how does the "BPCC" do to record in RAW 1080p on SD cards?

[Brawl]

hello, I have read that the new hack on the canon's is capable to have RAW shooting in video! I have also read that is very important to have a CF slot because as much fast the card is ad much high pixel resolution you can take on a single frame. meanwhile I have discovered the BPCC (Blackmagic Pocket Cinema Camera) and it is capable to shoot in RAW 1080p on SD cards.

I wish to ask you wich is the difference?
Why the BPCC can shoot at 1080p RAW on SD cards but the Canon 550D can not?

thx a lot for the explanation!

[CFP]

The Blackmagic cameras record (lossless) compressed 12-bit RAW videos. The Canon DSLR record uncompressed 14-bit RAW videos.

That means that the Magic Lantern videos are way bigger. So it's impossible to record RAW videos with slow write speeds. But Canon's SD-Controllers are really slow so that they can't handle the required write speeds. The 550D has a 21 Megabyte/s write speed limit. But uncompressed 1920 X 1080 14-bit RAW videos require 83 Megabyte/s write speed.

[Brawl]

The Blackmagic cameras record (lossless) compressed 12-bit RAW videos. The Canon DSLR record uncompressed 14-bit RAW videos.

That means that the Magic Lantern videos are way bigger. So it's impossible to record RAW videos with slow write speeds. But Canon's SD-Controllers are really slow so that they can't handle the required write speeds. The 550D has a 21 Megabyte/s write speed limit. But uncompressed 1920 X 1080 14-bit RAW videos require 83 Megabyte/s write speed.

thx for reply, how many megabytes write speed require the compressed 12-bit RAW videos? could be possible to port it on 550D?

thx for help!



p.s.

here some example of  compressed 12-bit RAW videos differences

Common DSLR Shot



RAW Wide Dynamic Range (compressed 12-bit RAW)


source (maybe spam I can edit if you want): link

[CFP]

Well, uncompressed 14-bit 1920 X 1080 videos are 3.46 Megabyte per frame.
Uncompressed 12-bit 1920 X 1080 videos are only 2.97 Megabyte per frame.

So uncompressed 12-bit videos are almost 15% smaller than uncompressed 14-bit videos. So instead of 83 Megabyte/s 12-bit videos need only 71 Megabyte/s write speed. And since Blackmagic adds some kind of compression, the size should be reduced by 20-50%. But since the BMPCC isn't released yet and the specs site doesn't say anything about the type of compression, I can't tell you for sure.

There were some tests with compression but they failed and as far as I know nobody tries to continue them at the moment.
So it's probably impossible to get the Magic Lantern RAW videos compressed.

I think the images on the Blackmagic website are a bit overstated. Of course, the H.264 videos have only 8-bit but they aren't that bad. Still, with 14-bit color depth we have 64 times more information than with 8-bit. There's no doubt that the higher values are better

[SDX]

The SanDisk Extreme Pro SDHC/SDXC UHS-1 Memory Cards (2011) perform at 95 MByte/s..
SD cards can be as fast as CF cards, but no producer has hitherto implemented controllers that do the speed, into their devices.

http://www.sandisk.com/products/memory-cards/sd/extremepro-sdxc-sdhc-uhs-1-95mbs/
http://www.amazon.com/dp/B005VDRD4C

[Brawl]

Well, uncompressed 14-bit 1920 X 1080 videos are 3.46 Megabyte per frame.
Uncompressed 12-bit 1920 X 1080 videos are only 2.97 Megabyte per frame.

So uncompressed 12-bit videos are almost 15% smaller than uncompressed 14-bit videos. So instead of 83 Megabyte/s 12-bit videos need only 71 Megabyte/s write speed. And since Blackmagic adds some kind of compression, the size should be reduced by 20-50%. But since the BMPCC isn't released yet and the specs site doesn't say anything about the type of compression, I can't tell you for sure.

There were some tests with compression but they failed and as far as I know nobody tries to continue them at the moment.
So it's probably impossible to get the Magic Lantern RAW videos compressed.

