Added "pause" functionality to file player unit

YBAudioUnit/YBAudioFilePlayer.h

@@ -32,16 +32,32 @@
 @property (nonatomic, readwrite, strong) NSURL *fileURL;
 - (void)setFileURL:(NSURL *)fileURL typeHint:(AudioFileTypeID)typeHint;
 
+/**
+     Read-only property containing the player's current playback time,
+     offset from the beginning of the file.
+ */
+@property (nonatomic, readonly) AudioTimeStamp currentPlayTime;
+
 /**
 	Convenience method to set the entire file as scheduled region,
     prime the buffers of the player and set the start time stamp as `now`.
  */
 - (void)scheduleEntireFilePrimeAndStartImmediately;
 
 /**
-    Convenience method to unschedule previously scheduled regions.
+    Convenience method to unschedule the current region and schedule from the specified
+    time up to the end of the file. This can be used to `pause` the player unit by giving
+    the current playback time. To `continue` playback after `pausing`, send -setStartTimeStampImmediately.
+ */
+- (void)rescheduleEntireFileBeginningAtPlaybackTime:(AudioTimeStamp)timestamp;
+
+/**
+    Convenience method to unschedule and reschedule the entire file beginning at the current
+    playback time. This can be used to `pause` the player unit at the current position.
+    To `continue` playback after `pausing`, send -setStartTimeStampImmediately.
+    @see -rescheduleEntireFileBeginningAtPlaybackTime:
  */
-- (void)unschedule;
+- (void)rescheduleEntireFileBeginningAtCurrentPlaybackTime;
 
 /**
     Methods to set and get the region of the file that is scheduled for playback.

YBAudioUnit/YBAudioFilePlayer.m

@@ -17,6 +17,26 @@ - (id)initWithAUNode:(AUNode)auNode audioUnit:(AudioUnit)auAudioUnit inGraph:(YB
 @implementation YBAudioFilePlayer {
     AudioFileID _audioFileID;
     ScheduledAudioFileRegion _region;
+    AudioStreamBasicDescription _fileASBD;
+    UInt64 _filePacketsCount;
+}
+
+/**
+    Overriden because kAudioUnitProperty_CurrentPlayTime is the playTime relative to the mStartFrame,
+    while it often makes more sense to have the time from the beginning of the file.
+    In case the player is stopped (currentPlayTime == -1.) the mStartFrame of the current region is
+    reported back, which often makes sense as this is often used as the cue point at which the player is `paused`.
+ */
+- (AudioTimeStamp)currentPlayTime {
+    AudioTimeStamp currentPlayTime;
+    UInt32 dataSize = sizeof(currentPlayTime);
+    YBAudioThrowIfErr(AudioUnitGetProperty(_auAudioUnit, kAudioUnitProperty_CurrentPlayTime, kAudioUnitScope_Global, 0, &currentPlayTime, &dataSize));
+    if (currentPlayTime.mSampleTime == -1.) {
+        currentPlayTime.mSampleTime = 0;
+    }
+    currentPlayTime.mFlags = kAudioTimeStampSampleTimeValid;
+    currentPlayTime.mSampleTime += _region.mStartFrame;
+    return currentPlayTime;
 }
 
 - (void)setFileURL:(NSURL *)fileURL {
@@ -39,6 +59,14 @@ - (void)setFileURL:(NSURL *)fileURL typeHint:(AudioFileTypeID)typeHint {
     if (_fileURL) {
         YBAudioThrowIfErr(AudioFileOpenURL((__bridge CFURLRef)fileURL, kAudioFileReadPermission, typeHint, &_audioFileID));
         YBAudioThrowIfErr(AudioUnitSetProperty(_auAudioUnit, kAudioUnitProperty_ScheduledFileIDs, kAudioUnitScope_Global, 0, &_audioFileID, sizeof(AudioFileID)));
+
+        // Get number of audio packets in the file:
+        UInt32 propsize = sizeof(_filePacketsCount);
+        YBAudioThrowIfErr(AudioFileGetProperty(_audioFileID, kAudioFilePropertyAudioDataPacketCount, &propsize, &_filePacketsCount));
+
+        // Get file's asbd:
+        propsize = sizeof(_fileASBD);
+        YBAudioThrowIfErr(AudioFileGetProperty(_audioFileID, kAudioFilePropertyDataFormat, &propsize, &_fileASBD));
     }
 }
 
@@ -48,35 +76,36 @@ - (void)scheduleEntireFilePrimeAndStartImmediately {
     [self setStartTimeStampSampleTime:-1.];
 }
 
