microphone input without I2S?

[holms32]

hello. new here, new to esp!

I did run some examplecodes from phil schatzmann with the ESP32_A2DP library
bt_music_sender_write_8bit to send sound from esp32 to bt-speaker
bt_music_sender_receiver_32bit to recive sound from bt-device to esp32

but what i cant quite understand is.. do i need to use "I2S" when im using in-ear headphones with mic, 4pin 3.5mm stereo jack plug for future testing of the esp32..?

the sound transfer was perfect for my project with the internal dac but most examples shows using I2S and im not sure i need it for the microphone? perhaps really really bad soundquality?

my goal was to use gpio to turn on/off "input/output" sound channels and feed it to my phone. It will work allmost as a walkie talkie. Half-duplex... but if it works dubplex it would be great.