As per official documentation
Android 10 (API level 29) and higher imposes a priority scheme that can switch the input audio stream between apps while they are running. In most cases, if a new app acquires the audio input, the previously capturing app continues to run but receives silence. In some cases, the system can continue to deliver audio to both apps. The various sharing scenarios are explained below.
Other than some special cases, audio is not shared between apps.
But I have seen many apps sharing the audio input without being in the above special cases.
For eg. Zoom, when I'm on a call in zoom and start an audio recorder then both the apps are getting audio though zoom audio decreases in intensity.
Similarly, Omlet arcade is able to record mic audio even when mic access is given to other apps.
How is it possible? And as per the documentation, this shouldn't be allowed.
Update:
Was able to achieve it with the usage of Oboe. But it is not consistent on all devices. This also causes a sync issue in my live streaming app. Audio is audible with a delay
This is not possible in Android 5+ . You need a rooted phone to perform this action. In Omlet Arcade Whenever you play a Game and switch ON in-game mic, Omlet Arcade will stop receiving any audio input. However, Omlet Arcade will still function but you have to restart it in order to get voice input back.
Though, in a recent MIUI bug, People were able to listen to calls on Zoom and in-game mic apps. In your case, it might be not official Android and Edited Android like MIUI and OxygenOS
Related
I use:
MediaRecorder.setAudioSource(int)
or
AudioRecord.Builder.setAudioSource(int)
record both voice in call.
I need to know that record call for caller only, mean could't record my voice in the call (voice from mic) possible or not.
Recording only caller's voice could not well supported on all devices/implementations.
Moreover this behaviour could change from one Android version to another according to what Manufacturers want to open their devices.
Many devices can record only BOTH streams, others can record only from MIC...
Starting from Android 7.1 Nougat up to 8.1 it is not possibile to record Voicecalls if the App is not signed using the System Certificate, so only System App developed by the Vendor could record voicecalls.
Few bugs were discovered in these years to let the developer records even if the System denies it, but those remains quite secrets to few developers.
However to record only called voice you have to set the Source as "AudioSource.VOICE_DOWNLINK".
This question might seem to be a repetition of the questions such as following:
How to play an audio file on a voice call in android
Background Audio for a Call in Progress - Possible?
The answers of these questions suggests that it is not possible to play a pre-recorded audio on a voice call in android. I want to know why it is not possible? What is the limitation (hardware/software)? Is it really a limitation or done purposely? Can we alter the source code of android to make it possible?
I think this is a limitation, imposed for security reasons and restricted at the OS level.
Let's analyze the security threat, first of all. If you were able to play custom audio files to the callee, a whole world of cons opens up: you could trick customer supports, you could pretend to be someone else, you could give unauthorized purchase confirmations, and so on. For this reason, neither Android nor iOS allows this functionality.
On Android, you won't be able to do so in a programmatic way, simply because the current APIs won't allow you to do so. It is stated in the official documentation as well, as pointed out here. If you dig into the source code, you can probably enable this feature by accessing the microphone output during a phone call, but that would require running your custom version of Android. A good starting point would be the AudioTrack source, available here.
EDIT: a good example of an audio mod involves enabling the Nexus 5 earpiece as a second loudspeaker (requires root). Can be found here.
After a thorough research, what I have come to know is that there are more than one limitations/hurdles to make it possible. These limitations/hurdles are at three different levels.
First limitation is at API level, because there is no high-level API to play sound files in the conversation audio during a call as mentioned in Android official documentation.
Second limitation is at Radio Interface Layer (RIL). RIL passes on complete control of the call to Radio Daemon (rild) of the Linux library which then further passes the control to the vendor RIL. That means we cannot manipulate voice call in android source code.
Even if we are able to remove these two limitations, we may still not be able to play audio file to an ongoing voice call. Because there is a third limitation. Every vendor has their own library of RIL that communicates with Radio Daemon (rild). This requires that vendor RIL to be open source which is not actually. Hardware vendors do not usually make their device drivers code available.
Detail discussion on this topic is present at this link.
