It's the fastest open source ETC1 encoder that I'm aware of.
Notice the lack of any PSNR/MSE/SSIM statistics anywhere (that I can see). Also, the developer doesn't seem to get that the other tools/libraries he compares his stuff against were optimized for quality, not raw speed. In particular, rg_etc1 (and crunch's ETC1 support) was tuned to compete against the reference encoder along both the quality and perf. axes.
Anyhow, there are some interesting things to learn from etcpak:
- Best quality doesn't always matter. It obviously depends on your use case. If you have 10 gigs of textures to compress then iteration speed can be very important.
- The value spectrum spans from highest quality/slow encode (to ship final assets) to crap quality/fast as hell encode (favoring iteration speed).
- Visually, the ETC1/2 formats are nicely forgiving. Even a low quality ETC1 encoder produces decent enough looking output for many use cases.