OpenGL ES + MediaPlayer 渲染播放视频+滤镜效果

字节流动

发布于 2020-11-30 10:48:30

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发布于 2020-11-30 10:48:30

文章被收录于专栏：字节流动

之前曾经写过用SurfaceView，TextureView+MediaPlayer 播放视频，和 ffmpeg avi 解码后SurfaceView播放视频，今天再给大家来一篇 OpenGL ES+MediaPlayer 来播放视频。

当年也曾呆过camera开发组近一年时间，可惜那时候没写博客的意识，没能给自己给大家留下多少干货分享。

上个效果图吧：

用 OpenGL 着色器实现黑白（灰度图）效果。

即 0.299,0.587,0.114 CRT中转灰度的模型

下面看具体实现的逻辑：

如果你曾用 OpenGL 实现过贴图，那么就容易理解多了。

和图片不同的是，视频需要不断地刷新，每当有新的一帧来时，我们都应该更新纹理，然后重新绘制。用 OpenGL 播放视频就是把视频贴到屏幕上。

对openGL不熟的同学先看这里：学 OpenGL 必知道的图形学知识

1.先写顶点着色器和片段着色器

顶点着色器：

attribute vec4 aPosition;//顶点位置
attribute vec4 aTexCoord;//S T 纹理坐标
varying vec2 vTexCoord;
uniform mat4 uMatrix;
uniform mat4 uSTMatrix;
void main() {
    vTexCoord = (uSTMatrix * aTexCoord).xy;
    gl_Position = uMatrix*aPosition;
}

片段着色器：

#extension GL_OES_EGL_image_external : require
precision mediump float;
varying vec2 vTexCoord;
uniform samplerExternalOES sTexture;
void main() {
    gl_FragColor=texture2D(sTexture, vTexCoord);
}

对着色器语言不懂的同学看这里：http://blog.csdn.net/king1425/article/details/71425556

samplerExternalOES 代替贴图片时的 sampler2D ,作用就是和s urfaceTexture 配合进行纹理更新和格式转换。

2.MediaPlayer的输出

在 GLVideoRenderer 的构造函数中初始化 MediaPlayer ：

mediaPlayer=new MediaPlayer();
        try{
            mediaPlayer.setDataSource(context, Uri.parse(videoPath));
        }catch (IOException e){
            e.printStackTrace();
        }
        mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
        mediaPlayer.setLooping(true);

        mediaPlayer.setOnVideoSizeChangedListener(this);

onSurfaceCreated函数中使用SurfaceTexture来设置MediaPlayer的输出。

我们要用SurfaceTexture 创建一个Surface，然后将这个Surface作为MediaPlayer的输出表面。

SurfaceTexture的主要作用就是，从视频流和相机数据流获取新一帧的数据，获取新数据调用的方法是updateTexImage。

需要注意的是MediaPlayer的输出往往不是RGB格式（一般是YUV），而GLSurfaceView需要RGB格式才能正常显示。

所以我们先在onSurfaceCreated中将生成纹理的代码改成这样：

textureId = textures[0];
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
ShaderUtils.checkGlError("ws-------glBindTexture mTextureID");

GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER,
        GLES20.GL_NEAREST);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER,
        GLES20.GL_LINEAR);

GLES11Ext.GL_TEXTURE_EXTERNAL_OES的用处是什么？

之前提到视频解码的输出格式是YUV的（YUV420sp，应该是），那么这个扩展纹理的作用就是实现YUV格式到RGB的自动转化，我们就不需要再为此写YUV转RGB的代码了。

然后在onSurfaceCreated的最后加上如下代码:

 surfaceTexture = new SurfaceTexture(textureId);
        surfaceTexture.setOnFrameAvailableListener(this);//监听是否有新的一帧数据到来

        Surface surface = new Surface(surfaceTexture);
        mediaPlayer.setSurface(surface);
        surface.release();

        if (!playerPrepared){
            try {
                mediaPlayer.prepare();
                playerPrepared=true;
            } catch (IOException t) {
                Log.e(TAG, "media player prepare failed");
            }
            mediaPlayer.start();
            playerPrepared=true;
        }

用SurfaceTexture 创建一个Surface，然后将这个Surface作为MediaPlayer的输出表面.

