FFmpeg实现视频播放

• 前言

本篇只做环境配置以及具体代码实现，不做源码讲解。

• 运行环境

开发软件：Android Studio:3.4.1；运行系统Mac；编译方式cmake

• 新建一个modue，修改build.gradle配置，具体配置如下所示

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
android {
    compileSdkVersion 28


    defaultConfig {
        applicationId "com.lee.jniffmpeg"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags "-frtti -fexceptions"
            }
        }
        //ndk编译生成.so文件
        ndk {
            moduleName "ffmpeg"         //生成的so名字
            abiFilters 'x86', 'x86_64', 'armeabi-v7a', 'arm64-v8a'  //输出指定三种abi体系结构下的so库。
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    externalNativeBuild {
        cmake {
            path file('src/main/cpp/CMakeLists.txt')
        }
    }

}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

• 在main文件下创建cpp文件夹，添加CMakeLists.txt，添加native-lib.cpp，然后点击右键，

Link C++ Project With Gradle

CMakeLists.tx的内容如下所示：

cmake_minimum_required(VERSION 3.4.1)
include_directories(../cpp/include)
set(SOURCES)
file(GLOB_RECURSE SOURCES ${CMAKE_SOURCE_DIR}/*.cpp ${CMAKE_SOURCE_DIR}/*.c)
# 把系统的log库导入进来
find_library( log-lib
        log )

set(distribution_DIR ../../../../libs)
add_library( yuv
        SHARED
        IMPORTED)
set_target_properties( yuv
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libyuv.so)
# 把libfmod.so预加载进来
add_library( avcodec-56
        SHARED
        IMPORTED)
set_target_properties( avcodec-56
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libavcodec-56.so)

# 把libfmodL.so预加载进来
add_library( avdevice-56
        SHARED
        IMPORTED)
set_target_properties( avdevice-56
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libavdevice-56.so)

add_library( avfilter-5
        SHARED
        IMPORTED)
set_target_properties( avfilter-5
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libavfilter-5.so)
add_library( avformat-56
        SHARED
        IMPORTED)
set_target_properties( avformat-56
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libavformat-56.so)
add_library( avutil-54
        SHARED
        IMPORTED)
set_target_properties( avutil-54
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libavutil-54.so)
add_library( postproc-53
        SHARED
        IMPORTED)
set_target_properties( postproc-53
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libpostproc-53.so)
add_library( swresample-1
        SHARED
        IMPORTED)
set_target_properties( swresample-1
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libswresample-1.so)
add_library( swscale-3
        SHARED
        IMPORTED)
set_target_properties( swscale-3
        PROPERTIES IMPORTED_LOCATION
        ${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libswscale-3.so)

#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11"


add_library( # Sets the name of the library.
        ffmpeg

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        ${SOURCES})
#用于native_window
#find_library(
#             android-lib
#             android
#)

target_link_libraries( ffmpeg
        yuv
        avutil-54
        swresample-1
        avcodec-56
        avformat-56
        swscale-3
        postproc-53
        avfilter-5
        avdevice-56
        -landroid#用于native_window
        ${log-lib} )

native-lib.cpp的内容如下如下所示

#include <jni.h>
#include <string>
#include <cstdlib>
#include <android/log.h>

using namespace std;
extern "C"//由于是C和C++混编，必须添加
{
//编码
#include "libavcodec/avcodec.h"
//封装格式处理
#include "libavformat/avformat.h"
//像素处理
#include "libswscale/swscale.h"
#include "libavutil/avutil.h"
#include "libavutil/frame.h"
}

#define LOGI(FORMAT, ...) __android_log_print(ANDROID_LOG_INFO,"jason",FORMAT,##__VA_ARGS__);
#define LOGE(FORMAT, ...) __android_log_print(ANDROID_LOG_ERROR,"jason",FORMAT,##__VA_ARGS__);

extern "C" JNIEXPORT jstring JNICALL
Java_com_lee_jniffmpeg_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

• 编译libyuv库和ffmpeg库（具体编译方式以后有时间再写）

编译成功后如下所示

• 具体实现代码

（1）新建DjPlayer文件，加载静态的so文件

package com.lee.jniffmpeg;

import android.view.Surface;

public class DjPlayer {
    public native void render(String input,Surface surface);

    static {
        System.loadLibrary("ffmpeg");
    }
}

（2）新建player.cpp文件，用来进行jni的相关实现

#include <jni.h>
#include <string>
#include <cstdlib>
#include <android/log.h>
#include <unistd.h>
#include <android/native_window_jni.h>
#include <android/native_window.h>
#include "libyuv/libyuv.h"

using namespace std;
extern "C"//由于是C和C++混编，必须添加
{
//编码
#include "libavcodec/avcodec.h"
//封装格式处理
#include "libavformat/avformat.h"
//像素处理
#include "libswscale/swscale.h"