This is software related due to the prioritization of audio routing in Android.
Take a look into the CallManager where you can dig into the method setAudioMode(). After the audio mode was set to MODE_IN_COMMUNICATION the following code is called
audioManager.requestAudioFocusForCall(AudioManager.STREAM_VOICE_CALL,
AudioManager.AUDIOFOCUS_GAIN_TRANSIENT);
From this point on the telephony service has the highest priority and won't let any other audio play in parallel.
Note: You can play back the audio data only to the standard output device. Currently, that is the mobile device speaker or a Bluetooth headset. You cannot play sound files in the conversation audio during a call.
See official link
http://developer.android.com/guide/topics/media/mediaplayer.html
By implementing the AudioManager.OnAudioFocusChangeListener you can get the state of the audiomanager. so by this if any music is playing in the background you can get the AudioManager states(playing and pausing is completely in developer hands) similarly......
Some of the native music players in android device where handling this, they restrict the music when call is in TelephonyManager.EXTRA_STATE_OFFHOOK.so this scenario is also completely in developer hand (whether to handle or not) if he is not handling both will play parallel y
I'm developing audio app(iOS/Android), and I can't find nowhere information:
How can a app read or set the microphone gain?
Are audio Digital Signal Processing tools available for the headphone jack?
Also I realize that some manufacturers develop specific accessibility features (like mono sound mode, or sound balance (left - right) on samsung devices), but they don't provide any API to check or control this feature. When I turn on/off mono mode on Samsung GS3 in logs I see:
I/AudioHardwareTinyALSA( 1904): setParameters(toMono=0)
I/audio_wfd_hw( 1904): adev_set_parameters() toMono=0
So I guess this feature provided by samsung specific hardware driver.
May be in some way is possible to get pointer to AudioHardwareTinyALSA an set mono on or off?
Thanks.
There's no API in Android for controlling the input volume (you can mute/unmute the mic during voice calls / VoIP, but that's about the level of control that you've got).
The mic gains are typically set by the OEMs as part of their acoustic tuning process, in order to optimize the performance for each use-case (speech recognition, camera recording, handset call, etc) for that particular product.
Mono/stereo recording should simply be decided by whether the app requests 1 or 2 channels for the recording. At least that's the way it has worked on every product I've worked on, as far as I can recall.
There are plenty apps in google play, which can record calls. Some of them just turn on loudspeaker and record sound via microphone, others should be able to record audio steams directly. I know that android provides class for recording. (which doesn't work on lot of devices probably because of some SW restrictions).
So here is my question: Is there possibility to find some device, where call recording will be possible via MediaRecorder(VOICE_CALL)? I found that call recording apps are available for Galaxy SII and SIII so does it means that MediaRecorder(VOICE_CALL) work on these devices?
EDIT------------
Generally, if i want to use MediaRecorder to record calls i need kernel which supports it (for example som custom kernel)?
I'm currently searching for options on how to manipulate audio on android. The goal is to process audio from the microphone in real time during a phone call. The best solution would be to do this on a native call. But rebuilding a telephone app (no VOIP) would be fine too. Are there any ways to achieve this with Android APIs (also undocumented)?
If not, which steps would be necessary to get things running?
On iOS there are some apps which manipulate voice but create a VOIP connection. I heard that on Android you can "clone" the telephone app and eventually feed it with your own audio stream? Aren't there apps which add noises during a call? What kind of APIs are involved?
The best solution would be to do this on a native call.
This is not possible. You have no access to the in-call audio stream, except perhaps in speakerphone mode.
But rebuilding a telephone app (no VOIP) would be fine too.
The last official word from Google (2010), the entire OS has no access to the in-call audio stream, as it is all handled at a lower level. Even if newer versions of Android do have access to the in-call audio stream, "rebuilding a telephone app" is only possible if you are creating custom firmware.
As a drawback i could imagine to record the Downlink Stream using the MediaRecorder API and write it back to hardware using AudioTracks write() method. By this i could manipulate incoming voice. But still I think this wont work during phone calls. And I do not see a way to choose different hardware destinations.