Android 基於ffmpeg開發簡易播放器 - EGL和OpenGLESGLES顯示YUV視頻

EGL和OpenGLESGLES顯示YUV視頻

1.EGL

EGL是OpenGL ES與系統原始窗口的適配層：

Display：用於與原生窗口創建鏈接。 Surface：用於渲染的區域。 Context：建立渲染上下文。指的是OpenGL ES項目運行須要的全部數據結構。如：定點，着色器，頂點數據矩陣。

2.GLSL

頂點着色器針對每一個頂點執行一次，用於肯定頂點的位置。

片元着色器針對每一個片元（像素）執行一次，用於肯定片元（像素）的顏色。

3.Android向底層傳遞Surface句柄

public class XPlay extends GLSurfaceView implements Runnable,SurfaceHolder.Callback
{
    public XPlay(Context context, AttributeSet attrs) {
        super( context, attrs );
    }

    @Override
    public void run() {
        Open("/sdcard/outyuv",getHolder().getSurface());

    }
    
    @Override
    public void surfaceCreated(SurfaceHolder var1)
    {
        new Thread( this ).start();
    }

    @Override
    public void surfaceChanged(SurfaceHolder var1, int var2, int var3, int var4)
    {

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder var1)
    {

    }
    public native void Open(String url,Object surface);
}
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4.獲取原始窗口

#include <android/native_window_jni.h>
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extern "C"
JNIEXPORT void JNICALL
Java_aplay_testopengles_XPlay_Open(JNIEnv *env, jobject instance, jstring url_, jobject surface) {
    //1 獲取原始窗口
    ANativeWindow *nwin = ANativeWindow_fromSurface(env,surface);
}
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ANativeWindow_fromSurface()：返回與Java Surface對象關聯的ANativeWindow，經過本地代碼與之交互。這得到了返回的ANativeWindow的引用; 使用結束以後要使用ANativeWindow_release()，這樣它纔不會泄漏。

ANativeWindow * ANativeWindow_fromSurface(
  JNIEnv *env,
  jobject surface
)
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ANativeWindow：不透明類型，提供對本地窗口的訪問。

