Pixel Buffer will not append to AVAssetWriterInput on device - ios

Question

I'm trying to take an image and convert it into a video file in Swift. I was able to get the code to work in the iOS simulator, but it won't work on an actual device. It errors out when I try to append the pixel buffer to the AVAssetWriterInput. I was wondering if anyone here has run into the same issue previously. Here's the code:
func createVideoFromImage(img: CGImageRef) -> Void {
var error: NSError?
let frameSize = CGSizeMake(CGFloat(CGImageGetWidth(img)), CGFloat(CGImageGetHeight(img)))
let fileName = "\(uniqueString()).m4v"
let assetWriter = AVAssetWriter(URL: fileUrl(fileName), fileType: AVFileTypeAppleM4V, error: &error)
let outputSettings = [
AVVideoCodecKey: AVVideoCodecH264,
AVVideoWidthKey: frameSize.width,
AVVideoHeightKey: frameSize.height
]
let assetWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: outputSettings)
let pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: assetWriterInput, sourcePixelBufferAttributes: nil)
if assetWriter.canAddInput(assetWriterInput) {
assetWriter.addInput(assetWriterInput)
}
assetWriter.startWriting()
assetWriter.startSessionAtSourceTime(kCMTimeZero)
let buffer:CVPixelBufferRef = pixelBufferFromCGImage(img, frameSize: frameSize)
if pixelBufferAdaptor.assetWriterInput.readyForMoreMediaData {
let frameTime = CMTimeMakeWithSeconds(0, 30)
let pixelBufferAppend = pixelBufferAdaptor.appendPixelBuffer(buffer, withPresentationTime: frameTime)
if pixelBufferAppend {
assetWriterInput.markAsFinished()
assetWriter.finishWritingWithCompletionHandler { () -> Void in
switch assetWriter.status {
case AVAssetWriterStatus.Failed:
println("Error: \(assetWriter.error)")
default:
let path = self.fileUrl(fileName).path!
let content = NSFileManager.defaultManager().contentsAtPath(path)
println("Video: \(path) \(content?.length)")
}
}
} else {
println("failed to append pixel buffer")
}
}
}
func pixelBufferFromCGImage (img: CGImageRef, frameSize: CGSize) -> CVPixelBufferRef {
let options = [
"kCVPixelBufferCGImageCompatibilityKey": true,
"kCVPixelBufferCGBitmapContextCompatibilityKey": true
]
var pixelBufferPointer = UnsafeMutablePointer<Unmanaged<CVPixelBuffer>?>.alloc(1)
let buffered:CVReturn = CVPixelBufferCreate(kCFAllocatorDefault, UInt(frameSize.width), UInt(frameSize.height), OSType(kCVPixelFormatType_32ARGB), options, pixelBufferPointer)
let lockBaseAddress = CVPixelBufferLockBaseAddress(pixelBufferPointer.memory?.takeUnretainedValue(), 0)
var pixelData:UnsafeMutablePointer<(Void)> = CVPixelBufferGetBaseAddress(pixelBufferPointer.memory?.takeUnretainedValue())
let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.NoneSkipFirst.rawValue)
let space:CGColorSpace = CGColorSpaceCreateDeviceRGB()
var context:CGContextRef = CGBitmapContextCreate(pixelData, UInt(frameSize.width), UInt(frameSize.height), 8, CVPixelBufferGetBytesPerRow(pixelBufferPointer.memory?.takeUnretainedValue()), space, bitmapInfo)
CGContextDrawImage(context, CGRectMake(0, 0, frameSize.width, frameSize.height), img)
CVPixelBufferUnlockBaseAddress(pixelBufferPointer.memory?.takeUnretainedValue(), 0)
return pixelBufferPointer.memory!.takeUnretainedValue()
}
pixelBufferAppend returns false! Any help would be greatly appreciated. I have been scratching my head on this all night!

Answer 1

I was finally able to figure what was going on. The device could only support encoding frames up to 1920x1080px - reduced the image size and it worked. Change frameSize to be a variable and use the following code:
if frameSize.width > maxImageSize.width || frameSize.height > maxImageSize.height {
let scale = min((maxImageSize.width/frameSize.width), (maxImageSize.height/frameSize.height))
frameSize = CGSizeMake((scale * frameSize.width), (scale * frameSize.height))
}