Android音视频预览摄像头画面

Posted 2022-10-22 zhangke3016

利用OpenGL生成纹理并绑定到SurfaceTexture上，然后把Camera的预览数据设置到SurfaceTexture中，OpenGL拿到摄像头数据并显示出来。

1. 顶点与片元着色器

片元着色器：

#extension GL_OES_EGL_image_external:require
precision mediump float;
varying vec2 a_position;
uniform samplerExternalOES vTexture;
void main()
    gl_FragColor = texture2D(vTexture,a_position);

1. 注意前面要加 #extension GL_OES_EGL_image_external:require声明。
2. 之前的sampler2D 变成了 samplerExternalOES

顶点着色器:

attribute vec4 v_position;
attribute vec2 f_position;
varying vec2 a_position;
void main()
    gl_Position = v_position;
    a_position = f_position;

2. 创建Program

        mProgram = ShaderUtil.createProgram(ShaderUtil.getRawResource(mContext, R.raw.demo2_vertex_shader),
                ShaderUtil.getRawResource(mContext, R.raw.demo2_fragment_shader));
        if (mProgram == 0)
            throw new RuntimeException("create program fail");
        
        v_position = GLES20.glGetAttribLocation(mProgram, "v_position");
        f_positon = GLES20.glGetAttribLocation(mProgram, "f_position");

3. 生成并绑定纹理

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

        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);

        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_REPEAT);
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_REPEAT);
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
        //创建Camera预览的SurfaceTexture
        mSurfaceTexture = new SurfaceTexture(textureId);
        if (mOnSurfaceCreateListener != null)
            mOnSurfaceCreateListener.onSurfaceCreate(mSurfaceTexture);
        

        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, 0);

需要注意使用的是GLES11Ext.GL_TEXTURE_EXTERNAL_OES:

GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);

在创建纹理后我们将纹理id作为SurfaceTexture的构造参数传入，并通过回调通知外层处理Camera：

  mSurfaceTexture = new SurfaceTexture(textureId);
 if (mOnSurfaceCreateListener != null)
         mOnSurfaceCreateListener.onSurfaceCreate(mSurfaceTexture);
  

4. 刷新显示

  //将纹理图像更新为图像流中的最新帧。只有在拥有纹理的OpenGL ES上下文在调用线程上是最新的时，才      可以调用此方法。
//它将隐式地将其纹理绑定到GL_TEXTURE_EXTERNAL_OES纹理目标
       mSurfaceTexture.updateTexImage();
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        GLES20.glClearColor(1.0f, 0, 0, 1f);

        GLES20.glUseProgram(mProgram);

        GLES20.glEnableVertexAttribArray(v_position);
        GLES20.glVertexAttribPointer(v_position, 2, GLES20.GL_FLOAT, false, 8, mVertexBuffer);

        GLES20.glEnableVertexAttribArray(f_positon);
        GLES20.glVertexAttribPointer(f_positon, 2, GLES20.GL_FLOAT, false, 8, mFragmentBuffer);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
        GLES20.glBindTexture(mProgram, 0);

注意要先调用纹理图像更新为图像流中的最新帧。：

mSurfaceTexture.updateTexImage();

外部GLSurfaceView处理逻辑：

public Demo2SurfaceView(Context context, AttributeSet attrs) 
        super(context, attrs);
        setEGLContextClientVersion(2);
        Demo2Renderer demo2Renderer = new Demo2Renderer(context);
        //Camera 管理类
        mDemo2Camera = new Demo2Camera(context);
        demo2Renderer.setOnSurfaceCreateListener(new Demo2Renderer.OnSurfaceCreateListener() 
            @Override
            public void onSurfaceCreate(SurfaceTexture surfaceTexture) 
                mDemo2Camera.initCamera(surfaceTexture, cameraId);
                //注册当一个新的图像帧可用于SurfaceTexture时要调用的回调。
                surfaceTexture.setOnFrameAvailableListener(Demo2SurfaceView.this);
            
        );
        setRenderer(demo2Renderer);
        setRenderMode(RENDERMODE_WHEN_DIRTY);
    

    public void onDestory() 
        if (mDemo2Camera != null)
            mDemo2Camera.stopPreview();
        
    

    @Override
    public void onFrameAvailable(SurfaceTexture surfaceTexture) 
        //手动请求刷新
        requestRender();
    

再来看下这个Demo2Camera管理类：

    public Demo2Camera(Context context)
        this.width = DisplayUtil.getScreenWidth(context);
        this.height = DisplayUtil.getScreenHeight(context);
    

    public void initCamera(SurfaceTexture surfaceTexture,int cameraId)
        this.mSurfaceTexture = surfaceTexture;
        setCameraParm(cameraId);
    

    private void setCameraParm( int cameraId) 
        try 
            mCamera = Camera.open(cameraId);
           //将SurfaceTexture设置为预览surface
            mCamera.setPreviewTexture(mSurfaceTexture);

            Camera.Parameters parameters = mCamera.getParameters();
            parameters.setFlashMode("off");
            parameters.setPreviewFormat(ImageFormat.NV21);

            Camera.Size size = getFitSize(parameters.getSupportedPictureSizes());
            parameters.setPictureSize(size.width, size.height);

            size = getFitSize(parameters.getSupportedPreviewSizes());
            parameters.setPreviewSize(size.width, size.height);
            
            mCamera.setParameters(parameters);
            //开始预览
            mCamera.startPreview();
        catch (Exception e)
            e.printStackTrace();
        
    

    private Camera.Size getFitSize(List<Camera.Size> sizes) 
        if(width < height) 
            int t = height;
            height = width;
            width = t;
        

        for(Camera.Size size : sizes) 
            if(1.0f * size.width / size.height == 1.0f * width / height) 
                return size;
            
        
        return sizes.get(0);
    

关键处理逻辑在：

mCamera.setPreviewTexture(mSurfaceTexture);

此时将Camera、SurfaceTexture、OpenGL连接在一起了，看下预览的画面。

what? 现在显示怎么是这样的？方向歪到姥姥家了，咳咳，那下面开始调整方向。

5. 调整预览方向

改造顶点着色器：

attribute vec4 v_position;
attribute vec2 f_position;
uniform mat4 uMatrix;
varying vec2 a_position;
void main()
    gl_Position = v_position * uMatrix;
    a_position = f_position;

增加矩阵：

uniform mat4 uMatrix;

Renderer构造方法中置空矩阵：

Matrix.setIdentityM(matrix, 0);

查找到矩阵对应着色器中的id：

 uMatrix = GLES20.glGetUniformLocation(mProgram, "uMatrix");

@Override
    public void onSurfaceChanged(GL10 gl, int width, int height) 
        GLES20.glViewport(0, 0, width, height);
        setAngle(-90, 0, 0, 1);
        setAngle(180, 1, 0, 0);
        setAngle(180, 0, 1, 0);
    

    public void setAngle(float angle, float x, float y, float z)
        Matrix.rotateM(matrix, 0, angle, x, y, z);
    

Matrix.rotateM(matrix, o, a, x, y, z):
a:
正数：逆时针旋转
负数：顺时针旋转
x、y、z：分别表示相应坐标轴

矩阵赋值：

...
GLES20.glUseProgram(mProgram);
GLES20.glUniformMatrix4fv(uMatrix, 1, false, matrix, 0);
...