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HD and UHD ( 2K+ ) Digital Cinema
Various topics: HD, UHD (2K / 4K) Digital Cinema acquisition to distribution.

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Old May 9th, 2005, 10:16 AM   #16
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I knew what it meant, I was just trying to emphasize that once your down to the electronic level most people get lost when i try and explain stuff to them. I had a feeling you would know what it meant anyway. But i'm really glad some people know what i'm talking about, horray!

Juan:
Since i'm using an fpga I'm playing ignorant and either going to use an external asynchronous FIFO and write programs around sending clock when needed and when data in/out is ready. Or just download the app note code from xilinx and modify it to fit the depth and width i need. In fpga's your code gets translatted to gray code or something, which to me is completely beyond me or anyone i know. Texas insturments make FIFO's and I've been going over their data sheets to help me understand and I think I almost have solved my current problems in the camera head design. Hopefully. But i want to see if i can change the ccd timings so that i can avoid having to use ram as a buffer, block ram isn't big enough and i don't want to wire external ram.
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Old May 9th, 2005, 11:54 AM   #17
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Yes, I know what you mean.
I know that situation with VHDL.What happens when you are placing the logical structures by drawing the gates through any of the available software packages out there? Is it still grey code?
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Old May 9th, 2005, 03:34 PM   #18
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Honestly I don't completely understand what goes on inside an asyncronous fifo and I have even less of a clue about what this gray code is.

What i do understand is that it should end up like a syncronous fifo, so that if your reading to fast your going to get into a situation where your fifo is empty and that will have to be handled, or you will get data gaps or something. I've haven't had a chance to test it though. It only gets translated to gray code, then it is output into binary. I think the gray code has to do with transistioning from one clock speed to the other.

I don't know if that is what your asking about. I'm just a beginner with fpga stuff.
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Old May 9th, 2005, 03:46 PM   #19
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This thread is completely off topic, but now back onto topic of the dalsa camera. I just clicked on the specs to the pantera SA-2M30 and something caught my eye. The 7.4 um x 7.4 um pixels. Then i looked at some of the other stuff and the pixel response stuff.

I know dalsa makes ccds, but what is really odd is that the handful of specs listed match the kodak KAI-2093 that i'm designing around. Even the absolute QE is pretty much a match. It could be just nothing, but the specs are so similar. Not much to go by except pixel sizes, avaiable resolutions (kodak has 2 2mp sensors, both the same res), type of sensor and QE and optical format size. Because of this I think that it might just be a cameralink camera based on the KAI-2093, but i could be wrong. Just a thought
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Old May 9th, 2005, 07:54 PM   #20
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Quote:
Originally Posted by Valeriu Campan
Radek,
A 720p will look much nicer than 1080i rescaled & deinterlaced.
All a matter of opinion.
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Old May 9th, 2005, 09:05 PM   #21
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take note that if you were discarding one field the final image would be (HDV) 1440x540 which gives a little less pixels than 1280x720.
I guess best situation would be using some expensive motion compensated deinterlacer (e.g. Faroudja).In this case we could say that final image would be a little bit better than 1280x720.
Anyway Sony's camera is 3 sensors of 960x1080i, so things are difficult to determine.
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Old May 22nd, 2005, 10:26 AM   #22
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Quote:
Originally Posted by Radek Svoboda
But it close to single 2/3" in area hit by light, it has deeper DOF, when needed you use 35 mm adapter for shallower DOF.

One 2/3" may not better than three 1/3" CCD's.

Radek
Yes, thats right, but it is a bit more complex than that. On signal colour chip the light each pixel can absorb (because of the color filter discarding the wrong colours) is nearly the same. The colour that doesn't match are discarded. But in the end the light for the 1/4 matching pixels between single and three chips, is not too far apart (maybe clipping in the shadows because of the filter). They just calculate the missing pixels in Bayer. The problem that should crop up is thermal noise, as that wasted light has to be dissipated as something, most likely heat, this will probably reduce your range and introduce noise into the bottom end of the light range.

Quote:
Originally Posted by Keith Wakeham
I don't know how many people know what i talk about half the time. Right now i had to figure out how an asyncronous FIFO works because of all the different clock speeds in my camera head. I doubt many people know what a fifo is, oh well.
Keep going Keith we need more intelligent people around to balance things out.

As you guys summarise. Companies stratify the features of their products to manipulate people into paying a lot for the best features. If they did everything near right, then their profits might drop to near a tenth (still a lot for us). Radek, there are a lot of people running around here with no awareness of the commercial realities of what they are doing, or enough of the technical side (believe it or not). It requires a very big investment in time and research to gather the required knowledge and information first. Mike is getting taught this at university, so we are lucky to have him. But even he will be learning a lot of specialised knowledge outside that the university course will cover. Sure things can be done cheap and quick but by the knowledgeable. "Fools rush in where angles fear to tread" is the saying and I am not biting off more than I can chew, but waiting. Seen it happen before, where somebody lands up broke, disgruntled, happy with nobody but their inner circle, and nobody really happy with them. Just be happy with what you know people can do. So be patient and something should turn up one day. Actually the Sumix camera is probably going to be he closet to what you want, soon, very very soon, hopefully cheap, I have been in contact with them.
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