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@H_446_15@mPMediaItem *item = // obtain the media item NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // Get raw PCM data from the track NSURL *assetURL = [item valueForProperty:MPMediaItemPropertyAssetURL]; NSMutableData *data = [[NSMutableData alloc] init]; const uint32_t sampleRate = 16000; // 16k sample/sec const uint16_t bitDepth = 16; // 16 bit/sample/chAnnel const uint16_t chAnnels = 2; // 2 chAnnel/sample (stereo) NSDictionary *opts = [NSDictionary Dictionary]; AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:assetURL options:opts]; AVAssetReader *reader = [[AVAssetReader alloc] initWithAsset:asset error:NULL]; NSDictionary *setTings = [NSDictionary DictionaryWithObjectsAndKeys: [NSnumber numberWithInt:kAudioFormatLinearPCM],AVFormatIDKey,[NSnumber numberWithFloat:(float)sampleRate],AVSampleRateKey,[NSnumber numberWithInt:bitDepth],AVLinearPCMBitDepthKey,[NSnumber numberWithBool:NO],AVLinearPCMIsnonInterleaved,AVLinearPCMIsFloatKey,AVLinearPCMIsBigendianKey,nil]; AVAssetReaderTrackOutput *output = [[AVAssetReaderTrackOutput alloc] initWithTrack: [[asset tracks] objectATindex:0] outputSetTings:setTings]; [asset release]; [reader addOutput:output]; [reader startReading]; // read the samples from the asset and append them subsequently while ([reader status] != AVAssetReaderStatusCompleted) { CMSampleBufferRef buffer = [output copyNextSampleBuffer]; if (buffer == NULL) conTinue; CMBlockBufferRef blockBuffer = CMSampleBufferGetDataBuffer(buffer); size_t size = CMBlockBufferGetDataLength(blockBuffer); uint8_t *outBytes = malloc(sizE); CMBlockBufferCopyDataBytes(blockBuffer,size,outBytes); CMSampleBufferInvalidate(buffer); CFRelease(buffer); [data appendBytes:outBytes length:size]; free(outBytes);
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