struct ANativeWindow
{
#ifdef __cplusplus
    ANativeWindow()
        : flags(0), minSwapInterval(0), maxSwapInterval(0), xdpi(0), ydpi(0)
    {
        common.magic = ANDROID_NATIVE_WINDOW_MAGIC;
        common.version = sizeof(ANativeWindow);
        memset(common.reserved, 0, sizeof(common.reserved));
    }
    /* Implement the methods that sp<ANativeWindow> expects so that it
       can be used to automatically refcount ANativeWindow's. */ void incStrong(const void* id) const { common.incRef(const_cast<android_native_base_t*>(&common)); } void decStrong(const void* id) const { common.decRef(const_cast<android_native_base_t*>(&common)); } #endif struct android_native_base_t common; /* flags describing some attributes of this surface or its updater */ const uint32_t flags; /* min swap interval supported by this updated */ const int minSwapInterval; /* max swap interval supported by this updated */ const int maxSwapInterval; /* horizontal and vertical resolution in DPI */ const float xdpi; const float ydpi; /* Some storage reserved for the OEM's driver. */
    intptr_t    oem[4];
    /*
     * Set the swap interval for this surface.
     *
     * Returns 0 on success or -errno on error.
     */
    int     (*setSwapInterval)(struct ANativeWindow* window,
                int interval);
    /*
     * Hook called by EGL to acquire a buffer. After this call, the buffer
     * is not locked, so its content cannot be modified. This call may block if
     * no buffers are available.
     *
     * The window holds a reference to the buffer between dequeueBuffer and
     * either queueBuffer or cancelBuffer, so clients only need their own
     * reference if they might use the buffer after queueing or canceling it.
     * Holding a reference to a buffer after queueing or canceling it is only
     * allowed if a specific buffer count has been set.
     *
     * Returns 0 on success or -errno on error.
     */
    int     (*dequeueBuffer)(struct ANativeWindow* window,
                struct ANativeWindowBuffer** buffer);
    /*
     * hook called by EGL to lock a buffer. This MUST be called before modifying
     * the content of a buffer. The buffer must have been acquired with
     * dequeueBuffer first.
     *
     * Returns 0 on success or -errno on error.
     */
    int     (*lockBuffer)(struct ANativeWindow* window,
                struct ANativeWindowBuffer* buffer);
    /*
     * Hook called by EGL when modifications to the render buffer are done.
     * This unlocks and post the buffer.
     *
     * The window holds a reference to the buffer between dequeueBuffer and
     * either queueBuffer or cancelBuffer, so clients only need their own
     * reference if they might use the buffer after queueing or canceling it.
     * Holding a reference to a buffer after queueing or canceling it is only
     * allowed if a specific buffer count has been set.
     *
     * Buffers MUST be queued in the same order than they were dequeued.
     *
     * Returns 0 on success or -errno on error.
     */
    int     (*queueBuffer)(struct ANativeWindow* window,
                struct ANativeWindowBuffer* buffer);
    /*
     * hook used to retrieve information about the native window.
     *
     * Returns 0 on success or -errno on error.
     */
    int     (*query)(const struct ANativeWindow* window,
                int what, int* value);
    /*
     * hook used to perform various operations on the surface.
     * (*perform)() is a generic mechanism to add functionality to
     * ANativeWindow while keeping backward binary compatibility.
     *
     * DO NOT CALL THIS HOOK DIRECTLY.  Instead, use the helper functions
     * defined below.
     *
     *  (*perform)() returns -ENOENT if the 'what' parameter is not supported
     *  by the surface's implementation. * * The valid operations are: * NATIVE_WINDOW_SET_USAGE * NATIVE_WINDOW_CONNECT (deprecated) * NATIVE_WINDOW_DISCONNECT (deprecated) * NATIVE_WINDOW_SET_CROP (private) * NATIVE_WINDOW_SET_BUFFER_COUNT * NATIVE_WINDOW_SET_BUFFERS_GEOMETRY (deprecated) * NATIVE_WINDOW_SET_BUFFERS_TRANSFORM * NATIVE_WINDOW_SET_BUFFERS_TIMESTAMP * NATIVE_WINDOW_SET_BUFFERS_DIMENSIONS * NATIVE_WINDOW_SET_BUFFERS_FORMAT * NATIVE_WINDOW_SET_SCALING_MODE (private) * NATIVE_WINDOW_LOCK (private) * NATIVE_WINDOW_UNLOCK_AND_POST (private) * NATIVE_WINDOW_API_CONNECT (private) * NATIVE_WINDOW_API_DISCONNECT (private) * NATIVE_WINDOW_SET_BUFFERS_USER_DIMENSIONS (private) * NATIVE_WINDOW_SET_POST_TRANSFORM_CROP (private) * */ int (*perform)(struct ANativeWindow* window, int operation, ... ); /* * Hook used to cancel a buffer that has been dequeued. * No synchronization is performed between dequeue() and cancel(), so * either external synchronization is needed, or these functions must be * called from the same thread. * * The window holds a reference to the buffer between dequeueBuffer and * either queueBuffer or cancelBuffer, so clients only need their own * reference if they might use the buffer after queueing or canceling it. * Holding a reference to a buffer after queueing or canceling it is only * allowed if a specific buffer count has been set. */ int (*cancelBuffer)(struct ANativeWindow* window, struct ANativeWindowBuffer* buffer); void* reserved_proc[2]; }; 複製代碼

5.初始化EGL

#include <EGL/egl.h>
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///EGL
//1 EGL display建立和初始化
EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
if(display == EGL_NO_DISPLAY)
{
    LOGD("eglGetDisplay failed!");
    return;
}
if(EGL_TRUE != eglInitialize(display,0,0))
{
    LOGD("eglInitialize failed!");
    return;
}
//2 surface
//2-1 surface窗口配置
//輸出配置
EGLConfig config;
EGLint configNum;
EGLint configSpec[] = {
        EGL_RED_SIZE, 8,
        EGL_GREEN_SIZE, 8,
        EGL_BLUE_SIZE, 8,
        EGL_SURFACE_TYPE, 
        EGL_WINDOW_BIT, 
        EGL_NONE    // 屬性表以該常量爲結束符
};
if(EGL_TRUE != eglChooseConfig(display,configSpec,&config,1,&configNum))
{
    LOGD("eglChooseConfig failed!");
    return;
}
//建立surface
EGLSurface winsurface = eglCreateWindowSurface(display,config,nwin,0);
if(winsurface == EGL_NO_SURFACE)
{
    LOGD("eglCreateWindowSurface failed!");
    return;
}

