LAMEVMX: LAME Ain't an MP3 Encoder with VMX

LAMEVMX is a highly PowerPC-optimized build of the LAME MP3 encoder, version 3.100. It is largely based on tmkk's AltiVec/SSE Optimized LAME Encoder with the following changes:

PowerPC-only
Restored compatibility with Mac OS X 10.4 (works on 10.5 too)
Additional tweaks for G5
Compiler-tuned per architecture
Unified build system

The executable binary (698K, gzipped) is three-headed and selects the proper version for G3, G4 and G5 systems. The G3 version obviously doesn't have AltiVec, but is an optimized and tuned build for that platform. The G5 version has additional optimizations for the PowerPC 970. Run the binary with no arguments to see the selected version. It runs on Mac OS X 10.4 and 10.5. To use, just decompress it and chmod +x.

With Energy Saver set to Highest Performance, my Tiger-based Quad G5 achieves 25x playback speed and up (peaks at around 30x under -V1). The non-AltiVec version only benches at around 8x.

Although this version of LAME could probably be ported to POWER6 and later, which has built-in AltiVec (and later chips have VSX), these chips are better served by compiling with the built-in gcc intrinsics (more details) and this is how I run LAME on my own POWER9. However, this version is probably the best approach for 32-bit PowerPC systems, especially those that cannot run a sufficiently recent compiler, and because it is hand-tuned is probably perceptibly faster on these less powerful systems.

Source code is available from the repo on Github.

Cameron Kaiser