I am new to PulseAudio and ALSA, so please go easy on me. This might seem like a dumb question, but it is quite important to have it answered.
I am developing application on ARM imx6 board (lets call it BOARD1), with built-in sound card support. With ALSA, I am able to play audio throgh Headset_OUT. But now, we want to move to a new board (lets call it BOARD2), which does not have built in soundcard. But the idea is to connect a bluetooth module to the BOARD2 and have the audio streamed to the bluetooth speaker.
My question is, is it possible to use PULSEAUDIO to send/receive audio to external (bluetooth) audio device without local embedded soundcard (i.e. is it possible to do audio encoding/decoding in just software with pulseaudio and gstreamer combination) ?
Regards
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Today I've connected my bluetooth headphones(Ausdom M08) with PC(via bluetooth dongle).
When I open Skype or Discord I hear no sound on youtube, browser and so on. It only works on Skype and Discord - bad sound, not stereo.
I checked in Sounds Options and I have Ausdom M08 Stereo and Ausdom M08 Hands-Free. First one is default device and second one is default communication device.
When I try to force Skype and Discord to use that default device for sound output I hear no sound then, too!
What I tried:
-Disabling Hands Free Telephony, but I lose microphone function then.
-Tried to uninstall drivers and install again. Still the same.
-Disabling enhancements and exclusive controls of devices.
Literally I tried everything I found on internet or that I thought it can be.
Nothing works.
So the question is: How to make my PC output Stereo Sound from my headphones and still to be able to use microphone from it?
Thanks
There are a lot of missing information here: What PC dongle are you using? Which windows version?
From what I can see about the tech specs of Ausdom M08, it supports few basic profile (HSP/HFP/A2DP/AVRCP). A2DP profile lets you hear stereo audio (Ausdom M08 Stereo). HSP/HFP lets you use the microphone to Skype, but audio is limited to 8K-16K Hz sampling rate (Ausdom M08 Hands-Free). You can't use both Bluetooth profiles at the same time.
So to answer you question: You can't have stereo audio from your headphone while having microphone input.
There are proprietary codec developed by Qualcomm called aptX, which may support microphone over A2DP. But, you'll have to make sure both transmitter and receiver supports this codec.
Can anyone please elaborate following questions?
How bluetooth stack handles audio data?
How audio commands are processed?
Did we need any service to process audio data?
Thanks in advance.
Basically, voice commands over BLE require:
some audio codec for reducing required bandwidth (ADPCM and SBC are common, OPUS is emerging),
some audio streaming method through BLE,
decoding and getting the audio stream from BLE daemon to a command processing framework.
In the android world, command processing framework is google sauce (closed) that most easily gets its audio from an ALSA device. What is left to be done is getting audio from the remote to an ALSA device.
So for audio streaming, either you:
use a custom L2CAP channel or a custom GATT service, this requires a custom android service app and/or modifications to Bluedroid to handle those, it will need a way to inject audio stream as ALSA, most probably with a "loop" audio device driver,
declare audio as custom HID reports, this way, Bluedroid injects them back to the kernel, then add a custom HID driver that processes these reports and exposes an audio device.
Audio over BLE is not standard, so all implementations do not do the actual same thing. In Nexus Player case, implementation uses HID: It streams an ADPCM audio stream, chunked in HID reports. There is a special HID driver "hid-atv-remote.c" in Android linux kernel that exposes an ALSA device in addition to input device. Bluedroid has no information about audio, all it does is forwarding HID reports from BLE to UHID.
I'm new with linux and especially with sound system. I've read many articles about this subject but I'm still confused. I know that Alsa provides audio functionality to the rest of the system. This mean that Alsa is lowest "layer" on sound system (after hardware itself). I also know that ALSA by itself can only handle one application at a time. So here are my questions:
1)Is PulseAudio a bridge to provide usage of Alsa for multiple apps?
2)Are Gstreamer, Phonon and Xine same bridge programs as PulseAudio?
3)Is Alsa converting analog signal into digital signal?
My questions may seem stupid. Thank you.
The OSI model isn't really a good fit to ALSA, as it really only provides layer 1.
PulseAudio is an audio server and is the single client of a ALSA device interface. It provides something analogous to Layer 7 of the OSI model to applications. It mixes the audio output streams from each client application connection down to a single stream for output. It provides an alsa-compatible interface to audio client software (e.g. GStreamer and Xine) which acts as a proxy and connects to the audio server.
Analogue to digital (and digital to analogue) conversion takes place in hardware in what is referred to, rather confusingly, as a CoDec.
I'm working on university project that consists in audio speaker with bluetooth connected to mobile application.
I search a lot possibilities and bluetooth modules that comply my needs, but I have not found any module. I need a Bluetooth module that can receive audio and work in iOS and Android, but I see that a lot of modules with Classic Bluetooth (lowe than 3.0) do not work with iOS, but 3.0 and 4.0 version works with both but are not oriented in audio.
I'm looking for if someone can help me finding one kit with audio receive bluetooth for all plataforms intended for speaker and cheap. Or separately one bluetooth module receiver with 3.0 or upper version (because works in iOS), intended for audio streaming to an speaker, and with some UART pins (tx/rx for example) that can simplify the connection with a microcontroller. And one basic microcontroller oriented to bluetooth receives (with some bluetooth libraries) or simply to program with upp-level language. This microcontroller just receive the audio (bits) and send it to the speaker.
I read too that Smart Bluetooth or Bluetooth Low Energy works on iOS, but can't send audio, have small rate, but i think Smart Ready Bluetooth its possible, but not sure, I have just seen that supports Classic Bluetooth (oriented to audio) and Bluetooth Low Energy, it's possible sens audio with it?
In short, I'm looking for one module Bluetooth 3.o or 4.0 + EDR (that can send audio) for iOS and Android. I find HC05, CC2506X, or HC06 module, but I have read not works in iOS. And a basic microcontroller simply to program to receive this bluetooth audio to send in a speaker.
If someone know one basic kit, or useful information for me I would appreciate.
Thanks.
There is a bluetooth module BC127. it is available at Sparkfun. It dual mode. Means It can work as source and sink both.
Source means, It can Transmit Audio
Sink means, It can receive Audio
Here is link for https://learn.sparkfun.com/tutorials/understanding-the-bc127-bluetooth-module
Any Bluetooth module that acts as an A2DP Sink should work with both iOS and Android.
The specific Bluetooth version that the module implements is not important (as long as it's higher than 2.1), but it needs to be an A2DP Sink (which is only possible over classic Bluetooth)
I want to add a function to my App, where the user can choose to play the audio on a bluetooth enabled speaker. I have a Parrot Easydrive in my car and this works for phonecalls and for example the Dictafoon App among others.
I understand that I should use the Core Audio framework. WHen a bluetooth device is connected it is said that it is easy to stream the audio to that connection. I am now looking for Core Audio sample code (or a book) where connecting and streaming to a bluetooth device with Core Audio is explained.
Can anyone shed a light on this? If there is another framework or sample code which I can use please mention it!
Many thanks in advance!
You don't write any specific Core Audio code, it is the same process as is used to play audio via AirPlay.
Basically you put a MPVolumeView into your UI, and the underlying framework will redirect your audio output for you. Once you implement this you will be able to use Bluetooth and any AirPlay enabled device with your app.