afconvert and avconv performance

My Rubénerd Show podcast episodes are produced with a series of shell scripts to save me time and effort, so I’m always looking for ways to optimise them.

Today I learned about Apple’s afconvert utility. The manpage may as well have been written by GNU given its lack of useful info, but “-h” tells you all you need to know.

Currently I use avconv (previously ffmpeg) to convert CAFs from my iTelephone to an intermediate format. This is then rendered as FLAC for archival purposes, and MP3 for the podcast feed:

$ avconv -i "source.caf" "output.aiff"

Through some digging, the afconvert equivilent is:

$ afconvert -f caff -d BEI16 "source.caf" "output.aiff"

But how do they stack up? I ran these three times on the same 201.1MiB source file using afconvert in macOS Sierra, and the latest avconv from Homebrew:

Pass afconvert avconv
1 0.416s 1.189s
2 0.577s 1.339s
3 0.416s 1.302s

The results from this (albeit limited) test are clear, afconvert is faster. Whether I’d notice a second or two difference is another question, but I’ll be adjusting the scripts to preference afconvert when available.


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