音視訊實踐學習

• android全平臺編譯ffmpeg以及x264與fdk-aac實踐
• ubuntu下使用nginx和nginx-rtmp-module配置直播推流伺服器
• android全平臺編譯ffmpeg合併為單個庫實踐
• android-studio使用cmake編譯ffmpeg實踐
• android全平臺編譯ffmpeg視訊解碼器實踐
• android全平臺編譯ffmpeg支援命令列實踐
• android全平臺編譯ffmpeg視訊推流實踐
• android平臺下音訊編碼之編譯LAME庫轉碼PCM為MP3
• ubuntu平臺下編譯vlc-android視訊播放器實踐
• 圖解YU12、I420、YV12、NV12、NV21、YUV420P、YUV420SP、YUV422P、YUV444P的區別
• 圖解RGB565、RGB555、RGB16、RGB24、RGB32、ARGB32等格式的區別
• YUV420P、YUV420SP、NV12、NV21和RGB互相轉換並存儲為JPEG以及PNG圖片
• android全平臺編譯libyuv庫實現YUV和RGB的轉換

概述

libyuv是Google開源的實現各種YUV與RGB之間相互轉換、旋轉、縮放的庫。它是跨平臺的，可在Windows、Linux、Mac、Android等作業系統，x86、x64、arm

環境配置

作業系統：ubuntu 16.05
ndk版本：android-ndk-r16b

開始編譯

第一步：先克隆出最新的libyuv版本

git clone git@github.com:lemenkov/libyuv.git

第二步：重新命名libyuv為jni，編輯Android.mk檔案，註釋掉JPEG相關的配置

第三步：新建Application.mk檔案

APP_ABI := armeabi-v7a x86 x86_64
APP_PLATFORM := android-
 
16
APP_STL := stlport_static  
APP_CPPFLAGS += -fno-rtti  

開始編譯ndk-build

工程實踐

還是基於之前的graphic4android工程，新建native-libyuv工程，配置可以參考之前的配置：

enum Type {
    TYPE_YUV420P_TO_RGB24 = 0,
    TYPE_NV12_TO_RGB24 = 1,
    TYPE_NV21_TO_RGB24 = 2
};

/**
 * I420就是YUV420P
 * @param yuvData
 * @param rgb24
 * @param width
 * @param height
 */
void I420_TO_RGB24(unsigned char *yuvData, unsigned char *rgb24, int width, int height) {

    unsigned char *ybase = yuvData;
    unsigned char *ubase = &yuvData[width * height];
    unsigned char *vbase = &yuvData[width * height * 5 / 4];
    //YUV420P轉RGB24
    libyuv::I420ToRGB24(ybase, width, ubase, width / 2, vbase, width / 2,
                        rgb24,
                        width * 3, width, height);

}

/**
 * NV12屬於YUV420SP
 * @param yuvData
 * @param rgb24
 * @param width
 * @param height
 */
void NV12_TO_RGB24(unsigned char *yuvData, unsigned char *rgb24, int width, int height) {

    unsigned char *ybase = yuvData;
    unsigned char *uvbase = &yuvData[width * height];
    //NV12轉RGB24
    libyuv::NV12ToRGB24(ybase, width, uvbase, width,
                        rgb24,
                        width * 3, width, height);

}

/**
 * NV21屬於YUV420SP
 * @param yuvData
 * @param rgb24
 * @param width
 * @param height
 */
void NV21_TO_RGB24(unsigned char *yuvData, unsigned char *rgb24, int width, int height) {

    unsigned char *ybase = yuvData;
    unsigned char *vubase = &yuvData[width * height];
    //NV21轉RGB24
    libyuv::NV21ToRGB24(ybase, width, vubase, width,
                        rgb24,
                        width * 3, width, height);

}

void drawYUV(const char *path, int type, int width, int height, ANativeWindow_Buffer buffer) {
    FILE *file = fopen(path, "rb");

    int frameSize = width * height * 3 / 2;

    unsigned char *yuvData = new unsigned char[frameSize];

    fread(yuvData, 1, frameSize, file);

    unsigned char *rgb24 = new unsigned char[width * height * 3];

    //YUV轉RGB24
    switch (type) {
        case TYPE_YUV420P_TO_RGB24:
            //YUV420P轉RGB24
            I420_TO_RGB24(yuvData, rgb24, width, height);
            break;
        case TYPE_NV12_TO_RGB24:
            //YUV420SP轉RGB24
            NV12_TO_RGB24(yuvData, rgb24, width, height);
            break;
        case TYPE_NV21_TO_RGB24:
            //YUV420SP轉RGB24
            NV21_TO_RGB24(yuvData, rgb24, width, height);
            break;
    }

    uint32_t *line = (uint32_t *) buffer.bits;
    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            int index = y * width + x;
            line[x] = rgb24[index * 3] << 16
                      | rgb24[index * 3 + 1] << 8
                      | rgb24[index * 3 + 2];
        }
        line = line + buffer.stride;
    }

    //釋放記憶體
    delete[] yuvData;
    delete[] rgb24;

    //關閉檔案控制代碼
    fclose(file);
}

void yuv2rgb(JNIEnv *env, jobject obj, jstring yuvPath, jint type, jint width, jint height,
             jobject surface) {

    const char *path = env->GetStringUTFChars(yuvPath, 0);

    //獲取目標surface
    ANativeWindow *window = ANativeWindow_fromSurface(env, surface);
    if (NULL == window) {
        ThrowException(env, "java/lang/RuntimeException", "unable to get native window");
        return;
    }
    //預設的是RGB_565
    int32_t result = ANativeWindow_setBuffersGeometry(window, 0, 0, WINDOW_FORMAT_RGBA_8888);
    if (result < 0) {
        ThrowException(env, "java/lang/RuntimeException", "unable to set buffers geometry");
        //釋放視窗
        ANativeWindow_release(window);
        window = NULL;
        return;
    }
    ANativeWindow_acquire(window);

    ANativeWindow_Buffer buffer;
    //鎖定視窗的繪圖表面
    if (ANativeWindow_lock(window, &buffer, NULL) < 0) {
        ThrowException(env, "java/lang/RuntimeException", "unable to lock native window");
        //釋放視窗
        ANativeWindow_release(window);
        window = NULL;
        return;
    }

    //繪製YUV420P
    drawYUV(path, type, width, height, buffer);

    //解鎖視窗的繪圖表面
    if (ANativeWindow_unlockAndPost(window) < 0) {
        ThrowException(env, "java/lang/RuntimeException",
                       "unable to unlock and post to native window");
    }

    env->ReleaseStringUTFChars(yuvPath, path);
    //釋放
    ANativeWindow_release(window);
}

直接呼叫libyuv庫裡的函式即可完成轉換過程

專案地址：native-libyuv
https://github.com/byhook/graphic4android