Canon 5D MarkII: Why compression?

[Elektronkind]

ZFS is designed for flash.

Erm, not really (and I have about 80TB under ZFS where I work, with that number growing.)

ZFS can *use* flash, that is SSDs where the memory cells have a much higher MTBF than your typical CF/SD/SDHC card, but it uses it as a backing store for its intent log (the ZIL). Losing it is not detrimental to your pool's health, however.

It may get to a point where flash (maybe not NAND type) can be used with modern file systems at a use rate consummate with cameras, but other than write fatigue, there is still the obstacle of the camera CPU and memory capacity to implement these file systems, not to mention the provisions in the camera's OS to implement these as well.

I would like to see ZFS used if only for its built-in data integrity aspects (recordsize checksumming) but I think that camera hardware and the OSes that run them will have to catch up, and most importantly, support would have to be seen in the Windows world for it. ZFS is half-way there on the Mac as it is.

/dale

 

[butterfly0fdoom]

What claim? I said the EU tax is not a HARD limit. They should just not cripple the cameras and sell them at a higher price, paying the tax.

There's no such hard limit. They should stop the stupidity and sell them at a higher price then.

Why? The camera is, first and foremost, a CAMERA. Video is a secondary feature, and not everyone wants to pay more just for longer movies that require larger memory cards that require even more money.

Of course many people would be filming continuously more than 30 minutes to record events.

And those people ought to be investing in a camcorder, then. You know, something designed to record video from the get-go.

 

[ChrisA]

Is there a reason why they're using the h.264 for video compression or why couldn't they offer a uncompressed option?

I suppose you could still shoot enough video in uncompressed mode with a 8 or 16gb memory card.

Or is there an entirely different reason why they don't offer uncompressed .mov for video?

Uncompressed video Is about 4.5 MB per frame. At 30 frames per second that would about 150MB per second. Is you card that fast? Even if it were fast enough you'd fill the card quickly. One minute would be 9 GB. Even a high end card could hold only a few seconds of data.

Uncompressed video is very rare. You don't see it used in many places. About the only place most end users will ever see uncompressed video is inside video cable leading to a monitor

 

[alphaod]

Is there a reason why they're using the h.264 for video compression or why couldn't they offer a uncompressed option?

I suppose you could still shoot enough video in uncompressed mode with a 8 or 16gb memory card.

Or is there an entirely different reason why they don't offer uncompressed .mov for video?

What kind of production equipment do you have that can process uncompressed 1080p video? If you want a 1080p video camera just go get a red camera.

 

[cube]

And those people ought to be investing in a camcorder, then. You know, something designed to record video from the get-go.

You still don't get it. The point is not to save money but to avoid the hassle of dealing with two cameras at the same time.

 

[cube]

Erm, not really (and I have about 80TB under ZFS where I work, with that number growing.)

ZFS can *use* flash, that is SSDs where the memory cells have a much higher MTBF than your typical CF/SD/SDHC card, but it uses it as a backing store for its intent log (the ZIL). Losing it is not detrimental to your pool's health, however.

It may get to a point where flash (maybe not NAND type) can be used with modern file systems at a use rate consummate with cameras, but other than write fatigue, there is still the obstacle of the camera CPU and memory capacity to implement these file systems, not to mention the provisions in the camera's OS to implement these as well.

I would like to see ZFS used if only for its built-in data integrity aspects (recordsize checksumming) but I think that camera hardware and the OSes that run them will have to catch up, and most importantly, support would have to be seen in the Windows world for it. ZFS is half-way there on the Mac as it is.

/dale

Sun has a ZFS/Flash initiative, as per the CEO's blog, but it's a bit ambiguous what it means.

 

[Elektronkind]

Sun has a ZFS/Flash initiative, as per the CEO's blog, but it's a bit ambiguous what it means.

This has to do with what's called "readzila" and "writezila" - using SSDs as a cache device for reads and wrights to the ZFS Intent Log, aka the ZIL.

This speeds up those operations *considerably* and make a very fine complement to ZFS as a whole.

See:
http://mags.acm.org/communications/200807/?searchterm=adam+leventhal&pg=49

/dale

 

[cube]

No he's saying there will be new producs combining ZFS, Flash and silicon. He not only talks about storage gear but also about "appliances".

 

[Elektronkind]

No he's saying there will be new producs combining ZFS, Flash and silicon. He not only talks about storage gear but also about "appliances".

Yes, and I've actually been beta testing one of these products (really, the software behind it) for the past year. Think storage appliances.

But in these products, flash is a compliment to ZFS in the way I already described - a combined solution with traditional disk and not wholly flash. You'll see in the coming weeks how this pans out.

The generally static world of mass storage is about to turned on end.

/dale

 

[butterfly0fdoom]

You still don't get it. The point is not to save money but to avoid the hassle of dealing with two cameras at the same time.

Camcorders can take still images, too. If photography is more important, you buy a camera. If filming is more important, you buy a camcorder. Both can perform the other function, but it's a secondary feature.

 

[ftaok]

Camcorders can take still images, too. If photography is more important, you buy a camera. If filming is more important, you buy a camcorder. Both can perform the other function, but it's a secondary feature.

But why can't you have one device that does both functions extremely well? The 5D MkII is an excellent camera and by judging some of the video coming from it, I'm going to say that it's an excellent video camera as well.

 

[cpcarrot]

Just to answer the original post. You won’t get uncompressed on any camera at the moment simply because the bitrate would be way, way too high. For uncompressed 1080p at 30 frames per second, by my maths you are looking at:

Say 30 bits per pixel (assuming higher end color space)
1920 x 1080 = 2,073,600 pixels per frame
So 30 fps gives a bitrate of 30 x 30 x 2,073,600 = 1,866,240,000 bit/s or 1866 Mbits/s.

That’s quite a lot! To give some comparisons for other bitrates used in video cameras:

HDV Cameras – Bitrate = 25 Mbits/s (so about 75 times smaller)
AVCHD Cameras – Bitrate = 17-24 Mbits/s depending on model (so between 77 and 110 times smalle)
XDCam EX (As used by the Sony EX1) – Bitrate = 35 Mbit/s
XDCam HD422 – Bitrate = 50Mbit/s
DVCPRO HD – Bitrate = upto 100Mbit/s

Basically the recording media would have to be sooooo fast to record uncompressed it just isn’t doable in anything remotely considered portable (you could do it with a RAID array but you can’t exactly lug one of those round with you very easily…

They could up the bitrate on the Canon and create better quality video, but generally speaking the manufacturer selects a bit rate based on the maximum the electronics and recording media can cope with and sticks to that. Seems rather unlikely therefore that Canon can increase in the bitrate in any easy way…