[OpenGL]从零开始写一个Android平台下的全景视频播放器——2.3 使用GLSurfaceView和MediaPlayer播放一个平面视频（下）

Github项目地址,欢迎star~！

为了方便没有准备好梯子的同学，我把项目在CSDN上打包下载，不过更新会慢一些

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视频颠倒的问题

其实，不要更新mSTMatrix，将他设为单位阵，一般就会显示正常的视频。。
在使用mSTMatrix的情况下，解决方法就是修改顶点数组或者修改纹理数组，我们采用修改顶点数组的方案：

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

屏幕尺寸自适应

如何才能让显示出来的宽高比符合视频的宽高比呢？ 答案依然是正交投影！
但是有一些不同，因为我们现在有两个尺寸，一个是屏幕的宽高，一个是视频的宽高，在之前显示图片的时候，我们直接采用了把图片去掉一部分，以适应”绘制一个正方形区域”的要求，那有没有更好的解决方案呢？
分析一下吧，其实无非就两种情况：

• 屏幕宽高比小于视频宽高比，如图：
  
• 屏幕宽高比大于视频宽高比，如图：
  

其中，蓝色的是我们的视频区域，蓝色坐标轴是OpenGL屏幕坐标轴，黄色的是纹理坐标轴，注意，我将所有的规范坐标都放到了视频的四个角落，这是因为我们要保证视频完全显示，不变形并且最大化的显示，而我们的纹理坐标和顶点坐标就是像这四个顶点描述的这样子。

这两种情况，只要搞定一种，另外一种也就很容易推导出来了。

• 获取视频尺寸

  获取视频的尺寸可以设置一个监听器：

 mediaPlayer.setOnVideoSizeChangedListener(this);@Overridepublic void onVideoSizeChanged(MediaPlayer mp, int width, int height) {    Log.d(TAG, "onVideoSizeChanged: "+width+" "+height);    updateProjection(width,height);}

之前提过，屏幕尺寸是在onSurfaceCreated获取的。
有了这两个尺寸，我们就可以更新Projection矩阵了，代码可能有些难以理解，对于videoRatio>screenRatio，其实就是我们是将videoHeight/videoWidth当做一个单位来处理（因为之前的坐标映射），然后我们用screenHeight/screenWidth再去除这个单位，来获得屏幕Y轴方向应该有的范围

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);}

屏幕比例16:10，第一个视频比例4:3，第二个视频比例2:1

MediaPlayer和GLSurfaceView生命周期控制

首先，主活动的生命周期中和GLSurfaceView主要有两个，和MediaPlayer相关的有三个，我们会在后面做播放控制的时候再详细说明。

@Overrideprotected void onDestroy() {    super.onDestroy();    glRenderer.getMediaPlayer().release();}@Overrideprotected void onPause() {    super.onPause();    glSurfaceView.onPause();    glRenderer.getMediaPlayer().pause();}@Overrideprotected void onResume() {    super.onResume();    glSurfaceView.onResume();}

顺便贴一下所有的代码
GLRenderer.java

package com.martin.ads.panoramaopengltutorial;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 java.nio.ShortBuffer;import javax.microedition.khronos.egl.EGLConfig;import javax.microedition.khronos.opengles.GL10;/** * Created by Ads on 2016/11/13. */public class GLRenderer implements GLSurfaceView.Renderer        , SurfaceTexture.OnFrameAvailableListener, MediaPlayer.OnVideoSizeChangedListener {    private static final String TAG = "GLRenderer";    private Context context;    private int aPositionHandle;    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 uMatrixHandle;    private final float[] textureVertexData = {            1f,0f,            0f,0f,            1f,1f,            0f,1f    };    private FloatBuffer textureVertexBuffer;    private int uTextureSamplerHandle;    private int aTextureCoordHandle;    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 GLRenderer(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.vertex_shader);        String fragmentShader= ShaderUtils.readRawTextFile(context, R.raw.fragment_shader);        programId=ShaderUtils.createProgram(vertexShader,fragmentShader);        aPositionHandle= GLES20.glGetAttribLocation(programId,"aPosition");        uMatrixHandle=GLES20.glGetUniformLocation(programId,"uMatrix");        uSTMMatrixHandle = GLES20.glGetUniformLocation(programId, "uSTMatrix");        uTextureSamplerHandle=GLES20.glGetUniformLocation(programId,"sTexture");        aTextureCoordHandle=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");        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);        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();                surfaceTexture.getTransformMatrix(mSTMatrix);                updateSurface = false;            }        }        GLES20.glUseProgram(programId);        GLES20.glUniformMatrix4fv(uMatrixHandle,1,false,projectionMatrix,0);        GLES20.glUniformMatrix4fv(uSTMMatrixHandle, 1, false, mSTMatrix, 0);        vertexBuffer.position(0);        GLES20.glEnableVertexAttribArray(aPositionHandle);        GLES20.glVertexAttribPointer(aPositionHandle, 3, GLES20.GL_FLOAT, false,                12, vertexBuffer);        textureVertexBuffer.position(0);        GLES20.glEnableVertexAttribArray(aTextureCoordHandle);        GLES20.glVertexAttribPointer(aTextureCoordHandle,2,GLES20.GL_FLOAT,false,8,textureVertexBuffer);        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,textureId);        GLES20.glUniform1i(uTextureSamplerHandle,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;    }}

