Do i need to use FFT? Is there any SDK or smth?
Without FFT you can visualize the "scope" of the audio, the actual waveform of the sound. If you want sonogram or something like gfx equalizer does, you'll need to preprocess the audio with FFT. For this there are some SDK support, it's called Accelerator framework. You might want to check out the Apple's aurioTouch2 example.
Related
I would like to use AVAudioFoundation for microphone input for speech detection as shown in this ios example and simultaneously detect the pitch of the user’s voice through the same microphone input, using AudioKit. The latter API is probably a wrapper around the first, but has its own classes and initialization. Is there a way to provide AudioKit with an existing microphone configuration like in the speech example, or some alternative way to use the Speech API and AudioKit’s microphone pitch detection API simultaneously? How might I achieve this?
EDIT: The question is a little more complex
I need to be able to synchronize 3 things: touch events, audio kit detection times, and speech detection times. Each of these operates on a different timebase. Speech gives me segment timestamps with respect to the beginning of audio recording. The timestamp for UITouch events will be different. I am not sure what AudioKit uses for its timestamps. There is some mention of host time and AV timestamps here, but I'm not sure this will get me anywhere.
Speech and audio synchronization is a little unclear. May I have a lead for how this might work?
I am building an iOS app that allows the user to play guitar sounds - e.g. plucking or strumming.
I'd like to allow the user to apply pitch shifting or wah-wah (compression) on the guitar sound being played.
Currently, I am using audio samples of the guitar sound.
I've done some basic read-ups on DSP and audio synthesis, but I'm no expert in it. I saw libraries such as csound and stk, and it appears that the sounds they produced are synthesized (i.e. not played from audio samples). I am not sure how to apply them, or if I can use them to apply effects such as pitch shifting or wah-wah to audio samples.
Can someone point me in the right direction for this?
You can use open-source audio processing libraries. Essentially, you are getting audio samples in and you need to process them and send them as samples out. The processing can be done by these libraries, or you use one of your own. Here's one DSP-Library (Disclaimer: I wrote this). Look at the process(float,float) method for any of the classes to see how one does this.
Wah-wah and compression are 2 completely different effects. Wah-wah is a lowpass filter whose center frequency varies slowly, whereas compression is a method to equalize the volume. The above library has a Compressor class that you can check out.
The STK does have effects classes as well, not just synthesis classes (JCRev) is one for reverb but I would highly recommend staying away from it as they are really hard to compile and maintain.
If you haven't seen this already, check out Julius Smith's excellent, and comprehensive book Physical Audio Signal Processing
How do I play multiple audio and change its volume using Novocaine?
thanks!
There is similar question which I wrote quite a lengthy response for
Using Novocaine in an audio app
Basically playing multiple sounds at once involves mixing the various sounds down sample by sample. Changing volume involves multiplying samples in the audio buffer by some amplitude value. That is if you want your output to be twice as loud simply multiply every sample by 2.0f. Accelerate framework can help you with this.
Is it possible to read the spectrum data from the currently playing track in iOS? For example, to make an equalizer similar to the one in iTunes?
Apple has a sample program, "aurioTouch," which can display time and frequency domain waveforms.
http://developer.apple.com/library/ios/#samplecode/aurioTouch/Introduction/Intro.html
Is it possible to do "Markerless motion capturing" using a normal webcam, in real time? Are there any Open source frameworks available?
I need to construct a 3d model which will be animated using the captured data.
You could start with The Artvertiser (full source code available at the link).
You could also look at using the Ferns library, I'm not sure but I think it might be a part of the latest OpenCV.