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FFmpeg解码MP4文件为YUV文件

FFmpeg解码MP4文件为YUV文件

作者: 张俊峰0613 | 来源:发表于2018-12-22 12:18 被阅读0次

    前言

    前面我学了编译FFmpeg的Android库,写了一个命令行使用FFmpeg的Android Demo,C文件都在虚拟机实现,然后ndk编译成so库,再导入Android studio使用,Android代码中没有C/C++文件,很纯净的样子。但是,在虚拟机写C代码的时候,没有自动补全功能,很不方便。所以这次用Cmake编译JNI,直接在Android studio中使用代码补全功能!

    1、编译Android版FFmpeg并移植到Android studio中

    1.1、编译FFmpeg的Android库

    Android FFmpeg JNI开发入门_编译不同ABI的so库

    1.2、创建一个支持C++的Android项目

    把红框的选项都勾选上


    生成之后的项目目录


    1.2、将so库移植到Android项目中

    在libs目录下新建对应ABI的文件夹,比如armeabi-v7a,然后将编译生成的对应ABI的so库拷贝进去;
    再将头文件拷贝进去,就是生成的include目录;



    然后修改app的build.gradle文件如下;


    再修改CmakeLists.txt文件,指定依赖库:

    # For more information about using CMake with Android Studio, read the
    # documentation: https://d.android.com/studio/projects/add-native-code.html
    
    # Sets the minimum version of CMake required to build the native library.
    
    cmake_minimum_required(VERSION 3.4.1)
    
    # Creates and names a library, sets it as either STATIC
    # or SHARED, and provides the relative paths to its source code.
    # You can define multiple libraries, and CMake builds them for you.
    # Gradle automatically packages shared libraries with your APK.
    
    add_library( # Sets the name of the library.
            native-lib
    
            # Sets the library as a shared library.
            SHARED
    
            # Provides a relative path to your source file(s).
            src/main/cpp/native-lib.cpp)
    
    # Searches for a specified prebuilt library and stores the path as a
    # variable. Because CMake includes system libraries in the search path by
    # default, you only need to specify the name of the public NDK library
    # you want to add. CMake verifies that the library exists before
    # completing its build.
    
    find_library( # Sets the name of the path variable.
            log-lib
    
            # Specifies the name of the NDK library that
            # you want CMake to locate.
            log)
    
    
    include_directories(libs/include)
    set(DIR ../../../../libs)
    
    add_library( avcodec-57
            SHARED
            IMPORTED )
    set_target_properties( avcodec-57
            PROPERTIES IMPORTED_LOCATION
            ${DIR}/armeabi-v7a/libavcodec-57.so )
    
    add_library( avdevice-57
            SHARED
            IMPORTED)
    set_target_properties( avdevice-57
            PROPERTIES IMPORTED_LOCATION
            ${DIR}/armeabi-v7a/libavdevice-57.so )
    
    add_library( avfilter-6
            SHARED
            IMPORTED)
    set_target_properties( avfilter-6
            PROPERTIES IMPORTED_LOCATION
            ${DIR}/armeabi-v7a/libavfilter-6.so )
    
    add_library( avformat-57
            SHARED
            IMPORTED)
    set_target_properties( avformat-57
            PROPERTIES IMPORTED_LOCATION
            ${DIR}/armeabi-v7a/libavformat-57.so )
    
    add_library( avutil-55
            SHARED
            IMPORTED )
    set_target_properties( avutil-55
            PROPERTIES IMPORTED_LOCATION
            ${DIR}/armeabi-v7a/libavutil-55.so )
    
    add_library( postproc-54
            SHARED
            IMPORTED )
    set_target_properties( postproc-54
            PROPERTIES IMPORTED_LOCATION
            ${DIR}/armeabi-v7a/libpostproc-54.so )
    
    add_library( swresample-2
            SHARED
            IMPORTED )
    set_target_properties( swresample-2
            PROPERTIES IMPORTED_LOCATION
            ${DIR}/armeabi-v7a/libswresample-2.so )
    
    add_library( swscale-4
            SHARED
            IMPORTED)
    set_target_properties( swscale-4
            PROPERTIES IMPORTED_LOCATION
            ${DIR}/armeabi-v7a/libswscale-4.so )
    
