Why no 2K mode for the 2/3 Scarlet?

[Erik Ahrend]

Hi to all, my first post here, been a lurker for a while and just decided to step in..

I was wondering, why no 2K mode for the 2/3 Scarlet? Nearly all the other models have this feature, and considering the Scarlet is capable of 150 fps in burst mode, shooting 2K should allow for something like 200/250 fps and still retain enough IQ for Full HD..That sounds like a VERY interesting feature to me.

Just wondering, probably there is a good reason for it..

Best.

 

[GPSchnyder]

Good Question. Maybe just not written down?

 

[Erik Ahrend]

I really hope you are right...

 

[Jeff Kilgroe]

Cropping down the imaging area doesn't guarantee that you will get faster frame rates. Based on 150fps being a burst ability, I'm guessing that's probably the max cycle rate of the sensor. Cropping down may however allow for faster sustained rates, possibly approaching 150fps.

Not sure why you would want to crop down to 2K though. That won't retain enough bayer data to provide a full HD image and you would be effectively shooting a 6.1mm wide imaging area or something similar to a 1/3" sensor camera.

 

[Erik Ahrend]

Cropping down the imaging area doesn't guarantee that you will get faster frame rates. Based on 150fps being a burst ability, I'm guessing that's probably the max cycle rate of the sensor.

That´s an interesting fact. I was approaching this issue from a pure "data-transfer" point of view..

Not sure why you would want to crop down to 2K though. That won't retain enough bayer data to provide a full HD image and you would be effectively shooting a 6.1mm wide imaging area or something similar to a 1/3" sensor camera.

Obviously the only reason for shooting 2K is faster frame rates. Anyhow,I mainly have a photographic background, so I might be loosing the point here. I thought you needed "just" 1080 pixels wide for full HD. 2K should provide just enough data for it..Can you pleae explain what you mean when you say it wouldn´t have enough "Bayer data" to provide Full HD?

Cheers.

Erik.

 

[Kenneth Elkington]

Obviously the only reason for shooting 2K is faster frame rates. Anyhow,I mainly have a photographic background, so I might be loosing the point here. I thought you needed "just" 1080 pixels wide for full HD. 2K should provide just enough data for it..Can you pleae explain what you mean when you say it wouldn´t have enough "Bayer data" to provide Full HD?

Cheers.

Erik.

http://en.wikipedia.org/wiki/Bayer_pattern

That is a good explanation of what he's talking about.

The Red uses what's called a Bayer pattern sensor, so instead of the sensor recording 2000 horizontal RGB pixels, it records 2000 individual Red green and blue pixels, meaning that the RGB output is significantly lower(it may seem like this would downres to 1/3 of the horizontal resolution the modern debayering algorithms yield substantially higher than that, in the neighborhood of 3/4 of the resolution. Red claims a measurable resolution of 3.5k from a debayered 4k stream.). The reality is you will likely be able to get a usable full HD image from a 2k stream. Slumdog Millionaire was shot in 2k Bayer format and still has a good Full HD image, it's just not going to be as good as when you would be using 3k.

 

[Birns and Sawyer]

Edit: Kenneth beat me to it, but here's my post anyway:

With a Bayer patern sensor, you're not recording RGB values to every pixel, so when you do the de-bayering, you can't average those colors together and still have 100% of the image quality. I think that the current bayer algorithm achieves somewhere around 78% of the spatial resolution.

That's why some people like to call the R1 a 3.2K camera, because you would have to scale the image down to 3.2K to account for the de-bayer. That's why 2K is really only good enough for 720p finish, or SD finish. If you want to get a good 2K image, you'd preferably shoot at least 3K.

 

[Erik Ahrend]

Thanks guys for taking the time, those are great answers, but in any event I still see that every other Red camera in the catalog has the 2K mode!! I know, I can be a quite stubborn..:bleh:

Cheers, Erik

 

[Andrew Gentle]

I asked the very same question on Scarletuser just yesterday:
http://scarletuser.com/showthread.php?t=2551
I figured that if you follow the framerates of the One then 300 fps burst would be possible on Scarlet. There are probably other limitations though.

 

[Jeff Kilgroe]

but in any event I still see that every other Red camera in the catalog has the 2K mode!!:bleh:

Yes, but every other camera in the catalog has a much larger sensor with larger photosites. The photosites on the 2/3" Scarlet are 3nm (0.003mm) in size. On the Mysterium-X sensor they are 5nm, RED One has 5.4nm photosites and the upcoming Monstro sensor has 6nm photosites.