MainActivity.java

package com.martin.ads.panoramaopengltutorial;import android.opengl.GLSurfaceView;import android.os.Environment;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;public class MainActivity extends AppCompatActivity {    private GLSurfaceView glSurfaceView;    private GLRenderer glRenderer;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        glSurfaceView= (GLSurfaceView) findViewById(R.id.surface_view);        glSurfaceView.setEGLContextClientVersion(2);        glRenderer=new GLRenderer(this, Environment.getExternalStorageDirectory().getPath()+"/360Video/video.mp4");        glSurfaceView.setRenderer(glRenderer);        glSurfaceView.setRenderMode(GLSurfaceView.RENDERMODE_CONTINUOUSLY);    }    @Override    protected void onDestroy() {        super.onDestroy();        glRenderer.getMediaPlayer().release();    }    @Override    protected void onPause() {        super.onPause();        glSurfaceView.onPause();        glRenderer.getMediaPlayer().pause();    }    @Override    protected void onResume() {        super.onResume();        glSurfaceView.onResume();    }}

ShaderUtils.java

package com.martin.ads.panoramaopengltutorial;import android.content.Context;import android.opengl.GLES20;import android.util.Log;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;public class ShaderUtils {    private static final String TAG = "ShaderUtils";    public static void checkGlError(String label) {        int error;        while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {            Log.e(TAG, label + ": glError " + error);            throw new RuntimeException(label + ": glError " + error);        }    }    public static int createProgram(String vertexSource, String fragmentSource) {        int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexSource);        if (vertexShader == 0) {            return 0;        }        int pixelShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentSource);        if (pixelShader == 0) {            return 0;        }        int program = GLES20.glCreateProgram();        if (program != 0) {            GLES20.glAttachShader(program, vertexShader);            checkGlError("glAttachShader");            GLES20.glAttachShader(program, pixelShader);            checkGlError("glAttachShader");            GLES20.glLinkProgram(program);            int[] linkStatus = new int[1];            GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linkStatus, 0);            if (linkStatus[0] != GLES20.GL_TRUE) {                Log.e(TAG, "Could not link program: ");                Log.e(TAG, GLES20.glGetProgramInfoLog(program));                GLES20.glDeleteProgram(program);                program = 0;            }        }        return program;    }    public static int loadShader(int shaderType, String source) {        int shader = GLES20.glCreateShader(shaderType);        if (shader != 0) {            GLES20.glShaderSource(shader, source);            GLES20.glCompileShader(shader);            int[] compiled = new int[1];            GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compiled, 0);            if (compiled[0] == 0) {                Log.e(TAG, "Could not compile shader " + shaderType + ":");                Log.e(TAG, GLES20.glGetShaderInfoLog(shader));                GLES20.glDeleteShader(shader);                shader = 0;            }        }        return shader;    }    public static String readRawTextFile(Context context, int resId) {        InputStream inputStream = context.getResources().openRawResource(resId);        try {            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));            StringBuilder sb = new StringBuilder();            String line;            while ((line = reader.readLine()) != null) {                sb.append(line).append("\n");            }            reader.close();            return sb.toString();        } catch (IOException e) {            e.printStackTrace();        }        return null;    }}