    # Specifies libraries CMake should link to your target library. You
    # can link multiple libraries, such as libraries you define in this
    # build script, prebuilt third-party libraries, or system libraries.
    
    target_link_libraries( # Specifies the target library.
            native-lib
            avutil-55
            avcodec-57
            avformat-57
            avdevice-57
            swresample-2
            swscale-4
            postproc-54
            avfilter-6
            # Links the target library to the log library
            # included in the NDK.
            ${log-lib})
    

    2、写代码

    2.1、布局文件

    <?xml version="1.0" encoding="utf-8"?>
    
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/activity_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
    
        </LinearLayout>
    
        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="12dp"
            android:text=""
            android:id="@+id/editText1" />
    
        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="12dp"
            android:text=""
            android:id="@+id/editText2" />
    
        <Button
            android:text="开始解码为YUV"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/button" />
    
    
        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
    
        </ScrollView>
    
    </LinearLayout>
    

    2.2、生成jni头文件

    新建FFmpeg.java文件,加载so库,定义native方法;

    public class FFmpeg {
        static {
            System.loadLibrary("avutil-55");
            System.loadLibrary("avcodec-57");
            System.loadLibrary("avformat-57");
            System.loadLibrary("avdevice-57");
            System.loadLibrary("swresample-2");
            System.loadLibrary("swscale-4");
            System.loadLibrary("postproc-54");
            System.loadLibrary("avfilter-6");
        }
        
        public static native int decode(String inputurl, String outputurl);
    }
    

    生成头文件;
    命令行:javah 包名.类名

    javah com.example.zjf.ffmpegdecoder.FFmpeg
    

    将生成的头文件拖到cpp目录下,然后在native-lib.cpp中实现头文件的方法;


    2.3、实现jni方法

    添加用到的头文件;

    #include <jni.h>
    #include <string>
    
    #ifdef __cplusplus
    extern "C" {
    #include <libavutil/log.h>
    #include <libavcodec/avcodec.h>
    #include <libavformat/avformat.h>
    #include <libswscale/swscale.h>
    #include <libavutil/imgutils.h>
    
    #include "com_example_zjf_ffmpegdecoder_FFmpeg.h"
    #include <android/log.h>
    #define LOGE(format, ...)  __android_log_print(ANDROID_LOG_ERROR, "(>_<)", format, ##__VA_ARGS__)
    #define LOGI(format, ...)  __android_log_print(ANDROID_LOG_INFO,  "(^_^)", format, ##__VA_ARGS__)
    #endif
    /*
     * Class:     com_example_zjf_ffmpegdecoder_FFmpeg
     * Method:    decode
     * Signature: (Ljava/lang/String;Ljava/lang/String;)I
     */
    JNIEXPORT jint JNICALL Java_com_example_zjf_ffmpegdecoder_FFmpeg_decode
            (JNIEnv *evn, jclass clazz, jstring inputurl, jstring outputurl){
    
    }
    
    #ifdef __cplusplus
    }
    #endif
    

    这样就有了自动补全的功能;


    jni代码;

    #include <jni.h>
    #include <string>
    
    #ifdef __cplusplus
    extern "C" {
    #include <libavutil/log.h>
    #include <libavcodec/avcodec.h>
    #include <libavformat/avformat.h>
    #include <libswscale/swscale.h>
    #include <libavutil/imgutils.h>
    
