I want to know if I can use AVAudioSession for recording audio in Apple Watch, also I want to know if there is differences in audio quality recorded by Apple Watch and iPhone?
You can't use AVAudioSession on watchOS.
WKInterfaceController has method presentAudioRecorderControllerWithOutputURL on watchOS 2 that is used to record audio. Apple's docs have more information.
There's an enum WKAudioRecorderPreset (Apple's docs) you can use to specify quality. watchOS 2 is geared towards voice recording but there is HighQualityAudio option which records at 44.1kHz/96kbps with AAC or 705.6 kbps with LPCM.
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How do I make physical ring/silent switch work again when I want to play and record audio at the same time using AVAudioSessionCategoryPlayAndRecord? I just cannot find an answer to that anywhere.
AVAudioSessionCategoryPlayAndRecord is designed for audio-centric apps, where the purpose of the app is to play music. When this category is set, audio will not be silenced by the mute switch or the screen lock. VOIP apps and music apps desire this behavior.
If you want audio to be silenced by the mute switch, you'll need to switch the category to AVAudioSessionCategoryAmbient or AVAudioSessionCategorySoloAmbient when not recording.
If you have access to the WWDC developer videos, I'd suggest watching "WWDC 2010 session 412 Audio Development for iPhone OS part 1".
I'm an inexperienced XCode use and programmer in general so keep that in mind. I'm trying to use the microphone on the iPhone while at the same time allowing the user to play audio while using the "iPod music picker", but when the user selects music and plays it the recorder stops working? I have no idea what is going on here? Also, on a side note, how do you implement forward and back iPod buttons?
Thanks so much!
Sounds like this is an Audio Session issue - you're probably in a mode where you can either play or record, but not both at the same time.
Check out the Audio Session Programming Guide which should explain how to configure your session.
AVAudioSessionCategoryPlayAndRecord — Use this category for an application that inputs and outputs audio. The input and output need not occur simultaneously, but can if needed. This is the category to use for audio chat applications.
AVAudioSessionCategoryAmbient - This category allows audio from the iPod, Safari, and other built-in applications to play while your application is playing audio. You could, for example, use this category for an application that provides a virtual musical instrument that a user plays along to iPod audio.
I want to play prerecorded audio for users in an iPhone application. Is the best way to play this audio to use openAL? Is there any other way that might be beneficial for what I want to accomplish?
Thanks!
Joe
For most needs, I've found AVAudioPlayer to be an excellent choice for audio playback.
OpenAL covers most audio cases nicely and it is tied to the Core Audio so playback speed is never lagged. Based on what details you gave, OpenAL will take of your needs
In the documentation I see several Apple frameworks for audio. All of them seem to be targeted at playing and recording audio. So I wonder what the big differences are between these?
Audio Toolbox
Audio Unit
AV Foundation
Core Audio
Did I miss a guide that gives a good overview of all these?
I made a brief graphical overview of Core Audio and its (containing) frameworks:
The framework closest to the hardware is Audio Unit. Based on that there is OpenAL and AudioToolbox with AudioQueue. On top, you can find the Media Player and AVFoundation (Audio & Video) frameworks.
Now it depends on what you want to do: just a small recording, use AVFoundation, which is the easiest one to use. (Media Player has no options for recording, it is - as the name says - just a media player.)
Do you want to do serious real-time signal processing? Use Audio Unit. But believe me, this is the hardest way. :-)
With iOS 8.0 Apple introduced AVAudioEngine, an Objective-C/Swift based audio graph system in AV Foundation. This encapsulates some dirty C-stuff from Audio Units. Due to the complexity of Audio Unit it is maybe worth a look.
Further readings in the Apple Documentation:
Core Audio Overview: Introduction
Multimedia Programming Guide
Audio & Video Starting Point
Core Audio is the lowest-level of all the frameworks and also the oldest.
Audio Toolbox is just above Core Audio and provides many different APIs that make it easier to deal with sound but still gives you a lot of control. There's ExtAudioFile, AudioConverter, and several other useful APIs.
Audio Unit is a framework for working with audio processing chains for both sampled audio data and MIDI. It's where the mixer and the various filters and effects such as reverb live.
AV Foundation is a new and fairly high-level API for recording and playing audio on the iPhone OS. All of them are available on both OS X and iOS, though AV Foundation requires OS X 10.8+.
Core Audio is not actually a framework, but an infrastructure that contains many different frameworks. Any audio that comes out of you iOS speaker is, in fact, managed by Core Audio.
The lowest-level in Core Audio that you can get is by using Audio Units, which you can work with by using the AudioToolbox and the AudioUnit frameworks.
The AudioToolbox framework also provides a bit higher level abstractions to deal with playing/recording of audio using AudioQueues, or managing various audio formats by using various Converter and File Services.
Finally, AV Foundation provides high level access to playing one specific file, and MediaPlayer gives you access (and playback) to your iPod library.
This site has a short and excellent overview of core features the different API's:
http://cocoawithlove.com/2011/03/history-of-ios-media-apis-iphone-os-20.html
Here you can find an overview of all iOS and OSX audio frameworks:
https://developer.apple.com/library/ios/documentation/MusicAudio/Conceptual/CoreAudioOverview/WhatsinCoreAudio/WhatsinCoreAudio.html#//apple_ref/doc/uid/TP40003577-CH4-SW4
I want to play H.264 video streamed from network. To play video iphone provides the media player API. Does anyone one aware of any documented or undocumented API for decoding and playing single video frame?
Is it Live video or on demand ?
If live the only way is to use iPhone OS 3 with MediaPlayer.
take a look at the discussions group from apple there is some interesting thread.