Great! Very informative.
I was pretty familiar with this topic but I totally Ignored the scene/display referred data terminology.
As far as I understand, If I had linear 16bit raw footage (aka scene referred input data) I could composite all my CG generated 16/32 bit linear on the footage, working in linear space in blender and use the Exposure slider without any problem (or almost).
My only curiosity is:
When shooting raw video with a ACES compliant camera , every pixel has a certain value stored in it, which changes in a linear fashion with the light intensity that hits the pixel sensor.
To make the whole ACES system work, the value stored should be the exact luminance value, not an arbitrary voltage number which may change from sensor to sensor.
Is that the case?
If yes, this is a good reason to use real world intensities units and Phisically correct shaders in blender (As I would like to do), because if I use ,say, a 60W point lamp in blender at 2m from an almost white diffuse 3d paper sheet, and the shoot (almost) the same scene with a good camera in real life, the pixel 32bit raw value stored for a certain area of the shaded sheet in the render, should reasonably accurately match the values in the real footage.
Anyway, since the limited video capabilities of my camera (what you said is probably perfectly correct: compressed encoded 8bit per channel gamma 2.2 sRGB profile), all I can do is take the footage as it is, work on the CGI separately, and try to color correct/grade it to match the look of the display referred footage, possibly add a grading at the end of the pipeline and reduce the exporting compression to limit the additional data loss due to double compression.
I tried Magic Lantern to shoot raw videos , but the 700d is probably not capable to handle the bitrate, or at least my class 10 SD card @95 MBps is not.
I was thinking about at least linearizing the footage just after the input node with a reverse gamma correction, but with compression and only 8bits per channel… meh… I’m skeptikal.
By the way thanks again for your answers!