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March 14th, 2002, 06:01 PM | #1 |
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XL1 and Uncompressed
Hi.
I'm looking for a reference to a great Canon XL1 technician. Someone who has the camera open regularly and knows video electronics at the analog level. (not just component swapping) My motivation is crack my XL1 and get a component video signal out. Component = (Y, R-Y, B-Y) While I'm not terribly hopeful, it really would extend the range of the XL1 even at the cost of some conversion electronics. I'm NOT interested the S-Video the XL1 currently does produce. The motivation is to access the analog signal prior to digitization, get it into component format, and then route it into the component input of something like Aurora Igniter or Digital Voodoo card. Skipping the 4:1:1 sampling and compression would allow much more chroma information and detail to be captured. No, the 20 MB/S doesn't scare me in the least. Yes, those CCDs (lame S/N ratio) are still the weak link. I realize there are lots of costs and tradeoffs involved. Lugging around a Mac, capture card, RAID, while shooting isn't everyone's cup of tea. But, hey you need the practice for HD anyway. ;-) Different stuff, same luggability issues. Also, until this is accomplished and we see an image there isn't much to debate (except theoretically). Hey, if those great Germans can do a Mini35, the least we can add to the soup is "uncompressed"! Please, help me find a good tech and I'll post the images. - Cheers, Philip Hainline ps. I changed the Subject since the original was a little over constrained. This one is probably too general.... (oops, looks like the subject only changes at the message level, not the forum level. Sorry.) Last edited by hainline; March 16th, 2002 at 12:07 PM. |
March 15th, 2002, 02:37 AM | #2 |
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I think the viewfinder is getting a component signal
(not sure)... There where some threads on it and the watchdog has the pin layout of it inside an article about a switchable color/black&white viewfinder. You might try this before busting open your XL1. Just remember to set the viewfinder options in your menu to all the "natural/normal" settings. Good luck.
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March 15th, 2002, 05:37 PM | #3 |
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The signal in the XL1 is RBG from the CCD through the analog procesing and A/D converter to the DSP chip. In the DSP chip the 9-bit RBG from the A/D chips is processed and converted to Y/C, and exits as 13.5 Hz 8-bit Y and C signals. An interface circuit converts the 8-bit Y/C to a 27 Mhz 8-bit serial data signal. This goes into the same video/audio signal processor chip that creates the analog outputs, processes the audio inputs, prepares the DV signal for recording (by adding digitized audio, data code, etc.), and extrcts the video/audio from the playback signal.
Yes, the EVF output is Y, R-Y and B-Y, and it is derived from the output of the interface section in camera mode and the playback section when in VCR mode. Last edited by Don Palomaki; March 15th, 2002 at 07:07 PM. |
March 16th, 2002, 02:19 AM | #4 |
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dpalomaki .. YOU are THE man of the day!
It sounds like you are the guy I want to talk to about this cam!!!! I too keep thinking the same thing. Give me the component signals. I want to know if there's a decent breakout box that doesn't cost $1,500? And has a decent s/n ratio. But I thought that in dv, the signal is laid down as RGB, so is it possible that you are mistaken when you mention it going into y/c, 1st? I mean why go RGB...y/c...rgb? Is it about the dsp, presets, Wt. bal., etc? Does this mean that it outputs y/c cleaner (because it's 1st) than firewire? Or maybe live, anyway? Right now I go firewire into another deck (live). Any idea if you used the VF's plug, will it be displaying the whole shabang? Battery level, exp. meter? Or is that part of the other pins and the signal composites them together for a mixed signal in the VF? dpalomaki, if you really know this cam's guts, PLEASE, PLEASE PLEASE, take a little time and go through it slightly more in-depth than this post was (as well as live vs. tape, 1394 vs. s-video vs. composite) and I'll beg Chris to give you a page. This really is the lowdown and I thank you for your post!