//3 context 建立關聯的上下文
const EGLint ctxAttr[] = {
        EGL_CONTEXT_CLIENT_VERSION,2,EGL_NONE
};
EGLContext context = eglCreateContext(display,config,EGL_NO_CONTEXT,ctxAttr);
if(context == EGL_NO_CONTEXT)
{
    LOGD("eglCreateContext failed!");
    return;
}
if(EGL_TRUE != eglMakeCurrent(display,winsurface,winsurface,context))
{
    LOGD("eglMakeCurrent failed!");
    return;
}

LOGD("EGL Init Success!");
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EGLDisplay eglGetDisplay(EGLNativeDisplayType display_id)：返回須要顯示內容的對象的句柄。

EGLDisplay：EGL把這些不一樣平臺的顯示系統抽象爲一個獨立的類型：EGLDisplay。

eglInitialize()：初始化EGLDisplay。

EGLBoolean eglInitialize(EGLDisplay display, EGLint* majorVersion, EGLint* minorVersion);  
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EGLConfig：初始化EGLDisplay事後，要選擇一個合適的「繪圖表面」。

EGLBoolean eglChooseConfig(EGLDisplay display,  
                           const EGLint* attribs,    // 你想要的屬性事先定義到這個數組裏  
                           EGLConfig* configs,       // 圖形系統將返回若干知足條件的配置到該數組  
                           EGLint maxConfigs,        // 上面數組的容量  
                           EGLint* numConfigs);      // 圖形系統返回的可用的配置個數  
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eglCreateWindowSurface()：爲建立好的EGLDisplay建立窗口。

EGLSurface eglCreateWindowSurface(EGLDisplay display,  
                                  EGLConfig config,  
                                  EGLNativeWindowType window, // 在Windows上就是HWND類型  
                                  const EGLint* attribs);     // 此屬性表非彼屬性表 
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EGLSurface：EGLSurface 能夠是由 EGL 分配的離屏緩衝區（稱爲「pbuffer」），或由操做系統分配的窗口。EGL 窗口 Surface 經過 eglCreateWindowSurface() 調用被建立。該調用將「窗口對象」做爲參數，在 Android 上，該對象能夠是 SurfaceView、SurfaceTexture、SurfaceHolder 或 Surface，全部這些對象下面都有一個 BufferQueue。當您進行此調用時，EGL 將建立一個新的 EGLSurface 對象，並將其鏈接到窗口對象的 BufferQueue 的生產方接口。此後，渲染到該 EGLSurface 會致使一個緩衝區離開隊列、進行渲染，而後排隊等待消耗方使用。

eglCreateContext()：eglCreateContext爲當前渲染API（使用eglBindAPI設置）建立EGL渲染context，並返回context的句柄。 context而後能夠用於渲染到EGL繪圖表面。 若是eglCreateContext沒法建立渲染context，則返回EGL_NO_CONTEXT。

EGLContext eglCreateContext(EGLDisplay display,
 	EGLConfig config,
 	EGLContext share_context,
 	EGLint const * attrib_list);
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display：指定EGL顯示鏈接。

config：指定定義可用於渲染context的幀緩衝區資源的EGL幀緩衝區配置。

share_context：指定用於共享數據的另外一個EGL渲染context，由與context相對應的客戶端API定義。 數據也與share_context共享數據的全部其餘context共享。 EGL_NO_CONTEXT表示不會發生共享。

attrib_list：爲正在建立的context指定屬性和屬性值。 只能指定屬性EGL_CONTEXT_CLIENT_VERSION。

EGLContext：OpenGL ES 圖形上下文，它表明了OpenGL狀態機；若是沒有它，OpenGL指令就沒有執行的環境。

eglMakeCurrent()：eglMakeCurrent將context綁定到當前渲染線程以及繪製和讀取表面。 繪製用於全部GL操做，除了讀取的任何像素數據（glReadPixels，glCopyTexImage2D和glCopyTexSubImage2D），它取自讀取的幀緩衝區值。

若是調用線程已經有當前的渲染context，那麼該context將被刷新並標記爲再也不是最新的。

當context首次生成時，viewport和scissor尺寸被設置爲繪製表面的大小。 當context隨後變爲當前時，viewport和scissor不會被修改。

