Android上使用OpenGLES2.0显示YUV数据

转自：http://blog.csdn.net/ueryueryuery/article/details/17608185

在Android上用OpenGLES来显示YUV图像，之所以这样做，是因为：

1.Android本身也不能直接显示YUV图像，YUV转成RGB还是必要的；

2.YUV手动转RGB会占用大量的CPU资源，如果以这样的形式播放视频，手机会很热，所以我们尽量让GPU来做这件事；

3.OpenGLES是Android集成到自身框架里的第三方库，它有很多的可取之处。

博主的C/C++不是很好，所以整个过程是在Java层实现的，大家见笑，我主要参考（但不限于）以下文章，十分感谢这些朋友的分享：

1. http://blog.csdn.net/xiaoguaihai/article/details/8672631

2.http://chenshun87.blog.163.com/blog/static/18859389201232011727615/

3.http://blog.csdn.net/ypist/article/details/8950903

4.http://blog.csdn.net/wanglang3081/article/details/8480281

5.http://blog.csdn.net/xdljf/article/details/7178620

一、首先我先说一下这个解决方案是怎么运行的，给大家一个概念

1.显示在哪 -> GLSurfaceVIew

2.谁来把数据贴到GLSurfaceVIew上 -> Renderer

3.谁来负责YUV数据转换成RGB -> GL中的Program/Shader

一句话说明白就是：GL的Program/Shader把用户传过来的YUV数据，转换成RGB数据后，通过Renderer贴在GLSurfaceView上。

二、怎么检查你的手机是不是支持GLES2.0呢，使用下面的代码段就行了：

 public static boolean detectOpenGLES20(Context context) {
     ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
     ConfigurationInfo info = am.getDeviceConfigurationInfo();
     return (info.reqGlEsVersion >= 0x20000);
 }

一般的手机，都是会支持GLES2.0的，大家不必担心。

三、开搞

A 先要有一个GLSurfaceView，把它放入你的布局中就好了。

找到这个家伙，对它进行简单的设置，并为它设置一个Renderer。

Renderer的作用就是在GLSurfaceView上画出图像。

 mGLSurface = (GLFrameSurface) findViewById(R.id.glsurface);
 mGLSurface.setEGLContextClientVersion(2);
 mGLFRenderer = new GLFrameRenderer(this, mGLSurface);
 mGLSurface.setRenderer(mGLFRenderer);

B 再就是看下GLFrameRenderer怎么来写了

 public class GLFrameRenderer implements Renderer {

     private ISimplePlayer mParentAct; //请无视之
     private GLSurfaceView mTargetSurface;
     private GLProgram prog = new GLProgram(0);
     private int mVideoWidth = -1, mVideoHeight = -1;
     private ByteBuffer y;
     private ByteBuffer u;
     private ByteBuffer v;

     public GLFrameRenderer(ISimplePlayer callback, GLSurfaceView surface) {
         mParentAct = callback; //请无视之
         mTargetSurface = surface;
     }

     @Override
     public void onSurfaceCreated(GL10 gl, EGLConfig config) {
         Utils.LOGD("GLFrameRenderer :: onSurfaceCreated");
         if (!prog.isProgramBuilt()) {
             prog.buildProgram();
             Utils.LOGD("GLFrameRenderer :: buildProgram done");
         }
     }

     @Override
     public void onSurfaceChanged(GL10 gl, int width, int height) {
         Utils.LOGD("GLFrameRenderer :: onSurfaceChanged");
         GLES20.glViewport(0, 0, width, height);
     }

     @Override
     public void onDrawFrame(GL10 gl) {
         synchronized (this) {
             if (y != null) {
                 // reset position, have to be done
                 y.position(0);
                 u.position(0);
                 v.position(0);
                 prog.buildTextures(y, u, v, mVideoWidth, mVideoHeight);
                 GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
                 GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
                 prog.drawFrame();
             }
         }
     }