    #include "com_example_zjf_ffmpegdecoder_FFmpeg.h"
    #include <android/log.h>
    #define LOGE(format, ...)  __android_log_print(ANDROID_LOG_ERROR, "(>_<)", format, ##__VA_ARGS__)
    #define LOGI(format, ...)  __android_log_print(ANDROID_LOG_INFO,  "(^_^)", format, ##__VA_ARGS__)
    #endif
    /*
     * Class:     com_example_zjf_ffmpegdecoder_FFmpeg
     * Method:    decode
     * Signature: (Ljava/lang/String;Ljava/lang/String;)I
     */
    JNIEXPORT jint JNICALL Java_com_example_zjf_ffmpegdecoder_FFmpeg_decode
            (JNIEnv *env, jclass clazz, jstring input_jstr, jstring output_jstr){
        AVFormatContext *pFormatCtx;
        int i,videoindex;
        AVCodecContext *pCodecCtx;
        AVCodec *pCodec;
        AVFrame *pFrame,*pFrameYUV;
        uint8_t *out_buffer;
        AVPacket *pPacket;
        int y_size;
        int ret, got_picture;
        struct SwsContext *img_convert_ctx;
        FILE *fp_yuv;
        int frame_cnt;
        clock_t time_start, time_finish;
        double  time_duration = 0.0;
        char input_str[500]={0};
        char output_str[500]={0};
        char info[1000]={0};
        sprintf(input_str,"%s",env->GetStringUTFChars(input_jstr, NULL));
        sprintf(output_str,"%s",env->GetStringUTFChars(output_jstr, NULL));
    
        /*初始化avformat并注册编译进avformat库里面所有的复用器(muxers),
        解复用器(demuxers)和协议模块*/
        av_register_all();
        /**网络功能的全局初始化(可选的,在使用网络协议时有必要调用)*/
        avformat_network_init();
        //初始化一个AVFormatContext
        pFormatCtx = avformat_alloc_context();
    
        //打开输入的视频文件
        if (avformat_open_input(&pFormatCtx,input_str,NULL,NULL) != 0){
            LOGE("Couldn't open input stream.\n");
            return -1;
        }
    
        //获取视频文件信息
        if (avformat_find_stream_info(pFormatCtx,NULL) < 0){
            LOGE("Couldn't find stream information.\n");
            return -1;
        }
    
        videoindex = -1;
        ///遍历视音频流的个数
        for (int i = 0; i < pFormatCtx -> nb_streams; i++) {
            if (pFormatCtx->streams[i]/*视音频流*/->codec->codec_type == AVMEDIA_TYPE_VIDEO){
                videoindex = i;
                break;
            }
        }
    
        if(videoindex==-1){
            LOGE("Couldn't find a video stream.\n");
            return -1;
        }
    
        //指向AVCodecContext的指针
        pCodecCtx = pFormatCtx->streams[videoindex]->codec;
        //指向AVCodec的指针.查找解码器
        pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
        if (pCodec == NULL)
        {
            LOGE("Couldn't find Codec.\n");
            return -1;
        }
    
        //打开解码器
        if (avcodec_open2(pCodecCtx,pCodec,NULL) < 0){
            LOGE("Couldn't open codec.\n");
            return -1;
        }
    
        //用来保存数据缓存的对像
        pFrame = av_frame_alloc();
        pFrameYUV = av_frame_alloc();
    
        out_buffer=(unsigned char *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P,  pCodecCtx->width, pCodecCtx->height,1));
        av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize,out_buffer,
                             AV_PIX_FMT_YUV420P,pCodecCtx->width, pCodecCtx->height,1);
    
        pPacket = (AVPacket *)av_malloc(sizeof(AVPacket));
    
        img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
                                         pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
    
        sprintf(info,   "[Input     ]%s\n", input_str);
        sprintf(info, "%s[Output    ]%s\n",info,output_str);
        sprintf(info, "%s[Format    ]%s\n",info, pFormatCtx->iformat->name);
        sprintf(info, "%s[Codec     ]%s\n",info, pCodecCtx->codec->name);
        sprintf(info, "%s[Resolution]%dx%d\n",info, pCodecCtx->width,pCodecCtx->height);
    
        fp_yuv=fopen(output_str,"wb+");
        if(fp_yuv==NULL){
            printf("Cannot open output file.\n");
            return -1;
        }
    
        frame_cnt = 0;
        time_start = clock();
    
        while(av_read_frame(pFormatCtx, pPacket) >= 0){
            if(pPacket->stream_index == videoindex){
                ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, pPacket);
                if(ret < 0){
                    LOGE("Decode Error.\n");
                    return -1;
                }
                if(got_picture){
                    sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
                              pFrameYUV->data, pFrameYUV->linesize);
    
