4:4:4 10bit single CMOS HD project

[Jason Rodriguez]

I found it would drop frames occassionally due to bus saturation.

David, was there anything else on the PCI bus? Seems like PCI should be capable of capturing @ 94MB/s without any problems when the theoretical limit is 133MB/s.

Or is this another problem with the framegrabber not having a buffer on-board an it's in fact using up 16-bits per pixel with padded zeros for a 12-bit signal. Or each pixel is using 2 bytes. That would give you 124MB/s for 30fps at 1920x1080, and yes, at that rate I'm sure you would drop some frames from time to time.

But again, I'm thinking that 24fps at 12-bit being 77MB/s and 30fps being 94MB/s shouldn't be any problems for the PCI bus, again, only if you're actually transfering 12-bits over the bus and not 16-bits.

[David Newman]

I was trying for 1920x1080 @ 24p = 95MB/s. Yes there are other things on the PCI bus but nothing active at the time. The theoretical 133MB/s is not reachable. 100MB/s is more likely what you will get. 95MB/s was occassionally too close to that limit.

[Jason Rodriguez]

BTW, just curious, how are you guys getting 95MB/s for 1920x1080?

with 2 bytes per pixel (16-bits), 1920x1080x24 = 99MB/s
with 1.5 bytes per pixel (12-bit), 1920x1080x24 = 74.6MB/s

So if that's the case, then 99MB/s is right underneath your 100MB/s limit, and you'd probably run into some problems. BTW, I'm not doubting your numbers, I'm just trying to see what I'm overlooking for that 4MB/s difference.

[David Newman]

:)

1920x1080x24x2 = 99532800 Bytes/s

Divide 1024 = 97200 KB/s

Divide 1024 again = 94.9 MB/s

[Jason Rodriguez]

"Divide 1024": Doh! ;-)

[Obin Olson]

http://www.dv3productions.com/pub/fr...color look.jpg

this image even got our programmer aroused..trust me thats not an easy task. ;)

as the frame says 1080p converted to 720p and CC capture from 12bit

[Hayden Rivers]

wow.

[Obin Olson]

BTW just so you guys know this 3300rgb has more dynamic range then the Panasonic dvx100 that we have .. I find this really nice ;) the face photo was much darker on the dark side with the dvx100 then the raw file from the 3300rgb

[Aaron Shaw]

how much latitude would you estimate your camera has?

[Obin Olson]

not sure without a professional test..but it's more then standard DV 3ccd cameras

[Steve Nordhauser]

Another thought on the frame rate calcuations. Unless the capture board has a full frame of buffer (the Epix doesn't), you get the peak, not the average data rate over the bus. Average is the way you are calculating. For the peak value, look at the clock rate you are using - I'm guessing around 60MHz. In 12 bit, unpacked transfers, that is two bytes per pixel so 120MB/sec for the active readout and then quiet during the blanking.

Obin, I'm really impressed with your 3300 images.

[Aaron Shaw]

Do you think you could run a few tests? I'm not sure how you would go about that exactly but it would be very interesting.

I'm also VERY impressed by that image. Very well done.

[Joshua Starnes]

Obin, what type of lenses are you using for these shots? Are you still using those c-mount lenses from a 16mm camera?

[Wayne Morellini]

<<<-- Originally posted by David Newman : I was trying for 1920x1080 @ 24p = 95MB/s. Yes there are other things on the PCI bus but nothing active at the time. The theoretical 133MB/s is not reachable. 100MB/s is more likely what you will get. 95MB/s was occassionally too close to that limit. -->>>

David, as Steve said, but there would be another additional problem when going so close to maxinum trasnfer values, That even though the extra periphials on he PCI bus might no be used, the system might be still polling them (interegating there existence or some other minor activity) that will interrupt capture work flow.

Jason:
I think you can get away with 8 bits, if you do the gamma curve and some setup on board the camera itself, as Sumix and Drake does. I don't know if SI allows you to do this setup though, but I imagine a firmware upgrade might. Actually what embedded processor does the SI cameras use, if it is a regular type of processsor (ARM or maybe Mips, and Nec or Samsung had one too) then this canbe upgraded in future design to a chip with 1-2 megabyte embedded ram on chip (I think they go to at least 16MB nowdays). With some innovative programming the ram could be used as a circular buffer, never even having to store a full frame, just enough (less than 50% to average out 24fps). I realise that certain memories don't like a speed of 50MBs but I image they can work a lot faster, especially if we are talking about 32bit memory. Those Cameralink card I pionted out recently had a 2MB buffer chip, which is also another route.

Cinelink
I have 1920 Monitor (everybody should have, so cheap now, even Phillips). Mutlithreading on save causing problems, that sounds right. Congradulations on getting this far.

[Obin Olson]

We could get away with 8bit if the camera head could gamma correct the images BEFORE save..this would be a very nice feature..Steve??

thanks for the good words Steve...I myself am impressed by the images! I do want a chip that has no checkerboard though ;)

Steve how am I getting 60mhz from the 3300rgb @ 12bit with no FIFO overflow on the 32bit EPix card?