JSJP_Student/Pods/DOUAudioStreamer/src/DOUAudioDecoder.m

/* vim: set ft=objc fenc=utf-8 sw=2 ts=2 et: */
/*
 *  DOUAudioStreamer - A Core Audio based streaming audio player for iOS/Mac:
 *
 *      https://github.com/douban/DOUAudioStreamer
 *
 *  Copyright 2013-2016 Douban Inc.  All rights reserved.
 *
 *  Use and distribution licensed under the BSD license.  See
 *  the LICENSE file for full text.
 *
 *  Authors:
 *      Chongyu Zhu <i@lembacon.com>
 *
 */

#import "DOUAudioDecoder.h"
#import "DOUAudioFileProvider.h"
#import "DOUAudioPlaybackItem.h"
#import "DOUAudioLPCM.h"
#include <AudioToolbox/AudioToolbox.h>
#include <pthread.h>

typedef struct {
  AudioFileID afid;
  SInt64 pos;
  void *srcBuffer;
  UInt32 srcBufferSize;
  AudioStreamBasicDescription srcFormat;
  UInt32 srcSizePerPacket;
  UInt32 numPacketsPerRead;
  AudioStreamPacketDescription *pktDescs;
} AudioFileIO;

typedef struct {
  AudioStreamBasicDescription inputFormat;
  AudioStreamBasicDescription outputFormat;

  AudioFileIO afio;

  SInt64 decodeValidFrames;
  AudioStreamPacketDescription *outputPktDescs;

  UInt32 outputBufferSize;
  void *outputBuffer;

  UInt32 numOutputPackets;
  SInt64 outputPos;

  pthread_mutex_t mutex;
} DecodingContext;

@interface DOUAudioDecoder () {
@private
  DOUAudioPlaybackItem *_playbackItem;
  DOUAudioLPCM *_lpcm;

  AudioStreamBasicDescription _outputFormat;
  AudioConverterRef _audioConverter;

  NSUInteger _bufferSize;
  DecodingContext _decodingContext;
  BOOL _decodingContextInitialized;
}
@end

@implementation DOUAudioDecoder

@synthesize playbackItem = _playbackItem;
@synthesize lpcm = _lpcm;

+ (AudioStreamBasicDescription)defaultOutputFormat
{
  static AudioStreamBasicDescription defaultOutputFormat;

  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    defaultOutputFormat.mFormatID = kAudioFormatLinearPCM;
    defaultOutputFormat.mSampleRate = 44100;

    defaultOutputFormat.mBitsPerChannel = 16;
    defaultOutputFormat.mChannelsPerFrame = 2;
    defaultOutputFormat.mBytesPerFrame = defaultOutputFormat.mChannelsPerFrame * (defaultOutputFormat.mBitsPerChannel / 8);

    defaultOutputFormat.mFramesPerPacket = 1;
    defaultOutputFormat.mBytesPerPacket = defaultOutputFormat.mFramesPerPacket * defaultOutputFormat.mBytesPerFrame;

    defaultOutputFormat.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked;
  });

  return defaultOutputFormat;
}

+ (instancetype)decoderWithPlaybackItem:(DOUAudioPlaybackItem *)playbackItem
                             bufferSize:(NSUInteger)bufferSize
{
  return [[[self class] alloc] initWithPlaybackItem:playbackItem
                                         bufferSize:bufferSize];
}

- (instancetype)initWithPlaybackItem:(DOUAudioPlaybackItem *)playbackItem
                          bufferSize:(NSUInteger)bufferSize
{
  self = [super init];
  if (self) {
    _playbackItem = playbackItem;
    _bufferSize = bufferSize;
    _lpcm = [[DOUAudioLPCM alloc] init];

    _outputFormat = [[self class] defaultOutputFormat];
    [self _createAudioConverter];

    if (_audioConverter == NULL) {
      return nil;
    }
  }

  return self;
}

- (void)dealloc
{
  if (_decodingContextInitialized) {
    [self tearDown];
  }

  if (_audioConverter != NULL) {
    AudioConverterDispose(_audioConverter);
  }
}

- (void)_createAudioConverter
{
  AudioStreamBasicDescription inputFormat = [_playbackItem fileFormat];

  OSStatus status = AudioConverterNew(&inputFormat, &_outputFormat, &_audioConverter);
  if (status != noErr) {
    _audioConverter = NULL;
  }
}

