c# - 从 VideoPlayer 获取当前帧纹理

Question

在这篇文章中说明了Using new Unity VideoPlayer and VideoClip API to play video可以“根据需要检索每一帧的纹理”

请问将当前帧作为 Texture2D 的正确方法是什么？

编辑:

回答后我这样做了，但它不起作用:

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

public class AverageColorFromTexture : MonoBehaviour {

    public VideoClip videoToPlay;
    public Light lSource;

    private Color targetColor;
    private VideoPlayer videoPlayer;
    private VideoSource videoSource;
    private Renderer rend;
    private Texture tex;
    private AudioSource audioSource;

    void Start()
    {
        Application.runInBackground = true;
        StartCoroutine(playVideo());
    }

    IEnumerator playVideo()
    {

        rend = GetComponent<Renderer>();

        videoPlayer = gameObject.AddComponent<VideoPlayer>();
        audioSource = gameObject.AddComponent<AudioSource>();

        //Disable Play on Awake for both Video and Audio
        videoPlayer.playOnAwake = false;
        audioSource.playOnAwake = false;

        videoPlayer.source = VideoSource.VideoClip;
        videoPlayer.audioOutputMode = VideoAudioOutputMode.AudioSource;
        videoPlayer.EnableAudioTrack(0, true);
        videoPlayer.SetTargetAudioSource(0, audioSource);

        //Set video To Play then prepare Audio to prevent Buffering
        videoPlayer.clip = videoToPlay;
        videoPlayer.Prepare();

        //Wait until video is prepared
        while (!videoPlayer.isPrepared)
        {
            Debug.Log("Preparing Video");
            yield return null;
        }
        Debug.Log("Done Preparing Video");

        //Assign the Texture from Video to Material texture
        tex = videoPlayer.texture;
        rend.material.mainTexture = tex;

        //Enable new frame Event
        videoPlayer.sendFrameReadyEvents = true;

        //Subscribe to the new frame Event
        videoPlayer.frameReady += OnNewFrame;

        //Play Video
        videoPlayer.Play();

        //Play Sound
        audioSource.Play();

        Debug.Log("Playing Video");
        while (videoPlayer.isPlaying)
        {
            Debug.LogWarning("Video Time: " + Mathf.FloorToInt((float)videoPlayer.time));
            yield return null;
        }
        Debug.Log("Done Playing Video");
    }

    void OnNewFrame(VideoPlayer source, long frameIdx)
    {
        Texture2D videoFrame = (Texture2D)source.texture;

        targetColor = CalculateAverageColorFromTexture(videoFrame);
        lSource.color = targetColor ;
    }


    Color32 CalculateAverageColorFromTexture(Texture2D tex)
    {
        Color32[] texColors = tex.GetPixels32();
        int total = texColors.Length;
        float r = 0;
        float g = 0;
        float b = 0;

        for(int i = 0; i < total; i++)
        {
            r += texColors[i].r;
            g += texColors[i].g;
            b += texColors[i].b;
        }
        return new Color32((byte)(r / total) , (byte)(g / total) , (byte)(b / total) , 0);
    }
}

Answer 1

您可以通过三个步骤正确地做到这一点:

1. 通过设置 VideoPlayer.sendFrameReadyEvents 启用新框架事件为 true。

2. 订阅VideoPlayer.frameReady事件

3. 您分配给 VideoPlayer.frameReady 的功能新框架可用时将调用事件。只需从 VideoPlayer 访问视频帧，它将通过强制转换 VideoPlayer.texture 传递给参数到 Texture2D.

就是这样。

---

在代码中:

在 video.Play() 之前添加这些:

// Enable new frame Event
videoPlayer.sendFrameReadyEvents = true;

// Subscribe to the new frame Event
videoPlayer.frameReady += OnNewFrame;

这是您的 OnNewFrame 函数签名。

void OnNewFrame(VideoPlayer source, long frameIdx)
{
    Texture2D videoFrame = (Texture2D)source.texture;
    // Do anything with the videoFrame Texture.
}

值得注意的是，启用该事件的成本很高。在执行此操作之前，请确保您需要每一帧。

Texture2D videoFrame = (Texture2D)source.texture; 和 Texture2D videoFrame = source.texture as Texture2D; 都失败了。

我把 Debug.Log(source.texture); 放在 OnNewFrame 函数里面得到:

