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POAVAssetReader making mp3 file bigger?
 

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    <p>It appears that my song file that I am trying to grab from the user library is being blown up to 50MB after the code below. However, I know this song to be 7.2MB. I'd like to attach the music file (DRM free) to an email, but 50MB is obviously too big. The code I use is below. Any help would be appreciated :)</p> <pre><code>-(void)findSong { MPMediaQuery *query = [MPMediaQuery songsQuery]; NSArray *songsQuery = [query collections]; //create media item MPMediaItemCollection *mySong = [songsQuery objectAtIndex:1]; NSLog(@"song name: %@",[[mySong representativeItem]valueForProperty:MPMediaItemPropertyTitle]); NSURL *assetURL = [[mySong representativeItem]valueForProperty:MPMediaItemPropertyAssetURL]; AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil]; NSError *assetError = nil; AVAssetReader *assetReader = [[AVAssetReader assetReaderWithAsset:songAsset error:&amp;assetError] retain]; if (assetError) { NSLog (@"error: %@", assetError); return; } AVAssetReaderOutput *assetReaderOutput = [[AVAssetReaderAudioMixOutput assetReaderAudioMixOutputWithAudioTracks:songAsset.tracks audioSettings: nil] retain]; if (! [assetReader canAddOutput: assetReaderOutput]) { NSLog (@"can't add reader output... die!"); return; } [assetReader addOutput: assetReaderOutput]; NSArray *dirs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectoryPath = [dirs objectAtIndex:0]; NSString *exportPath = [[documentsDirectoryPath stringByAppendingPathComponent:EXPORT_NAME] retain]; if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath]) { [[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil]; } NSURL *exportURL = [NSURL fileURLWithPath:exportPath]; AVAssetWriter *assetWriter = [[AVAssetWriter assetWriterWithURL:exportURL fileType:AVFileTypeCoreAudioFormat error:&amp;assetError] retain]; if (assetError) { NSLog (@"error: %@", assetError); return; } AudioChannelLayout channelLayout; memset(&amp;channelLayout, 0, sizeof(AudioChannelLayout)); channelLayout.mChannelLayoutTag = kAudioChannelLayoutTag_Stereo; NSDictionary *outputSettings = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:kAudioFormatLinearPCM], AVFormatIDKey, [NSNumber numberWithFloat:44100.0], 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] retain]; 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: ^ { // NSLog (@"top of block"); while (assetWriterInput.readyForMoreMediaData) { CMSampleBufferRef nextBuffer = [assetReaderOutput copyNextSampleBuffer]; if (nextBuffer) { // append buffer [assetWriterInput appendSampleBuffer: nextBuffer]; // NSLog (@"appended a buffer (%d bytes)", // CMSampleBufferGetTotalSampleSize (nextBuffer)); convertedByteCount += CMSampleBufferGetTotalSampleSize (nextBuffer); } else { // done! [assetWriterInput markAsFinished]; [assetWriter finishWriting]; [assetReader cancelReading]; NSDictionary *outputFileAttributes = [[NSFileManager defaultManager] attributesOfItemAtPath:exportPath error:nil]; NSLog(@"export path: %@",exportPath); NSLog (@"done. file size is %ld",[outputFileAttributes fileSize]); NSURL *exportURL = [NSURL fileURLWithPath:exportPath]; NSData *data = [NSData dataWithContentsOfURL:exportURL]; data = [ChannelViewController gzipData:data]; [self performSelectorOnMainThread:@selector(sendMailWithData:) withObject:data waitUntilDone:NO]; // release a lot of stuff [assetReader release]; [assetReaderOutput release]; [assetWriter release]; [assetWriterInput release]; [exportPath release]; break; } } }]; NSLog (@"bottom of convertTapped:"); } </code></pre>
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