[Openexr-devel] Multiview YCA files.

[Neall Verheyde]

To reduce file size for our stereo-pair renders, I'm experimenting with YCA 
encoded images.

Something like this is the goal:

channels (type chlist):
    A, 16-bit floating-point, sampling 1 1
    Y, 16-bit floating-point, sampling 1 1
    RY, 16-bit floating-point, sampling 2 2
    BY, 16-bit floating-point, sampling 2 2
    right.A, 16-bit floating-point, sampling 1 1
    right.Y, 16-bit floating-point, sampling 1 1
    right.RY, 16-bit floating-point, sampling 2 2
    right.BY, 16-bit floating-point, sampling 2 2

The problem I'm encountering is the RgbaOutputFile class does not seem to 
support writing out more than four channels, and it does not support writing 
out the multi-view prefix.  The RgbaReader class seems to have some support for 
the latter feature, although we are currently using the lower-level 
Input/OutputFile classes for reading and writing.  This suggests we have to 
pack and unpack the YCA channels, with help from the functions in ImfRgbaYca.h 
but doing this looks to be complicated if the private RgbaOutputFile::ToYca 
helper class is any indication.

Is there a relatively painless way to create multiview YCA images without 
having to cut-and-paste swaths of private implementation contained inside 
ImfRgbaFile.cpp?  I'm currently using OpenEXR 1.7.1.


Thanks,

Neall.
Gener8 Digital Media