow I doubt a camera can compress it on the fly like that.
Click to expand...
True, but I believe that it's just a matter of a year or two before it'll be possible on mass-market cameras. I suspect that something like the Cell -- or some specialized processor -- will make it possible to encode/decode the Fidelity Range Extensions (which support 10-bit and 12-bit coding and 4:4:4 sampling) even on a "low-end" HD camcorder.
 
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