From fbef0349036292f94902d0c3102a7418cfa6f9a9 Mon Sep 17 00:00:00 2001
From: Christopher Snowhill <kode54@gmail.com>
Date: Sat, 15 Jan 2022 02:09:26 -0800
Subject: [PATCH] Cog Audio: Further overhaul output buffering and track queue
 code

---
 Audio/AudioPlayer.h            |  3 +-
 Audio/AudioPlayer.m            | 10 ++++--
 Audio/Chain/ConverterNode.m    | 18 ++++++++++
 Audio/Chain/OutputNode.h       |  3 +-
 Audio/Chain/OutputNode.m       |  5 ++-
 Audio/Chain/RefillNode.m       | 22 ++++++++++--
 Audio/Output/OutputCoreAudio.h |  4 +++
 Audio/Output/OutputCoreAudio.m | 63 +++++++++++++++++++++-------------
 8 files changed, 93 insertions(+), 35 deletions(-)

diff --git a/Audio/AudioPlayer.h b/Audio/AudioPlayer.h
index 10aa16249..545888103 100644
--- a/Audio/AudioPlayer.h
+++ b/Audio/AudioPlayer.h
@@ -95,9 +95,10 @@
 //- (BufferChain *)bufferChain;
 - (void)launchOutputThread;
 - (void)endOfInputPlayed;
-- (void)endOfInputPlayedOut;
 - (void)sendDelegateMethod:(SEL)selector withObject:(id)obj waitUntilDone:(BOOL)wait;
 - (void)sendDelegateMethod:(SEL)selector withObject:(id)obj withObject:(id)obj2 waitUntilDone:(BOOL)wait;
+
+- (BOOL)chainQueueHasTracks;
 @end
 
 @protocol AudioPlayerDelegate
diff --git a/Audio/AudioPlayer.m b/Audio/AudioPlayer.m
index 2d057cd65..33cf8f847 100644
--- a/Audio/AudioPlayer.m
+++ b/Audio/AudioPlayer.m
@@ -261,7 +261,7 @@
 
 - (void)notifyStreamChanged:(id)userInfo
 {
-	[self sendDelegateMethod:@selector(audioPlayer:didBeginStream:) withObject:userInfo waitUntilDone:NO];
+	[self sendDelegateMethod:@selector(audioPlayer:didBeginStream:) withObject:userInfo waitUntilDone:YES];
 }
 
 - (void)addChainToQueue:(BufferChain *)newChain
@@ -446,12 +446,16 @@
         [semaphore signal];
 	}
 	
+    [self notifyStreamChanged:[bufferChain userInfo]];
 	[output setEndOfStream:NO];
 }
 
-- (void)endOfInputPlayedOut
+- (BOOL)chainQueueHasTracks
 {
-    [self notifyStreamChanged:[bufferChain userInfo]];
+    @synchronized (chainQueue) {
+        return [chainQueue count] > 0;
+    }
+    return NO;
 }
 
 - (void)sendDelegateMethod:(SEL)selector withObject:(id)obj waitUntilDone:(BOOL)wait
diff --git a/Audio/Chain/ConverterNode.m b/Audio/Chain/ConverterNode.m
index bbe28e592..4352e1415 100644
--- a/Audio/Chain/ConverterNode.m
+++ b/Audio/Chain/ConverterNode.m
@@ -8,6 +8,9 @@
 
 #import "ConverterNode.h"
 
+#import "BufferChain.h"
+#import "OutputNode.h"
+
 #import "Logging.h"
 
 #import <audio/conversion/s16_to_float.h>
@@ -1243,6 +1246,21 @@ static float db_to_scale(float db)
                 break;
         }
         
+        for (;;)
+        {
+            void * ptr;
+            BufferChain * bufferChain = controller;
+            AudioPlayer * audioPlayer = [bufferChain controller];
+            VirtualRingBuffer * buffer = [[audioPlayer output] buffer];
+            dataRead = [buffer lengthAvailableToReadReturningPointer:&ptr];
+            if (dataRead) {
+                [refillNode writeData:(float*)ptr floatCount:dataRead / sizeof(float)];
+                [buffer didReadLength:dataRead];
+            }
+            else
+                break;
+        }
+        
         [self setupWithInputFormat:previousOutputFormat outputFormat:outputFormat];
     }
     else
diff --git a/Audio/Chain/OutputNode.h b/Audio/Chain/OutputNode.h
index a9e0b534d..1b42b896f 100644
--- a/Audio/Chain/OutputNode.h
+++ b/Audio/Chain/OutputNode.h
@@ -32,7 +32,8 @@
 - (void)resetAmountPlayed;
 
