Thanks for the fast reply!
I haven't been able to run FastRawViewer on the command line, but after some digging and some trial and error, I've found something that might work. I think FRV is using LibRaw, which does have some associated command line tools, and which itself is a fork of the dcraw CLI tool.
Using the precompiled LibRaw binaries for macos (from
https://www.libraw.org/download), and piping the output to the `convert` tool from ImageMagick, I can get a not-unbearably-slow jpeg render:
./dcraw_emu -h -T -Z - /path/to/file.NEF | convert - /path/to/file.jpg
For the dcraw_emu arguments, h provides a half-size file and seems to be their fastest render mode; T produces TIFF output; "Z -" redirects the output so I can pipe it to `convert`.
The NEF render handled by dcraw_emu takes about 600ms on my mac (which sounds kinda slow to me, but maybe this is normal for RAW file rendering)
LibRaw download:
https://www.libraw.org/downloadLibRaw usage notes:
https://www.libraw.org/docs/Samples-LibRaw.htmldcraw:
https://www.dechifro.org/dcraw/Additionally, it looks like dcraw could be a viable alternative to FRV/libraw for our purposes. It seems to be a single c file that is supposedly able to be compiled on a variety of systems, but if PMP gets the option to invoke arbitrary raw render binaries, that could be left as an exercise for the user