在onDrawFrame中

 synchronized (this){
            if (updateSurface){
                surfaceTexture.updateTexImage();//获取新数据
                surfaceTexture.getTransformMatrix(mSTMatrix);//让新的纹理和纹理坐标系能够正确的对应,mSTMatrix的定义是和projectionMatrix完全一样的。
                updateSurface = false;
            }
        }

在有新数据时，用updateTexImage来更新纹理，这个getTransformMatrix的目的，是让新的纹理和纹理坐标系能够正确的对应, mSTMatrix 的定义是和 projectionMatrix 完全一样的。

private final float[] vertexData = {
            1f,-1f,0f,
            -1f,-1f,0f,
            1f,1f,0f,
            -1f,1f,0f
    };



    private final float[] textureVertexData = {
            1f,0f,
            0f,0f,
            1f,1f,
            0f,1f
    };

vertexData 代表要绘制的视口坐标。textureVertexData 代表视频纹理，与屏幕坐标对应

然后我们读取坐标，在此自己我们先与着色器映射。

在onSurfaceCreated映射

aPositionLocation= GLES20.glGetAttribLocation(programId,"aPosition");
uMatrixLocation=GLES20.glGetUniformLocation(programId,"uMatrix");
uSTMMatrixHandle = GLES20.glGetUniformLocation(programId, "uSTMatrix");
uTextureSamplerLocation=GLES20.glGetUniformLocation(programId,"sTexture");
aTextureCoordLocation=GLES20.glGetAttribLocation(programId,"aTexCoord");

onDrawFrame中读取：

        GLES20.glUseProgram(programId);
        GLES20.glUniformMatrix4fv(uMatrixLocation,1,false,projectionMatrix,0);
        GLES20.glUniformMatrix4fv(uSTMMatrixHandle, 1, false, mSTMatrix, 0);

        vertexBuffer.position(0);
        GLES20.glEnableVertexAttribArray(aPositionLocation);
        GLES20.glVertexAttribPointer(aPositionLocation, 3, GLES20.GL_FLOAT, false,
                12, vertexBuffer);

        textureVertexBuffer.position(0);
        GLES20.glEnableVertexAttribArray(aTextureCoordLocation);
        GLES20.glVertexAttribPointer(aTextureCoordLocation,2,GLES20.GL_FLOAT,false,8,textureVertexBuffer);

        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,textureId);

        GLES20.glUniform1i(uTextureSamplerLocation,0);
        GLES20.glViewport(0,0,screenWidth,screenHeight);
        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

GLVideoRenderer 全部代码如下：

package com.ws.openglvideoplayer;

import android.content.Context;
import android.graphics.SurfaceTexture;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.net.Uri;
import android.opengl.GLES11Ext;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
import android.util.Log;
import android.view.Surface;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

/**
 * Created by Shuo.Wang on 2017/3/19.
 */

public class GLVideoRenderer implements GLSurfaceView.Renderer
        , SurfaceTexture.OnFrameAvailableListener, MediaPlayer.OnVideoSizeChangedListener  {


    private static final String TAG = "GLRenderer";
    private Context context;
    private int aPositionLocation;
    private int programId;
    private FloatBuffer vertexBuffer;
    private final float[] vertexData = {
            1f,-1f,0f,
            -1f,-1f,0f,
            1f,1f,0f,
            -1f,1f,0f
    };

    private final float[] projectionMatrix=new float[16];
    private int uMatrixLocation;

    private final float[] textureVertexData = {
            1f,0f,
            0f,0f,
            1f,1f,
            0f,1f
    };
    private FloatBuffer textureVertexBuffer;
    private int uTextureSamplerLocation;
    private int aTextureCoordLocation;
    private int textureId;

    private SurfaceTexture surfaceTexture;
    private MediaPlayer mediaPlayer;
    private float[] mSTMatrix = new float[16];
    private int uSTMMatrixHandle;

    private boolean updateSurface;
    private boolean playerPrepared;
    private int screenWidth,screenHeight;
    public GLVideoRenderer(Context context,String videoPath) {
        this.context = context;
        playerPrepared=false;
        synchronized(this) {
            updateSurface = false;
        }
        vertexBuffer = ByteBuffer.allocateDirect(vertexData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(vertexData);
        vertexBuffer.position(0);

        textureVertexBuffer = ByteBuffer.allocateDirect(textureVertexData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(textureVertexData);
        textureVertexBuffer.position(0);

        mediaPlayer=new MediaPlayer();
        try{
            mediaPlayer.setDataSource(context, Uri.parse(videoPath));
        }catch (IOException e){
            e.printStackTrace();
        }
        mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
        mediaPlayer.setLooping(true);

        mediaPlayer.setOnVideoSizeChangedListener(this);
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        String vertexShader = ShaderUtils.readRawTextFile(context, R.raw.simple_vertex_shader);
        String fragmentShader= ShaderUtils.readRawTextFile(context, R.raw.simple_fragment_shader);
        programId=ShaderUtils.createProgram(vertexShader,fragmentShader);
        aPositionLocation= GLES20.glGetAttribLocation(programId,"aPosition");

