/*

    File:       CoreAudioPlayback.c

    Description: Utility functions for building a simple AUGraph

                 to play buffers of audio data.

    Originally introduced at WWDC 2005 at Session 201:

        "Harnessing the Audio Capabilities of QuickTime 7" 

    Copyright:   © Copyright 2004, 2005 Apple Computer, Inc.

             All rights reserved.

    Disclaimer: IMPORTANT:  This Apple software is supplied to you by

    Apple Computer, Inc. ("Apple") in consideration of your agreement to the

    following terms, and your use, installation, modification or

    redistribution of this Apple software constitutes acceptance of these

    terms.  If you do not agree with these terms, please do not use,

    install, modify or redistribute this Apple software.

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    subject to these terms, Apple grants you a personal, non-exclusive

    license, under AppleÕs copyrights in this original Apple software (the

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    Software, with or without modifications, in source and/or binary forms;

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    without modifications, you must retain this notice and the following

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    Inc. may be used to endorse or promote products derived from the Apple

    Software without specific prior written permission from Apple.  Except

    as expressly stated in this notice, no other rights or licenses, express

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    any patent rights that may be infringed by your derivative works or by

    other works in which the Apple Software may be incorporated.

    The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

    MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

    THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

    FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

    OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

    IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

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*/

#include "CoreAudioPlayback.h"

// Return a ComponentDescription for a default output device AU

static void ConfigureOutputDescription(ComponentDescription *inOutputDesc)

{

    inOutputDesc->componentType = kAudioUnitType_Output;

    inOutputDesc->componentSubType = kAudioUnitSubType_DefaultOutput;

    inOutputDesc->componentManufacturer = kAudioUnitManufacturer_Apple;

    inOutputDesc->componentFlags = 0;

    inOutputDesc->componentFlagsMask = 0;

}

// Set the stream format on the output device AU.

// This only needs to set the input scope, since the output describes the audio hw settings.

static OSStatus SetOutputUnitStreamFormat(AudioUnit outputUnit, AudioStreamBasicDescription *asbd)

{

    return (AudioUnitSetProperty(outputUnit, kAudioUnitProperty_StreamFormat,

                                 kAudioUnitScope_Input, 0, asbd, sizeof(AudioStreamBasicDescription)));

}

// Set the channel layout on the output device AU.

// This only needs to set the input scope, since the output describes the audio hw settings.

// Setting the channel layout here helps route channels properly, but note that the OutputAU

// does not do channel mixdown.

static OSStatus SetOutputUnitChannelLayout(AudioUnit outputUnit, QTPropertyValuePtr layoutProperty, UInt32 size)

{

    return (AudioUnitSetProperty(outputUnit, kAudioUnitProperty_AudioChannelLayout,

                                 kAudioUnitScope_Input,0, layoutProperty, size));

}

// Return a ComponentDescription for a ScheduledSoundPlayer AU

static void ConfigureScheduledPlayerDescription(ComponentDescription *inPlayerDesc)

{

    inPlayerDesc->componentType = kAudioUnitType_Generator;

    inPlayerDesc->componentSubType = kAudioUnitSubType_ScheduledSoundPlayer;

    inPlayerDesc->componentManufacturer = kAudioUnitManufacturer_Apple;

    inPlayerDesc->componentFlags = 0;

    inPlayerDesc->componentFlagsMask = 0;

}   

// Set the stream format on the ScheduledSoundPlayer AU.

// This only needs to set the output scope, since the unit doesn't have an input scope.

static OSStatus SetPlayerUnitStreamFormat(AudioUnit playerUnit, AudioStreamBasicDescription *asbd)

{

    return (AudioUnitSetProperty(playerUnit, kAudioUnitProperty_StreamFormat,

                                 kAudioUnitScope_Output, 0, asbd, sizeof(AudioStreamBasicDescription)));

}

// Build a simple AUGraph containing a Default Output AU sourced by a ScheduledSoundPlayer AU.

// This allows us to schedule (from any thread) buffers of audio data to play automatically.

