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：

这里写图片描述

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

这里写图片描述

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(我的习惯是这样，你也可以后边根据需要再写这个)

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);

}

samplerExternalOES代替贴图片时的sampler2D,作用就是和surfaceTexture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);

}

这里写图片描述

到此结束，我们已经实现了openGL ES+MediaPlayer 渲染播放视频+滤镜效果。后期将讲述全景视频原理及实现过程，敬请关注~