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aqofflinerender.cpp

/*

    File: aqofflinerender.cpp

Abstract: Demonstrates the use of AudioQueueOfflineRender

 Version: 1.0

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*/

// standard includes

#include <AudioToolbox/AudioQueue.h>

#include <AudioToolbox/AudioFile.h>

#include <AudioToolbox/ExtendedAudioFile.h>

// helpers

#include "CAXException.h"

#include "CAStreamBasicDescription.h"

// the application specific info we keep track of

struct AQTestInfo

    AudioFileID                     mAudioFile;

    CAStreamBasicDescription        mDataFormat;

    AudioQueueRef                   mQueue;

    AudioQueueBufferRef             mBuffer;

    SInt64                          mCurrentPacket;

    UInt32                          mNumPacketsToRead;

    AudioStreamPacketDescription    *mPacketDescs;

    bool                            mFlushed;

    bool                            mDone;

};

#pragma mark- Helper Functions

// ***********************

// CalculateBytesForTime Utility Function

    // we only use time here as a guideline

    // we are really trying to get somewhere between 16K and 64K buffers, but not allocate too much if we don't need it

void CalculateBytesForTime (CAStreamBasicDescription & inDesc, UInt32 inMaxPacketSize, Float64 inSeconds, UInt32 *outBufferSize, UInt32 *outNumPackets)

    static const int maxBufferSize = 0x10000;   // limit size to 64K

    static const int minBufferSize = 0x4000;    // limit size to 16K

    if (inDesc.mFramesPerPacket) {

        Float64 numPacketsForTime = inDesc.mSampleRate / inDesc.mFramesPerPacket * inSeconds;

        *outBufferSize = numPacketsForTime * inMaxPacketSize;

    } else {

        // if frames per packet is zero, then the codec has no predictable packet == time

        // so we can't tailor this (we don't know how many Packets represent a time period

        // we'll just return a default buffer size

        *outBufferSize = maxBufferSize > inMaxPacketSize ? maxBufferSize : inMaxPacketSize;

        // we're going to limit our size to our default

    if (*outBufferSize > maxBufferSize && *outBufferSize > inMaxPacketSize) {

        *outBufferSize = maxBufferSize;

    } else {

        // also make sure we're not too small - we don't want to go the disk for too small chunks

        if (*outBufferSize < minBufferSize) {

            *outBufferSize = minBufferSize;

    *outNumPackets = *outBufferSize / inMaxPacketSize;

#pragma mark- AQOutputCallback

// ***********************

// AudioQueueOutputCallback function used to push data into the audio queue

static void AQTestBufferCallback(void *inUserData, AudioQueueRef inAQ, AudioQueueBufferRef inCompleteAQBuffer)

    AQTestInfo * myInfo = (AQTestInfo *)inUserData;

    if (myInfo->mDone) return;

    UInt32 numBytes;

    UInt32 nPackets = myInfo->mNumPacketsToRead;

    OSStatus result = AudioFileReadPackets(myInfo->mAudioFile,      // The audio file from which packets of audio data are to be read.

                                           false,                   // Set to true to cache the data. Otherwise, set to false.

                                           &numBytes,               // On output, a pointer to the number of bytes actually returned.

                                           myInfo->mPacketDescs,    // A pointer to an array of packet descriptions that have been allocated.

                                           myInfo->mCurrentPacket,  // The packet index of the first packet you want to be returned.

                                           &nPackets,               // On input, a pointer to the number of packets to read. On output, the number of packets actually read.

                                           inCompleteAQBuffer->mAudioData); // A pointer to user-allocated memory.

    if (result) {

        DebugMessageN1 ("Error reading from file: %d\n", (int)result);

        exit(1);

    // we have some data

    if (nPackets > 0) {

        inCompleteAQBuffer->mAudioDataByteSize = numBytes;

        result = AudioQueueEnqueueBuffer(inAQ,                                  // The audio queue that owns the audio queue buffer.

                                         inCompleteAQBuffer,                    // The audio queue buffer to add to the buffer queue.

                                         (myInfo->mPacketDescs ? nPackets : 0), // The number of packets of audio data in the inBuffer parameter. See Docs.

                                         myInfo->mPacketDescs);                 // An array of packet descriptions. Or NULL. See Docs.

        if (result) {

            DebugMessageN1 ("Error enqueuing buffer: %d\n", (int)result);

            exit(1);

        myInfo->mCurrentPacket += nPackets;

    } else {

        // **** This ensures that we flush the queue when done -- ensures you get all the data out ****

        if (!myInfo->mFlushed) {

            result = AudioQueueFlush(myInfo->mQueue);

            if (result) {

                DebugMessageN1("AudioQueueFlush failed: %d", (int)result);

                exit(1);

            myInfo->mFlushed = true;

        result = AudioQueueStop(myInfo->mQueue, false);

        if (result) {

            DebugMessageN1("AudioQueueStop(false) failed: %d", (int)result);

            exit(1);