I think the images on the Blackmagic website are a bit overstated. Of course, the H.264 videos have only 8-bit but they aren't that bad. Still, with 14-bit color depth we have 64 times more information than with 8-bit. There's no doubt that the higher values are better

ok I'll wait! thank you for help! have a nice week!

[Brawl]

The SanDisk Extreme Pro SDHC/SDXC UHS-1 Memory Cards (2011) perform at 95 MByte/s..
SD cards can be as fast as CF cards, but no producer has hitherto implemented controllers that do the speed, into their devices.

http://www.sandisk.com/products/memory-cards/sd/extremepro-sdxc-sdhc-uhs-1-95mbs/
http://www.amazon.com/dp/B005VDRD4C

do you believe that could be possible to destroy the limit? for example could be theoretically possible to destroy the 550D 21 Megabyte/s write speed limit? or the limit is a hardware factor?

thx!

[SDX]

they apear to be hardware limit

[Brawl]

they apear to be hardware limit

wow this surprise me a lot. do we have any evidence that the hardware limit could be, maybe, to have under control and separate markets? for example if i want to have two different products (called A and B) i need them to be different from each others. so if CF and SD were similar thay -had- to limit one of them?
if this were true they are playing with our money.

what do you think about it? thx

[mageye]

A hardware limit is what you face if you try and run the very latest software on a PC that is 10 years old. You reach a hardware limit, that whatever you do; you cannot exceed a hardware limit.

It's a hardware LIMIT.

[Brawl]

A hardware limit is what you face if you try and run the very latest software on a PC that is 10 years old. You reach a hardware limit, that whatever you do; you cannot exceed a hardware limit.

It's a hardware LIMIT.

does it mean that Canon use SD card slots that are from old generation of hardware? but for example the Black Magic guys sells SD card slots in their devices that are modern generation? is this the true reason why Black Pocket Cinema Camera can have RAW video at 1080p (12bit) on SD card but "with Canon we can't"? thx!

[driftwood]

In a word. Yes. The SD controller is not that great in most DSLRs of pre-last year. BMCC may well be using better memory controllers. A simple explanation is found here;-

http://www.tested.com/tech/photography/455053-how-sd-card-speeds-are-often-limited-slow-memory-controllers/

[Brawl]

In a word. Yes. The SD controller is not that great in most DSLRs of pre-last year. BMCC may well be using better memory controllers. A simple explanation is found here;-

http://www.tested.com/tech/photography/455053-how-sd-card-speeds-are-often-limited-slow-memory-controllers/

Thank you so much I will read it in the depth in the next days!

I know that ML is a custom firmware and have nothing to do with Canon, but I do not like the market of this days. it is like if Canon has some kind of scepter you know? like a queen of some fantasy story.
I believe that this market is glued by something that I cannot see and understand. but the "feeling" is not positive.
What I understand is that my money are not so many and is not easy to move in the market with a budget limit factor.
I feel like maybe would be an openness if we could enjoy video making also with Nikon and Black Magic using Magic Lantern. We are stuck. Sure I can not talk for anyone, but yes, I feel abosolutley like this.
I have not alredy bought a dslr, I have my money "in my bag", have been passed years and I still not have a decision. But I'm studing to be a film director, and the camera is the last problem after all.... but maybe now is my avidity I do not understand what, but if now I know all those stuff about ML and RAW video, now with this story of the SD card hardware limit factor I have not the same pleasure of before to go out at the shop and spend a lot of money for a Canon 600D. I do not know what to do.

thx for you opinion,

Dan

[mageye]

There are several reasons why the BMCC will be able to handle RAW and ProRes formats. One of the big ones is the fact that it has SDXC memory card support which is a newer standard, is capable of much higher capacity and bandwidth (speed) than the older SD cards.

Apparently SDXC has speeds of 104 MB/s (UHS-I) and 312 MB/s (UHS-II)

Check out this information from the source:

https://www.sdcard.org/consumers/sdxc_capabilities/

[Brawl]

 

thx!