I've been unable to find an ouput for the ACES format. Although this is an ambitious academy-sponsored format, I don't see any support for After Effects yet. The VFX firm involved is using with Nuke. The format specifically requested for renders is
ACES EXRs 0 3ch., 16 bits/ch. floating point – ie. 2048 x 858
Any information or suggestions appreciated.
As far as file format goes, ACES just uses EXR, although a resricted set of features are supported. If you write out an EXR from AE using either None, Piz, or B44A compression, you should have an ACES-compliant EXR. (Also, do not check the 32-bit float box.)
But ACES files are also supposed to be in ACES color space. You can do this using the Color Profile Utility or the output module if you install the ICC profile here. Although you should know that ACES is a little convoluted right now, and this profile will make an ACES scene-referred image but won't let you preview with the ACES RRT.