     /**
      * this method will be called from native code, it happens when the video is about to play or
      * the video size changes.
      */
     public void update(int w, int h) {
         Utils.LOGD("INIT E");
         if (w > 0 && h > 0) {
             if (w != mVideoWidth && h != mVideoHeight) {
                 this.mVideoWidth = w;
                 this.mVideoHeight = h;
                 int yarraySize = w * h;
                 int uvarraySize = yarraySize / 4;
                 synchronized (this) {
                     y = ByteBuffer.allocate(yarraySize);
                     u = ByteBuffer.allocate(uvarraySize);
                     v = ByteBuffer.allocate(uvarraySize);
                 }
             }
         }

         mParentAct.onPlayStart(); //请无视之
         Utils.LOGD("INIT X");
     }

     /**
      * this method will be called from native code, it's used for passing yuv data to me.
      */
     public void update(byte[] ydata, byte[] udata, byte[] vdata) {
         synchronized (this) {
             y.clear();
             u.clear();
             v.clear();
             y.put(ydata, 0, ydata.length);
             u.put(udata, 0, udata.length);
             v.put(vdata, 0, vdata.length);
         }

         // request to render
         mTargetSurface.requestRender();
     }
 }

代码很简单，Renderer主要处理这么几个事：

1.Surface create的时候，我初始化了一些需要用到的Program/Shader，因为马上就要用到它们了；

2.Surface change的时候，重置一下画面；

3.onDrawFrame()时，把数据真正地“画”上去；

4.至于两个update方法，是用来把图像的宽高/数据传过来的。

C 看GLProgram是怎么写的，它的作用是向Renderer提供计算单元，你所有对数据的处理，都在这儿了。

 public boolean isProgramBuilt() {
     return isProgBuilt;
 }

 public void buildProgram() {
     createBuffers(_vertices, coordVertices);
     if (_program <= 0) {
         _program = createProgram(VERTEX_SHADER, FRAGMENT_SHADER);
     }
     Utils.LOGD("_program = " + _program);

     /*
      * get handle for "vPosition" and "a_texCoord"
      */
     _positionHandle = GLES20.glGetAttribLocation(_program, "vPosition");
     Utils.LOGD("_positionHandle = " + _positionHandle);
     checkGlError("glGetAttribLocation vPosition");
     if (_positionHandle == -1) {
         throw new RuntimeException("Could not get attribute location for vPosition");
     }
     _coordHandle = GLES20.glGetAttribLocation(_program, "a_texCoord");
     Utils.LOGD("_coordHandle = " + _coordHandle);
     checkGlError("glGetAttribLocation a_texCoord");
     if (_coordHandle == -1) {
         throw new RuntimeException("Could not get attribute location for a_texCoord");
     }

     /*
      * get uniform location for y/u/v, we pass data through these uniforms
      */
     _yhandle = GLES20.glGetUniformLocation(_program, "tex_y");
     Utils.LOGD("_yhandle = " + _yhandle);
     checkGlError("glGetUniformLocation tex_y");
     if (_yhandle == -1) {
         throw new RuntimeException("Could not get uniform location for tex_y");
     }
     _uhandle = GLES20.glGetUniformLocation(_program, "tex_u");
     Utils.LOGD("_uhandle = " + _uhandle);
     checkGlError("glGetUniformLocation tex_u");
     if (_uhandle == -1) {
         throw new RuntimeException("Could not get uniform location for tex_u");
     }
     _vhandle = GLES20.glGetUniformLocation(_program, "tex_v");
     Utils.LOGD("_vhandle = " + _vhandle);
     checkGlError("glGetUniformLocation tex_v");
     if (_vhandle == -1) {
         throw new RuntimeException("Could not get uniform location for tex_v");
     }

     isProgBuilt = true;
 }

 /**
  * build a set of textures, one for Y, one for U, and one for V.
  */
 public void buildTextures(Buffer y, Buffer u, Buffer v, int width, int height) {
     boolean videoSizeChanged = (width != _video_width || height != _video_height);
     if (videoSizeChanged) {
         _video_width = width;
         _video_height = height;
         Utils.LOGD("buildTextures videoSizeChanged: w=" + _video_width + " h=" + _video_height);
     }

