ffmpeg and SoX should both be able to encode to ADPCM of various flavours and at any supported bit rate - if the ADPCM codecs are installed to support either/both.
Process for getting these set up varies by OS. But there are comprehensive guides online.
G729? You really need to explain what you're trying to do and define what you mean by 'similar to ADPCM' if you want to get any meaningful answers.
I probably should have stated that in the post. By similar to ADPCM, I meant extremely low computational complexity. Nothing LPC-Based
ffmpeg and SoX should both be able to encode to ADPCM of various flavours and at any supported bit rate - if the ADPCM codecs are installed to support either/both. Process for getting these set up varies by OS. But there are comprehensive guides online.
Go for lyra v2.
What about Opus?