I am developing an iPhone application (like Audio Processing). I have to give some effect to the audios.
If it is desktop app, many options are there. We can get good examples and full project like audacity. But I want to develop for iPhone.
I got an app with reverb option; (take a look at following link). Just I watch the "video", I did not test this application in my iPhone device.
http://www.appstorehq.com/reverb-iphone-89870/app
My question is; How can I develop the app with reverb functionality ? Is there any documentation for that ? If it is, just share with us.
NOTE: We can use AudioUnit to develop the app with reverb functionality (I am not clear with this.).
EDIT: I don't like to use any third party library.
If anybody having knowledge about this, please share with us.
Thanks.
if yourre targeting ios5 you can just the audio unit subtype kAudioUnitSubType_Reverb2 of the effect audio unit.
reverb unit
AudioComponentDescription auEffectUnitDescription;
auEffectUnitDescription.componentType = kAudioUnitType_Effect;
auEffectUnitDescription.componentSubType = kAudioUnitSubType_Reverb2;
auEffectUnitDescription.componentManufacturer = kAudioUnitManufacturer_Apple;
AUGraphAddNode(
processingGraph,
&auEffectUnitDescription,
&auEffectNode),
Failing that you could just write your own reverb code in the remoteio callback. A simple delay might be easier to do and would sound similar.
iOS 5.0 brings native OpenAL support, so it is now much easier - you don't have to code the algorithm yourself. It also bring support for a variety of reverb spaces:
Small Room
Medium Room
Large Room (2 configurations)
Medium Hall (3 configurations)
Large Hall (2 configurations)
Plate
Medium Chamber
Large Chamber
Cathedral
I suggest that you try the ObjectAL wrapper which already has a great support for the reverb effect:
https://github.com/kstenerud/ObjectAL-for-iPhone
Grab the source from this repository, load "ObjectAL.xcodeproj" and run the ObjectALDemo target on any iOS 5.0 device (should also work on the simulator). This will give you a good starting point and feeling of what the reverb effect is capable of.
If you still don't to use any 3rd party library, you can just grab the relevant pieces from ObjectAL. Look for the reverb-related code in the following source files (and their corresponding headers):
https://github.com/kstenerud/ObjectAL-for-iPhone/blob/master/ObjectAL/ObjectAL/OpenAL/ALListener.m
https://github.com/kstenerud/ObjectAL-for-iPhone/blob/master/ObjectAL/ObjectAL/OpenAL/ALSource.m
https://github.com/kstenerud/ObjectAL-for-iPhone/blob/master/ObjectAL/ObjectAL/OpenAL/ALWrapper.m
Good luck with your project!
AUs are a good place to start.
write your own reverb AU which contains a reverb implementation. there are tons of ways to implement a reverb. a medium/long convolution reverb is much to ask from a phone, but something such as a FDN (feedback delay network) will not require a lot of memory or CPU.
both implementations are easy to implement, if you're familiar with audio programming and optimization. the tough part is actually making one that sounds very good and performs well.
if you're unable to write optimal low level code or you do not (presently) understand basic audio signal processing, then you'll have a few obstacles to overcome -- it may be a long road in that case.
Searching the iOS documentation for "reverb" produces a link to the Core Audio Overview, which references reverb as an "effect unit." Perhaps that's worth further study?
No good, I have attempted the audio unit approach and even though it is in the documentation it is "not" implemented yet by the apple engineers. Each time you call the function to set the reverb property you will only get failure status code. You would have to implement your own reverb effect. Try reading some DSP book and you might find a clue.
you need to learn some DSP-level coding, the DSP cookbook book is okay and there are others out there. But basically you need to be comfortable with handling audio signal in the frequency domain and things such as FFT's. Once you have that, implementing a reverb filter should be straight-forward.
This is an answer I've given before, but I believe it is relevant here. I am going to agree with the others and say that you are going to have to become a bit more familiar with core-audio if you want to do this properly.
I highly recommend this core-audio book. It will teach what you need to do this right and will save you a lot of frustration.
The chapter on audio effects has not been published yet, but if it is anything like the rest of the book it's worth the wait.
EDIT
You will most likely need to do this with an audio effect (which is a form of an audio unit).
Related
I want to do some DSP effect processing, create effect like flanger, echo, etc.
Could it be done via OpenAL? Or should I use enterely different framework/library?
Since iOS 5.0 some of the DSP effects are natively supported by OpenAL.
For example, reverb is supported with emulation for more than 10 different spaces (Small/Medium/Large Room, Medium/Large Hall, Plate, Medium/Large Chamber, Cathedral and several variations).
You can find a good reference implementation in the ObjectAL wrapper. The repository is available at https://github.com/kstenerud/ObjectAL-for-iPhone
Grab the source from this repository, load "ObjectAL.xcodeproj" and run the ObjectALDemo target on any iOS 5.0 device (should also work on the simulator). This will give you a good starting point and feeling of what the reverb effect is capable of. I personally recommend taking advantage of the ObjectAL library instead of working with OpenAL directly.
Good luck with your project!
Just write your own audio library. iOS devices don't have hardware acceleration for OpenAL. It isnt particularly difficult to do, and then you can also use apples audio units (some of which are hardware accelerated).
i'm trying to make a C++ engine that will read a mp3 file, and make some image zoom/translation depending on the time of the reading sound file. I think I could use OpenGL ES to render what I want, and calling some OpenGL ES instructions in my C++ files, and init my drawing context in Obj-C/Java. I want to do the same for the sound, but i don't really know what to use, and if I can really do it or not in C++.
