C# 使用SDL2实现Mp4文件播放音视频操作

using SDL2;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks; 
namespace CvNetVideo
{
 public unsafe class SDLHelper
 {
  private IntPtr screen;
  private IntPtr sdlrenderer;
  private IntPtr sdltexture;
  SDL.SDL_Rect sdlrect;
  SDL.SDL_Event sdlevent;
  bool isInit = false;
  public SDLHelper()
  { 
  }  
  public void SDL_MaximizeWindow()
  {
 
  } 
  public int SDL_Init(int width, int height, IntPtr intPtr)
  {
   lock (this)
   {
    if (!isInit)
    {
     // 初始化调用SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_AUDIO | SDL.SDL_INIT_TIMER)
     if (SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_AUDIO | SDL.SDL_INIT_TIMER) < 0)
     {
      Console.WriteLine("Could not initialize SDL - {0}\n", SDL.SDL_GetError());
      return -1;
     }
     isInit = true;
    }
    #region SDL调用
    if (sdltexture != IntPtr.Zero)
    {
     SDL.SDL_DestroyTexture(sdltexture);
    }
    if (sdlrenderer != IntPtr.Zero)
    {
     SDL.SDL_DestroyRenderer(sdlrenderer);
    }
    if (screen != IntPtr.Zero)
    {
     SDL.SDL_DestroyWindow(screen);
     SDL.SDL_RaiseWindow(screen);
     SDL.SDL_RestoreWindow(screen);
    }
    //创建显示窗口 
    screen = SDL.SDL_CreateWindowFrom(intPtr);
    SDL.SDL_ShowWindow(screen);
 
    SDL.SDL_SetWindowSize(screen, width, height);
    //screen = SDL.SDL_CreateWindow("SDL EVENT TEST", SDL.SDL_WINDOWPOS_UNDEFINED, SDL.SDL_WINDOWPOS_UNDEFINED, width, height, SDL.SDL_WindowFlags.SDL_WINDOW_OPENGL | SDL.SDL_WindowFlags.SDL_WINDOW_RESIZABLE);
    //screen = SDL.SDL_CreateWindow("SDL EVENT TEST", SDL.SDL_WINDOWPOS_UNDEFINED, SDL.SDL_WINDOWPOS_UNDEFINED, screen_w, screen_h, SDL.SDL_WindowFlags.SDL_WINDOW_OPENGL | SDL.SDL_WindowFlags.SDL_WINDOW_RESIZABLE);
    if (screen == IntPtr.Zero)
    {
     Console.WriteLine("Can't creat a window:{0}\n", SDL.SDL_GetError());
     return -1;
    }
 
    //创建渲染器
    sdlrenderer = SDL.SDL_CreateRenderer(screen, -1, SDL.SDL_RendererFlags.SDL_RENDERER_ACCELERATED);
    //创建纹理 
    sdltexture = SDL.SDL_CreateTexture(sdlrenderer, SDL.SDL_PIXELFORMAT_IYUV, (int)SDL.SDL_TextureAccess.SDL_TEXTUREACCESS_STREAMING, width, height);
    #endregion
 
    return 0;
   }
  } 
  public int SDL_Display(int width, int height, IntPtr pixels, int pixelsSize,
   int pitch)
  {
   lock (this)
   {
    #region SDL 视频数据渲染播放
    //设置纹理的数据
    sdlrect.x = 0;
    sdlrect.y = 0;
    sdlrect.w = width;
    sdlrect.h = height;
    //SDL.SDL_UpdateTexture(sdltexture, ref sdlrect, pixels, pitch);
    SDL.SDL_UpdateTexture(sdltexture, IntPtr.Zero, pixels, pitch);
    //复制纹理信息到渲染器目标
    SDL.SDL_RenderClear(sdltexture);
    //SDL.SDL_Rect srcRect = sdlrect;
    //SDL.SDL_RenderCopy(sdlrenderer, sdltexture, ref srcRect, ref sdlrect);
 
    SDL.SDL_RenderCopy(sdlrenderer, sdltexture, IntPtr.Zero, IntPtr.Zero);
    //视频渲染显示
    SDL.SDL_RenderPresent(sdlrenderer);
    return 0;
   }   
   #endregion   
  }
 }
 public unsafe class SDLAudio
 {
  class aa
  {
   public byte[] pcm;
   public int len;
  }
  int lastIndex = 0;
 
  private List<aa> data = new List<aa>();
 
  //private List<byte> data = new List<byte>();
  SDL.SDL_AudioCallback Callback;
  public void PlayAudio(IntPtr pcm, int len)
  {
   lock (this)
   {
    byte[] bts = new byte[len];
    Marshal.Copy(pcm, bts, 0, len);
    data.Add(new aa
    {
     len = len,
     pcm = bts
    });
   }
 
   //SDL.SDL_Delay(10);
  }
  void SDL_AudioCallback(IntPtr userdata, IntPtr stream, int len)
  {
   SDL 2.0 
   SDL.SDL_RWFromMem(stream, 0, len);
   //if (audio_len == 0)
   // return;
   //len = (len > audio_len ? audio_len : len);
   if (data.Count == 0)
   {
    for (int i = 0; i < len; i++)
    {
     ((byte*)stream)[i] = 0;
    }
    return;
   }
   for (int i = 0; i < len; i++)
   {
    if (data[0].len > i)
    {
     ((byte*)stream)[i] = data[0].pcm[i];
    }
    else
     ((byte*)stream)[i] = 0;
   }
   data.RemoveAt(0);   
  }
  public int SDL_Init()
  {
   Callback = SDL_AudioCallback;
   #region SDL调用
    初始化调用SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_AUDIO | SDL.SDL_INIT_TIMER)
   //if (SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_AUDIO | SDL.SDL_INIT_TIMER) < 0)
   //{
   // Console.WriteLine("Could not initialize SDL - {0}\n", SDL.SDL_GetError());
   // return -1;
   /