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POConsecutive calls to startRecordingToOutputFileURL:
 

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  1. POConsecutive calls to startRecordingToOutputFileURL:
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    <p><a href="http://developer.apple.com/library/ios/#DOCUMENTATION/AVFoundation/Reference/AVCaptureFileOutput_Class/Reference/Reference.html" rel="noreferrer">The Apple docs</a> seem to indicate that while recording video to a file, the app can change the URL on the fly with no problem. But I'm seeing a problem. When I try this, the recording delegate gets called with an error...</p> <blockquote> <p>The operation couldn’t be completed. (OSStatus error -12780.) Info dictionary is: { AVErrorRecordingSuccessfullyFinishedKey = 0; }</p> </blockquote> <p><em>(funky single quote in "couldn't" comes from logging [error localizedDescription])</em></p> <p>Here's the code, which is basically tweaks to WWDC10 AVCam sample:</p> <p><strong>1) Start recording. Start timer to change the output URL every few seconds</strong></p> <pre><code>- (void) startRecording { // start the chunk timer self.chunkTimer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(chunkTimerFired:) userInfo:nil repeats:YES]; AVCaptureConnection *videoConnection = [AVCamCaptureManager connectionWithMediaType:AVMediaTypeVideo fromConnections:[[self movieFileOutput] connections]]; if ([videoConnection isVideoOrientationSupported]) { [videoConnection setVideoOrientation:[self orientation]]; } if ([[UIDevice currentDevice] isMultitaskingSupported]) { [self setBackgroundRecordingID:[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{}]]; } NSURL *fileUrl = [[ChunkManager sharedInstance] nextURL]; NSLog(@"now recording to %@", [fileUrl absoluteString]); [[self movieFileOutput] startRecordingToOutputFileURL:fileUrl recordingDelegate:self]; } </code></pre> <p><strong>2) When the timer fires, change the output file name without stopping recording</strong></p> <pre><code>- (void)chunkTimerFired:(NSTimer *)aTimer { if ([[UIDevice currentDevice] isMultitaskingSupported]) { [self setBackgroundRecordingID:[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{}]]; } NSURL *nextUrl = [self nextURL]; NSLog(@"changing capture output to %@", [[nextUrl absoluteString] lastPathComponent]); [[self movieFileOutput] startRecordingToOutputFileURL:nextUrl recordingDelegate:self]; } </code></pre> <p>Note: [self nextURL] generates file urls like file-0.mov, file-5.mov, file-10.mov and so on.</p> <p><strong>3) This gets called each time the file changes, and every other invocation is an error...</strong></p> <pre><code>- (void) captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error { id delegate = [self delegate]; if (error &amp;&amp; [delegate respondsToSelector:@selector(someOtherError:)]) { NSLog(@"got an error, tell delegate"); [delegate someOtherError:error]; } if ([self backgroundRecordingID]) { if ([[UIDevice currentDevice] isMultitaskingSupported]) { [[UIApplication sharedApplication] endBackgroundTask:[self backgroundRecordingID]]; } [self setBackgroundRecordingID:0]; } if ([delegate respondsToSelector:@selector(recordingFinished)]) { [delegate recordingFinished]; } } </code></pre> <p>When this runs, file-0 gets written, then we see error -12780 right after changing the url to file-5, file-10 gets written, then an error, then okay, and so on.</p> <p>It's appears that changing the URL on the fly doesn't work, but it stops the writing which allows the next URL change to work.</p> <p>Any help would be much appreciated.</p>
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    1. CO+1 for the massive bounty, here's some points back to you. Wish I knew the answer...
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    2. CO:-) Thanks. I would gladly trade the points for a solution.
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    3. CO@danh Do you need a frame accurate solution, or it would be fine for you if you loose some frames between videos?
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