I searched for library so I found Bass and Fmod (which is not free for commercial use). They said it's multicross platform (Windows, Unix, MacOS) but I dont understand if it manners for mobile, and if I can really use it. Does anyone have been through this? Do you recommand me another free library?
Thanks again, and I apologize for my poor english,
Arnaud
Have a look at libpd (Pure Data for embedded applications)
http://download.puredata.info/libpd (the library has been released very recently, but the code is very mature indeed)
http://createdigitalmusic.com/2010/10/libpd-put-pure-data-in-your-app-on-an-iphone-or-android-and-everywhere-free/
Audio is often problematic and it is pretty much always a good idea to write your own high-level API that does exactly what you want to do (and nothing else) and to assume you will then be writing a thin layer between it and whatever audio library you are using underneath. If you're lucky and there's a library available that does things the way you would do them then it's trivial. If not, at least it's still possible. In either case, your app code is not tied to an external sound API.
I have used FMOD on multiple different commercial projects over the years for PC, Mac and iPhone, and have always liked it - but it's not free. OpenAL has always seemed sorta, I dunno: clunky? But you only have to deal with it when writing your API layer, and your app code never has to see it.
It's easy for me to say "write your own API" since I've been writing commercial games for 20 years and so know what I think an audio API should look like. If you don't have your own idea how you think it should be, then I suggest you look at a 3rd party library that makes sense to you and take the functions from it that you will be using and write your own API to do be a set of functions that do nothing but call those.
Since you have both OpenAL and FMOD available to you free for development you can then make your API work with both, and chances are it's then going to work with anything else you might come across.
OpenAL may be your best bet. Look at this answer: Android OpenAL?
It seems possible to compile OpenAL on Android.
If you are looking for just PCM audio input/output ( and not MP3 decoding ) try PortAudio or RTAudio
RtAudio or PortAudio, which one to use?
Is there any possible way to do reverb using OpenAL on iOS? Anyone have any code snippets to achieve this effect? I know it's not included in the OpenAL library for iOS, but I would think there's still a way to program it in.
Thanks.
Reverb is now natively supported in OpenAL (as of iOS 5.0). You can view a sample implementation on the ObjectAL project:
https://github.com/kstenerud/ObjectAL-for-iPhone
Just grab the most recent source from this repository, load "ObjectAL.xcodeproj" and run the ObjectALDemo target on any iOS 5.0 device (should also work on the simulator).
The actual implementation lies in two places:
https://github.com/kstenerud/ObjectAL-for-iPhone/blob/master/ObjectAL/ObjectAL/OpenAL/ALListener.m
https://github.com/kstenerud/ObjectAL-for-iPhone/blob/master/ObjectAL/ObjectAL/OpenAL/ALSource.m
Look for the word 'reverb' in these files (and the corresponding header files) to find the name of the OpenAL properties and constants used to set and control the reverb effect.
Good luck!
You could use pre-rendered audio if the situation allows it. If you want to do it real time look into DSP. Theres no way do to this out of the box that I am aware of.
The additional desktop APIs like EFX and EAX use hardware signal processing. Maybe in the future these hand held devices will implement the full OpenAL and OpenGL APIs, but for now we have the stripped down versions, for practical reasons like cost and battery life etc.
I'm sure there is a way, but its not going to be easy.
I have a children's iPhone application that I am writing and I need to be able to shift the pitch of a sound sample using Core Audio. Does anyone have any example code I could look at where this is done. There are many music and game apps in the app store that do this so I know I am not the first one. However, I cannot find any examples of it being done.
you can use dirac-2 from dsp dimension for pitch shifting on the iphone. quote: -
"DIRAC2 is available as both a commercial object library offering unlimited sample rates and phase locked multichannel support and as a free single channel, 44.1/48kHz LE version."
use the soundtouch open source project to change pitch
Here is the link : http://www.surina.net/soundtouch/
Once you add soundtouch to your project, you have to give the input sound file path, output sound file path and pitch change as the input.
Since it takes more time to process your sound its better to modify soundtouch so that when you record the voice, directly give the data for processing. It will make your application better.
I know it's too late for the person who asked but it is really a valuable link (As I found) for any one else who is looking for the solution of the same problem.
So Here we have latest DIRAC3 with it's own audio player classes which will take care of run time pitch and speed(explore for god knows what more) shifting. Run the sample and have huge round of applause for that.
Try Dirac - it's the best technology out there and it's available on Win, Linux, MacOS X and iOS. We're using it in all our products (and a couple of others do as well, search for "Capo" on the App Store). They're at version 3 now which has seen a huge increase in performance since previous versions. Hope this helps.
See: Related question
How much control over pitch do you need... could you precalculate all the different sounds?
If the answer is yes, then you can just pick the right sounds and play them.
You could also use Audio Converter Services in conjunction with AVAudioPlayer, which will allow you to resample the audio (which will effectively repitch them, though they'll change duration).
Alternatively, as the related question points out, you could use OpenAL and AL_PITCH
I may be doing an iPhone-based application doing near-real-time sound-processing (filtering, etc). I was wondering the best way to get started. Would I want to create an audio cue for recording and processing sound, as described here?
Edit:
I should be clear. I am not asking how to do signal processing, in general. I know some of that and my team's expert will handle the rest. I asking what the "low level" interfaces to sound data on the iphone are.
Edit2:
My iphone development has been pushed back a week or two so I don't have access to the deve kit right now. Once I have access to the kit, I'll mark one answer or another correct.
Sound processing is a big subject. AudioQueue will get you the raw data. Apple provides two samples that will get you started using AudioQueue: SpeakHere and AurioTouch.
I used SpeakHere as a starting point for some audio processing I wanted to do. It's relatively easy to understand, and has all the pieces to do input and output.