Differences

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--- doc:appunti:linux:audio:audio_recording [2019/04/23 12:45] – [Audio Recording With Android] niccolo
+++ doc:appunti:linux:audio:audio_recording [2019/05/22 15:51] – [Electrical compatibility and hardware autodetection] niccolo
@@ Line 171: / Line 171: @@
 ====== Audio Recording With Android ======
-Recording audio using an **external microphone** connected to an **Android device** can be a real nightmare. We tried the hard way using a Chinese, no-brand **wireless UHF microphone**!
+Recording audio using an **external microphone** connected to an **Android device** can be a real nightmare. We tried the hard way using a Chinese, no-brand, **wireless UHF microphone**!
-We can group the problems you can fece in three main categories:
+We can group the problems you can face in three main categories:
   * Physical connection
@@ Line 189: / Line 189: @@
 As stated above, the first problem is **powering the microphone** itself, because generally we will use an **electret** one. It is a **common practice** to provide the power on the same line of the microphone signal, so **requiring just two wires** for both power (from the device to the mic) and for signal (from the mic to the device). The power, also called //bias current//, is generally in the range of **2.5** to **5.0 volt**.
-FIXME: How much current is provided in our test? Is the current always present or switched-on only at jack insertion?
+On a Xiaomi Mi A1 smartphone, which has a **TRRS 3.5 mm jack, CTIA standard**, we measured a bias current of **2.19 volt** between the microphone (sleeve) and the ground (ring).
 Another parameter which should be considered is the **impedence** FIXME
@@ Line 215: / Line 215: @@
   * [[https://forum.xda-developers.com/showthread.php?t=2072612|External Mic on Galaxy Devices]]
   * [[https://stackoverflow.com/questions/19255908/android-forcing-external-microphone-jack-input-3-5mm-to-stay-on|Android: Forcing external microphone (jack input 3.5mm) to stay on]]
+  * [[https://forum.xda-developers.com/showthread.php?t=1042051|App that turns off microphone AGC (Auto-Gain Control)?]]
+  * [[https://stackoverflow.com/questions/47394634/difference-between-voice-communication-and-mic-in-mediarecorder-audiosource|Difference between VOICE_COMMUNICATION and MIC in MediaRecorder.AudioSource]]
+  * [[https://stackoverflow.com/questions/47359587/what-is-the-best-audiosource-setting-for-calls|What is the best audiosource setting for calls?]]
+  * [[https://amp.reddit.com/r/androidapps/comments/4wo8sz/app_to_force_android_to_use_external_microphone/|App to force android to use external microphone when one is plugged in]]