So it makes a lot more sense to offer 2K modes on these other sensors due to their larger attributes. 2K on the S35 Mysterium-X sensor still gives us the equivalent of a 2/3" imaging area. 2K cropped out of a 2/3" Scarlet sensor is a whole lot smaller and less desirable.

I figured that if you follow the framerates of the One then 300 fps burst would be possible on Scarlet. There are probably other limitations though.

But we can't really do that. This is not the RED One. RED One's Mysterium sensor has a maximum cycle rate of 120Hz. No burst ability. The only way to record anything at 120Hz in the One is to use a 2K, 2:1 crop of the sensor because that is the only way 120fps can not overload the internal processors or exceed internal bandwidth. Given that the Scarlet 2/3" shoots up to 120fps in 3K and 150fps burst, there has to be a reason for that burst. I'm guessing that much more than a burst at that speed would possibly overload or overheat the sensor.

With Scarlet, we're talking about an entirely new sensor, new supporting electronics, etc.. This is all pure speculation in most ways. But we have to recognize that the Mysterium-X will have a maximum cycle rate. The S35 EPIC-X allows for 250fps at 2K, but this is a bad comparison or reference. It's bad because the supporting electronics in the EPIC-X and internal data paths are presumably a lot more capable. Also with the lower photosite density, it's probably easier to manufacture a higher-speed version of the sensor.

 

[Gavin Greenwalt]

My guess would be it's not the sensor overloading but the DSP.

It probably can't actually process that much data in real time so it's going up against the RAM of the system. Once the RAM is full it needs time for the compression to catch up.

*wild speculation*

 

[Jeff Kilgroe]

Possibly... But then again, I'd be surprised if the system actually has that much RAM.

Edit> Nevermind. Seems reasonable. 3K 16:9 @ 12bpc would be about 7.59MB/ frame. 150 fps for a 3 second burst would require about 3.4GB of space. I suppose it's easy to assume there's 4+GB of memory inside the camera.

Could be the internal DSP or other ASICs in that the burst is a way to keep them from melting down and it may not be the sensor that is the first to fatigue under heat.

*more wild speculation*

 

[Kenneth Elkington]

Could be the internal DSP or other ASICs in that the burst is a way to keep them from melting down and it may not be the sensor that is the first to fatigue under heat.

*more wild speculation*

I find this to be the more likely case actually.The photosites on the 2/3 scarlet are 3nm versus 5nm on s35. It's a CMOS process and generally as the architecture gets smaller in CMOS it produces less heat. The processors in the 2/3 are built for 3k and a continued data rate of 42 MB a second, so I'd assume that the processors and not the sensor are the limiting factor in this case.

 

[Erik Ahrend]

If the limiting factor is the processor I see no reason for it not being able to shoot higher FPS in lower resolution, the processor just "moves"data, a lower K could give a similar amount of gross data shooting at higher rate, the processor would be doing the same amount of work...

Erik.

 

[Lawrence Bansbach]

Could be the internal DSP or other ASICs in that the burst is a way to keep them from melting down and it may not be the sensor that is the first to fatigue under heat.

*more wild speculation*

I find this to be the more likely case actually.

Most likely Mysterium X is capable of at least the 180-fps burst that was quoted for the original Scarlet design. Testing probably revealed a heat issue and the burst rate was scaled back to 150 fps.

The processors in the 2/3 are built for 3k and a continued data rate of 42 MB a second, so I'd assume that the processors and not the sensor are the limiting factor in this case.

It's been said here that Redcode 42 doesn't precisely denote the data rate in MB/sec but rather a quality level. Besides the original Scarlet was supposedly capable of a sustained 100 MB/sec at the highest frame rates, and I've seen nothing that indicates this has changed.

 

[Kenneth Elkington]

It's been said here that Redcode 42 doesn't precisely denote the data rate in MB/sec but rather a quality level. Besides the original Scarlet was supposedly capable of a sustained 100 MB/sec at the highest frame rates, and I've seen nothing that indicates this has changed.

I was just using it as a rough benchmark of what will likely be typical data throughput for the 2/3. I also don't think using any specs from the old Scarlet is relevant any longer. Some technology from that design may remain, but it's likely that the new brains are designed from the ground up to conform to the individual needs and capabilities of each.

 

[Chris Newman]

My (somewhat educated) guess is that all of the hardware in the 2/3 Scarlet has enough power and speed to do 2K at 180+ fps, but as Jim has said, Scarlet has hardware that is not as flexible or configurable as Epic's. This may mean more is integrated into ASICs and less in FPGAs, which also translates to lower cost and lower power & heat.