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POHow to read and write audio file using NSInputStream and NSOutputStream
 

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    <p>I record and save the caf audio file using AVAudioRecorder. When I convert the (300 mb).caf to .wav format the Application crashed with error(Received memory warning. Level=1 and Received memory warning. Level=2). How to use NSInputStream for reading audio file and NSOutputStream for writing audio file.</p> <pre><code>-(void) convertToWav:(NSNumber *) numIndex { // set up an AVAssetReader to read from the iPod Library int index = [numIndex integerValue]; NSString *strName; NSString *strFilePath1 =[delegate.strCassettePathSide stringByAppendingPathComponent:@"audio_list.plist"]; bool bTapeInfoFileExists = [[NSFileManager defaultManager] fileExistsAtPath:strFilePath1]; if (bTapeInfoFileExists) { NSMutableDictionary *dictInfo = [[NSMutableDictionary alloc] initWithContentsOfFile:strFilePath1]; if ([dictInfo valueForKey:@"lastName"]) strName =[dictInfo valueForKey:@"lastName"]; else strName= [delegate.arrNameList objectAtIndex:0]; } else { strName = [delegate.arrNameList objectAtIndex:0]; } NSString *cafFilePath =[[delegate.arrSessionList objectAtIndex:index] valueForKey:@"path"]; NSURL *assetURL = [NSURL fileURLWithPath:cafFilePath]; AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil]; NSError *assetError = nil; AVAssetReader *assetReader = [AVAssetReader assetReaderWithAsset:songAsset error:&amp;assetError] ; if (assetError) { NSLog (@"error: %@", assetError); return; } AVAssetReaderOutput *assetReaderOutput = [AVAssetReaderAudioMixOutput assetReaderAudioMixOutputWithAudioTracks:songAsset.tracks audioSettings: nil]; if (! [assetReader canAddOutput: assetReaderOutput]) { NSLog (@"can't add reader output... die!"); return; } [assetReader addOutput: assetReaderOutput]; NSString *strWavFileName = [NSString stringWithFormat:@"%@.wav",[[cafFilePath lastPathComponent] stringByDeletingPathExtension]]; NSString *wavFilePath = [delegate.strCassettePathSide stringByAppendingPathComponent:strWavFileName]; if ([[NSFileManager defaultManager] fileExistsAtPath:wavFilePath]) { [[NSFileManager defaultManager] removeItemAtPath:wavFilePath error:nil]; } NSURL *exportURL = [NSURL fileURLWithPath:wavFilePath]; AVAssetWriter *assetWriter = [AVAssetWriter assetWriterWithURL:exportURL fileType:AVFileTypeWAVE error:&amp;assetError]; if (assetError) { NSLog (@"error: %@", assetError); return; } AppDelegate *appDelegate =[[UIApplication sharedApplication]delegate]; int nSampleRate=[[appDelegate.dictWAVQuality valueForKey:@"samplerate"] integerValue]; AudioChannelLayout channelLayout; memset(&amp;channelLayout, 0, sizeof(AudioChannelLayout)); channelLayout.mChannelLayoutTag = kAudioChannelLayoutTag_Stereo; NSDictionary *outputSettings = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:kAudioFormatLinearPCM], AVFormatIDKey, [NSNumber numberWithFloat:nSampleRate], AVSampleRateKey, [NSNumber numberWithInt:2], AVNumberOfChannelsKey, [NSData dataWithBytes:&amp;channelLayout length:sizeof(AudioChannelLayout)], AVChannelLayoutKey, [NSNumber numberWithInt:16], AVLinearPCMBitDepthKey, [NSNumber numberWithBool:NO], AVLinearPCMIsNonInterleaved, [NSNumber numberWithBool:NO],AVLinearPCMIsFloatKey, [NSNumber numberWithBool:NO], AVLinearPCMIsBigEndianKey, nil]; AVAssetWriterInput *assetWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:outputSettings]; if ([assetWriter canAddInput:assetWriterInput]) { [assetWriter addInput:assetWriterInput]; } else { NSLog(@"can't add asset writer input... die!"); return; } assetWriterInput.expectsMediaDataInRealTime = NO; [assetWriter startWriting]; [assetReader startReading]; AVAssetTrack *soundTrack = [songAsset.tracks objectAtIndex:0]; CMTime startTime = CMTimeMake (0, soundTrack.naturalTimeScale); [assetWriter startSessionAtSourceTime: startTime]; __block UInt64 convertedByteCount = 0; dispatch_queue_t mediaInputQueue = dispatch_queue_create("mediaInputQueue", NULL); [assetWriterInput requestMediaDataWhenReadyOnQueue:mediaInputQueue usingBlock: ^ { while (assetWriterInput.readyForMoreMediaData) { CMSampleBufferRef nextBuffer = [assetReaderOutput copyNextSampleBuffer]; if (nextBuffer) { // append buffer [assetWriterInput appendSampleBuffer: nextBuffer]; convertedByteCount += CMSampleBufferGetTotalSampleSize (nextBuffer); } else { [assetWriterInput markAsFinished]; // [assetWriter finishWriting]; [assetReader cancelReading]; [dictTemp setValue:wavFilePath forKey:@"path"]; [dictTemp setValue:nil forKey:@"progress"]; [delegate.arrSessionList replaceObjectAtIndex:index withObject:dictTemp]; NSString *strListFilePath = [delegate.strCassettePathSide stringByAppendingPathComponent:@"audiolist.plist"]; [delegate.arrSessionList writeToFile:strListFilePath atomically:YES]; break; } } }];} </code></pre>
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    1. COIt might be useful to show us some of the code you have.
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    2. COneilco I updated with my code
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