-- (void)unschedule {
-    [self reset];
-}
-
-- (void)setRegionEntireFile {
-    // Get number of audio packets in the file:
-    UInt64 nPackets = 0;
-    UInt32 propsize = sizeof(UInt64);
-    YBAudioThrowIfErr(AudioFileGetProperty(_audioFileID, kAudioFilePropertyAudioDataPacketCount, &propsize, &nPackets));
-
-    // Get file's asbd:
-    AudioStreamBasicDescription fileASBD = {0};
-    propsize = sizeof(fileASBD);
-    YBAudioThrowIfErr(AudioFileGetProperty(_audioFileID, kAudioFilePropertyDataFormat, &propsize, &fileASBD));
-
-    // Tell the file player AU to play the entire file and with which point in the graph's time it should start (at time 0)
-    // This makes sure the players start at the same time and stay perfectly sync.
+- (void)resetRegionToEntireFileWithStartFrame:(SInt64)startFrame {
     _region.mTimeStamp.mFlags = kAudioTimeStampSampleTimeValid;
-    _region.mTimeStamp.mSampleTime = 0;
+    _region.mTimeStamp.mSampleTime = 0; /* Relative to graph's time line */
     _region.mAudioFile = _audioFileID;
     _region.mLoopCount = 0;
-    _region.mStartFrame = 0;
-    _region.mFramesToPlay = nPackets * fileASBD.mFramesPerPacket;
-
+    _region.mStartFrame = startFrame;
+    _region.mFramesToPlay = (_filePacketsCount * _fileASBD.mFramesPerPacket) - startFrame;
+}
+
+- (void)rescheduleEntireFileBeginningAtPlaybackTime:(AudioTimeStamp)timestamp {
+    [self unschedule];
+    NSAssert((timestamp.mFlags & kAudioTimeStampSampleTimeValid), nil);
+    [self resetRegionToEntireFileWithStartFrame:timestamp.mSampleTime];
+    YBAudioThrowIfErr(AudioUnitSetProperty(_auAudioUnit, kAudioUnitProperty_ScheduledFileRegion, kAudioUnitScope_Global, 0, &_region, sizeof(_region)));
+    [self primeBuffers];
+}
+
+- (void)rescheduleEntireFileBeginningAtCurrentPlaybackTime {
+    [self rescheduleEntireFileBeginningAtPlaybackTime:self.currentPlayTime];
+}
+
+- (void)setRegionEntireFile {
+    [self resetRegionToEntireFileWithStartFrame:0];
     YBAudioThrowIfErr(AudioUnitSetProperty(_auAudioUnit, kAudioUnitProperty_ScheduledFileRegion, kAudioUnitScope_Global, 0, &_region, sizeof(_region)));
 }
 
 - (void)setRegion:(ScheduledAudioFileRegion*)region {
-    memcpy(&_region, region, sizeof(_region));
+    if (region != &_region) {
+        memcpy(&_region, region, sizeof(_region));
+    }
     YBAudioThrowIfErr(AudioUnitSetProperty(_auAudioUnit, kAudioUnitProperty_ScheduledFileRegion, kAudioUnitScope_Global, 0, &_region, sizeof(_region)));
 }
 
@@ -96,7 +125,7 @@ - (void)primeBuffersWithFrames:(UInt32)numberOfFrames {
 - (id)initWithAUNode:(AUNode)auNode audioUnit:(AudioUnit)auAudioUnit inGraph:(YBAudioUnitGraph *)graph {
     self = [super initWithAUNode:auNode audioUnit:auAudioUnit inGraph:graph];
     if (self) {
-        
+
     }
     return self;
 }

YBAudioUnit/YBScheduledSoundPlayer.h

@@ -17,10 +17,22 @@
 @interface YBScheduledSoundPlayer : YBAudioUnitNode
 
 /**
-    Read-only property containing the player's current playback time.
+    Read-only property containing the player's current playback time,
+    offset from its start time.
  */
 @property (nonatomic, readonly) AudioTimeStamp currentPlayTime;
 
+/**
+    Read-only property indicating whether playback has started.
+ */
+@property (nonatomic, readonly) BOOL isPlaying;
+
+/**
+    Read-only property indicating whether the startTimeStamp has been set,
+    i.e. if it is scheduled and possibly playing.
+ */
+@property (nonatomic, readonly) BOOL hasStartTimeStamp;
+
 /**
     Methods to set the ScheduleStartTimeStamp property.
     @see kAudioUnitProperty_ScheduleStartTimeStamp
@@ -29,4 +41,10 @@
 - (void)setStartTimeStampSampleTime:(Float64)startSampleTime;
 - (void)setStartTimeStamp:(AudioTimeStamp*)startTime;
 