EGLBoolean eglMakeCurrent(	EGLDisplay display,
 	EGLSurface draw,
 	EGLSurface read,
 	EGLContext context);
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6.頂點和片元shader初始化

#include <GLES2/gl2.h>
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頂點着色器

片元着色器

//頂點和片元shader初始化
//頂點shader初始化
GLint vsh = InitShader(vertexShader,GL_VERTEX_SHADER);
//片元yuv420 shader初始化
GLint fsh = InitShader(fragYUV420P,GL_FRAGMENT_SHADER);
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//頂點着色器glsl
#define GET_STR(x) #x
static const char *vertexShader = GET_STR(
    attribute vec4 aPosition; //頂點座標
    attribute vec2 aTexCoord; //材質頂點座標
    varying vec2 vTexCoord;   //輸出的材質座標
    void main(){
        vTexCoord = vec2(aTexCoord.x,1.0-aTexCoord.y);//以左上角爲座標原點
        gl_Position = aPosition;
    }
);

//片元着色器,軟解碼和部分x86硬解碼
static const char *fragYUV420P = GET_STR(
    precision mediump float;    //精度
    varying vec2 vTexCoord;     //頂點着色器傳遞的座標
    uniform sampler2D yTexture; //輸入的材質（不透明灰度，單像素）
    uniform sampler2D uTexture;
    uniform sampler2D vTexture;
    void main(){
        vec3 yuv;//承載輸入的信息
        vec3 rgb;//承載輸出的信息
        yuv.r = texture2D(yTexture,vTexCoord).r;//獲取指定座標的材質顏色
        yuv.g = texture2D(uTexture,vTexCoord).r - 0.5;
        yuv.b = texture2D(vTexture,vTexCoord).r - 0.5;
        rgb = mat3(1.0,     1.0,    1.0,
                   0.0,-0.39465,2.03211,
                   1.13983,-0.58060,0.0)*yuv;//指定的yuv轉換爲rgb的公式
        //輸出像素顏色
        gl_FragColor = vec4(rgb,1.0);
    }
);

GLint InitShader(const char *code,GLint type)
{
    //建立shader
    GLint sh = glCreateShader(type);
    if(sh == 0)
    {
        LOGD("glCreateShader %d failed!",type);
        return 0;
    }
    //加載shader
    glShaderSource(sh,
                   1,    //shader數量
                   &code, //shader代碼
                   0);   //代碼長度
    //編譯shader
    glCompileShader(sh);

    //獲取編譯狀況
    GLint status;
    glGetShaderiv(sh,GL_COMPILE_STATUS,&status);
    if(status == 0)
    {
        LOGD("glCompileShader failed!");
        return 0;
    }
    LOGD("glCompileShader success!");
    return sh;
}
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7.建立渲染程序

//建立渲染程序
GLint program = glCreateProgram();
if(program == 0)
{
    LOGD("glCreateProgram failed!");
    return;
}
//渲染程序中加入着色器代碼
glAttachShader(program,vsh);
glAttachShader(program,fsh);

//連接程序
glLinkProgram(program);
GLint status = 0;
glGetProgramiv(program,GL_LINK_STATUS,&status);
if(status != GL_TRUE)
{
    LOGD("glLinkProgram failed!");
    return;
}
glUseProgram(program);
LOGD("glLinkProgram success!");
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8.傳遞頂點數據

//加入三維頂點數據 兩個三角形組成正方形
static float vers[] = {
        1.0f,-1.0f,0.0f,
        -1.0f,-1.0f,0.0f,
        1.0f,1.0f,0.0f,
        -1.0f,1.0f,0.0f,
};
GLuint apos = (GLuint)glGetAttribLocation(program,"aPosition");
glEnableVertexAttribArray(apos);
//傳遞頂點
glVertexAttribPointer(apos,3,GL_FLOAT,GL_FALSE,12,vers);
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9.傳遞材質數據

//加入材質座標數據
static float txts[] = {
        1.0f,0.0f , //右下
        0.0f,0.0f,
        1.0f,1.0f,
        0.0f,1.0f
};
GLuint atex = (GLuint)glGetAttribLocation(program,"aTexCoord");
glEnableVertexAttribArray(atex);
glVertexAttribPointer(atex,2,GL_FLOAT,GL_FALSE,8,txts);
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10.材質紋理初始化

int width = 424;
int height = 240;
    