     // building texture for Y data
     if (_ytid < 0 || videoSizeChanged) {
         if (_ytid >= 0) {
             Utils.LOGD("glDeleteTextures Y");
             GLES20.glDeleteTextures(1, new int[] { _ytid }, 0);
             checkGlError("glDeleteTextures");
         }
         // GLES20.glPixelStorei(GLES20.GL_UNPACK_ALIGNMENT, 1);
         int[] textures = new int[1];
         GLES20.glGenTextures(1, textures, 0);
         checkGlError("glGenTextures");
         _ytid = textures[0];
         Utils.LOGD("glGenTextures Y = " + _ytid);
     }
     GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, _ytid);
     checkGlError("glBindTexture");
     GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_LUMINANCE, _video_width, _video_height, 0,
             GLES20.GL_LUMINANCE, GLES20.GL_UNSIGNED_BYTE, y);
     checkGlError("glTexImage2D");
     GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
     GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
     GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
     GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);

     // building texture for U data
     if (_utid < 0 || videoSizeChanged) {
         if (_utid >= 0) {
             Utils.LOGD("glDeleteTextures U");
             GLES20.glDeleteTextures(1, new int[] { _utid }, 0);
             checkGlError("glDeleteTextures");
         }
         int[] textures = new int[1];
         GLES20.glGenTextures(1, textures, 0);
         checkGlError("glGenTextures");
         _utid = textures[0];
         Utils.LOGD("glGenTextures U = " + _utid);
     }
     GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, _utid);
     GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_LUMINANCE, _video_width / 2, _video_height / 2, 0,
             GLES20.GL_LUMINANCE, GLES20.GL_UNSIGNED_BYTE, u);
     GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
     GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
     GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
     GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);

     // building texture for V data
     if (_vtid < 0 || videoSizeChanged) {
         if (_vtid >= 0) {
             Utils.LOGD("glDeleteTextures V");
             GLES20.glDeleteTextures(1, new int[] { _vtid }, 0);
             checkGlError("glDeleteTextures");
         }
         int[] textures = new int[1];
         GLES20.glGenTextures(1, textures, 0);
         checkGlError("glGenTextures");
         _vtid = textures[0];
         Utils.LOGD("glGenTextures V = " + _vtid);
     }
     GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, _vtid);
     GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_LUMINANCE, _video_width / 2, _video_height / 2, 0,
             GLES20.GL_LUMINANCE, GLES20.GL_UNSIGNED_BYTE, v);
     GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
     GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
     GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
     GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
 }

 /**
  * render the frame
  * the YUV data will be converted to RGB by shader.
  */
 public void drawFrame() {
     GLES20.glUseProgram(_program);
     checkGlError("glUseProgram");

     GLES20.glVertexAttribPointer(_positionHandle, 2, GLES20.GL_FLOAT, false, 8, _vertice_buffer);
     checkGlError("glVertexAttribPointer mPositionHandle");
     GLES20.glEnableVertexAttribArray(_positionHandle);

     GLES20.glVertexAttribPointer(_coordHandle, 2, GLES20.GL_FLOAT, false, 8, _coord_buffer);
     checkGlError("glVertexAttribPointer maTextureHandle");
     GLES20.glEnableVertexAttribArray(_coordHandle);

     // bind textures
     GLES20.glActiveTexture(_textureI);
     GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, _ytid);
     GLES20.glUniform1i(_yhandle, _tIindex);

     GLES20.glActiveTexture(_textureII);
     GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, _utid);
     GLES20.glUniform1i(_uhandle, _tIIindex);