        // reading nPackets == 0 is our EOF condition

        myInfo->mDone = true;

// ***********************

#pragma mark- Main Render Function

void DoAQOfflineRender(CFURLRef sourceURL, CFURLRef destinationURL)

    // main audio queue code

    try {

        AQTestInfo myInfo;

        myInfo.mDone = false;

        myInfo.mFlushed = false;

        myInfo.mCurrentPacket = 0;

        // get the source file

        XThrowIfError(AudioFileOpenURL(sourceURL, 0x01/*fsRdPerm*/, 0/*inFileTypeHint*/, &myInfo.mAudioFile), "AudioFileOpen failed");

        UInt32 size = sizeof(myInfo.mDataFormat);

        XThrowIfError(AudioFileGetProperty(myInfo.mAudioFile, kAudioFilePropertyDataFormat, &size, &myInfo.mDataFormat), "couldn't get file's data format");

        printf ("File format: "); myInfo.mDataFormat.Print();

        // create a new audio queue output

        XThrowIfError(AudioQueueNewOutput(&myInfo.mDataFormat,      // The data format of the audio to play. For linear PCM, only interleaved formats are supported.

                                          AQTestBufferCallback,     // A callback function to use with the playback audio queue.

                                          &myInfo,                  // A custom data structure for use with the callback function.

                                          CFRunLoopGetCurrent(),    // The event loop on which the callback function pointed to by the inCallbackProc parameter is to be called.

                                                                    // If you specify NULL, the callback is invoked on one of the audio queue’s internal threads.

                                          kCFRunLoopCommonModes,    // The run loop mode in which to invoke the callback function specified in the inCallbackProc parameter.

                                          0,                        // Reserved for future use. Must be 0.

                                          &myInfo.mQueue),          // On output, the newly created playback audio queue object.

                                          "AudioQueueNew failed");

        UInt32 bufferByteSize;

        // we need to calculate how many packets we read at a time and how big a buffer we need

        // we base this on the size of the packets in the file and an approximate duration for each buffer

            bool isFormatVBR = (myInfo.mDataFormat.mBytesPerPacket == 0 || myInfo.mDataFormat.mFramesPerPacket == 0);

            // first check to see what the max size of a packet is - if it is bigger

            // than our allocation default size, that needs to become larger

            UInt32 maxPacketSize;

            size = sizeof(maxPacketSize);

            XThrowIfError(AudioFileGetProperty(myInfo.mAudioFile, kAudioFilePropertyPacketSizeUpperBound, &size, &maxPacketSize), "couldn't get file's max packet size");

            // adjust buffer size to represent about a second of audio based on this format

            CalculateBytesForTime(myInfo.mDataFormat, maxPacketSize, 1.0/*seconds*/, &bufferByteSize, &myInfo.mNumPacketsToRead);

            if (isFormatVBR) {

                myInfo.mPacketDescs = new AudioStreamPacketDescription [myInfo.mNumPacketsToRead];

            } else {

                myInfo.mPacketDescs = NULL; // we don't provide packet descriptions for constant bit rate formats (like linear PCM)

            printf ("Buffer Byte Size: %d, Num Packets to Read: %d\n", (int)bufferByteSize, (int)myInfo.mNumPacketsToRead);

        // if the file has a magic cookie, we should get it and set it on the AQ

        size = sizeof(UInt32);

        OSStatus result = AudioFileGetPropertyInfo (myInfo.mAudioFile, kAudioFilePropertyMagicCookieData, &size, NULL);

        if (!result && size) {

            char* cookie = new char [size];

            XThrowIfError (AudioFileGetProperty (myInfo.mAudioFile, kAudioFilePropertyMagicCookieData, &size, cookie), "get cookie from file");

            XThrowIfError (AudioQueueSetProperty(myInfo.mQueue, kAudioQueueProperty_MagicCookie, cookie, size), "set cookie on queue");

            delete [] cookie;

        // channel layout?

        OSStatus err = AudioFileGetPropertyInfo(myInfo.mAudioFile, kAudioFilePropertyChannelLayout, &size, NULL);

        AudioChannelLayout *acl = NULL;

        if (err == noErr && size > 0) {

            acl = (AudioChannelLayout *)malloc(size);

            XThrowIfError(AudioFileGetProperty(myInfo.mAudioFile, kAudioFilePropertyChannelLayout, &size, acl), "get audio file's channel layout");

            XThrowIfError(AudioQueueSetProperty(myInfo.mQueue, kAudioQueueProperty_ChannelLayout, acl, size), "set channel layout on queue");

        //allocate the input read buffer

        XThrowIfError(AudioQueueAllocateBuffer(myInfo.mQueue, bufferByteSize, &myInfo.mBuffer), "AudioQueueAllocateBuffer");