//材質紋理初始化
//設置紋理層
glUniform1i( glGetUniformLocation(program,"yTexture"),0); //對於紋理第1層
glUniform1i( glGetUniformLocation(program,"uTexture"),1); //對於紋理第2層
glUniform1i( glGetUniformLocation(program,"vTexture"),2); //對於紋理第3層

//建立opengl紋理
GLuint texts[3] = {0};
//建立三個紋理
glGenTextures(3,texts);

//設置紋理屬性
glBindTexture(GL_TEXTURE_2D,texts[0]);
//縮小的過濾器
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
//設置紋理的格式和大小
glTexImage2D(GL_TEXTURE_2D,
             0,           //細節基本 0默認
             GL_LUMINANCE,//gpu內部格式 亮度，灰度圖
             width,height, //拉昇到全屏
             0,             //邊框
             GL_LUMINANCE,//數據的像素格式 亮度，灰度圖 要與上面一致
             GL_UNSIGNED_BYTE, //像素的數據類型
             NULL                    //紋理的數據
);

//設置紋理屬性
glBindTexture(GL_TEXTURE_2D,texts[1]);
//縮小的過濾器
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
//設置紋理的格式和大小
glTexImage2D(GL_TEXTURE_2D,
             0,           //細節基本 0默認
             GL_LUMINANCE,//gpu內部格式 亮度，灰度圖
             width/2,height/2, //拉昇到全屏
             0,             //邊框
             GL_LUMINANCE,//數據的像素格式 亮度，灰度圖 要與上面一致
             GL_UNSIGNED_BYTE, //像素的數據類型
             NULL                    //紋理的數據
);

//設置紋理屬性
glBindTexture(GL_TEXTURE_2D,texts[2]);
//縮小的過濾器
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
//設置紋理的格式和大小
glTexImage2D(GL_TEXTURE_2D,
             0,           //細節基本 0默認
             GL_LUMINANCE,//gpu內部格式 亮度，灰度圖
             width/2,height/2, //拉昇到全屏
             0,             //邊框
             GL_LUMINANCE,//數據的像素格式 亮度，灰度圖 要與上面一致
             GL_UNSIGNED_BYTE, //像素的數據類型
             NULL                    //紋理的數據
);
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11.紋理顯示

////紋理的修改和顯示
FILE *fp = fopen(url,"rb");
if(!fp)
{
    LOGD("open file %s failed!",url);
    return;
}
    
unsigned char *buf[3] = {0};//將顯示的材質存放到buf中
buf[0] = new unsigned char[width*height];
buf[1] = new unsigned char[width*height/4];
buf[2] = new unsigned char[width*height/4];

for(int i = 0; i<10000;i++)
{
    //420p   yyyyyyyy uu vv
    if(feof(fp) == 0)
    {
        //yyyyyyyy
        fread(buf[0],1,width*height,fp);
        fread(buf[1],1,width*height/4,fp);
        fread(buf[2],1,width*height/4,fp);
    }

    //激活第1層紋理,綁定到建立的opengl紋理
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D,texts[0]);
    //替換紋理內容
    glTexSubImage2D(GL_TEXTURE_2D,0,0,0,width,height,GL_LUMINANCE,GL_UNSIGNED_BYTE,buf[0]);

    //激活第2層紋理,綁定到建立的opengl紋理
    glActiveTexture(GL_TEXTURE0+1);
    glBindTexture(GL_TEXTURE_2D,texts[1]);
    //替換紋理內容
    glTexSubImage2D(GL_TEXTURE_2D,0,0,0,width/2,height/2,GL_LUMINANCE,GL_UNSIGNED_BYTE,buf[1]);

    //激活第2層紋理,綁定到建立的opengl紋理
    glActiveTexture(GL_TEXTURE0+2);
    glBindTexture(GL_TEXTURE_2D,texts[2]);
    //替換紋理內容
    glTexSubImage2D(GL_TEXTURE_2D,0,0,0,width/2,height/2,GL_LUMINANCE,GL_UNSIGNED_BYTE,buf[2]);

    //三維繪製
    glDrawArrays(GL_TRIANGLE_STRIP,0,4);
    //窗口顯示
    eglSwapBuffers(display,winsurface);
}
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