}

#define LOGI(FORMAT, ...) __android_log_print(ANDROID_LOG_INFO,"jason",FORMAT,##__VA_ARGS__);
#define LOGE(FORMAT, ...) __android_log_print(ANDROID_LOG_ERROR,"jason",FORMAT,##__VA_ARGS__);

extern "C"
JNIEXPORT void JNICALL
Java_com_lee_jniffmpeg_DjPlayer_render(JNIEnv *env, jobject thiz, jstring input_jstr,
                                       jobject surface) {
    const char *input_cstr = env->GetStringUTFChars(input_jstr, NULL);
    //1.注册组件
    av_register_all();

    //封装格式上下文
    AVFormatContext *pFormatCtx = avformat_alloc_context();

    //2.打开输入视频文件
    if (avformat_open_input(&pFormatCtx, input_cstr, NULL, NULL) != 0) {
        LOGE("%s", "打开输入视频文件失败");
        return;
    }
    //3.获取视频信息
    if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
        LOGE("%s", "获取视频信息失败");
        return;
    }

    //视频解码，需要找到视频对应的AVStream所在pFormatCtx->streams的索引位置
    int video_stream_idx = -1;
    int i = 0;
    for (; i < pFormatCtx->nb_streams; i++) {
        //根据类型判断，是否是视频流
        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_stream_idx = i;
            break;
        }
    }

    //4.获取视频解码器
    AVCodecContext *pCodeCtx = pFormatCtx->streams[video_stream_idx]->codec;
    AVCodec *pCodec = avcodec_find_decoder(pCodeCtx->codec_id);
    if (pCodec == NULL) {
        LOGE("%s", "无法解码");
        return;
    }

    //5.打开解码器
    if (avcodec_open2(pCodeCtx, pCodec, NULL) < 0) {
        LOGE("%s", "解码器无法打开");
        return;
    }

    //编码数据
    AVPacket *packet = (AVPacket *) av_malloc(sizeof(AVPacket));

    //像素数据（解码数据）
    AVFrame *yuv_frame = av_frame_alloc();
    AVFrame *rgb_frame = av_frame_alloc();

    //native绘制
    //窗体
    ANativeWindow *nativeWindow = ANativeWindow_fromSurface(env, surface);
    //绘制时的缓冲区
    ANativeWindow_Buffer outBuffer;

    int len, got_frame, framecount = 0;
    //6.一阵一阵读取压缩的视频数据AVPacket
    while (av_read_frame(pFormatCtx, packet) >= 0) {
        //解码AVPacket->AVFrame
        len = avcodec_decode_video2(pCodeCtx, yuv_frame, &got_frame, packet);

        //Zero if no frame could be decompressed
        //非零，正在解码
        if (got_frame) {
            LOGI("解码%d帧", framecount++);
            //lock
            //设置缓冲区的属性（宽、高、像素格式）
            ANativeWindow_setBuffersGeometry(nativeWindow, pCodeCtx->width, pCodeCtx->height,
                                             WINDOW_FORMAT_RGBA_8888);
            ANativeWindow_lock(nativeWindow, &outBuffer, NULL);

            //设置rgb_frame的属性（像素格式、宽高）和缓冲区
            //rgb_frame缓冲区与outBuffer.bits是同一块内存
            avpicture_fill((AVPicture *) rgb_frame, static_cast<const uint8_t *>(outBuffer.bits),
                           PIX_FMT_RGBA, pCodeCtx->width, pCodeCtx->height);

            //YUV->RGBA_8888
            libyuv::I420ToARGB(yuv_frame->data[0], yuv_frame->linesize[0],
                               yuv_frame->data[2], yuv_frame->linesize[2],
                               yuv_frame->data[1], yuv_frame->linesize[1],
                               rgb_frame->data[0], rgb_frame->linesize[0],
                               pCodeCtx->width, pCodeCtx->height);

            //unlock
            ANativeWindow_unlockAndPost(nativeWindow);

            usleep(1000 * 16);

        }

        av_free_packet(packet);

    }
}

• 编写相关的kotlin代码，进行调用