Question

I’m using AVAssetWriter with a AVAssetWriterInputPixelBufferAdaptor to capture video from an AVCaptureSession. I’m writing the file to the App’s Caches directory. After I’m done I save the video to the camera roll.

Now here’s the problem:
Things work fine for short capture sessions from 10 to 20 mins. After about 30 mins I get this error when calling [assetWriter finishWriting]:

Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" 
UserInfo=0x1a1d30 {NSLocalizedFailureReason=An unknown error occurred (268451843), 
NSUnderlyingError=0x1936e0 "The operation couldn’t be completed. (OSStatus error 
268451843.)", NSLocalizedDescription=The operation could not be completed}

Another interesting thing is, it actually does save the video to the camera roll, but after a certain point the video seems to be corrupt. VLC shows the length of the video to be 1 hour, but only plays the first 30min. and then cuts black.

I am clueless why its doing that.

I’m on iOS 5.0, iPhone 4S, recording with 30 FPS, 1920×1080 and using AVFileTypeMPEG4.

Any ideas?

Answer 1

My best practice for saving a huge files to the library is the following code (originaly from avcam by apple):

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library writeVideoAtPathToSavedPhotosAlbum:outputFileURL
                            completionBlock:^(NSURL *assetURL, NSError *error) {
                                if (error) {
                                    // writing error occur
                                }
                            }];
[library release];

where outputFileURL is a url to the temporary camera file (which you can save on the application temp folder or documents).
You are welcome to take a look at an example project i’ve put on github: AVCam-CameraReleaseTest which seems to work on long videos (3GS iOS 4.0)