+ (void)mp3ToPCMWithMp3File:(NSString*)mp3FilePath outPutPCMPath:(NSString*)outPutPCMPath mp3ToPcmComplete:(Mp3ToPcmComplete)mp3ToPcmComplete {
AVAsset*asset = [OCmp3ToPCMreadMp3FileWithMp3File:mp3FilePath];
AVAssetReader*assetReader = [OCmp3ToPCMinitAssetReaderWithAsset:asset];
AudioChannelLayoutchannelLayout;
memset(&channelLayout,0,sizeof(channelLayout));
channelLayout.mChannelLayoutTag = kAudioChannelLayoutTag_Stereo;
NSDictionary*outputSettings =@{AVFormatIDKey:@(kAudioFormatLinearPCM), // 音频格式
AVSampleRateKey:@(44100), // 采样率
// AVSampleRateKey : @(22050), // 采样率
AVNumberOfChannelsKey:@(2), // 通道数 1 || 2
AVChannelLayoutKey: [NSDatadataWithBytes:&channelLayoutlength:sizeof(channelLayout)], // 声音效果（立体声）
AVLinearPCMBitDepthKey:@(16), // 音频的每个样点的位数
AVLinearPCMIsNonInterleaved:@NO, // 音频采样是否非交错
AVLinearPCMIsFloatKey:@NO, // 采样信号是否浮点数
AVLinearPCMIsBigEndianKey:@NO// 音频采用高位优先的记录格式
};
AVAssetReaderAudioMixOutput *readerAudioMixOutput = [[AVAssetReaderAudioMixOutput alloc] initWithAudioTracks:asset.tracks audioSettings:outputSettings];
if(![assetReadercanAddOutput:readerAudioMixOutput]) {
NSLog(@"can't add readerAudioMixOutput");
return;
}
[assetReaderaddOutput:readerAudioMixOutput];
AVAssetWriter*assetWriter = [OCmp3ToPCMinitAssetWriterWithPCMName:outPutPCMPath];
if(![assetWritercanApplyOutputSettings:outputSettingsforMediaType:AVMediaTypeAudio]) {
NSLog(@"can't apply outputSettings");
return;
}
AVAssetWriterInput *writerInput = [[AVAssetWriterInput alloc] initWithMediaType:AVMediaTypeAudio outputSettings:outputSettings];
writerInput.expectsMediaDataInRealTime = NO;
if(![assetWritercanAddInput:writerInput]) {
NSLog(@"can't add writerInput");
return;
}
[assetWriteraddInput:writerInput];
[assetReaderstartReading];
[assetWriterstartWriting];
AVAssetTrack *track = asset.tracks.firstObject;
if(!track) {
return;
}
CMTimestartTime =CMTimeMakeWithSeconds(0, track.naturalTimeScale);
[assetWriterstartSessionAtSourceTime:startTime];
dispatch_queue_t mediaInputQueue = dispatch_queue_create([@"mediaInputQueue" cStringUsingEncoding:NSASCIIStringEncoding], DISPATCH_QUEUE_SERIAL);
[writerInputrequestMediaDataWhenReadyOnQueue:mediaInputQueue usingBlock:^{
while(writerInput.isReadyForMoreMediaData) {
CMSampleBufferRefnextBuffer = readerAudioMixOutput.copyNextSampleBuffer;
if(nextBuffer) {
[writerInputappendSampleBuffer:nextBuffer];
}else{
[writerInputmarkAsFinished];
[assetReadercancelReading];
[assetWriterfinishWritingWithCompletionHandler:^{
NSLog(@"mp3转pcm完成");
if(mp3ToPcmComplete) {
mp3ToPcmComplete();
}
}];
break;
}
}
}];
}
+ (AVAsset*)readMp3FileWithMp3File:(NSString*)mp3FilePath {
NSURL*fileURL = [NSURLfileURLWithPath:mp3FilePath];
AVAsset*asset = [AVAssetassetWithURL:fileURL];
returnasset;
}
+ (AVAssetReader*)initAssetReaderWithAsset:(AVAsset*)asset {
NSError*error;
AVAssetReader*assetReader;
assetReader = [[AVAssetReaderalloc]initWithAsset:asseterror:&error];
returnassetReader;
}
+ (AVAssetWriter*)initAssetWriterWithPCMName:(NSString*)outPutPCMPath {
NSError*error;
AVAssetWriter*assetWriter;
NSURL*outPutURL = [NSURLfileURLWithPath:outPutPCMPath];
assetWriter = [[AVAssetWriteralloc]initWithURL:outPutURLfileType:AVFileTypeWAVEerror:&error];
returnassetWriter;
}