- (void)_fillMagicCookieForAudioFileID:(AudioFileID)inputFile
{
  UInt32 cookieSize = 0;
  OSStatus status = AudioFileGetPropertyInfo(inputFile, kAudioFilePropertyMagicCookieData, &cookieSize, NULL);

  if (status == noErr && cookieSize > 0) {
    void *cookie = malloc(cookieSize);

    status = AudioFileGetProperty(inputFile, kAudioFilePropertyMagicCookieData, &cookieSize, cookie);
    if (status != noErr) {
      free(cookie);
      return;
    }

    status = AudioConverterSetProperty(_audioConverter, kAudioConverterDecompressionMagicCookie, cookieSize, cookie);
    free(cookie);
    if (status != noErr) {
      return;
    }
  }
}

- (BOOL)setUp
{
  if (_decodingContextInitialized) {
    return YES;
  }

  AudioFileID inputFile = [_playbackItem fileID];
  if (inputFile == NULL) {
    return NO;
  }

  _decodingContext.inputFormat = [_playbackItem fileFormat];
  _decodingContext.outputFormat = _outputFormat;
  [self _fillMagicCookieForAudioFileID:inputFile];

  UInt32 size;
  OSStatus status;

  size = sizeof(_decodingContext.inputFormat);
  status = AudioConverterGetProperty(_audioConverter, kAudioConverterCurrentInputStreamDescription, &size, &_decodingContext.inputFormat);
  if (status != noErr) {
    return NO;
  }

  size = sizeof(_decodingContext.outputFormat);
  status = AudioConverterGetProperty(_audioConverter, kAudioConverterCurrentOutputStreamDescription, &size, &_decodingContext.outputFormat);
  if (status != noErr) {
    return NO;
  }

  AudioStreamBasicDescription baseFormat;
  UInt32 propertySize = sizeof(baseFormat);
  AudioFileGetProperty(inputFile, kAudioFilePropertyDataFormat, &propertySize, &baseFormat);

  double actualToBaseSampleRateRatio = 1.0;
  if (_decodingContext.inputFormat.mSampleRate != baseFormat.mSampleRate &&
      _decodingContext.inputFormat.mSampleRate != 0.0 &&
      baseFormat.mSampleRate != 0.0) {
    actualToBaseSampleRateRatio = _decodingContext.inputFormat.mSampleRate / baseFormat.mSampleRate;
  }

  double srcRatio = 1.0;
  if (_decodingContext.outputFormat.mSampleRate != 0.0 &&
      _decodingContext.inputFormat.mSampleRate != 0.0) {
    srcRatio = _decodingContext.outputFormat.mSampleRate / _decodingContext.inputFormat.mSampleRate;
  }

  _decodingContext.decodeValidFrames = 0;
  AudioFilePacketTableInfo srcPti;
  if (_decodingContext.inputFormat.mBitsPerChannel == 0) {
    size = sizeof(srcPti);
    status = AudioFileGetProperty(inputFile, kAudioFilePropertyPacketTableInfo, &size, &srcPti);
    if (status == noErr) {
      _decodingContext.decodeValidFrames = (SInt64)(actualToBaseSampleRateRatio * srcRatio * srcPti.mNumberValidFrames + 0.5);

      AudioConverterPrimeInfo primeInfo;
      primeInfo.leadingFrames = (UInt32)(srcPti.mPrimingFrames * actualToBaseSampleRateRatio + 0.5);
      primeInfo.trailingFrames = 0;

      status = AudioConverterSetProperty(_audioConverter, kAudioConverterPrimeInfo, sizeof(primeInfo), &primeInfo);
      if (status != noErr) {
        return NO;
      }
    }
  }

  _decodingContext.afio.afid = inputFile;
  _decodingContext.afio.srcBufferSize = (UInt32)_bufferSize;
  _decodingContext.afio.srcBuffer = malloc(_decodingContext.afio.srcBufferSize);
  _decodingContext.afio.pos = 0;
  _decodingContext.afio.srcFormat = _decodingContext.inputFormat;

  if (_decodingContext.inputFormat.mBytesPerPacket == 0) {
    size = sizeof(_decodingContext.afio.srcSizePerPacket);
    status = AudioFileGetProperty(inputFile, kAudioFilePropertyPacketSizeUpperBound, &size, &_decodingContext.afio.srcSizePerPacket);
    if (status != noErr) {
      free(_decodingContext.afio.srcBuffer);
      return NO;
    }

