namespace GraphicsConsoleApplication
{
    class Program
    {
        static double[,] YUV2RGB_CONVERT_MATRIX = new double[3, 3] { { 1, 0, 1.4022 }, { 1, -0.3456, -0.7145 }, { 1, 1.771, 0 } };

        static void Main(string[] args)
        {
            int width = 352;
            int height = 288;
            int imgSize = width * height;
            int frameSize = imgSize + (imgSize >> 1);

            byte[] yuv = new byte[frameSize];
            byte[] rgb = new byte[3 * imgSize];

            using (FileStream fs = File.OpenRead("E:\\cer\\tempete.cif"))
            {
                int frame = (int)fs.Length / frameSize;
                using (BinaryReader br = new BinaryReader(fs))
                {
                    int index = 0;
                    while (br.PeekChar() != -1)
                    {
                        // 循环读取每一桢
                        br.Read(yuv, 0, frameSize);

                        // 转换为 RGB
                        ConvertYUV2RGB(yuv, rgb, width, height);

                        // 写 BMP 文件。
                        WriteBMP(rgb, width, height, string.Format("E:\\cer\\YUV2BMP\\yuv2bmp_{0}.bmp", index++)); 
                    }
                }
            }
        }

        /// <summary>
        /// 将转换后的 RGB 图像数据按照 BMP 格式写入文件。
        /// </summary>
        /// <param name="rgbFrame">RGB 格式图像数据。</param>
        /// <param name="width">图像宽（单位：像素）。</param>
        /// <param name="height">图像高（单位：像素）。</param>
        /// <param name="bmpFile"> BMP 文件名。</param>
        static void WriteBMP(byte[] rgbFrame, int width, int height, string bmpFile)
        {
            // 写 BMP 图像文件。
            int yu = width * 3 % 4;
            int bytePerLine = 0;
            yu = yu != 0 ? 4 - yu : yu;
            bytePerLine = width * 3 + yu;

            using (FileStream fs = File.Open(bmpFile, FileMode.Create))
            {
                using (BinaryWriter bw = new BinaryWriter(fs))
                {
                    bw.Write('B');
                    bw.Write('M');
                    bw.Write(bytePerLine * height + 54);
                    bw.Write(0);
                    bw.Write(54);
                    bw.Write(40);
                    bw.Write(width);
                    bw.Write(height);
                    bw.Write((ushort)1);
                    bw.Write((ushort)24);
                    bw.Write(0);
                    bw.Write(bytePerLine * height);
                    bw.Write(0);
                    bw.Write(0);
                    bw.Write(0);
                    bw.Write(0);

                    byte[] data = new byte[bytePerLine * height];
                    int gIndex = width * height;
                    int bIndex = gIndex * 2;

                    for (int y = height - 1, j = 0; y >= 0; y--, j++)
                    {
                        for (int x = 0, i = 0; x < width; x++)
                        {
                            data[y * bytePerLine + i++] = rgbFrame[bIndex + j * width + x];    // B
                            data[y * bytePerLine + i++] = rgbFrame[gIndex + j * width + x];    // G
                            data[y * bytePerLine + i++] = rgbFrame[j * width + x];  // R
                        }
                    }

                    bw.Write(data, 0, data.Length);
                    bw.Flush();
                }
            }
        }

        /// <summary>
        /// 将一桢 YUV 格式的图像转换为一桢 RGB 格式图像。
        /// </summary>
        /// <param name="yuvFrame">YUV 格式图像数据。</param>
        /// <param name="rgbFrame">RGB 格式图像数据。</param>
        /// <param name="width">图像宽（单位：像素）。</param>
        /// <param name="height">图像高（单位：像素）。</param>
        static void ConvertYUV2RGB(byte[] yuvFrame, byte[] rgbFrame, int width, int height)
        {
            int uIndex = width * height;
            int vIndex = uIndex + ((width * height) >> 2);
            int gIndex = width * height;
            int bIndex = gIndex * 2;

            int temp = 0;

            for (int y = 0; y < height; y++)
            {
                for (int x = 0; x < width; x++)
                {
                    // R分量
                    temp = (int)(yuvFrame[y * width + x] + (yuvFrame[vIndex + (y / 2) * (width / 2) + x / 2] - 128) * YUV2RGB_CONVERT_MATRIX[0, 2]);
                    rgbFrame[y * width + x] = (byte)(temp < 0 ? 0 : (temp > 255 ? 255 : temp));

                    // G分量
                    temp = (int)(yuvFrame[y * width + x] + (yuvFrame[uIndex + (y / 2) * (width / 2) + x / 2] - 128) * YUV2RGB_CONVERT_MATRIX[1, 1] + (yuvFrame[vIndex + (y / 2) * (width / 2) + x / 2] - 128) * YUV2RGB_CONVERT_MATRIX[1, 2]);
                    rgbFrame[gIndex + y * width + x] = (byte)(temp < 0 ? 0 : (temp > 255 ? 255 : temp));

                    // B分量
                    temp = (int)(yuvFrame[y * width + x] + (yuvFrame[uIndex + (y / 2) * (width / 2) + x / 2] - 128) * YUV2RGB_CONVERT_MATRIX[2, 1]);
                    rgbFrame[bIndex + y * width + x] = (byte)(temp < 0 ? 0 : (temp > 255 ? 255 : temp));
                }
            }
        }
    }
}