I sent this as a reply to someone by email, but it makes a good blog post too. Here's what Basis does today right now (i.e. this is what we ship for OSX/Windows/Linux):
1. RDO BC1-5: Like crunch's, slower but higher quality/smaller files (supports up to 32K codebooks, LZ-specific RDO optimizations - crunch is limited to only 8K codebooks, no LZ RDO)
This competes against crunch's original BC1-5 RDO solution, which is extremely fast (I wrote it for max speed) but lower quality for same bitrate. The decrease in bitrate for same quality completely depends on the content and the LZ codec you use, but it can be as high as 20% according to one large customer. On the other hand, for some texture's it'll only be a few percent.
crunch's RDO is limited to 8K codebooks so Basis can be used were crunch cannot due to quality concerns.
crunch's RDO is limited to 8K codebooks so Basis can be used were crunch cannot due to quality concerns.
Some teams prefer fast encoding at lower quality, and some prefer higher quality (especially on normal maps) at lower speed. We basically gave away the lower quality option in crunch.
2. RDO ETC1: Up to 32K codebooks, no LZ-specific RDO optimizations yet.
Crunch doesn't support ETC1 RDO.
You could compress to ETC1 .CRN, then unpack that to .KTX, to give you a "poor man's" equivalent to direct ETC1 RDO, but you'll still be limited to 8K codebooks max (which is too low quality for many normal maps and some albedo textures).
3. .basis: universal (supports transcoding to BC1-5, BC7, PVRTC1 4bpp opaque, ETC1, more formats on the way)
crunch doesn't support this.
We provide all of the C++ decoder/transcoder source code, which builds using emscripten.
.basis started as a custom ETC1 system we wrote for Netflix, then I figured out how to make it universal. Note that I recently open sourced the key ETC1S->BC1 transcoding technique in crunch publicly (to help the Khronos universal GPU texture effort along by giving them the key info they needed to implement their own solution):
4. Non-RDO BC7: superior to ispc_texcomp's. Written in ispc.
I'm currently working on RDO BC7 and better support for PVRTC. We are building a portfolio of encoders for all the formats, as fast as we can. We're going to keep adding encoders over the next few years.
Our intention is not to compete against crunch (that's commercial suicide). I put a ton of value into crunch, and after Alexander optimized .CRN more its value went through the roof. A bunch of large teams are using it on commercial products because it works so well.