Re: [Linphone-developers] Audio framework

[Sylvain Berfini]

Hi Cosmina,

On Android there are two audio drivers: AAudio (the new one) and OpenSLES (the deprecated one).
AAudio is currently only supported on devices running Android 9 and newer.

AAudio has many advantages over OpenSLES, two of them being the capacity to choose which device to use using it's ID and being able to choose the usage & content type for which you will play/record sound.
Sadly AAudio isn't yet properly supported on all Android devices (such as Samsung for example), that's why we offer the choice in the settings to choose which device/driver you want to use by default.

That being said, no matter which device you choose echo cancellation should work, either by using the device hardware feature or our software one if you enabled it in the audio settings.

Regarding Oboe, it's merely a wrapper above AAudio & OpenSLES so you would have to implement your audio logic only once. It also contains a few workarounds for some specific devices.
We do have a msoboe plugin for our linphone SDK but it is disabled by default, I created it as a proof of concept and to check if it bring a significant improvement over our existing sound cards, but it didn't.
You can still build it using cmake's -DENABLE_OBOE=ON parameter if you want to test it but I don't recommend it for production, it is only a PoC.

Lastly microphone isn't picked at random, it depends on the output audio route.
By default it is using the one at the bottom, but it you switch to speakerphone, headset or bluetooth it will switch to use the matching microphone.

Of course it's possible there is an issue on some devices we don't know about.
If you need a support contract, please see that with our sales department.

Cheers,

Sylvain Berfini
Head of Mobile & Desktop Apps Department

+33 (0)9 52 63 65 05
sylvain.berfini@belledonne-communications.com

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Le 19/01/2022 à 15:41, Cosmina Nicolau a écrit :

Hi, I want to ask a few questions about the audio settings on linphone apk.

I am working with Zebra TC21 devices, with Android 10. 

The current version of the linphone apk which I'm perform all the tests is 4.5.6 (linphone SDK 5.0.49).

In the settings of defeault input/output audio on the device, it lists the following options: 

• On default input audio device:  AAudio Microphone: TC21, openSLES Microphone: TC21 and Android SND (deprecated) Unknown: Android Sound card
• On default output audio device: AAudio Earpice: TC21, AAudio Speaker TC21, openSLES Earpice: TC21, openSLES Speaker: TC21, ANDROID SND (deprecated) Unknown: Android Sound card

For what I gather, the items in that list are the differents audio frameworks that are available in these device.

Can you tell me how they differ mainly or how it affects the behavior of the microphone in using one or the other? Because I am having echo problems in calls and I do not know if this can be a factor to consider.

Testing if I select as audio output any of the Speaker options, the audio comes out through the speaker in handsfree mode, and if I switch to Earpice mode, comes out through the internal speaker, why can't the same be done to select the microphones? I mean, the device has two built-in microphones, one at the top used for handsfree mode and one at the bottom used for handset mode, the problem is that randomly choose one at random when making calls , why has this behavior? is there any way to force to use one in particular always?

I have seen that there is another audio framework called Oboe, why doesn't my device list it? I have seen this repository in gitlab, is it necessary to implement it as a plugin in the linphone sdk? 

Thanks and BR

--

Cosmina Nicolau Technician IT Headquarters - Paseo Castellana, 200 - SPACES - Madrid 28046 ES Labs - Calle Innovación, 17   Getafe, Madrid 28906 ES https://www.joifilabs.com/

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