        uMatrixLocation=GLES20.glGetUniformLocation(programId,"uMatrix");
        uSTMMatrixHandle = GLES20.glGetUniformLocation(programId, "uSTMatrix");
        uTextureSamplerLocation=GLES20.glGetUniformLocation(programId,"sTexture");
        aTextureCoordLocation=GLES20.glGetAttribLocation(programId,"aTexCoord");


        int[] textures = new int[1];
        GLES20.glGenTextures(1, textures, 0);

        textureId = textures[0];
        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
        ShaderUtils.checkGlError("glBindTexture mTextureID");
   /*GLES11Ext.GL_TEXTURE_EXTERNAL_OES的用处？
      之前提到视频解码的输出格式是YUV的（YUV420p，应该是），那么这个扩展纹理的作用就是实现YUV格式到RGB的自动转化，
      我们就不需要再为此写YUV转RGB的代码了*/
        GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER,
                GLES20.GL_NEAREST);
        GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER,
                GLES20.GL_LINEAR);

        surfaceTexture = new SurfaceTexture(textureId);
        surfaceTexture.setOnFrameAvailableListener(this);//监听是否有新的一帧数据到来

        Surface surface = new Surface(surfaceTexture);
        mediaPlayer.setSurface(surface);
        surface.release();

        if (!playerPrepared){
            try {
                mediaPlayer.prepare();
                playerPrepared=true;
            } catch (IOException t) {
                Log.e(TAG, "media player prepare failed");
            }
            mediaPlayer.start();
            playerPrepared=true;
        }
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
        Log.d(TAG, "onSurfaceChanged: "+width+" "+height);
        screenWidth=width; screenHeight=height;
    }

    @Override
    public void onDrawFrame(GL10 gl) {
        GLES20.glClear( GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
        synchronized (this){
            if (updateSurface){
                surfaceTexture.updateTexImage();//获取新数据
                surfaceTexture.getTransformMatrix(mSTMatrix);//让新的纹理和纹理坐标系能够正确的对应,mSTMatrix的定义是和projectionMatrix完全一样的。
                updateSurface = false;
            }
        }
        GLES20.glUseProgram(programId);
        GLES20.glUniformMatrix4fv(uMatrixLocation,1,false,projectionMatrix,0);
        GLES20.glUniformMatrix4fv(uSTMMatrixHandle, 1, false, mSTMatrix, 0);

        vertexBuffer.position(0);
        GLES20.glEnableVertexAttribArray(aPositionLocation);
        GLES20.glVertexAttribPointer(aPositionLocation, 3, GLES20.GL_FLOAT, false,
                12, vertexBuffer);

        textureVertexBuffer.position(0);
        GLES20.glEnableVertexAttribArray(aTextureCoordLocation);
        GLES20.glVertexAttribPointer(aTextureCoordLocation,2,GLES20.GL_FLOAT,false,8,textureVertexBuffer);

        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,textureId);

        GLES20.glUniform1i(uTextureSamplerLocation,0);
        GLES20.glViewport(0,0,screenWidth,screenHeight);
        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
    }

    @Override
    synchronized public void onFrameAvailable(SurfaceTexture surface) {
        updateSurface = true;
    }

    @Override
    public void onVideoSizeChanged(MediaPlayer mp, int width, int height) {
        Log.d(TAG, "onVideoSizeChanged: "+width+" "+height);
        updateProjection(width,height);
    }

    private void updateProjection(int videoWidth, int videoHeight){
        float screenRatio=(float)screenWidth/screenHeight;
        float videoRatio=(float)videoWidth/videoHeight;
        if (videoRatio>screenRatio){
            Matrix.orthoM(projectionMatrix,0,-1f,1f,-videoRatio/screenRatio,videoRatio/screenRatio,-1f,1f);
        }else Matrix.orthoM(projectionMatrix,0,-screenRatio/videoRatio,screenRatio/videoRatio,-1f,1f,-1f,1f);
    }

    public MediaPlayer getMediaPlayer() {
        return mediaPlayer;
    }
}

要实现上图中的滤镜视频效果，只需用0.299,0.587,0.114 CRT中转灰度的模型算法。（自己可以网上搜寻更多效果，这里只是抛砖引玉）

更改片段着色器即可：

#extension GL_OES_EGL_image_external : require
precision mediump float;
varying vec2 vTexCoord;
uniform samplerExternalOES sTexture;
void main() {
    //gl_FragColor=texture2D(sTexture, vTexCoord);

        vec3 centralColor = texture2D(sTexture, vTexCoord).rgb;
        gl_FragColor = vec4(0.299*centralColor.r+0.587*centralColor.g+0.114*centralColor.b);

}