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From: pozz <pozzugno@gmail.com>
Newsgroups: comp.arch.embedded
Subject: Voice compression
Date: Wed, 2 Apr 2025 18:33:56 +0200
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I need to manage some audio voice streams. They will be saved on a non 
volatile memory as raw arrays of unsigned char.

The main goal is to play these audio streams through a DAC/PWM. I'm not 
interested in high quality, a "mid/low" quality could be good.

My hardware is a poor AVR8 8-bits MCU.

I have a limited memory space, so I'm searching a good voice codec with 
compression. Lower the bitrate, more streams I can store. 16kbps can be 
good for my application. Maximum 24kbps.

By using 4-bits ADPCM I could have 32kpbs at 8kHz sampling rate. With 
3-bits ADPCM I could read 24kbps.

I tried to reduce sampling frequency to 4kHz, but the quality is 
drastically reduced.

I know there are many others voice codecs that reduce the bitrate a lot, 
but the decoder seems too complex to implement on AVR8.

Any suggestions?