    _decodingContext.afio.numPacketsPerRead = _decodingContext.afio.srcBufferSize / _decodingContext.afio.srcSizePerPacket;
    _decodingContext.afio.pktDescs = (AudioStreamPacketDescription *)malloc(sizeof(AudioStreamPacketDescription) * _decodingContext.afio.numPacketsPerRead);
  }
  else {
    _decodingContext.afio.srcSizePerPacket = _decodingContext.inputFormat.mBytesPerPacket;
    _decodingContext.afio.numPacketsPerRead = _decodingContext.afio.srcBufferSize / _decodingContext.afio.srcSizePerPacket;
    _decodingContext.afio.pktDescs = NULL;
  }

  _decodingContext.outputPktDescs = NULL;
  UInt32 outputSizePerPacket = _decodingContext.outputFormat.mBytesPerPacket;

  _decodingContext.outputBufferSize = (UInt32)_bufferSize;
  _decodingContext.outputBuffer = malloc(_decodingContext.outputBufferSize);

  if (outputSizePerPacket == 0) {
    size = sizeof(outputSizePerPacket);
    status = AudioConverterGetProperty(_audioConverter, kAudioConverterPropertyMaximumOutputPacketSize, &size, &outputSizePerPacket);
    if (status != noErr) {
      free(_decodingContext.afio.srcBuffer);
      free(_decodingContext.outputBuffer);
      if (_decodingContext.afio.pktDescs != NULL) {
        free(_decodingContext.afio.pktDescs);
      }
      return NO;
    }

    _decodingContext.outputPktDescs = (AudioStreamPacketDescription *)malloc(sizeof(AudioStreamPacketDescription) * _decodingContext.outputBufferSize / outputSizePerPacket);
  }

  _decodingContext.numOutputPackets = _decodingContext.outputBufferSize / outputSizePerPacket;
  _decodingContext.outputPos = 0;

  pthread_mutex_init(&_decodingContext.mutex, NULL);
  _decodingContextInitialized = YES;

  return YES;
}

- (void)tearDown
{
  if (!_decodingContextInitialized) {
    return;
  }

  free(_decodingContext.afio.srcBuffer);
  free(_decodingContext.outputBuffer);

  if (_decodingContext.afio.pktDescs != NULL) {
    free(_decodingContext.afio.pktDescs);
  }

  if (_decodingContext.outputPktDescs != NULL) {
    free(_decodingContext.outputPktDescs);
  }

  pthread_mutex_destroy(&_decodingContext.mutex);
  _decodingContextInitialized = NO;
}

static OSStatus decoder_data_proc(AudioConverterRef inAudioConverter, UInt32 *ioNumberDataPackets, AudioBufferList *ioData, AudioStreamPacketDescription **outDataPacketDescription, void *inUserData)
{
  AudioFileIO *afio = (AudioFileIO *)inUserData;

  if (*ioNumberDataPackets > afio->numPacketsPerRead) {
    *ioNumberDataPackets = afio->numPacketsPerRead;
  }

  UInt32 outNumBytes;
  OSStatus status = AudioFileReadPackets(afio->afid, FALSE, &outNumBytes, afio->pktDescs, afio->pos, ioNumberDataPackets, afio->srcBuffer);
  if (status != noErr) {
    return status;
  }

  afio->pos += *ioNumberDataPackets;

  ioData->mBuffers[0].mData = afio->srcBuffer;
  ioData->mBuffers[0].mDataByteSize = outNumBytes;
  ioData->mBuffers[0].mNumberChannels = afio->srcFormat.mChannelsPerFrame;

  if (outDataPacketDescription != NULL) {
    *outDataPacketDescription = afio->pktDescs;
  }

  return noErr;
}

- (DOUAudioDecoderStatus)decodeOnce
{
  if (!_decodingContextInitialized) {
    return DOUAudioDecoderFailed;
  }

  pthread_mutex_lock(&_decodingContext.mutex);

  DOUAudioFileProvider *provider = [_playbackItem fileProvider];
  if ([provider isFailed]) {
    [_lpcm setEnd:YES];
    pthread_mutex_unlock(&_decodingContext.mutex);
    return DOUAudioDecoderFailed;
  }
  if (![provider isFinished]) {
    NSUInteger dataOffset = [_playbackItem dataOffset];
    NSUInteger expectedDataLength = [provider expectedLength];
    NSInteger receivedDataLength  = (NSInteger)([provider receivedLength] - dataOffset);

