Record system audio (undocumented API) - Android Software/Hacking General [Developers Only]

After a lot of browsing through the source code of Android I was unable to find any methods that would allow recording from the system audio output. Only recording from the MIC is available.
So do you have any ideas (maybe via NDK) how to make recording possible from other sources (system out audio, FM radio, bluetooth headset)? Is there any way to utilize /dev/audio without rooting the phone?

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[Q] Details of Audio Codec and Bluetooth Chipset in Sensation XE

Hi
I am attempting to implement the Handsfree Device (rather than Hands Free Gateway) profile on the Sensation XE. After a lot of digging around it is apparent that the audio routing supported by Android is not capable of routing a audio to the BT SCO separately from that sent to the local earpiece or speaker.
This makes it impossible to implement a standard Handsfree Device using official (or even internal) Android APIs.
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or
2) Modify the Audio Codec configuration such that it directly routes audio from handset local audio devices (mic and earpiece/speaker) to the Bt SCO (rather than routing it to the radio).
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Cheers
Robinov

[Q] Selective audio redirection

Is there any way of selectively sending audio from different apps to different output streams on an Android pbone?
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Samsung device does not support sharing of mic ?

I am creating an application were I record VOIP call using media recorder, other than Samsung device call get connected audio feed also received at both end and call get recorded with both audio and video. But when comes to Samsung device we are facing problem to record audio stream in recorded call. During our initial finding it was observed that Samsung device does not allow sharing of Mic when it is in use. We had tried with different audio source which are available, if I comment this two lines
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mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
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MIC (not working)
VOICE_DOWNLINK (not working)
VOICE_UPLINK (not working)
DEFAULT (not working)
CAMCORDER (not working)
VOICE_COMMUNICATION (not working)
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SCR Screen Recorder - Fail
Screen Recorder 5+ - Fail
Background Video Recorder - Fail
Mobizen for Samsung - Fail
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Android 10 system audio codecs change? - not bluetooth

Hello,
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