Andre,
Confucious said: "Never argue with man who have technical reference manual for camera and knows what he read." ...which Don has and does. <g>

Actually, isn't this getting awfully thick and irrelevent to Charles' original question?

Well I'm interested in the inner workings of the XL1S.

_____ thick and irrelevant
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V

If the XL1S gain control is analog, why is the knob designed to be discrete adjust (versus being a continuously variable pot)? That is, why can't I turn the knob between settings to get +4 dB etc.?

I didn't know that confuscious (+/- 500 B.C.) already knew about the existance of technical ref manuals for camera's...Because I was for over 30 years, toroughly involved in circuit and chip design for simular signal processing, and I know about the strip down exercises to be done for so called ref manuals to make them useable for repair people, I am not impressed by the "interconnected blocks" style wiring diagrams which are published through such channels...Sorry Don. Happy Newyear anyway!

Because the unusual 9-bit processing mentioned by Don I searched and found some info from Chris Hurd http://www.dvinfo.net/canon/skinny.php. Now I understand why Jeff Donald allways sees banding in the sky on his DV camera(XL1s I suppose) where it is seldon mentioned (although possible)in other DV articles. The XL1s apparently has only a 6-bit equavalent grayscale resolution... of course resampled on a 8-bit structure for the DV format. This makes me also conclude that gamma and WB are done in the (9-bit) digital domain. These are the two processes by which you "loose bits": 2 for gamma (4xgain at black) and 6 db for WB (=1-bit). Other processes ( pixel shift, noise reduction...) don't reduce grayscale resolution.

That makes a lot of sense. Thanks for doing the research on it. It's very useful information.

Jeff

> ... If the XL1S gain control is analog, why is the knob designed to be discrete adjust ...

The gain control is a switch that selects a specific voltage step on a voltage divider. That voltage is sent to the control/logic circuit. Depending on the voltage level you get the differnt gain settings, or automatic gain. The analog gain is selected in descrete steps, which works for video. If the control directly controlled the gain via a potentiometer (like many stereo volume controls) it could introduce noise, especially as it ages and would be hard preseed to provide logic selections as well.

As for the 6-bit grayscale. Not sure how that computes. Would be easy to check. Someone shoot a gray wedge and read the luma levels in the output. 6-bit implies only 64 possible values for the luma signal. The XL1 DSP shows 9-bit input, 8-bit output.

FYIW, the old L2 and Ai-Digital camcorders Hi-8 system used 6-bit for the color portion of their internals DSP.