ref: 898ad50ff987486f23880f1f8d23b64d2ba52e47
parent: b0b02fb3563b3d52a5630df947faf67a4842ba4d
author: Sigrid Solveig Haflínudóttir <ftrvxmtrx@gmail.com>
date: Tue Nov 17 08:10:54 EST 2020
audio page
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+Audio
+=====
+
+With Intel HDA audio one most likely will need to set a proper "pin"
+for the sound to play on the correct output, and "inpin" for recorded
+samples to come from the right input.
+
+The easy way to check which pins you have is, for output:
+
+ grep ' out ' /dev/audiostat
+
+For input:
+
+ grep ' in ' /dev/audiostat
+
+The output produced should give some idea about what those pins are.
+
+In order to check the currently used ones:
+
+ grep path /dev/audiostat
+
+As an example, on a Thinkpad T480s the interesting pins (output and
+input) are:
+
+ pin 20 out fix int N/A speaker ? eapd ← aout 2
+ pin 33 out jack ext right hpout black eapd ← aout 2, aout 3
+
+ pin 18 in fix int N/A micin ?
+ pin 25 in jack ext right micin black
+
+Pin 20 is the built-in speaker, 33 is headphones jack. Pin 18 is the
+built-in mic, 25 is the mic input on the same jack that 33 is on.
+
+By doing `echo pin 20 >/dev/audioctl; echo 50 >/dev/volume` the output
+is switched to built-in speaker and the volume is set to 50, to avoid
+blasting with full volume immediately.
+
+`echo inpin 18 >/dev/audioctl` will make reads from `/dev/audio`
+produce samples capture from the built-in mic. You can adjust mic
+gain by doing `echo recgain 50 >/dev/volume`. To test the mic you can
+run the following command (preferably while using headphones):
+
+ audio/pcmconv -i s16c1r44100 < '#A/audio' > /dev/audio
+
+`#A/audio` is used here due to the fact that `audio/mixfs` (if you
+have it running) binds on top of `/dev/audio` and can only be used for
+output.
+
+Specifically on Thinkpad T480s 9front seems to have trouble playing
+audio on headphones jack, the sound will be garbled. To avoid that
+you can switch the input to pin 25, and perhaps back to 18. That
+somehow fixes the issue.