AVAssetWriter fails when calling finishWritingWithCompletionHandler - audio

Question

I am using AVAssetWriter/AVAssetReader to transcode a PCM audio file to AAC. I have boiled it down to a simple project that works in iOS6 and fails in iOS7.
Every thing is going well until I get to [self.assetWriter finishWritingWithCompletionHandler:] Then the assetWriter goes into the failed state with the error set to -11800 AVFoundation unknown error with an internal error set to -12733 which apparently corresponds to SampleBufferNotReady.
dispatch_queue_t queue = dispatch_queue_create("audio.encode", DISPATCH_QUEUE_SERIAL);
success = [self.assetWriter startWriting];
if (!success)
{
[self showStatus:#"Export: writer failed to startWriting"];
return;
}
[self.assetWriter startSessionAtSourceTime:kCMTimeZero];
[assetWriterInput requestMediaDataWhenReadyOnQueue:queue
usingBlock:
^{
while([assetWriterInput isReadyForMoreMediaData])
{
NSAssert (self.assetWriter.status == AVAssetWriterStatusWriting, nil);
CMSampleBufferRef sampleBuffer = [assetReaderOutput copyNextSampleBuffer];
if (sampleBuffer)
{
NSAssert (CMSampleBufferIsValid(sampleBuffer), nil);
NSAssert (CMSampleBufferDataIsReady(sampleBuffer), nil);
BOOL success = [assetWriterInput appendSampleBuffer:sampleBuffer];
if (!success)
{
[self showError:self.assetWriter.error];
self.assetWriter = nil;
CFRelease(sampleBuffer);
return;
}
CFRelease(sampleBuffer);
}
else
{
if ([assetReader status] == AVAssetReaderStatusCompleted)
{
[assetWriterInput markAsFinished];
[self.assetWriter finishWritingWithCompletionHandler:^{
BOOL success = self.assetWriter.status == AVAssetWriterStatusCompleted;
if (success)
{
[self showStatus: #"Did it!"];
self.assetWriter = nil;
}
else
{
[self showError:self.assetWriter.error];
self.assetWriter = nil;
}
}];
}
else
{
[self showError:assetReader.error];
self.assetWriter = nil;
}
}
}
}
];
Note: I have posted a bug with Apple, posted to the dev forum and used a TSI. Haven't got any answers yet. My hope is one of you geniuses will point me to a workaround.

Answer 1

i have same problem with you, but finally i solve that problem, i use this method :
CMTime cmTime = CMTimeMake(longDuration, 1);
[assetWriter endSessionAtSourceTime:cmTime];
[assetWriter finishWritingWithCompletionHandler^(){
NSLog (#"finished writing");
];
usually we don't need call this if we call finishWritingWithCompletionHandler;
i hope this solve your problem.