Do you have to build ffmpeg from source to use 10-bit codecs in Windows? I'm trying to find somewhere I can download pre-built binaries of ffmpeg for Windows with 10-bit codec support.  Apparently, from what I've read, ffmpeg has to be either 8-bit or 10-bit, and the builds on www.ffmpeg.org for Windows are all 8-bit.

This thread on the ffmpeg forums suggests that there were 10-bit releases for a time, but no longer.

My google searching has turned up several sites with 10-bit builds from 2013, 2016, and so on, but nothing consistent over time.

Before I go to the trouble of trying to set up a way to build this from source, I just want to confirm-- there's no site regularly providing 10-bit Windows builds of ffmpeg, right?
Not quite. The x264 encoder, specifically, can be compiled with either 8-bit or 10-bit support, but not both.That restriction doesn't apply to x265 or any other encoders that I can think of. So, unless you need to encode to H.264 10-bit using x264, the regular builds of ffmpeg are fine.

You can fetch standalone binaries for 10-bit x264 from the official site at https://download.videolan.org/x264/binaries/ Too much hassle to compile ffmpeg with all other dependencies if you just need that one 10-bit encoder.

Edit: This is no longer true as of late Dec 2017. x264 now compiles and links as a multilib with both 8-bit and 10-bit support.