AudioSource VOICE_DOWNLINK

[GGLabCenter]

I saw in the enum class of AudioSource: voiceDownlink, // (if someone can explain me what it is, I will be grateful ;-) )

I don't know if it just some old comment, btw I searched something just for my curiosity, from Android source (https://developer.android.com/reference/android/media/MediaRecorder.AudioSource#VOICE_DOWNLINK):

"Voice call downlink (Rx) audio source. " (where Tx instead is VOICE_UPLINK).
Receive/RX mode and Transmit/Tx mode

It seems the audio in and audio out for connected devices (as for AUX in cars) or in voice calls ( you can record voice calls with them).

Some source:
https://stackoverflow.com/a/13090413/2873702
https://www.apple.com/shop/question/answers/product/HNNT2ZM/A/what-does-the-tx-to-rx-switch-mean/QTH7XPAJ99KFDJJ9K