Added AEAudioFileStreamer class, which serves the same purpose as AEA…

TheAmazingAudioEngine/AEAudioUnitFileStreamer.h

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+//
+//  AEAudioUnitFileStreamer.h
+//
+//  Created by Ryan King and Jeremy Huff of Hello World Engineering, Inc on 7/15/15.
+//  Copyright (c) 2015 Hello World Engineering, Inc. All rights reserved.
+//
+//  AudioFileStreamer is based on code written by Michael Tyson from The Amazing Audio Engine.
+//  It also uses code written by Rob Rampley for The Amazing Audio Engine.
+//  This source file is released under The Amazing Audio Engine license, pasted below.
+//  This notice, beginning with "Created by Ryan..." may not be removed or altered from any source distribution.
+//
+//
+//  The Amazing Audio Engine
+//
+//  Created by Michael Tyson on 25/11/2011.
+//
+//  This software is provided 'as-is', without any express or implied
+//  warranty.  In no event will the authors be held liable for any damages
+//  arising from the use of this software.
+//
+//  Permission is granted to anyone to use this software for any purpose,
+//  including commercial applications, and to alter it and redistribute it
+//  freely, subject to the following restrictions:
+//
+//  1. The origin of this software must not be misrepresented; you must not
+//     claim that you wrote the original software. If you use this software
+//     in a product, an acknowledgment in the product documentation would be
+//     appreciated but is not required.
+//
+//  2. Altered source versions must be plainly marked as such, and must not be
+//     misrepresented as being the original software.
+//
+//  3. This notice may not be removed or altered from any source distribution.
+//
+
+#import <Foundation/Foundation.h>
+#import "TheAmazingAudioEngine.h"
+
+/*  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *
+ *                                                                          *
+ *  These are defined here so that subclasses have access to these macros   *
+ *                                                                          *
+ *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  */
+
+#ifndef FS_CHECK_RESULT
+#define FS_CHECK_RESULT
+#define checkResult(result,operation) (_checkResult((result),(operation),strrchr(__FILE__, '/')+1,__LINE__))
+static inline BOOL _checkResult(OSStatus result, const char *operation, const char* file, int line) {
+    if ( result != noErr ) {
+        int fourCC = CFSwapInt32HostToBig(result);
+        NSLog(@"%s:%d: %s result %d %08X %4.4s\n", file, line, operation, (int)result, (int)result, (char*)&fourCC);
+        return NO;
+    }
+    return YES;
+}
+#define checkResultForError(resultop,operation,errormsg,errorval,resultvar,errorvar) if(!(_checkResult((resultvar)=(resultop),(operation),strrchr(__FILE__, '/')+1,__LINE__))) \
+{ \
+if ( (errorvar) ) \
+*(errorvar) = [NSError errorWithDomain:NSOSStatusErrorDomain code:(resultvar) userInfo:[NSDictionary dictionaryWithObject:@(errormsg) forKey:NSLocalizedDescriptionKey]]; \
+return (errorval); \
+}
+#endif
+
+/*!
+ * Audio file Streamer
+ *
+ *  This class allows you to play audio files through audio units without having to load the entire file into memory.
+ *
+ *  To use, create an instance, then add it to the audio controller.
+ *  
+ *  When subclassing this class, to modify the render callback methods, implement a pre or post render notification callback, as this class does.
+ */
+@interface AEAudioUnitFileStreamer : AEAudioUnitChannel
+{
+@protected
+    UInt32 _lengthInFrames;                         //!< Audio file length in frames
+    AudioStreamBasicDescription _audioDescription;  //!< Audio description
+    AudioStreamBasicDescription _controllerDescription; //!< The description of the audio controller's file type
+    volatile int32_t _playhead;                     //!< The location of the playhead in frames
+
+    // Audio unit related variables
+    AudioFileID _audioUnitFile;                     //!< The file to be played as an audio file ID
+}
+
+/*!
+ * Initializes an audio streamer
+ *
+ * @param url               URL to the file to load
+ * @param audioController   The audio controller
+ * @param error             If not NULL, the error on output
+ * @return The audio streamer, ready to be @link AEAudioController::addChannels: added @endlink to the audio controller.
+ */
+- (id) initWithURL: (NSURL*) url audioController: (AEAudioController*)audioController error:(NSError**) error;
+
+/*!
+ * Plays the audio streamer from it's current playhead position
+ */
+- (void) play;
+
+/*!
+ * Pauses the audio streamer at it's current playhead position
+ */
+- (void) pause;
+
+/*!
+ * Stops the audio streamer, resetting the playhead to the start of the file
+ */
+- (void) stop;
+
+/*!
+ * Mutes the streamer
+ */
+- (void) mute;
+
+/*!
+ * Unmutes the streamer
+ */
+- (void) unmute;
+
+@property (nonatomic, strong, readonly) NSURL *url;         //<! The URL of the audio file
+@property (nonatomic, readonly) NSTimeInterval duration;    //<! The length of the audio file in time
+@property (nonatomic, assign) NSTimeInterval currentTime;   //<! The current location of the playhead in time
+
+// AEAudioPlayable Properties
+@property (nonatomic, assign) BOOL channelIsPlaying;        //<! Whether the channel is playing or not
+
+@property (nonatomic, assign) int playbackDelay;            //<! The number of frames to wait before starting playback. Can be used to synchronize with effects audio units that introduce delay of their own.
+@property (nonatomic, assign) Float64 playbackDelayInSeconds;  //<! The number of seconds to wait before starting playback.
+@property (nonatomic, assign) BOOL looping;                 //<! If true, the audio file loops.
+
+@property (nonatomic, readonly) int32_t playbackStoppedCallbackScheduled;   //<! If true, disallows the channelIsPlayingProperty from being set to true
+
+@property (nonatomic, copy) void(^completionBlock)();       //<! The block to be called when playback ends
+
+// MARK: Debug Properties
+@property (nonatomic, readonly) int32_t currentFrame;       //<! The current frame of playback
+@property (nonatomic, readonly) UInt32 totalFrames;         //<! The total number of frames in the audio file
+
+@property (weak, readonly) AEAudioController* audioController;        //<! Our copy of the audio controller, which is needed for the postRender callback
+
+@end