sunlubo

func savePNG(_ frame: AVFrame, to url: String) throws {
    let fmtCtx = try AVFormatContext(format: nil, filename: url)

    guard let codec = AVCodec.findEncoderById(.PNG) else {
        fatalError("png codec doesn't exist")
    }
    guard let codecCtx = AVCodecContext(codec: codec) else {
        fatalError("Could not allocate video codec context")
    }
    codecCtx.width = frame.width