I want to process the stereo output from iOS devices, no matter what application causes them and visualize it in real-time.
Is it possible to use the generic output device (or anything else) to get at the audio data which are currently being played? Maybe as an input to a remoteIO unit?
In other words: I want to do what aurioTouch2 does (FFT only) but instead of using the microphone as input source, I want to process everything which is coming out of the speakers at a given time.
Kind regards
If your own app is playing using the RemoteIO Audio Unit, you can capture that content. You can not capture audio your app is playing using many of the other audio APIs. The iOS security sandbox will prevent your app from capturing audio that any other app is playing (unless that app explicitly exports audio via the Inter-App Audio API or equivalent).
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We're currently using Linphone library to make VOIP calls and they have their own solution for audio playback. However, we would like to display a visualizer for the audio that Linphone is outputting from within our own app. Is there a way that we can intercept this data (maybe through sample buffering) in order to draw up audio waves/volume meter in the user interface?
AVAudioPlayer or AVPlayer is out of the question since we do not have access to those objects. Is there a solution in place for AVAudioSession or in CoreAudio?
Only if the audio output app is exporting the audio data using Inter-App-audio or Audiobus. Otherwise the iOS security sandbox will hide that audio output from your app.
I'm aiming to create an audio-visualisation app for iOS. I need to somehow tap into the current audio output from another app (such as Apple's music app, or Spotify) and get the amplitude of the signal for each sample of the music. I will then perform an FFT algorithm on the data to convert it to the frequency-domain and display the data visually.
Is it possible to read this data from the audio output of other apps? If so, what do I need to use to extract this data?
No. The iOS security sandbox will prevent the reading of any audio samples from other apps via any public API (unless the playing app was coded to explicitly export audio data via inter-app audio or other similar interface).
I am looking at the feasibility of getting the current raw audio stream playing and do stuff with it such as stream it over Bluetooth or equalize it, etc. Is there any way to do this in iOS 8?
For example: apps such as Pandora/Spotify are playing music and I want to access the audio they are playing.
To process audio from another app, that app needs to participate in Inter-App Audio.
I don't know if your example apps do that.
I'm currently trying to get the outgoing audio signal of my iOS app to be able to send it to Audiobus. I need the AudioBufferLists which are outgoing to be able to route them. I'm using OpenAL for audio playback.
The best case would be that I can even modify the outgoing signal to put effects on it.
There currently appears to be no public API to access the output of OpenAL in an iOS app.
If you want the output, you will need to use another audio API to play the sound, such as Audio Queues with uncompressed raw PCM audio or the RemoteIO Audio Unit, in order to be able to grab the audio output buffers.
You might want to check out how this guy made his own audio mixing object for OpenAL so he could achieve this:
http://www.cuppadev.co.uk/openal-sucks-write-your-own-audio-mixer/
Rather than using OpenAL, you could use CoreAudio with the 3D Mixer Audio Unit (kAudioUnitSubType_AU3DMixerEmbedded). Then you have control over where your output goes. Obviously doing this will sacrifice some portability (you'll be OK with Mac OS X, but not Windows, Linux or Android).
Hey, I'm a new developer in Objective C. I'm trying to record the audio running out of iPhone speakers. I can capture the audio by mouth speaker and record it. But I cannot record the audio producing from my iPhone. Please help me.
Unfortunately, there is no way to directly capture from the "audio bus". You can either capture the audio via the internal microphone or headset microphone, but that's it. If you are rendering the audio, you could obviously also write that audio out to a file as well at the same time. That's pretty much your only option.
yes, you only get a handle on the audio generated by your process. There is no way to get the audio generated by the rest of the system.