Unity之获取Avpro视频画面并在本地创建缩略图

一、效果 

获取StreamingAssets文件夹下的所有视频（包含其子文件夹），获取指定时间的视频画面，然后将图片保存到本地磁盘中。

二、关于Avpro的事件监听

当指定视频时间进度时会触发FinishedSeeking，代表加载完成这时我们在进行缩略图创建功能，否则视频帧未更新创建缩略图会出现问题。

//使用方法   
mediaPlayer.Events.AddListener(OnVideoEvent);//监听private void OnVideoEvent(MediaPlayer mp, MediaPlayerEvent.EventType et, ErrorCode errorCode){switch (et){case MediaPlayerEvent.EventType.MetaDataReady:Debug.Log("当元数据(宽度，持续时间等)可用时触发");break;case MediaPlayerEvent.EventType.ReadyToPlay:Debug.Log("可以播放");break;case MediaPlayerEvent.EventType.Started:Debug.Log("播放开始时触发");break;case MediaPlayerEvent.EventType.FirstFrameReady:Debug.Log("第一帧渲染完成");break;case MediaPlayerEvent.EventType.FinishedPlaying:Debug.Log("视频结束");break;case MediaPlayerEvent.EventType.Closing:Debug.Log("媒体关闭时触发");break;case MediaPlayerEvent.EventType.Error:Debug.Log("发生错误时触发");break;case MediaPlayerEvent.EventType.SubtitleChange:Debug.Log("字幕改变时触发");break;case MediaPlayerEvent.EventType.Stalled:Debug.Log("当介质停止时触发(例如。当失去与媒体流的连接时)");break;case MediaPlayerEvent.EventType.Unstalled:Debug.Log("当媒体从停止状态恢复时触发(例如。当失去的连接重新建立时)");break;case MediaPlayerEvent.EventType.ResolutionChanged:Debug.Log("当视频的分辨率发生变化(包括加载)时触发，用于自适应流");break;case MediaPlayerEvent.EventType.StartedSeeking:Debug.Log("搜索开始时触发");break;case MediaPlayerEvent.EventType.FinishedSeeking:Debug.Log("搜索完成时触发 Seek视频指定时间跳转结束后调用");break;case MediaPlayerEvent.EventType.StartedBuffering:Debug.Log("缓冲开始时触发");break;case MediaPlayerEvent.EventType.FinishedBuffering:Debug.Log("缓冲完成时触发");break;case MediaPlayerEvent.EventType.PropertiesChanged:Debug.Log("当任何属性被触发(例如立体声包装被改变)-这必须手动触发");break;case MediaPlayerEvent.EventType.PlaylistItemChanged:Debug.Log("当新项目在播放列表中播放时触发");break;case MediaPlayerEvent.EventType.PlaylistFinished:Debug.Log("当播放列表结束时触发");break;case MediaPlayerEvent.EventType.TextTracksChanged:Debug.Log("当添加或删除文本轨道时触发");break;}}