    SInt64 packetNumber = _decodingContext.afio.pos + _decodingContext.afio.numPacketsPerRead;
    SInt64 packetDataOffset = packetNumber * _decodingContext.afio.srcSizePerPacket;

    SInt64 bytesPerPacket = _decodingContext.afio.srcSizePerPacket;
    SInt64 bytesPerRead = bytesPerPacket * _decodingContext.afio.numPacketsPerRead;

    SInt64 framesPerPacket = _decodingContext.inputFormat.mFramesPerPacket;
    double intervalPerPacket = 1000.0 / _decodingContext.inputFormat.mSampleRate * framesPerPacket;
    double intervalPerRead = intervalPerPacket / bytesPerPacket * bytesPerRead;

    double downloadTime = 1000.0 * (bytesPerRead - (receivedDataLength - packetDataOffset)) / [provider downloadSpeed];
    SInt64 bytesRemaining = (SInt64)(expectedDataLength - (NSUInteger)receivedDataLength);

    if (receivedDataLength < packetDataOffset ||
        (bytesRemaining > 0 &&
        downloadTime > intervalPerRead)) {
      pthread_mutex_unlock(&_decodingContext.mutex);
      return DOUAudioDecoderWaiting;
    }
  }

  AudioBufferList fillBufList;
  fillBufList.mNumberBuffers = 1;
  fillBufList.mBuffers[0].mNumberChannels = _decodingContext.inputFormat.mChannelsPerFrame;
  fillBufList.mBuffers[0].mDataByteSize = _decodingContext.outputBufferSize;
  fillBufList.mBuffers[0].mData = _decodingContext.outputBuffer;

  OSStatus status;

  UInt32 ioOutputDataPackets = _decodingContext.numOutputPackets;
  status = AudioConverterFillComplexBuffer(_audioConverter, decoder_data_proc, &_decodingContext.afio, &ioOutputDataPackets, &fillBufList, _decodingContext.outputPktDescs);
  if (status != noErr) {
    pthread_mutex_unlock(&_decodingContext.mutex);
    return DOUAudioDecoderFailed;
  }

  if (ioOutputDataPackets == 0) {
    [_lpcm setEnd:YES];
    pthread_mutex_unlock(&_decodingContext.mutex);
    return DOUAudioDecoderEndEncountered;
  }

  SInt64 frame1 = _decodingContext.outputPos + ioOutputDataPackets;
  if (_decodingContext.decodeValidFrames != 0 &&
      frame1 > _decodingContext.decodeValidFrames) {
    SInt64 framesToTrim64 = frame1 - _decodingContext.decodeValidFrames;
    UInt32 framesToTrim = (framesToTrim64 > ioOutputDataPackets) ? ioOutputDataPackets : (UInt32)framesToTrim64;
    int bytesToTrim = (int)(framesToTrim * _decodingContext.outputFormat.mBytesPerFrame);

    fillBufList.mBuffers[0].mDataByteSize -= (unsigned long)bytesToTrim;
    ioOutputDataPackets -= framesToTrim;

    if (ioOutputDataPackets == 0) {
      [_lpcm setEnd:YES];
      pthread_mutex_unlock(&_decodingContext.mutex);
      return DOUAudioDecoderEndEncountered;
    }
  }

  UInt32 inNumBytes = fillBufList.mBuffers[0].mDataByteSize;
  [_lpcm writeBytes:_decodingContext.outputBuffer length:inNumBytes];
  _decodingContext.outputPos += ioOutputDataPackets;

  pthread_mutex_unlock(&_decodingContext.mutex);
  return DOUAudioDecoderSucceeded;
}

- (void)seekToTime:(NSUInteger)milliseconds
{
  if (!_decodingContextInitialized) {
    return;
  }

  pthread_mutex_lock(&_decodingContext.mutex);

  double frames = (double)milliseconds * _decodingContext.inputFormat.mSampleRate / 1000.0;
  double packets = frames / _decodingContext.inputFormat.mFramesPerPacket;
  SInt64 packetNumebr = (SInt64)lrint(floor(packets));

  _decodingContext.afio.pos = packetNumebr;
  _decodingContext.outputPos = packetNumebr * _decodingContext.inputFormat.mFramesPerPacket / _decodingContext.outputFormat.mFramesPerPacket;
  
  pthread_mutex_unlock(&_decodingContext.mutex);
}

@end