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March 16th, 2002, 11:44 AM | #5 |
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Ok. Let's go slow and stay focused. I'll be glad to elaborate on
some of the issues, and describe the sweet spot that I'm trying to exploit. First, what I'm talking about is really expensive and requires alot of hardware resources. But, for the right problems can produce some very useful data streams. What I'm after is still up in the $15-20k range obviously depending on how much gear you alread have. JoPhoto, for background on the various sampling and compression issues, I would recommend either Scott Billups' book Digital Movie Making (www.pixelmonger.com) and Adam Wilt's excellent site. (www.adamwilt.com). If you really love this stuff go to Charles Poynton's site. (Home.InfoRamp.Net/~poynton/) > I want to know if there's a decent breakout box that > doesn't cost $1,500? And has a decent s/n ratio. Not yet. But some year very soon. I probably wouldn't be pursuing this line of inquiry if the great folks at P+S Technik hadn't built the Mini35. (www.mini35.com) Also, if they were planning to build one for any of the 2/3" chip cameras any time soon I'd also skip this whole thing too. This enables using 35mm primes (great glass) with real control over depth-of-field and ablilty to pull focus. Yes, the XL1's CCDs are the real weak link, but under very controlled lighting they will work. If one can get real component video out of the XL1 then you have the option of recording direct to disk with something like Aurora Igniter, Digital Voodoo, or CineWave. Running uncompressed to disk requires around 13-20 MB/S. This takes a real board, a serious disk array, *and* a fast DLT to back it up to tape anyway. Real expensive. Why bother? Uncompressd, as 4:2:2 is often called (but is really missing data due to the sampling), is great for a couple of things done under really controlled circumstances. Blue/Green Screen work - The quality of matte you can generate is dramatically better. Upconverting to film. You really need all the color. Even a DSR500 recording 4:1:1 is missing alot of color info. Compresssing to MPEG for DVD. More data (skipping the 4:1:1 sampling and 5-1 compression) will let the MPEG compresssor produce much nicer images. These three advantages *PLUS* the Mini35 enable a particular niche you can't hit even with the much better 2/3" cameras. Obviously, the good 2/3" cameras can get shots my proposed setup can't. Just a particular sweet spot some would be interested in. Now how does this fit into the the YUV out to the montitor. We are still trying to figure out what kind of signal really exists that is being sent to the viewfinder. What Don Palomaki has presented is that the analog CCD signal has been adjusted, digitized, and serialized. An "interface chip" then provides the various analog outputs and interleaves other data to the DV stream. The missing info at this point is which of these specialized chips does the 4:1:1 sampling and compression to the 25 m/bit/s (or 3.7 M/byte/s) DV stream that gets written to tape. Even if it is the "interface chip" it would probably take some fluke (on the part of the ASIC libraries) that a 4:2:2 stream is being converted to YUV for the viewfinder. > An interface circuit converts the 8-bit Y/C to a 27 Mhz 8-bit > serial data signal. This goes into the same video/audio signal processor chip that creates the > analog outputs, processes the audio inputs, prepares the DV signal for recording (by adding > digitized audio, data code, etc.), and extrcts the video/audio from the playback signal. Given Don's statement above I'm beginning to lose hope. Given that the "interface" circuit also handles the playback stream. The playback stream is DV, and thus is already sampled and compressed. I'll keep digging. - Phil Last edited by hainline; March 16th, 2002 at 12:03 PM. |
March 16th, 2002, 06:05 PM | #6 |
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If someone is serious about developeng a third party add-on to the XL1 for YUV video output, I suggest they contact Canon for assistance in development, at least assistance in getting informtion about the XL1 internals. Canon is a bit reluctant to give technical information to the average Joe or Jane, for little good is likely to come of it. It ain't like an old tube color TVs inside! But I suspect they would work with competent, serious folks with backing to make their project becoem a reality. After all, third party support only helps Canon.
Information about the signals available at the EVF jack is published on the Watchdog site. That is the easily available data stream, and maybe it is a usable signal, maybe not. I have no idea whether or not it can drive a standard 75 ohm input (I suspect not). Beyond that, for the investment in reverse engineering and modifying the XL1 internals to fish out a signal, one may well be better off starting out with a higher end machine with the desired bells and whistles. |
March 16th, 2002, 07:03 PM | #7 |
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<<<-- Originally posted by dpalomaki : ..... Beyond that, for the investment in reverse engineering and modifying the XL1 internals to fish out a signal, one may well be better off starting out with a higher end machine with the desired bells and whistles. -->>>
Phil, This is all interesting in a dull, technical way. But what are you trying to accomplish?? Off-hand I'd have to agree with dpalomaki's remark above. If you're just trying to get a different look or image for your work why not rent (or buy) equipment designed for the job? I'm no video circuit technician but I'm willing to bet that Canon is probably not concealing a $50,000 image in the XL1's circuits only to dilute it to a $5,000 when it gets dumped to tape.
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March 17th, 2002, 11:06 AM | #8 |
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What he is trying to do is to skip the compression stage.
Giving him the full color resolution without any compression artifacting. It would be real sweet to have this. But I doubt it will work without "opening" the camera. Not a lot of people want to do this, obviously... Interesting project though!
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March 18th, 2002, 09:55 AM | #9 |
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That's it exactly Rob.
I'm sure it will involve opening the case and some very careful plumbing. It really is a sweet spot around the mini35's depth of field. As I said above, if I thought anyone was going to build a mini35 for the 2/3" cameras I wouldn't even bother. I'd buy a DSR500 but still use the trick of going component to disk to skip the whole DV 4:1:1 and compression. In any case, Don has been extremely helpful relaying bits of info from the XL1 service manual. Not enough info to be conclusive, but there is a 27Mhz 8bit signal that *might* line up well with the SMPTE 125M format. If true, there is a very straight forward conversion to SDI. Who knows what's really on the bus since this is highly optimized consumer electronics. I'll be trying to order a manual today. Still diggin..... -Phil |
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