        // prepare a canonical interleaved capture format

        CAStreamBasicDescription captureFormat;

        captureFormat.mSampleRate = myInfo.mDataFormat.mSampleRate;

        captureFormat.SetAUCanonical(myInfo.mDataFormat.mChannelsPerFrame, true); // interleaved

        XThrowIfError(AudioQueueSetOfflineRenderFormat(myInfo.mQueue, &captureFormat, acl), "set offline render format");

        ExtAudioFileRef captureFile;

        // prepare a 16-bit int file format, sample channel count and sample rate

        CAStreamBasicDescription dstFormat;

        dstFormat.mSampleRate = myInfo.mDataFormat.mSampleRate;

        dstFormat.mChannelsPerFrame = myInfo.mDataFormat.mChannelsPerFrame;

        dstFormat.mFormatID = kAudioFormatLinearPCM;

        dstFormat.mFormatFlags = kLinearPCMFormatFlagIsPacked | kLinearPCMFormatFlagIsSignedInteger; // little-endian

        dstFormat.mBitsPerChannel = 16;

        dstFormat.mBytesPerPacket = dstFormat.mBytesPerFrame = 2 * dstFormat.mChannelsPerFrame;

        dstFormat.mFramesPerPacket = 1;

        // create the capture file

        XThrowIfError(ExtAudioFileCreateWithURL(destinationURL, kAudioFileCAFType, &dstFormat, acl, kAudioFileFlags_EraseFile, &captureFile), "ExtAudioFileCreateWithURL");

        // set the capture file's client format to be the canonical format from the queue

        XThrowIfError(ExtAudioFileSetProperty(captureFile, kExtAudioFileProperty_ClientDataFormat, sizeof(AudioStreamBasicDescription), &captureFormat), "set ExtAudioFile client format");

        // allocate the capture buffer, just keep it at half the size of the enqueue buffer

        // we don't ever want to pull any faster than we can push data in for render

        // this 2:1 ratio keeps the AQ Offline Render happy

        const UInt32 captureBufferByteSize = bufferByteSize / 2;

        AudioQueueBufferRef captureBuffer;

        AudioBufferList captureABL;

        XThrowIfError(AudioQueueAllocateBuffer(myInfo.mQueue, captureBufferByteSize, &captureBuffer), "AudioQueueAllocateBuffer");

        captureABL.mNumberBuffers = 1;

        captureABL.mBuffers[0].mData = captureBuffer->mAudioData;

        captureABL.mBuffers[0].mNumberChannels = captureFormat.mChannelsPerFrame;

        // lets start playing now - stop is called in the AQTestBufferCallback when there's

        // no more to read from the file

        XThrowIfError(AudioQueueStart(myInfo.mQueue, NULL), "AudioQueueStart failed");

        AudioTimeStamp ts;

        ts.mFlags = kAudioTimeStampSampleTimeValid;

        ts.mSampleTime = 0;

        // we need to call this once asking for 0 frames

        XThrowIfError(AudioQueueOfflineRender(myInfo.mQueue, &ts, captureBuffer, 0), "AudioQueueOfflineRender");

        // we need to enqueue a buffer after the queue has started

        AQTestBufferCallback(&myInfo, myInfo.mQueue, myInfo.mBuffer);

        while (true) {

            UInt32 reqFrames = captureBufferByteSize / captureFormat.mBytesPerFrame;

            XThrowIfError(AudioQueueOfflineRender(myInfo.mQueue, &ts, captureBuffer, reqFrames), "AudioQueueOfflineRender");

            captureABL.mBuffers[0].mData = captureBuffer->mAudioData;

            captureABL.mBuffers[0].mDataByteSize = captureBuffer->mAudioDataByteSize;

            UInt32 writeFrames = captureABL.mBuffers[0].mDataByteSize / captureFormat.mBytesPerFrame;

            printf("t = %.f: AudioQueueOfflineRender:  req %d fr/%d bytes, got %ld fr/%d bytes\n", ts.mSampleTime, (int)reqFrames, (int)captureBufferByteSize, writeFrames, (int)captureABL.mBuffers[0].mDataByteSize);

            XThrowIfError(ExtAudioFileWrite(captureFile, writeFrames, &captureABL), "ExtAudioFileWrite");

            if (myInfo.mFlushed) break;

            ts.mSampleTime += writeFrames;

        CFRunLoopRunInMode(kCFRunLoopDefaultMode, 1, false);

        XThrowIfError(AudioQueueDispose(myInfo.mQueue, true), "AudioQueueDispose(true) failed");

        XThrowIfError(AudioFileClose(myInfo.mAudioFile), "AudioQueueDispose(false) failed");

        XThrowIfError(ExtAudioFileDispose(captureFile), "ExtAudioFileDispose failed");

        if (myInfo.mPacketDescs) delete [] myInfo.mPacketDescs;

        if (acl) free(acl);

    catch (CAXException e) {

        char buf[256];

        fprintf(stderr, "Error: %s (%s)\n", e.mOperation, e.FormatError(buf));

    return;

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