iOS: convert UIImage to CMSampleBuffer - ios

Question

Some questions address how to convert a CMSampleBuffer to a UIImage, but there are no answers on how to do the reverse, i.e., convert UIImage to CMSampleBuffer.
This question is different from similar ones because the code below provides a starting point for converting a UIImage to a CVPixelBuffer, which hopefully someone with more AVFoundation expertise can help fix to convert to a CMSampleBuffer.
func convertImageToBuffer(from image: UIImage) -> CVPixelBuffer? {
let attrs = [
String(kCVPixelBufferCGImageCompatibilityKey) : kCFBooleanTrue,
String(kCVPixelBufferCGBitmapContextCompatibilityKey) : kCFBooleanTrue
] as [String : Any]
var buffer : CVPixelBuffer?
let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(image.size.width), Int(image.size.height), kCVPixelFormatType_32ARGB, attrs as CFDictionary, &buffer)
guard (status == kCVReturnSuccess) else {
return nil
}
CVPixelBufferLockBaseAddress(buffer!, CVPixelBufferLockFlags(rawValue: 0))
let pixelData = CVPixelBufferGetBaseAddress(buffer!)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGContext(data: pixelData, width: Int(image.size.width), height: Int(image.size.height), bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(buffer!), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue)
context?.translateBy(x: 0, y: image.size.height)
context?.scaleBy(x: 1.0, y: -1.0)
UIGraphicsPushContext(context!)
image.draw(in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
UIGraphicsPopContext()
CVPixelBufferUnlockBaseAddress(buffer!, CVPixelBufferLockFlags(rawValue: 0))
return buffer
}

Answer 1

You are halfway done. Just convert CVPixelBuffer to CMSampleBuffer:
extension UIImage {
var cvPixelBuffer: CVPixelBuffer? {
let attrs = [
String(kCVPixelBufferCGImageCompatibilityKey): kCFBooleanTrue,
String(kCVPixelBufferCGBitmapContextCompatibilityKey): kCFBooleanTrue
] as [String: Any]
var buffer: CVPixelBuffer?
let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(self.size.width), Int(self.size.height), kCVPixelFormatType_32ARGB, attrs as CFDictionary, &buffer)
guard status == kCVReturnSuccess else {
return nil
}
CVPixelBufferLockBaseAddress(buffer!, CVPixelBufferLockFlags(rawValue: 0))
let pixelData = CVPixelBufferGetBaseAddress(buffer!)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGContext(data: pixelData, width: Int(self.size.width), height: Int(self.size.height), bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(buffer!), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue)
context?.translateBy(x: 0, y: self.size.height)
context?.scaleBy(x: 1.0, y: -1.0)
UIGraphicsPushContext(context!)
self.draw(in: CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height))
UIGraphicsPopContext()
CVPixelBufferUnlockBaseAddress(buffer!, CVPixelBufferLockFlags(rawValue: 0))
return buffer
}
func createCMSampleBuffer() -> CMSampleBuffer? {
let pixelBuffer = cvPixelBuffer
var newSampleBuffer: CMSampleBuffer?
var timimgInfo: CMSampleTimingInfo?
var videoInfo: CMVideoFormatDescription?
CMVideoFormatDescriptionCreateForImageBuffer(allocator: nil, imageBuffer: pixelBuffer!, formatDescriptionOut: &videoInfo)
CMSampleBufferCreateForImageBuffer(allocator: kCFAllocatorDefault,
imageBuffer: pixelBuffer!,
dataReady: true,
makeDataReadyCallback: nil,
refcon: nil,
formatDescription: videoInfo!,
sampleTiming: &timimgInfo,
sampleBufferOut: &newSampleBuffer)
return newSampleBuffer!
}
}