Open source codecs are important to everyone as license fees erode the ability to provide free content without some form of subscription or sponsorship, which can lead to filtering of content. Here are a couple updates for the end of 2018.
In the early 2000’s, Speex by Xiph.org (now making Opus) was great for dialup modem streaming of voice content. The Opus codec effectively replaces Speex and the latest Opus release further enhances performance.
If your FFMPEG was compiled with libopus support, encoding Opus audio with FFmpeg is like:
ffmpeg -i voice.wav -ac 1 -cutoff 4000 -b:a 6000 -ar 8000 -vbr off -frame_duration 60 -application voip voice.opus
YouTube seemingly leapt to enable AV1 for standard definition videos, due to waiting for GPUs to enable AV1.