+/**
+    Convenience method to unschedule previously scheduled regions.
+    If the player unit has already started playback, it will stop.
+ */
+- (void)unschedule;
+
 @end

YBAudioUnit/YBScheduledSoundPlayer.m

@@ -9,7 +9,9 @@
 #import "YBScheduledSoundPlayer.h"
 #import "YBAudioException.h"
 
-@implementation YBScheduledSoundPlayer
+@implementation YBScheduledSoundPlayer {
+    BOOL _hasStartTimeStamp;
+}
 
 - (AudioTimeStamp)currentPlayTime {
     AudioTimeStamp currentPlayTime;
@@ -27,10 +29,30 @@ - (void)setStartTimeStampSampleTime:(Float64)startSampleTime {
     startTime.mFlags = kAudioTimeStampSampleTimeValid;
     startTime.mSampleTime = startSampleTime;
     YBAudioThrowIfErr(AudioUnitSetProperty(_auAudioUnit, kAudioUnitProperty_ScheduleStartTimeStamp, kAudioUnitScope_Global, 0, &startTime, sizeof(startTime)));
+    _hasStartTimeStamp = YES;
 }
 
 - (void)setStartTimeStamp:(AudioTimeStamp*)startTime {
     YBAudioThrowIfErr(AudioUnitSetProperty(_auAudioUnit, kAudioUnitProperty_ScheduleStartTimeStamp, kAudioUnitScope_Global, 0, &startTime, sizeof(startTime)));
+    _hasStartTimeStamp = YES;
+}
+
+- (BOOL)isPlaying {
+    AudioTimeStamp currentPlayTime;
+    UInt32 dataSize = sizeof(currentPlayTime);
+    YBAudioThrowIfErr(AudioUnitGetProperty(_auAudioUnit, kAudioUnitProperty_CurrentPlayTime, kAudioUnitScope_Global, 0, &currentPlayTime, &dataSize));
+    return (currentPlayTime.mSampleTime != -1.);
 }
 
+- (void)unschedule {
+    [self reset];
+}
+
+- (void)reset {
+    _hasStartTimeStamp = NO;
+    [super reset];
+}
+
+
+@synthesize hasStartTimeStamp = _hasStartTimeStamp;
 @end

YBAudioUnitExample/YBViewController.m

@@ -18,6 +18,7 @@ @interface YBViewController ()
 @implementation YBViewController {
     __weak IBOutlet UIButton *startStopButton;
     __weak IBOutlet UILabel *timeLabel;
+    __weak IBOutlet UIButton *playPauseButton;
     NSTimer *timer;
 
     YBAudioUnitGraph *graph;
@@ -80,6 +81,7 @@ - (void)viewDidLoad {
 
 - (void)viewDidUnload {
     timeLabel = nil;
+    playPauseButton = nil;
     [super viewDidUnload];
     startStopButton = nil;
     graph = nil;
@@ -133,10 +135,24 @@ - (IBAction)mixerPanAction:(UISlider*)sender {
 - (IBAction)rescheduleAction:(id)sender {
     [guitarPlayerNode unschedule];
     [guitarPlayerNode scheduleEntireFilePrimeAndStartImmediately];
+
     [bandPlayerNode unschedule];
     [bandPlayerNode scheduleEntireFilePrimeAndStartImmediately];
 }
 
+- (IBAction)playPauseAction:(id)sender {
+    AudioTimeStamp currentPlayTime = [guitarPlayerNode currentPlayTime];
+    if ([guitarPlayerNode isPlaying]) {
+        [guitarPlayerNode rescheduleEntireFileBeginningAtPlaybackTime:currentPlayTime];
+        [bandPlayerNode rescheduleEntireFileBeginningAtPlaybackTime:currentPlayTime];
+        [playPauseButton setTitle:@"Play" forState:UIControlStateNormal];
+    } else {
+        [guitarPlayerNode setStartTimeStampImmediately];
+        [bandPlayerNode setStartTimeStampImmediately];
+        [playPauseButton setTitle:@"Pause" forState:UIControlStateNormal];
+    }
+}
+
 - (IBAction)distortionAction:(id)sender {
     YBParameterViewController *filterViewController = [[YBParameterViewController alloc] init];
     filterViewController.filter = distortionFilter;