基于C#实现乱码视频效果

private void btn_convert_Click(object sender, EventArgs e)
        {
            string framePath = Application.StartupPath + "\\temp";
            if (Directory.Exists(framePath))
            {
                Directory.Delete(framePath, true);
            }
            Directory.CreateDirectory(framePath);

            //string newFramePath = Application.StartupPath + "\\newTemp";
            //if (Directory.Exists(newFramePath))
            //{
            //    Directory.Delete(newFramePath, true);
            //}
            //Directory.CreateDirectory(newFramePath);


            FFmpegUtil.Split(axWindowsMediaPlayer1.URL, framePath);


            List<char> listChar = new List<char>();
            for (char i = 'a'; i <= 'z'; i++)
            {
                listChar.Add(i);
            }
            for (char i = 'A'; i <= 'Z'; i++)
            {
                listChar.Add(i);
            }
            for (char i = '0'; i <= '9'; i++)
            {
                listChar.Add(i);
            }

            string[] imgUrls = Directory.GetFiles(framePath);
            Bitmap img = null;
            for (int u = 0; u < imgUrls.Length; u++)
            {
                img = (Bitmap)Image.FromFile(imgUrls[u]);
                double threshold = ImageUtil.GetAverageThreshold(img);
                ImageUtil.Threshold(img, threshold);

                StringBuilder builder = new StringBuilder();
                Random random = new Random();

                for (int y = 0; y < img.Height; y += 16)
                {
                    for (int x = 0; x < img.Width; x += 8)
                    {
                        if (ImageUtil.GetGrayValue(img.GetPixel(x, y)) < threshold)
                        {
                            builder.Append(listChar[random.Next(62)]);
                        }
                        else
                        {
                            builder.Append(" ");
                        }

                    }
                    builder.Append("\r\n");
                }
                File.WriteAllText(@"C:\Users\Zero\Desktop\a\b\" + u + ".txt", builder.ToString());
            }
            MessageBox.Show("转换完成");

        }

        private void btn_show_Click(object sender, EventArgs e)
        {
            new FormShow(@"C:\Users\Zero\Desktop\a\b\").Show();
        }

 private void FormShow_Load(object sender, EventArgs e)
        {
            List<string> list = Directory.GetFiles(_path, "*.txt").ToList();
            if (list.Count == 0)
            {
                return;
            }
            list.Sort((a, b) =>
            {
                string reg = "[0-9]+";
                int a_index = int.Parse(Regex.Match(a, reg).Value);
                int b_index = int.Parse(Regex.Match(b, reg).Value);
                return a_index.CompareTo(b_index);
            });
            richTextBox1.Text = File.ReadAllText(list[0]);
            Width = richTextBox1.Lines.Max(s => s).Length * 5;
            Height = richTextBox1.Lines.Length * 10;
            Location = new Point(Location.X, 10);

            new Task(async () =>
            {
                foreach (string str in list)
                {
                    if (!this.IsDisposed)
                    {
                        this.BeginInvoke(new Action(() =>
                        {
                            richTextBox1.Text = File.ReadAllText(str);
                        }));
                    }
                    await Task.Delay(260);
                }
            }).Start();
        }