OSStatus BuildAUGraphPlayer(AudioChannelLayout *layout, UInt32 layoutSize,

                            AudioStreamBasicDescription *asbd,

                            AUGraphPlayerRef *graphUnit, AudioUnit *thePlayerUnit)

{

    OSStatus err = noErr;

    // Create a new AUGraph

    *graphUnit = nil;

    err = NewAUGraph(graphUnit);

    if (err) 

        goto bail;  

    // Add an output unit, and a scheduled sound player unit

    // Configure the two units.  

    ComponentDescription    output_desc, player_desc;

    ConfigureOutputDescription(&output_desc);

    ConfigureScheduledPlayerDescription(&player_desc);

    // Create new nodes inside our AUGraph for the output unit

    // and the AUScheduledSoundPlayer unit.

    AUNode outputNode, playerNode;

    err = AUGraphNewNode(*graphUnit, &output_desc, 0, NULL, &outputNode);

    if (err)        

        goto bail;

    err = AUGraphNewNode(*graphUnit, &player_desc, 0, NULL, &playerNode);

    if (err) 

        goto bail;

    // Connect the two graph nodes together and specify the way inputs are ordered.

    // The player node will route its output to the output node

    // connect the player to the output unit. 

    err = AUGraphConnectNodeInput(*graphUnit, playerNode, 0, outputNode, 0);

    if (err) 

        goto bail;

    // Open the graph: Instantiates every Audio Unit in the graph.

    err = AUGraphOpen(*graphUnit);

    if (err) 

        goto bail;  

    // Get the output unit & the player unit from their respective nodes    

    AudioUnit theOutputUnit;

    err = AUGraphGetNodeInfo(*graphUnit, outputNode, NULL, NULL, NULL, &theOutputUnit);

    if (err) 

        goto bail;

    err = AUGraphGetNodeInfo(*graphUnit, playerNode, NULL, NULL, NULL, thePlayerUnit);

    if (err) 

        goto bail;

    // Configure stream formats of the output and player to the specified format

    err = SetOutputUnitStreamFormat(theOutputUnit, asbd);

    if (err) 

        goto bail;

    err = SetPlayerUnitStreamFormat(*thePlayerUnit, asbd);

    if (err) 

        goto bail;

    // Get the extraction channel layout and map the output device

    err = SetOutputUnitChannelLayout(theOutputUnit, layout, layoutSize);

    if (err) 

        goto bail;

    // Initialize the graph

    err = AUGraphInitialize(*graphUnit);

    if (err) 

        goto bail;

bail:

    if (err && (*graphUnit != nil))

        AUGraphClose(*graphUnit);

    return (err);       

}

// Start the player graph running.

OSStatus StartAUGraphPlayer(AUGraphPlayerRef graphUnit)

{

    OSStatus    err = noErr;

    UInt32      numNodes;

    AudioUnit   playerUnit = nil;

    // Start the AUGraph

    err = AUGraphStart(graphUnit);

    if (err)

        goto bail;

    // Locate the AUScheduledSoundPlayer that we need to start.

    // It was added last, so its node number is the node count.

    err = AUGraphGetNodeCount(graphUnit, &numNodes);

    if (!err)

        err = AUGraphGetNodeInfo(graphUnit, numNodes, nil, nil, nil, &playerUnit);

    if (err || (playerUnit == nil))

        goto bail;

    // Start playback of the scheduledPlayer unit by setting its start time.

    AudioTimeStamp theTimeStamp = {0};

    theTimeStamp.mFlags = kAudioTimeStampSampleTimeValid;

    theTimeStamp.mSampleTime = -1.;     // start now

    err = AudioUnitSetProperty(playerUnit,

                kAudioUnitProperty_ScheduleStartTimeStamp, kAudioUnitScope_Global, 0,

                &theTimeStamp, sizeof(theTimeStamp));

bail:

    return (err);

}

void StopAUGraphPlayer(AUGraphPlayerRef graphUnit)

{

    if (graphUnit != nil) { 

        (void) AUGraphStop(graphUnit);

        (void) AUGraphUninitialize(graphUnit);

    }

}

void CloseAUGraphPlayer(AUGraphPlayerRef graphUnit)

{

    if (graphUnit != nil) { 

        StopAUGraphPlayer(graphUnit);

        (void) AUGraphClose(graphUnit);

    }

}