TempBuffer 294 320x240 (UnityEngine.RenderTexture)

所以，看起来 Video.texture 属性返回的是 RenderTexture 类型，而不是应有的 Texture 类型。

我们必须将 RenderTexture 转换为 Texture2D。

void Start()
{
    videoFrame = new Texture2D(2, 2);]
    ...
}

//Initialize in the Start function
Texture2D videoFrame;

void OnNewFrame(VideoPlayer source, long frameIdx)
{
    RenderTexture renderTexture = source.texture as RenderTexture;

    if (videoFrame.width != renderTexture.width || videoFrame.height != renderTexture.height)
    {
        videoFrame.Resize(renderTexture.width, renderTexture.height);
    }
    RenderTexture.active = renderTexture;
    videoFrame.ReadPixels(new Rect(0, 0, renderTexture.width, renderTexture.height), 0, 0);
    videoFrame.Apply();
    RenderTexture.active = null;

    targetColor = CalculateAverageColorFromTexture(videoFrame);
    lSource.color = targetColor;
}

您问题的完整代码:

public class AverageColorFromTexture : MonoBehaviour
{
    public VideoClip videoToPlay;
    public Light lSource;

    private Color targetColor;
    private VideoPlayer videoPlayer;
    private VideoSource videoSource;
    private Renderer rend;
    private Texture tex;
    private AudioSource audioSource;

    void Start()
    {
        videoFrame = new Texture2D(2, 2);
        Application.runInBackground = true;
        StartCoroutine(playVideo());
    }

    IEnumerator playVideo()
    {
        rend = GetComponent<Renderer>();

        videoPlayer = gameObject.AddComponent<VideoPlayer>();
        audioSource = gameObject.AddComponent<AudioSource>();

        //Disable Play on Awake for both Video and Audio
        videoPlayer.playOnAwake = false;
        audioSource.playOnAwake = false;

        videoPlayer.source = VideoSource.VideoClip;
        videoPlayer.audioOutputMode = VideoAudioOutputMode.AudioSource;
        videoPlayer.EnableAudioTrack(0, true);
        videoPlayer.SetTargetAudioSource(0, audioSource);

        //Set video To Play then prepare Audio to prevent Buffering
        videoPlayer.clip = videoToPlay;
        videoPlayer.Prepare();

        //Wait until video is prepared
        while (!videoPlayer.isPrepared)
        {
            Debug.Log("Preparing Video");
            yield return null;
        }
        Debug.Log("Done Preparing Video");

        //Assign the Texture from Video to Material texture
        tex = videoPlayer.texture;
        rend.material.mainTexture = tex;

        //Enable new frame Event
        videoPlayer.sendFrameReadyEvents = true;

        //Subscribe to the new frame Event
        videoPlayer.frameReady += OnNewFrame;

        //Play Video
        videoPlayer.Play();

        //Play Sound
        audioSource.Play();

        Debug.Log("Playing Video");
        while (videoPlayer.isPlaying)
        {
            Debug.LogWarning("Video Time: " + Mathf.FloorToInt((float)videoPlayer.time));
            yield return null;
        }
        Debug.Log("Done Playing Video");
    }

    //Initialize in the Start function
    Texture2D videoFrame;

    void OnNewFrame(VideoPlayer source, long frameIdx)
    {
        RenderTexture renderTexture = source.texture as RenderTexture;


        if (videoFrame.width != renderTexture.width || videoFrame.height != renderTexture.height)
        {
            videoFrame.Resize(renderTexture.width, renderTexture.height);
        }
        RenderTexture.active = renderTexture;
        videoFrame.ReadPixels(new Rect(0, 0, renderTexture.width, renderTexture.height), 0, 0);
        videoFrame.Apply();
        RenderTexture.active = null;

        targetColor = CalculateAverageColorFromTexture(videoFrame);
        lSource.color = targetColor;
    }

    Color32 CalculateAverageColorFromTexture(Texture2D tex)
    {
        Color32[] texColors = tex.GetPixels32();
        int total = texColors.Length;
        float r = 0;
        float g = 0;
        float b = 0;

        for (int i = 0; i < total; i++)
        {
            r += texColors[i].r;
            g += texColors[i].g;
            b += texColors[i].b;
        }
        return new Color32((byte)(r / total), (byte)(g / total), (byte)(b / total), 0);
    }
}