Unity 获得视频的某一帧，生成缩略图

Unity 并无直接获取视频某一帧图像的API，所以想要生成缩略图就要自己写方法了，

图片和视频都可以用这种方式生成缩略图，另，转载请标明出处，谢谢。

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.Video;
 using System.IO;

 public class NewBehaviourScript : MonoBehaviour {

     VideoPlayer vp;
     Texture2D videoFrameTexture;
     RenderTexture renderTexture;
     void Start()
     {
         videoFrameTexture = new Texture2D(, );
         vp = GetComponent<VideoPlayer>();
         vp.playOnAwake = false;
         vp.waitForFirstFrame = true;

         vp.sendFrameReadyEvents = true;
         vp.frameReady += OnNewFrame;
         vp.Play();

     }
     int framesValue=;//获得视频第几帧的图片
     void OnNewFrame(VideoPlayer source, long frameIdx)
     {
         framesValue++;
         if (framesValue==) {
             renderTexture = source.texture as RenderTexture;
             if (videoFrameTexture.width != renderTexture.width || videoFrameTexture.height != renderTexture.height) {
                 videoFrameTexture.Resize (renderTexture.width, renderTexture.height);
             }
             RenderTexture.active = renderTexture;
             videoFrameTexture.ReadPixels (new Rect (, , renderTexture.width, renderTexture.height), , );
             videoFrameTexture.Apply ();
             RenderTexture.active = null;
             vp.frameReady -= OnNewFrame;
             vp.sendFrameReadyEvents = false;
         }
     }

     void OnDisable()
     {
         if (!File.Exists(Application.persistentDataPath+"/temp.jpg")) {
             ScaleTexture (videoFrameTexture, , , (Application.persistentDataPath+"/temp.jpg"));
         }
     }
     //生成缩略图
     void ScaleTexture(Texture2D source, int targetWidth, int targetHeight,string savePath)
     {

         Texture2D result = new Texture2D(targetWidth, targetHeight,TextureFormat.ARGB32, false);

         for (int i = ; i < result.height; ++i)
         {
             for (int j = ; j < result.width; ++j)
             {
                 Color newColor = source.GetPixelBilinear((float)j / (float)result.width, (float)i / (float)result.height);
                 result.SetPixel(j, i, newColor);
             }
         }
         result.Apply();
         File.WriteAllBytes(savePath, result.EncodeToJPG());
     }

 }