     GLES20.glActiveTexture(_textureIII);
     GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, _vtid);
     GLES20.glUniform1i(_vhandle, _tIIIindex);

     GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
     GLES20.glFinish();

     GLES20.glDisableVertexAttribArray(_positionHandle);
     GLES20.glDisableVertexAttribArray(_coordHandle);
 }

 /**
  * create program and load shaders, fragment shader is very important.
  */
 public int createProgram(String vertexSource, String fragmentSource) {
     // create shaders
     int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexSource);
     int pixelShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentSource);
     // just check
     Utils.LOGD("vertexShader = " + vertexShader);
     Utils.LOGD("pixelShader = " + pixelShader);

     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) {
             Utils.LOGE("Could not link program: ", null);
             Utils.LOGE(GLES20.glGetProgramInfoLog(program), null);
             GLES20.glDeleteProgram(program);
             program = 0;
         }
     }
     return program;
 }

 /**
  * create shader with given source.
  */
 private 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) {
             Utils.LOGE("Could not compile shader " + shaderType + ":", null);
             Utils.LOGE(GLES20.glGetShaderInfoLog(shader), null);
             GLES20.glDeleteShader(shader);
             shader = 0;
         }
     }
     return shader;
 }

 /**
  * these two buffers are used for holding vertices, screen vertices and texture vertices.
  */
 private void createBuffers(float[] vert, float[] coord) {
     _vertice_buffer = ByteBuffer.allocateDirect(vert.length * 4);
     _vertice_buffer.order(ByteOrder.nativeOrder());
     _vertice_buffer.asFloatBuffer().put(vert);
     _vertice_buffer.position(0);

     if (_coord_buffer == null) {
         _coord_buffer = ByteBuffer.allocateDirect(coord.length * 4);
         _coord_buffer.order(ByteOrder.nativeOrder());
         _coord_buffer.asFloatBuffer().put(coord);
         _coord_buffer.position(0);
     }
 }

 private void checkGlError(String op) {
     int error;
     while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
         Utils.LOGE("***** " + op + ": glError " + error, null);
         throw new RuntimeException(op + ": glError " + error);
     }
 }

 private static float[] squareVertices = { -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, }; // fullscreen

 private static float[] coordVertices = { 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, };// whole-texture

 private static final String VERTEX_SHADER = "attribute vec4 vPosition;\n" + "attribute vec2 a_texCoord;\n"
         + "varying vec2 tc;\n" + "void main() {\n" + "gl_Position = vPosition;\n" + "tc = a_texCoord;\n" + "}\n";

 private static final String FRAGMENT_SHADER = "precision mediump float;\n" + "uniform sampler2D tex_y;\n"
         + "uniform sampler2D tex_u;\n" + "uniform sampler2D tex_v;\n" + "varying vec2 tc;\n" + "void main() {\n"
         + "vec4 c = vec4((texture2D(tex_y, tc).r - 16./255.) * 1.164);\n"
         + "vec4 U = vec4(texture2D(tex_u, tc).r - 128./255.);\n"
         + "vec4 V = vec4(texture2D(tex_v, tc).r - 128./255.);\n" + "c += V * vec4(1.596, -0.813, 0, 0);\n"
         + "c += U * vec4(0, -0.392, 2.017, 0);\n" + "c.a = 1.0;\n" + "gl_FragColor = c;\n" + "}\n";

这里面代码比较复杂，我在这里稍作解释：

1.首先，buildProgram()目的要生成一个program，作用是用来将YUV->RGB，其中用到了2个shader（shader就相当于一个小运算器，它运行一段代码），第1个shader运行VERTEX_SHADER里的代码，目的是将坐标作为参数传入第2个shader；第2个shader来做YUV->RGB的运算。

2.buildTextures()是要生成3个贴图，分别为了显示R/G/B数据，三个贴图重合在一起，显示出来的就是彩色的图片。

3.drawFrame()是使用program来做运算，并真正去做画这个动作了。