I've read some information about recording audio you play on the application (with buttons), but haven't really understood the basics.
What do I need? Can I record audio being played in the application with Remote I/O Unit?
Are there any samples I could study?
Thanks
I want to give you a link to Apple's sample app as a comment. But SO does not allow me because I do not have 50 reputation. So here it is. Good luck.
Related
I would like to modulate the signal from the mic input with a sine wave at 200HZ (FM only). Anyone know of any good tutorials/articles that will help get me started?
Any info is very welcome
Thanks
I suggest you start here Audio File Stream Services Reference
Here you can also find some basic tutorials: Getting Started with Audio & Video.
Especially the SpeakHere example app could be interesting
Hope that helps you
The standard way to do audio processing in iOS or OSX is Core Audio. Here's Apple's overview of the framework.
However, Core Audio has a reputation of being very difficult to learn, especially if you don't have experience with C. If you're still wanting to learn Core Audio, then this book is the way to go: Learning Core Audio.
There are simpler ways to work with audio on iOS and OSX, one of them being AudioKit, which was developed specifically so developers can quickly prototype audio without having to deal with lower-level memory management, buffers, and pointer arithmetic.
There are examples showing both FM synthesis and audio input via the microphone, so you should have everything you need :)
Full disclosure: I am one of the developers of AudioKit.
I am trying to create a video player for iOS, but with some additional audio track reading. I have been checking out MPVideoPlayerController, and also AVPlayer in the AV Foundation, but it's all kinda vague.
What I am trying to do is play a video (from a local .mp4), and while the movie is playing get the current audio buffer/frames, so I can do some calculations and other (not video/audio relevant) actions that depend on the currently played audio. This means that the video should keep on playing, with its audio tracks, but I also want the live raw audio data for calculations (like i.e.: getting the amplitude for certain frequency's).
Does anyone have an example or hints to do this ? Of-course I checked out Apple's AV Foundation library documentation, but it was not clear enough for me.
After a really (really) long time Googling, I found a blog post that describes MTAudioProcessingTap. Introduced in iOS 6.0, it solves my problem perfectly.
The how-to/blogpost can be found here : http://chritto.wordpress.com/2013/01/07/processing-avplayers-audio-with-mtaudioprocessingtap/
I Hope it helps anyone else now....... The only thing popping up for me Googling (with a lot of different terms) is my own post here. And as long as you don't know MTAudioProcessingTap exists, you don't know how to Google for it :-)
After finally successfully finding a way to concatenate multiple voice files into one single audio file on the iPhone, I am am now trying to superimpose an audio file over the length of the voice file.
So basically I have two .m4a files:
voice.m4a which is about 10 seconds for example.
music.m4a which is about 5 seconds.
What I require is that two file be combined in such a manner that the resulting single audio file now contains the music in the background of the voice file for the length of it, so basically the resulting output should have the 10 seconds of voice and the 5seconds of music repeated twice. It is absolutely important to have a single file that contains all of this.
I am trying to get all of this done in an application on the iPhone.
Can anyone please help me out with this?
If you are looking to do that programmatically, you will need to go deeper down into CoreAudio. For a simpler solution you could use AudioQueues or for more fine grained control AudioUnits and an AUGraph. The MultiChannelMixer is the Audio Unit you are looking for. Unfortunately there is no space for an elaborate tutorial here (would take a couple of days to write just the tutorial itself), but I am hoping I could point you to the right direction.
If you decide to go down that path and want to do further audio programming then this one time simple example, then I strongly suggest you buy "Learning Core Audio, A Hands-on Guide to Audio Programming for Mac and iOS" - Chris Adamson, Kevin Avila. You can find it on Amazon, paperback or Kindle.
guys.
I'm working on some audio services on iOS.
I trying to search any examples or tutorials about
how audio service or stream can read a existing audio file than
process something like filter, than write another file.
Is there any body who can help me?
Dirac3LE (by Stephan M. Bernsee) is a great library for this job.
There are examples and manual included in the download.
It is particulary inteded for time and pitch manipulation
but in your case you'll be interested in its EAFRead and EAFWrite
classes.
If you want to get familiar with the lower level library that you can also use for microphone input/sound output, and that you can get raw samples into and out of, I would suggest taking a look at Audio Queue Services.
I used it in my side project to get audio from the microphone, and I also wrote some code you might find useful to do fast vectorized, FFT based FIR filtering on input audio. You can find the code here https://github.com/jamescarlson/FreeAPRS
Can anyone please give pointers how we can add re verb effect to a recording in an iPhone app?
Vocal live free on app store is a pretty good example of how I would want to include reverb effect.
Core Audio Overview in iOS documentation references reverb as an audio unit.
Any help beyond this will be helpful.
Yoy can use ObjectAL library. See link below
https://github.com/kstenerud/ObjectAL-for-iPhone.
If you have access to the raw audio data, you can simply convolute it with corresponding reverberation finite impulse response (FIR) filter kernel.