CVPixelBufferPool Error ( kCVReturnInvalidArgument/-6661) - swift

Question

I've implemented previous suggestions with Swift (How to use CVPixelBufferPool in conjunction with AVAssetWriterInputPixelBufferAdaptor in iPhone?),
but got stuck with an "kCVReturnInvalidArgument" (error value: -6661) when using CVPixelBufferPoolCreatePixelBuffer as guided.
I'm basically trying to create a movie from images, but as the buffer pool isn't created successfully, I can't append pixel buffers--here is my code for doing this.
Any suggestions are highly appreciated!
import Foundation
import Photos
import OpenGLES
import AVFoundation
import CoreMedia
class MovieGenerator {
var _videoWriter:AVAssetWriter
var _videoWriterInput: AVAssetWriterInput
var _adapter: AVAssetWriterInputPixelBufferAdaptor
var _buffer = UnsafeMutablePointer<Unmanaged<CVPixelBuffer>?>.alloc(1)
init(frameSize size: CGSize, outputURL url: NSURL) {
// delete file if exists
let sharedManager = NSFileManager.defaultManager() as NSFileManager
if(sharedManager.fileExistsAtPath(url.path!)) {
sharedManager.removeItemAtPath(url.path, error: nil)
}
// video writer
_videoWriter = AVAssetWriter(URL: url, fileType: AVFileTypeQuickTimeMovie, error: nil)
// writer input
var videoSettings = [AVVideoCodecKey:AVVideoCodecH264, AVVideoWidthKey:size.width, AVVideoHeightKey:size.height]
_videoWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: videoSettings)
_videoWriterInput.expectsMediaDataInRealTime = true
_videoWriter.addInput(_videoWriterInput)
// pixel buffer adapter
var adapterAttributes = [kCVPixelBufferPixelFormatTypeKey:kCVPixelFormatType_32BGRA, kCVPixelBufferWidthKey: size.width,
kCVPixelBufferHeightKey: size.height,
kCVPixelFormatOpenGLESCompatibility: kCFBooleanTrue]
_adapter = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: _videoWriterInput, sourcePixelBufferAttributes: adapterAttributes)
var poolCreateResult:CVReturn = CVPixelBufferPoolCreatePixelBuffer(nil, _adapter.pixelBufferPool, _buffer)
println("pool creation:\(poolCreateResult)")
_videoWriter.startWriting()
_videoWriter.startSessionAtSourceTime(kCMTimeZero)
}
func addImage(image:UIImage, frameNum:Int, fps:Int)->Bool {
self.createPixelBufferFromCGImage(image.CGImage, pixelBufferPtr: _buffer)
var presentTime:CMTime = CMTimeMake(Int64(frameNum), Int32(fps))
var result:Bool = _adapter.appendPixelBuffer(_buffer.memory?.takeUnretainedValue(), withPresentationTime: presentTime)
return result
}
func finalizeMovie(timeStamp: CMTime) {
_videoWriterInput.markAsFinished()
_videoWriter.endSessionAtSourceTime(timeStamp)
_videoWriter.finishWritingWithCompletionHandler({println("video writer finished with status: \(self._videoWriter.status)")})
}
func createPixelBufferFromCGImage(image: CGImage, pixelBufferPtr: UnsafeMutablePointer<Unmanaged<CVPixelBuffer>?>) {
let width:UInt = CGImageGetWidth(image)
let height:UInt = CGImageGetHeight(image)
let imageData:CFData = CGDataProviderCopyData(CGImageGetDataProvider(image))
let options:CFDictionary = [kCVPixelBufferCGImageCompatibilityKey:NSNumber.numberWithBool(true), kCVPixelBufferCGBitmapContextCompatibilityKey:NSNumber.numberWithBool(true)]
var status:CVReturn = CVPixelBufferCreate(kCFAllocatorDefault, width, height, OSType(kCVPixelFormatType_32BGRA), options, pixelBufferPtr)
assert(status != 0,"CVPixelBufferCreate: \(status)")
var lockStatus:CVReturn = CVPixelBufferLockBaseAddress(pixelBufferPtr.memory?.takeUnretainedValue(), 0)
println("CVPixelBufferLockBaseAddress: \(lockStatus)")
var pxData:UnsafeMutablePointer<(Void)> = CVPixelBufferGetBaseAddress(pixelBufferPtr.memory?.takeUnretainedValue())
let bitmapinfo = CGBitmapInfo.fromRaw(CGImageAlphaInfo.NoneSkipFirst.toRaw())
let rgbColorSpace:CGColorSpace = CGColorSpaceCreateDeviceRGB()
var context:CGContextRef = CGBitmapContextCreate(pxData, width, height, 8, 4*CGImageGetWidth(image), rgbColorSpace, bitmapinfo!)
CGContextDrawImage(context, CGRectMake(0, 0, CGFloat(width), CGFloat(height)), image)
CVPixelBufferUnlockBaseAddress(pixelBufferPtr.memory?.takeUnretainedValue(), 0)
}
}

