After much "Google trawling" I came up with some limited info about the Sony CCD sensors used in some of these cameras.
For example
www.unibrain.com/download/pdfs/ub1394cam/ICX445AQA.pdf Since most of the pin designations match those on the Ixus 60 diagram, I think we can be sure the two sensors are closely related cousins.
Of particular interest is this..
"Supports following modes
All-pixel scan mode (15 frame/s, 12.5 frame/s, 22.5 frame/s: MAX)
Center cut-out mode (30 frame/s, 25 frame/s)"
This suggests that the maximum video frame rate for this particular sensor is 30fps, however it also suggests it may be possible to clock the chip at different rates below this, (and potentially overclock it above this), as the CCD is controlled by a variant of this little chap...
http://www.analog.com/en/audiovideo-products/cameracamcorder-analog-front-ends/ad9923/products/product.htmlDatasheet.
http://www.analog.com/static/imported-files/data_sheets/AD9923A.pdfThe datasheet suggests the timing chip has a maximum resolution of 8192 px by 4096 lines which equates to a whopping 33,554,432 pixels, or 33 Megapixels, so there is every chance that some variant of this chip is used in most of the canon digic cameras. It is used in both of the schematics I posted about previously, indeed, it seems to be a common chip in other manufacturers offerings too.
If this is the case, then learning to control the timing of this device (and possibly also the Analog to Digital controller) either directly or through the existing firmware leads to some intersting possibilities, for example slower and faster video rates, higher video resolutions, sqeezing more info from the CCD and so forth.
I hope this helps fire the imagination of a few of the developers.
BTW: The SD600 that lead me on this quest had a blown fuse on the power board, which I tracked down very quickly with the aid of the schematic. My SMD soldering technique could do with some practice, but I managed to replace it
I now have another little toy in my collection.
