背景

在上一次的初次使用cmake编译jni后，这次cmake文件再次升级。利用网上的代码来编译一个简单的播放器。本文参照 Android+FFmpeg+ANativeWindow视频解码播放一文，在cmake下重新编译。特将过程分享给大家。

gradle 配置

apply plugin: 'com.android.application'android {    compileSdkVersion 22    buildToolsVersion "23.0.1"    //sourceSets.main.jni.srcDirs = ['jniLibs']    defaultConfig {        applicationId "jonesx.videoplayer"        minSdkVersion 9        targetSdkVersion 22        versionCode 1        versionName "1.0"        ndk {            abiFilters 'armeabi'        }        externalNativeBuild {            cmake {                arguments '-DANDROID_TOOLCHAIN=clang','-DANDROID_STL=gnustl_static'            }        }    }    buildTypes {        release {            minifyEnabled false            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'        }    }    externalNativeBuild {        cmake {            path "src/main/cpp/CMakeLists.txt"        }    }}dependencies {    compile fileTree(dir: 'libs', include: ['*.jar'])    compile 'com.android.support:appcompat-v7:22.2.1'    compile 'com.android.support:design:22.2.1'}

cmake 配置

整个工程的层级。

框架.png

cmake配置文件
CMakeLists.txt

cmake_minimum_required(VERSION 3.4.1)set(lib_src_DIR ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI})include_directories(        ${CMAKE_SOURCE_DIR}/include)add_library(avcodec-57_lib SHARED IMPORTED)set_target_properties(avcodec-57_lib PROPERTIES IMPORTED_LOCATION                             ${lib_src_DIR}/libavcodec-57.so)add_library(avformat-57_lib SHARED IMPORTED)set_target_properties(avformat-57_lib PROPERTIES IMPORTED_LOCATION                        ${lib_src_DIR}/libavformat-57.so)add_library(avutil-55_lib SHARED IMPORTED)set_target_properties(avutil-55_lib PROPERTIES IMPORTED_LOCATION                        ${lib_src_DIR}/libavutil-55.so)add_library(swresample-2_lib SHARED IMPORTED)set_target_properties(swresample-2_lib PROPERTIES IMPORTED_LOCATION                        ${lib_src_DIR}/libswresample-2.so)add_library(swscale-4_lib SHARED IMPORTED)set_target_properties(swscale-4_lib PROPERTIES IMPORTED_LOCATION                        ${lib_src_DIR}/libswscale-4.so)# build application's shared libadd_library(VideoPlayer SHARED            VideoPlayer.cpp)# Include libraries needed for VideoPlayer libtarget_link_libraries(VideoPlayerlogandroidavcodec-57_libavformat-57_libavutil-55_libswresample-2_libswscale-4_lib)

解释下，这里添加了依赖的so库，注意路径呀，我在这里坑了半天，还有同事拯救了我。
add_library(swscale-4_lib SHARED IMPORTED)
set_target_properties(swscale-4_lib PROPERTIES IMPORTED_LOCATION
${lib_src_DIR}/libswscale-4.so)
最后，不要忘了，target_link_libraries中添加对应的库。

