在Swift中从CVPixelBufferRef获取像素值

我怎样才能从一个CVPixelBufferRef RGB（或任何其他格式）的像素值？ 我尝试了很多方法，但没有成功。

func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) { let pixelBuffer: CVPixelBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer)! CVPixelBufferLockBaseAddress(pixelBuffer, 0) let baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer) //Get individual pixel values here CVPixelBufferUnlockBaseAddress(pixelBuffer, 0) } 

Answer 1

baseAddress是一个不安全的可变指针，或者更确切地说是一个UnsafeMutablePointer<Void> 。 将指针从Void转换为更具体的types后，可以轻松访问内存：

 // Convert the base address to a safe pointer of the appropriate type let byteBuffer = UnsafeMutablePointer<UInt8>(baseAddress) // read the data (returns value of type UInt8) let firstByte = byteBuffer[0] // write data byteBuffer[3] = 90 

确保使用正确的types（8,16或32位无符号整数）。 这取决于video格式。 最有可能的是8位。

缓冲区格式更新：

您可以在初始化AVCaptureVideoDataOutput实例时指定格式。 你基本上有以下select：

• BGRA：蓝色，绿色，红色和alpha值分别以32位整数存储的单一平面
• 420YpCbCr8BiPlanarFullRange：两个平面，第一个包含Y（亮度）值的每个像素的字节，第二个包含像素组的Cb和Cr（色度）值
• 420YpCbCr8BiPlanarVideoRange：与420YpCbCr8BiPlanarFullRange相同，但Y值限制在16-235的范围内（由于历史原因）

如果您对颜色值和速度感兴趣（或者说最大帧速率）不是问题，那么可以使用更简单的BGRA格式。 否则，采取更有效的原生video格式之一。

如果您有两架飞机，则必须获得所需飞机的基地址（请参阅video格式示例）：

video格式示例

 let pixelBuffer: CVPixelBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer)! CVPixelBufferLockBaseAddress(pixelBuffer, 0) let baseAddress = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0) let bytesPerRow = CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 0) let byteBuffer = UnsafeMutablePointer<UInt8>(baseAddress) // Get luma value for pixel (43, 17) let luma = byteBuffer[17 * bytesPerRow + 43] CVPixelBufferUnlockBaseAddress(pixelBuffer, 0) 

BGRA的例子

 let pixelBuffer: CVPixelBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer)! CVPixelBufferLockBaseAddress(pixelBuffer, 0) let baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer) let int32PerRow = CVPixelBufferGetBytesPerRow(pixelBuffer) let int32Buffer = UnsafeMutablePointer<UInt32>(baseAddress) // Get BGRA value for pixel (43, 17) let luma = int32Buffer[17 * int32PerRow + 43] CVPixelBufferUnlockBaseAddress(pixelBuffer, 0) 

Answer 2

Swift3更新：

 let pixelBuffer: CVPixelBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer)! CVPixelBufferLockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0)); let int32Buffer = unsafeBitCast(CVPixelBufferGetBaseAddress(pixelBuffer), to: UnsafeMutablePointer<UInt32>.self) let int32PerRow = CVPixelBufferGetBytesPerRow(pixelBuffer) // Get BGRA value for pixel (43, 17) let luma = int32Buffer[17 * int32PerRow + 43] CVPixelBufferUnlockBaseAddress(pixelBuffer, 0)