                    y_size=pCodecCtx->width*pCodecCtx->height;
                    fwrite(pFrameYUV->data[0],1,y_size,fp_yuv);    //Y
                    fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv);  //U
                    fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv);  //V
                    //Output info
                    char pictype_str[10]={0};
                    switch(pFrame->pict_type){
                        case AV_PICTURE_TYPE_I:sprintf(pictype_str,"I");break;
                        case AV_PICTURE_TYPE_P:sprintf(pictype_str,"P");break;
                        case AV_PICTURE_TYPE_B:sprintf(pictype_str,"B");break;
                        default:sprintf(pictype_str,"Other");break;
                    }
                    LOGI("Frame Index: %5d. Type:%s",frame_cnt,pictype_str);
                    frame_cnt++;
                }
            }
            av_free_packet(pPacket);
        }
    
        while (1) {
            ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, pPacket);
            if (ret < 0)
                break;
            if (!got_picture)
                break;
            sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
                      pFrameYUV->data, pFrameYUV->linesize);
            int y_size=pCodecCtx->width*pCodecCtx->height;
            fwrite(pFrameYUV->data[0],1,y_size,fp_yuv);    //Y
            fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv);  //U
            fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv);  //V
            //Output info
            char pictype_str[10]={0};
            switch(pFrame->pict_type){
                case AV_PICTURE_TYPE_I:sprintf(pictype_str,"I");break;
                case AV_PICTURE_TYPE_P:sprintf(pictype_str,"P");break;
                case AV_PICTURE_TYPE_B:sprintf(pictype_str,"B");break;
                default:sprintf(pictype_str,"Other");break;
            }
            LOGI("Frame Index: %5d. Type:%s",frame_cnt,pictype_str);
            frame_cnt++;
        }
    
        time_finish = clock();
        time_duration=(double)(time_finish - time_start);
    
        sprintf(info, "%s[Time      ]%fms\n",info,time_duration);
        sprintf(info, "%s[Count     ]%d\n",info,frame_cnt);
    
        sws_freeContext(img_convert_ctx);
    
        fclose(fp_yuv);
    
        av_frame_free(&pFrameYUV);
        av_frame_free(&pFrame);
        avcodec_close(pCodecCtx);
        avformat_close_input(&pFormatCtx);
        return 0;
    }
    
    #ifdef __cplusplus
    }
    #endif
    

    MainActivity.java

    public class MainActivity extends AppCompatActivity {
        private static final String TAG = "MainActivity";
        private Button button;
        private EditText editText1,editText2;
        private DecodeAsyncTask myTask;
        String folderurl;
        // Used to load the 'native-lib' library on application startup.
        static {
            System.loadLibrary("native-lib");
        }
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            button = (Button) findViewById(R.id.button);
            editText1 = (EditText) findViewById(R.id.editText1);
            editText2 = (EditText) findViewById(R.id.editText2);
            folderurl = Environment.getExternalStorageDirectory().getPath();
    
            myTask = new DecodeAsyncTask();
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    final String inputurl=folderurl+"/"+editText1.getText().toString();
                    final String outputurl=folderurl+"/"+editText2.getText().toString();
                    Log.d(TAG,"" + inputurl + "         " + outputurl);
                    myTask.execute(inputurl,outputurl);
                }
            });
        }
    
    
        @Override
        protected void onPause() {
            super.onPause();
            //如果异步任务不为空 并且状态是 运行时  ,就把他取消这个加载任务
            if(myTask !=null && myTask.getStatus() == AsyncTask.Status.RUNNING){
                myTask.cancel(true);
            }
        }
        private class DecodeAsyncTask extends AsyncTask<String,Void,Void>{
    
            @Override
            protected Void doInBackground(String... strings) {
                FFmpeg.decode(strings[0],strings[1]);
                return null;
            }
        }
    }
    
    运行截图

    源码地址:https://github.com/Xiaoben336/FFmpegDecoder

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