 - (void)endOfInputPlayed;
-- (void)endOfInputPlayedOut;
+
+- (BOOL)chainQueueHasTracks;
 
 - (double)secondsBuffered;
 
diff --git a/Audio/Chain/OutputNode.m b/Audio/Chain/OutputNode.m
index c971dee0d..0f3d480f4 100644
--- a/Audio/Chain/OutputNode.m
+++ b/Audio/Chain/OutputNode.m
@@ -69,9 +69,9 @@
     [controller endOfInputPlayed];
 }
 
-- (void)endOfInputPlayedOut
+- (BOOL)chainQueueHasTracks
 {
-    [controller endOfInputPlayedOut];
+    return [controller chainQueueHasTracks];
 }
 
 - (double)secondsBuffered
@@ -96,7 +96,6 @@
     }
 }
 
-
 - (double)amountPlayed
 {
     return amountPlayed;
diff --git a/Audio/Chain/RefillNode.m b/Audio/Chain/RefillNode.m
index 0b81935af..927b17cd0 100644
--- a/Audio/Chain/RefillNode.m
+++ b/Audio/Chain/RefillNode.m
@@ -13,13 +13,29 @@
 
 @implementation RefillNode
 
-- (id)initWithController:(id)c previous:(id)p {
-    self = [super initWithController:c previous:p];
+- (id)initWithController:(id)c previous:(id)p
+{
+    self = [super init];
+    if (self)
+    {
+        // This special node should be able to handle up to four buffers
+        buffer = [[VirtualRingBuffer alloc] initWithLength:BUFFER_SIZE * 4];
+        semaphore = [[Semaphore alloc] init];
+        readLock = [[NSLock alloc] init];
+        writeLock = [[NSLock alloc] init];
+        
+        initialBufferFilled = NO;
+        
+        controller = c;
+        endOfStream = NO;
+        shouldContinue = YES;
 
+        [self setPreviousNode:p];
+    }
+    
     return self;
 }
 
-
 - (void)writeData:(float *)data floatCount:(size_t)count
 {
     [self writeData:data amount:(int)(count * sizeof(float))];
diff --git a/Audio/Output/OutputCoreAudio.h b/Audio/Output/OutputCoreAudio.h
index 0dc2a38b7..829ef7f43 100644
--- a/Audio/Output/OutputCoreAudio.h
+++ b/Audio/Output/OutputCoreAudio.h
@@ -14,6 +14,8 @@
 #import <AudioUnit/AudioUnit.h>
 #import <AVFoundation/AVFoundation.h>
 
+#import <stdatomic.h>
+
 #import "Semaphore.h"
 
 @class OutputNode;
@@ -30,6 +32,8 @@
     BOOL started;
     BOOL paused;
     
+    atomic_long bytesRendered;
+    
     BOOL listenerapplied;
     
     float volume;
diff --git a/Audio/Output/OutputCoreAudio.m b/Audio/Output/OutputCoreAudio.m
index 563ff1aa3..05cdd7be2 100644
--- a/Audio/Output/OutputCoreAudio.m
+++ b/Audio/Output/OutputCoreAudio.m
@@ -29,6 +29,8 @@ extern void scale_by_volume(float * buffer, size_t count, float volume);
         running = NO;
         started = NO;
         
+        atomic_init(&bytesRendered, 0);
+        
         writeSemaphore = [[Semaphore alloc] init];
         readSemaphore = [[Semaphore alloc] init];
         
@@ -56,14 +58,9 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 }
 
 - (void)signalEndOfStream
-{
-    [outputController endOfInputPlayed];
-}
-
-- (void)signalEndOfStreamBuffered
 {
     [outputController resetAmountPlayed];
-    [outputController endOfInputPlayedOut];
+    [outputController endOfInputPlayed];
 }
 
