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    <p>I'm doing something similar in my own code. The following method returns some NSData for a AVURLAsset:</p> <pre><code>- (NSData *)extractDataForAsset:(AVURLAsset *)songAsset { NSError * error = nil; AVAssetReader * reader = [[AVAssetReader alloc] initWithAsset:songAsset error:&amp;error]; AVAssetTrack * songTrack = [songAsset.tracks objectAtIndex:0]; AVAssetReaderTrackOutput * output = [[AVAssetReaderTrackOutput alloc] initWithTrack:songTrack outputSettings:nil]; [reader addOutput:output]; [output release]; NSMutableData * fullSongData = [[NSMutableData alloc] init]; [reader startReading]; while (reader.status == AVAssetReaderStatusReading){ AVAssetReaderTrackOutput * trackOutput = (AVAssetReaderTrackOutput *)[reader.outputs objectAtIndex:0]; CMSampleBufferRef sampleBufferRef = [trackOutput copyNextSampleBuffer]; if (sampleBufferRef){ CMBlockBufferRef blockBufferRef = CMSampleBufferGetDataBuffer(sampleBufferRef); size_t length = CMBlockBufferGetDataLength(blockBufferRef); UInt8 buffer[length]; CMBlockBufferCopyDataBytes(blockBufferRef, 0, length, buffer); NSData * data = [[NSData alloc] initWithBytes:buffer length:length]; [fullSongData appendData:data]; [data release]; CMSampleBufferInvalidate(sampleBufferRef); CFRelease(sampleBufferRef); } } if (reader.status == AVAssetReaderStatusFailed || reader.status == AVAssetReaderStatusUnknown){ // Something went wrong. Handle it. } if (reader.status == AVAssetReaderStatusCompleted){ // You're done. It worked. } [reader release]; return [fullSongData autorelease]; } </code></pre> <p>I would recommend doing this on a background thread because it's time consuming.</p> <p>A drawback to this method is that the whole song is loaded into memory, which is of course limited.</p>
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    1. POExtract iPod Library raw PCM samples and play with sound effects
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    1. USTom Irving
    1. USTom Irving
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    1. COExcellent. This gets me half way there. I've been doing some research on audio frameworks and it seems that the only framework that suits my requirements is OpenAL. With a steep learning curve this is slightly offputting but could I use the NSData with something like Finch?
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    2. COI've never used Finch myself, so I'm unsure if it directly accepts NSData.
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    3. COFYI: I tried it, and I got EXC_BAD_ACCESS... I could remove it by checking the OSStatus returned by `CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer` before doing the `for`.
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      1. USLarme
 

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