VideoPlayer.cpp

//// Created by Jonesx on 2016/3/20.//#include #include "VideoPlayer.h"#include #include #include extern "C"{#include "libavcodec/avcodec.h"#include "libavformat/avformat.h"#include "libswscale/swscale.h"#include "libavutil/imgutils.h"};#define  LOG_TAG    "videoplayer"#define  LOGD(...)  __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__) JNIEXPORT jint JNICALL Java_jonesx_videoplayer_VideoPlayer_play        (JNIEnv *env, jclass clazz, jobject surface) {    LOGD("play");    // sd卡中的视频文件地址,可自行修改或者通过jni传入    char *file_name = "/sdcard/test.mp4";    av_register_all();    AVFormatContext *pFormatCtx = avformat_alloc_context();    // Open video file    if (avformat_open_input(&pFormatCtx, file_name, NULL, NULL) != 0) {        LOGD("Couldn't open file:%s\n", file_name);        return -1; // Couldn't open file    }    // Retrieve stream information    if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {        LOGD("Couldn't find stream information.");        return -1;    }    // Find the first video stream    int videoStream = -1, i;    for (i = 0; i < pFormatCtx->nb_streams; i++) {        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO            && videoStream < 0) {            videoStream = i;        }    }    if (videoStream == -1) {        LOGD("Didn't find a video stream.");        return -1; // Didn't find a video stream    }    // Get a pointer to the codec context for the video stream    AVCodecContext *pCodecCtx = pFormatCtx->streams[videoStream]->codec;    // Find the decoder for the video stream    AVCodec *pCodec = avcodec_find_decoder(pCodecCtx->codec_id);    if (pCodec == NULL) {        LOGD("Codec not found.");        return -1; // Codec not found    }    if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {        LOGD("Could not open codec.");        return -1; // Could not open codec    }    // 获取native window    ANativeWindow *nativeWindow = ANativeWindow_fromSurface(env, surface);    // 获取视频宽高    int videoWidth = pCodecCtx->width;    int videoHeight = pCodecCtx->height;    // 设置native window的buffer大小,可自动拉伸    ANativeWindow_setBuffersGeometry(nativeWindow, videoWidth, videoHeight,                                     WINDOW_FORMAT_RGBA_8888);    ANativeWindow_Buffer windowBuffer;    if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {        LOGD("Could not open codec.");        return -1; // Could not open codec    }    // Allocate video frame    AVFrame *pFrame = av_frame_alloc();    // 用于渲染    AVFrame *pFrameRGBA = av_frame_alloc();    if (pFrameRGBA == NULL || pFrame == NULL) {        LOGD("Could not allocate video frame.");        return -1;    }    // Determine required buffer size and allocate buffer    // buffer中数据就是用于渲染的,且格式为RGBA    int numBytes = av_image_get_buffer_size(AV_PIX_FMT_RGBA, pCodecCtx->width, pCodecCtx->height,                                            1);    uint8_t *buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));    av_image_fill_arrays(pFrameRGBA->data, pFrameRGBA->linesize, buffer, AV_PIX_FMT_RGBA,                         pCodecCtx->width, pCodecCtx->height, 1);    // 由于解码出来的帧格式不是RGBA的,在渲染之前需要进行格式转换    struct SwsContext *sws_ctx = sws_getContext(pCodecCtx->width,                                                pCodecCtx->height,                                                pCodecCtx->pix_fmt,                                                pCodecCtx->width,                                                pCodecCtx->height,                                                AV_PIX_FMT_RGBA,                                                SWS_BILINEAR,                                                NULL,                                                NULL,                                                NULL);    int frameFinished;    AVPacket packet;    while (av_read_frame(pFormatCtx, &packet) >= 0) {        // Is this a packet from the video stream?        if (packet.stream_index == videoStream) {            // Decode video frame            avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);            // 并不是decode一次就可解码出一帧            if (frameFinished) {                // lock native window buffer                ANativeWindow_lock(nativeWindow, &windowBuffer, 0);                // 格式转换                sws_scale(sws_ctx, (uint8_t const *const *) pFrame->data,                          pFrame->linesize, 0, pCodecCtx->height,                          pFrameRGBA->data, pFrameRGBA->linesize);                // 获取stride                uint8_t *dst = (uint8_t *) windowBuffer.bits;                int dstStride = windowBuffer.stride * 4;                uint8_t *src = (pFrameRGBA->data[0]);                int srcStride = pFrameRGBA->linesize[0];                // 由于window的stride和帧的stride不同,因此需要逐行复制                int h;                for (h = 0; h < videoHeight; h++) {                    memcpy(dst + h * dstStride, src + h * srcStride, srcStride);                }                ANativeWindow_unlockAndPost(nativeWindow);            }        }        av_packet_unref(&packet);    }    av_free(buffer);    av_free(pFrameRGBA);    // Free the YUV frame    av_free(pFrame);    // Close the codecs    avcodec_close(pCodecCtx);    // Close the video file    avformat_close_input(&pFormatCtx);    return 0;}

这里是正常的ffmpeg编解码流程。参见雷神

Paste_Image.png

这里又有一个坑点，由于我使用的是c++ 编译器clang，而ffmpeg的so库均为c语言的，故需添加
extern "C"{

include "libavcodec/avcodec.h"

include "libavformat/avformat.h"

include "libswscale/swscale.h"

include "libavutil/imgutils.h"

};
如果这里没添加extern "C"{}，即不是按C语言编译，就会存在undefined reference错误。下面是使用

VideoPlayer.java

package jonesx.videoplayer;/** * Created by Jonesx on 2016/3/12. */public class VideoPlayer {    static {        System.loadLibrary("VideoPlayer");    }    public static native int play(Object surface);}

MainActivity.java

这里使用的SufaceView来进行播放。

public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback {    SurfaceHolder surfaceHolder;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        SurfaceView surfaceView = (SurfaceView) findViewById(R.id.surface_view);        surfaceHolder = surfaceView.getHolder();        surfaceHolder.addCallback(this);    }    @Override    public void surfaceCreated(SurfaceHolder holder) {        new Thread(new Runnable() {            @Override            public void run() {                VideoPlayer.play(surfaceHolder.getSurface());            }        }).start();    }    @Override    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {    }    @Override    public void surfaceDestroyed(SurfaceHolder holder) {    }}

灰常简单的xml

<?xml version="1.0" encoding="utf-8"?>

收工，看效果，非常简陋，没暂停什么滴。
ps 补充源码 https://github.com/nothinglhw/cmakeDemo

test.png

Android(安卓)studio 2.2 JNI ffmpeg 简单的播放器（这里只有视频解码）

背景