Tanaka Masayuki’s PCMFlow722 library enables (half-duplex) two-way real-time HD voice over ESP-NOW on ESP32 boards with a speaker and a microphone, effectively transforming them into walkie-talkies. The library implements a G.722 wideband codec add-on for PCMFlow lightweight audio decode and PCM flow library for Arduino, which already supports uncompressed PCM, MP3, and FLAC audio codecs. PCM and FLAC take too much bandwidth over ESP-NOW, and MP3 is not suitable for real-time audio, so the legacy G.722 audio codec was selected instead. The keyword here is “HD voice,” since two-way audio over ESP-NOW was previously implemented in projects such as Atomic14’s esp32-walkie-talkie (5 years ago) and, more recently, the well-documented Adafruit ESP-NOW Walkie-Talkie project, but these typically rely on lower-quality G.711 audio or compressed audio. The PCMFlowG722 library and G.722 codec enable HD voice with “7 kHz audio at 16 kHz sampling using the same 64 kbps wire budget as G.711 […]
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Read more here: https://www.cnx-software.com/2026/05/30/pcmflow722-library-enables-two-way-real-time-hd-voice-over-esp-now-with-g-722-audio-codec/