 - (void)threadEntry:(id)arg
@@ -71,7 +68,9 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
     running = YES;
     started = NO;
     size_t eventCount = 0;
-    ssize_t delayedEvent = -1;
+    atomic_store(&bytesRendered, 0);
+    NSMutableArray *delayedEvents = [[NSMutableArray alloc] init];
+    BOOL delayedEventsPopped = YES;
     while (!stopping) {
         if (++eventCount == 128) {
             [self updateDeviceFormat];
@@ -82,6 +81,20 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
             [[outputController buffer] empty];
             [outputController setShouldReset:NO];
         }
+
+        while ([delayedEvents count]) {
+            size_t localBytesRendered = atomic_load_explicit(&bytesRendered, memory_order_relaxed);
+            if (localBytesRendered >= [[delayedEvents objectAtIndex:0] longValue]) {
+                if ([outputController chainQueueHasTracks])
+                    delayedEventsPopped = YES;
+                [self signalEndOfStream];
+                [delayedEvents removeObjectAtIndex:0];
+            }
+            else break;
+        }
+        
+        if (stopping)
+            break;
         
         void *writePtr;
         int toWrite = [[outputController buffer] lengthAvailableToWriteReturningPointer:&writePtr];
@@ -93,15 +106,6 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
         if (bytesRead) {
             [[outputController buffer] didWriteLength:bytesRead];
             [readSemaphore signal];
-            if (delayedEvent >= 0) {
-                if (bytesRead >= delayedEvent) {
-                    delayedEvent = -1;
-                    [self signalEndOfStreamBuffered];
-                }
-                else {
-                    delayedEvent -= bytesRead;
-                }
-            }
             continue;
         }
         else if ([outputController shouldContinue] == NO)
@@ -117,15 +121,19 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
         }
         else {
             // End of input possibly reached
-            if ([outputController endOfStream] == YES)
+            if (delayedEventsPopped && [outputController endOfStream] == YES)
             {
-                [self signalEndOfStream];
-                if (delayedEvent >= 0) {
-                    [self signalEndOfStreamBuffered];
-                    delayedEvent = -1;
+                long bytesBuffered = [[outputController buffer] bufferedLength];
+                bytesBuffered += atomic_load_explicit(&bytesRendered, memory_order_relaxed);
+                [delayedEvents addObject:[NSNumber numberWithLong:bytesBuffered]];
+                delayedEventsPopped = NO;
+                if (!started) {
+                    started = YES;
+                    if (!paused) {
+                        NSError *err;
+                        [_au startHardwareAndReturnError:&err];
+                    }
                 }
-                else
-                    delayedEvent = [[outputController buffer] bufferedLength];
             }
         }
         [readSemaphore signal];
@@ -411,6 +419,7 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
     __block Semaphore * readSemaphore = self->readSemaphore;
     __block OutputNode * outputController = self->outputController;
     __block float * volume = &self->volume;
+    __block atomic_long * bytesRendered = &self->bytesRendered;
     
     _au.outputProvider = ^AUAudioUnitStatus(AudioUnitRenderActionFlags * actionFlags, const AudioTimeStamp * timestamp, AUAudioFrameCount frameCount, NSInteger inputBusNumber, AudioBufferList * inputData)
     {
@@ -420,9 +429,12 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 
         amountToRead = inputData->mBuffers[0].mDataByteSize;
         
-        if (self->stopping == YES || [outputController shouldContinue] == NO)
+        if (self->stopping == YES || [outputController shouldContinue] == NO ||
+            ([[outputController buffer] isEmpty] && ![outputController chainQueueHasTracks]))
         {
+            // Chain is dead, fill out the serial number pointer forever with silence
             memset(readPointer, 0, amountToRead);
+            atomic_fetch_add(bytesRendered, amountToRead);
             self->stopping = YES;
             return 0;
         }
@@ -438,6 +450,7 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
             amountRead = toRead;
             [[outputController buffer] didReadLength:toRead];
             [outputController incrementAmountPlayed:amountRead];
+            atomic_fetch_add(bytesRendered, amountRead);
             [writeSemaphore signal];
         }
 
@@ -450,6 +463,8 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
             if (amountRead2 > (amountToRead - amountRead))
                 amountRead2 = amountToRead - amountRead;
             if (amountRead2) {
+                atomic_fetch_add(bytesRendered, amountRead2);
+
                 memcpy(readPointer + amountRead, readPtr, amountRead2);
                 [[outputController buffer] didReadLength:amountRead2];