三、脚本

using System.IO;
using UnityEngine;
using RenderHeads.Media.AVProVideo;
using System.Collections.Generic;
using System.Collections;
using System;
using System.Linq;public struct ThumbnailData
{public Action OnComplete;      //回调函数public float thumbnailTime;    //时间戳，用于生成缩略图的位置public MediaPlayer mediaPlayer;
}public class ThumbnailGenerator : MonoBehaviour
{public MediaPlayer mediaPlayer;ThumbnailData thumbnailData;//缩略图数据List<string> videoPaths = new List<string>();//所有视频路径void Start(){//获取指定文件夹下的所有视频GetAllVideoFile($"{Application.streamingAssetsPath}");//创建缩略图数据thumbnailData = new ThumbnailData(){OnComplete = () => { Debug.Log("********创建结束*******"); },thumbnailTime = 5,//缩略图时间mediaPlayer = mediaPlayer,};//创建缩略图GenThumbnail(thumbnailData);}#region 获取指定文件夹所有视频文件void GetAllVideoFile(string path){//获取文件夹下指定类型视频videoPaths = Directory.GetFiles(path, "*.*", SearchOption.AllDirectories).Where(s => IsAssignTypeFile(s)).ToList();}/// <summary>/// 判断是否是指定类型文件/// </summary>/// <param name="suffix">文件后缀</param>/// <returns></returns>bool IsAssignTypeFile(string suffix){string[] types = ".vid|.mp4|.wav".Split('|');//设置指定后缀//是指定类型for (int i = 0; i < types.Length; i++)if (suffix.EndsWith(types[i])) return true;return false;}#endregion#region 创建缩略图public void GenThumbnail(ThumbnailData _thumbnailData){thumbnailData = _thumbnailData;//视频状态监听 创建thumbnailData.mediaPlayer.Events.AddListener(OnVideoEvent);thumbnailData.mediaPlayer.OpenMedia(MediaPathType.AbsolutePathOrURL, videoPaths[0], false);thumbnailData.mediaPlayer.Control.Seek(thumbnailData.thumbnailTime);// 执行Seek操作}#endregion#region 视频状态监听int index;//当前视频地址private void OnVideoEvent(MediaPlayer mp, MediaPlayerEvent.EventType et, ErrorCode errorCode){switch (et){case MediaPlayerEvent.EventType.FinishedSeeking:Debug.Log("搜索完成时触发");//本地创建缩略图CreateThumbnailsLocally(mp);break;}}#endregion#region 在本地创建缩略图void CreateThumbnailsLocally(MediaPlayer mp){string path = mp.MediaPath.Path;//获取视频 RenderTextureRenderTexture renderTexture = GetVideoRenderTexture(mp);//将RenderTexture转换成texture2DTexture2D texture2D = RenderTexture2Texture2D(renderTexture);//将Texture2D写入本地string previewPath = Path.Combine(Path.GetDirectoryName(path), Path.GetFileNameWithoutExtension(path)) + ".png";Texture2dWriteLocal(texture2D, previewPath);//创建下一个缩略图index++;if (index < videoPaths.Count){Debug.Log("加载下一个缩略图：" + videoPaths[index]);//播放视频mp.OpenMedia(MediaPathType.AbsolutePathOrURL, videoPaths[index], false);mp.Control.Seek(thumbnailData.thumbnailTime);// 执行Seek操作}elsethumbnailData.OnComplete?.Invoke();//执行回调}#endregion#region 获取视频 RenderTextureMaterial mt;RenderTexture GetVideoRenderTexture(MediaPlayer mp){if (mt == null){mt = new Material(Shader.Find("AVProVideo/Internal/Resolve"));mt.color = Color.white;//颜色设置mt.DisableKeyword("USE_HSBC");//禁用USE_HSBC关键字}VideoRender.SetupMaterialForMedia(mt, mp, -1); //设置材质贴图等VideoRender.ResolveFlags resolveFlags = (VideoRender.ResolveFlags.ColorspaceSRGB | VideoRender.ResolveFlags.Mipmaps | VideoRender.ResolveFlags.PackedAlpha | VideoRender.ResolveFlags.StereoLeft);//播放器标志return VideoRender.ResolveVideoToRenderTexture(mt, null, mp.TextureProducer, resolveFlags);//将视频解析为RenderTexture}#endregion#region 将RenderTexture转换为Texture2Dprivate static Texture2D RenderTexture2Texture2D(RenderTexture renderTexture){int width = renderTexture.width;int height = renderTexture.height;Texture2D texture2D = new Texture2D(width, height, TextureFormat.ARGB32, false);RenderTexture.active = renderTexture;texture2D.ReadPixels(new Rect(0, 0, width, height), 0, 0);texture2D.wrapMode = TextureWrapMode.Clamp;texture2D.Apply();return texture2D;}#endregion#region 将Texture2d写入本地void Texture2dWriteLocal(Texture2D texture2D, string localPath){File.WriteAllBytes(localPath, texture2D.EncodeToPNG());}#endregion}

在使用avpro制作缩略图时，我尝试使用mediaPlayer.TextureProducer.GetTexture()；方法获取画面Texture,然后将其写入RenderTexture，在转换Texture2D写入本地会发现缩略图颜色泛白，经过排查MediaPlayer原脚本，发现在转换RenderTexture时需要使用avpro的指定shader处理才会显示正确的材质，感兴趣的朋友可以打开MediaPlayer脚本进行查看

原脚本查看方法：

注意：添加的MediaPlayer需要将AutoOpen和AutoPlay关掉