Answer 1

I can't exactly answer your question, frustratingly, but I am working on code that does essentially the same thing. And, mine happens to get further than the error you have been getting; it gets all the way to the point where it's attempting to add the images to the movie and then simply fails by never getting a successful result from appendPixelBuffer() -- and I'm not sure how to figure out why. I'm posting this in the hopes that it helps you get further, though.
(My code is adapted from AVFoundation + AssetWriter: Generate Movie With Images and Audio, and I used your post to help navigate som e of the pointer interop shenanigans...)
func writeAnimationToMovie(path: String, size: CGSize, animation: Animation) -> Bool {
var error: NSError?
let writer = AVAssetWriter(URL: NSURL(fileURLWithPath: path), fileType: AVFileTypeQuickTimeMovie, error: &error)
let videoSettings = [AVVideoCodecKey: AVVideoCodecH264, AVVideoWidthKey: size.width, AVVideoHeightKey: size.height]
let input = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: videoSettings)
let pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: input, sourcePixelBufferAttributes: nil)
input.expectsMediaDataInRealTime = true
writer.addInput(input)
writer.startWriting()
writer.startSessionAtSourceTime(kCMTimeZero)
var buffer: CVPixelBufferRef
var frameCount = 0
for frame in animation.frames {
let rect = CGRectMake(0, 0, size.width, size.height)
let rectPtr = UnsafeMutablePointer<CGRect>.alloc(1)
rectPtr.memory = rect
buffer = pixelBufferFromCGImage(frame.image.CGImageForProposedRect(rectPtr, context: nil, hints: nil).takeUnretainedValue(), size)
var appendOk = false
var j = 0
while (!appendOk && j < 30) {
if pixelBufferAdaptor.assetWriterInput.readyForMoreMediaData {
let frameTime = CMTimeMake(Int64(frameCount), 10)
appendOk = pixelBufferAdaptor.appendPixelBuffer(buffer, withPresentationTime: frameTime)
// appendOk will always be false
NSThread.sleepForTimeInterval(0.05)
} else {
NSThread.sleepForTimeInterval(0.1)
}
j++
}
if (!appendOk) {
println("Doh, frame \(frame) at offset \(frameCount) failed to append")
}
}
input.markAsFinished()
writer.finishWritingWithCompletionHandler({
if writer.status == AVAssetWriterStatus.Failed {
println("oh noes, an error: \(writer.error.description)")
} else {
println("hrmmm, there should be a movie?")
}
})
return true;
}
Where pixelBufferFromCGImage is defined like so:
func pixelBufferFromCGImage(image: CGImageRef, size: CGSize) -> CVPixelBufferRef {
let options = [
kCVPixelBufferCGImageCompatibilityKey: true,
kCVPixelBufferCGBitmapContextCompatibilityKey: true]
var pixBufferPointer = UnsafeMutablePointer<Unmanaged<CVPixelBuffer>?>.alloc(1)
let status = CVPixelBufferCreate(
nil,
UInt(size.width), UInt(size.height),
OSType(kCVPixelFormatType_32ARGB),
options,
pixBufferPointer)
CVPixelBufferLockBaseAddress(pixBufferPointer.memory?.takeUnretainedValue(), 0)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
let bitmapinfo = CGBitmapInfo.fromRaw(CGImageAlphaInfo.NoneSkipFirst.toRaw())
var pixBufferData:UnsafeMutablePointer<(Void)> = CVPixelBufferGetBaseAddress(pixBufferPointer.memory?.takeUnretainedValue())
let context = CGBitmapContextCreate(
pixBufferData,
UInt(size.width), UInt(size.height),
8, UInt(4 * size.width),
rgbColorSpace, bitmapinfo!)
CGContextConcatCTM(context, CGAffineTransformMakeRotation(0))
CGContextDrawImage(
context,
CGRectMake(0, 0, CGFloat(CGImageGetWidth(image)), CGFloat(CGImageGetHeight(image))),
image)
CVPixelBufferUnlockBaseAddress(pixBufferPointer.memory?.takeUnretainedValue(), 0)
return pixBufferPointer.memory!.takeUnretainedValue()
}

Answer 2

Per the docs for pixelBufferPool:
This property is NULL before the first call to startSessionAtTime:on the associated AVAssetWriter object.
Moving the call to CVPixelBufferPoolCreatePixelBuffer to the end of init should fix the immediate problem.
A few other observations:
You have your AVAssetWriterInputPixelBufferAdaptor configured for BGRA, but in createPixelBufferFromCGImage you're using RGB. Your final videos will look strange if the pixel formats are mismatched.
You don't need to call CVPixelBufferCreate in your createPixelBufferFromCGImage method. This defeats the purpose of using the buffer pool.
If you're running this in a tight loop, memory consumption will become a problem. Using autoreleasepool and being careful with takeUnretainedValue vs takeRetainedValue will help.
I've posted reference implementations for Swift 1.2, 2.0, and 3.0 that use buffer pools.