4:4:4 12-bit Uncompressed DVX100

[Stephen Birdsong]

Well, this is where offline editing comes in.
Use the codec for storage, and convert somehow to a smaller version of the file for editing.

Stephen

[Adam Burtle]

Not a lot of time for me to be on the forum lately.. but i'm glad to see this is coming along.

Juan, when you're ready to start developing for the XL1, if there is anything i can do (loan you one, etc) just let me know.. i can't wait to get one of your mods.

[Juan P. Pertierra]

Adam:

If by the time i am done with the DVX design none of the HD cameras have come out, I plan to apply this to the XL1s.

The one thing I DO need is the service manual. Once again, if anyone here has it please email me.

I can apply the exact same device I have on the DVX to the XL1 with a small modification of the probing hardware, but I need the service manual to actually do it.

[Stephen van Vuuren]

Juan:

I think the results on the XL1s would be interesting, although there is a risk they may not be useful. Canon's low pixel count and narrower latitude combined with lots of pixel shift might make the RAW image less than desirable.

Or the converse, it might make dramatic improvement depending on how much of Canon's processing occurs on the CCD block and how much in the codec assembling.

[Thomas Smet]

I am not so sure a mod for the xl1 would really be worth it. First of all I have a XL1 and like it so this isn't an attack on the XL1.

1. The chips in the XL1 are not the best and have a low pixel count.

2. The XL1 is an interlaced camera.

3. The XL1 runs at 30 frames per second unless you have a Pal camera then you can get 25.

4. The XL1 image is already soft without blowing it up. If you upscale an xl1 image it gets even worse. The detail just isn't there compared to the dvx100 or higher end cameras.

The XL1 with mod would still give you for the most part the same type of image qulaity that you have with the XL1 now. You would just have more color depth and accuracy. The same issues such as converting 30 fps to 24 would still be there. De-interlacing would still be there. The same soft picture with low pixel CCD's would still be there.

The reason the mod works well with the DVX100 is because it is already a great camera on it's own. Having a true 24P camera with CCD's with a high pixel count make the camera already high quality. Really the only downside to the image from the DVX is that the CCD's arent bigger than 1/3' and that the camera forces the image into a DV codec. The mod fixes the problem of getting rid of the dv codec and giving the true quality of the camera.

I would actually take a normal dvx100 over an XL1 with the mod anyday due to the other aspects that make good image quality.

Besides the XL1 is getting a little old and by the time Juan would have time to make the mod the "XL2" will be out and everybody will be trying to get rid of their XL1's. Now a mod for the XL2 is a different story.

[Michael F. Grgurev]

Pardon if I've missed any past posts on this and am being repetitive.. but as of far I can't find any.

The hype on the threat has been about getting 4:4:4 RGB out of DVX100, which peaks my curiosity just as much as the next guy. But how about 4:2:2? It seems like getting 4:2:2 (lets say 8-bit at least) out of a DV camera should be extensively easier.

I think Juan might have mentioned a type of switch to his mod that’ll allow you to go from 4:4:4 to 4:2:2, which is what I’m more practically interested in using, as it’ll take up less disk space, will be more software/hardware compatible, but will still be an awesome potential over DV.

If anything, might I inquire what would specifically be involved as far as trying to tap into a cameras pre-DV compressed signal and getting the video onto a PC. Is it a simple process of physically tapping into a cameras pre-DV Y/C stream and routing it through firewire then capturing it with anything that supports 4:2:2.. or (as I'm assuming) are then other technical dilemmas that are most likely beyond my intellect.

[Juan P. Pertierra]

Michael:

it is actually simpler to get 4:4:4 because that's what the camera natively captures. You would intuitively think that it should not be a lot of work to throw away samples and get 4:2:2, but the problem is that the camera captures 4:4:4 >>RGB<<. This means that to get any other YUV decimation I have to first convert RGB to YUV, and then discard samples. This is why it is just simpler to store the RGB that comes out of the camera.

About what is involved, there are two parts to it. First of all is finding where to get the signals and how to get them cleanly out of the camera, It sounds simple, but when you are trying to tap into ~40 pins of several 0.5mm surface mount chips it's not simple at all. Add to that the space constraint when the the camera case is completely closed and your options are narrowed down to custom work.

The second part of it is the actual device which interfaces this digital stream with whatever you want to record on, which is in itself, the hardest part of the project.

Now, if you didn't care about portability or price, you can get an expensive scientific digital capture card for your PC and capture the data RAW. But that means your camera is tied to your desktop PC, and the camera case open. Pretty useless, unless you won't be moving the camera at all.

If you want it to be portable, you basically need to design a small computer system in a box that interfaces the digital data to firewire or a drive.

And, you can't really use a small PC board like a PC104 because not one of them can handle the raw digital input at the fast rate the camera puts it out.

Hope this helps...

[Anders Holck Petersen]

Regarding monitoring of the signal I think you should just go for a standard DVI interface.

As the captured signal is not white balanced and has no gamma correction it would be unfit for a CRT based SDI monitor.

By using DVI you could keep the signal in 4:4:4 RGB and retain the full resolution. You would have to truncate the signal to 8 bit of cause. And you could use a cheap 1024x768 LCD panel as the monitor.

[Thomas Smet]

I took a look at that Sheervideo codec and it seems like it might work a little better than the microcosm codec from Digital Anarchy. From the website it seems this codec will be fast enough to capture and edit video with. We may even at some point in the future make drivers for editing systems to give us realtime video out through a decklink card or another card like it.

One of the downsides to the codec however is that it costs $150.00 and is only in beta right now for the windows version.

I for one do not mind spending $150 for a codec but some may not want to if the codec is going to cost $150 and right now only give them 10 bit video and very limited support for Windows. The Microcosm codec does cost $100.00 but their none16 codec is free and is 16bit.

I am sure in the near future the windows support will be fully added as well as 16 bit.

I figured the codec was going to be slow for the mod but it sure is hard to beat the price of free.

[David Mintzer]

Juan--Two stops is about right--at least in the digital slr world. For instance, I can take a raw image from my Canon 1D and grab an extra two stops or so when processing.

[Juan P. Pertierra]

Thanks David. I guess if the standard latitude of the DV output is about 6 stops, the RAW latitude should be about 8 stops?

Anders:
That's a very interesting idea, i'm going to look into the DVI specs...

[Justin Burris]

American Cinematographer (April '03) found the DVX output to be about 8 stops, so if we are getting 2 more stops... could we be looking at a 10 stop DV camera? Woo hoo!!!

[Juan P. Pertierra]

Interesting...what is a sure way to test this? Can I somehow to a comparison with my film camera?

[Justin Burris]

Juan,

The only way I know of would be with a lightmeter. I wouldn't recommend buying one just for this test, but if Purdue has photography classes or filmmaking classes, you can probably check one out for free from the school. Shouldn't be too hard to learn how to use it. The tech who checks it out to you may be able to give you a quick tutorial. If school is closed, your next best bet for rental is probably in Indy (depending on which campus you are at, Chicago may be closer).

On the other hand, if you are going to continue to use this mod yourself, buying a light meter may be the best way to go, depending on how good the monitoring situation is.

[Anders Holck Petersen]

I have both a lightmeter a DVX100 pal and a waveformmonitor so I should be able to test it
Don't know if I have the time though.