FFMPEG 之视频解码

我这里的so包是来自我的FFMPEG编译生成的，如果没有可以按照上一篇编译生成一下，在我的资源里边也有

首先先看项目目录

一、过程

1、首先创建native方法

   VideoUtils.java

public class VideoUtils {
    
public native static void decode(String input,String output);
    static{
        System.loadLibrary("avutil-54");
        System.loadLibrary("swresample-1");
        System.loadLibrary("avcodec-56");
        System.loadLibrary("avformat-56");
        System.loadLibrary("swscale-3");
        System.loadLibrary("postproc-53");
        System.loadLibrary("avfilter-5");
        System.loadLibrary("avdevice-56");
        System.loadLibrary("native-lib");
    }
}

2、使用javah命令生成头文件

3、在defaultConfig的和cmake平级的地方加入，因为我们只编译了armeabi平台

    ndk{
                abiFilters "armeabi"
            }

4、在CMakeLists中添加编译需要的so文件

cmake_minimum_required(VERSION 3.4.1)


add_library(native-lib
             SHARED
             src/main/cpp/native-lib.c )
find_library(log-lib
              log )


add_library(libavcodec-56
            SHARED
            IMPORTED)

set_target_properties(libavcodec-56
                      PROPERTIES IMPORTED_LOCATION
                      ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/armeabi/libavcodec-56.so)

add_library(libavdevice-56
            SHARED
            IMPORTED)
set_target_properties(libavdevice-56
                      PROPERTIES IMPORTED_LOCATION
                      ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/armeabi/libavdevice-56.so)

add_library(libavfilter-5
            SHARED
            IMPORTED)
set_target_properties(libavfilter-5
                      PROPERTIES IMPORTED_LOCATION
                      ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/armeabi/libavfilter-5.so)

add_library(libavformat-56
            SHARED
            IMPORTED)
set_target_properties(libavformat-56
                      PROPERTIES IMPORTED_LOCATION
                      ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/armeabi/libavformat-56.so)
add_library(libavutil-54
            SHARED
            IMPORTED)
set_target_properties(libavutil-54
                      PROPERTIES IMPORTED_LOCATION
                      ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/armeabi/libavutil-54.so)
add_library(libpostproc-53
            SHARED
            IMPORTED)
set_target_properties(libpostproc-53
                      PROPERTIES IMPORTED_LOCATION
                      ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/armeabi/libpostproc-53.so)

add_library(libswresample-1
            SHARED
            IMPORTED)
set_target_properties(libswresample-1
                      PROPERTIES IMPORTED_LOCATION
                      ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/armeabi/libswresample-1.so)
add_library(libswscale-3
           SHARED
           IMPORTED)
set_target_properties(libswscale-3
                      PROPERTIES IMPORTED_LOCATION
                      ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/armeabi/libswscale-3.so)

target_link_libraries(  native-lib
                        libavcodec-56
                        libavdevice-56
                        libavfilter-5
                        libavformat-56
                        libavutil-54
                        libpostproc-53
                        libswresample-1
                        libswscale-3
                       ${log-lib} )

如此以上，准备工作就做的差不多了，就只剩下编写ndk文件了

4、引入头文件和编译生成的头文件，并编写c文件

native-lib.c

#include "com_xiaofan_testffmpeg_VideoUtils.h"
#include <android/log.h>
#include <stdio.h>
#include <stdlib.h>

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

//封装格式
#include "include/libavformat/avformat.h"
//解码
#include "include/libavcodec/avcodec.h"
//缩放
#include "include/libswscale/swscale.h"
#include "include/libavutil/avutil.h"
#include "include/libavutil/frame.h"

JNIEXPORT void JNICALL Java_com_xiaofan_testffmpeg2_VideoUtils_decode(
        JNIEnv *env, jclass cls, jstring input_jstr, jstring output_jstr) {
    const char *input_cstr = (*env)->GetStringUTFChars(env, input_jstr,
                                                       JNI_FALSE);
    const char *output_cstr = (*env)->GetStringUTFChars(env, output_jstr,
                                                        JNI_FALSE);
    //1、注册组件
    av_register_all();
    //2、打开输入视频文件
    AVFormatContext *pFormatCtx = avformat_alloc_context();

    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++) {
        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", "无法打开解码器！");
        return;
    };
    //压缩数据
    AVPacket *packet = (AVPacket *) av_malloc(sizeof(AVPacket));
    //像素数据(解码数据)
    AVFrame *pFrame = av_frame_alloc();
    AVFrame *yuvFrame = av_frame_alloc();

    //只有指定了AVFrame的像素格式、画面大小才能真正分配内存
    //缓冲区分配内存
    uint8_t *out_buffer = (uint8_t *) av_malloc
            (avpicture_get_size(AV_PIX_FMT_YUV420P, pCodeCtx->width, pCodeCtx->height));
        //初始化缓冲区
    avpicture_fill((AVPicture *) yuvFrame, out_buffer, AV_PIX_FMT_YUV420P,
                   pCodeCtx->width, pCodeCtx->height);


        //输出文件
    FILE *fp_yuv = fopen(output_cstr, "wb");

    struct SwsContext *sws_ctx = sws_getContext(
            pCodeCtx->width, pCodeCtx->height, pCodeCtx->pix_fmt,
            pCodeCtx->width, pCodeCtx->height, AV_PIX_FMT_YUV420P,
            SWS_BILINEAR, NULL, NULL, NULL);
        //6、一帧一帧读取压缩的视频数据AVPacket
    int len, got_frame, framecount = 0;
    while (av_read_frame(pFormatCtx, packet) >= 0) {
        //AVPacket
        len = avcodec_decode_video2(pCodeCtx, pFrame, &got_frame, packet);
        //非零，正在解码
        if (got_frame) {
            //          转为指定的YUV420P像素帧
            sws_scale(sws_ctx, pFrame->data, pFrame->linesize, 0,
                      pFrame->height, yuvFrame->data, yuvFrame->linesize);
            //向YUV文件保存解码之后的帧数据
            int y_size = pCodeCtx->width * pCodeCtx->height;

            fwrite(yuvFrame->data[0], 1, y_size, fp_yuv);
            fwrite(yuvFrame->data[1], 1, y_size / 4, fp_yuv);
            fwrite(yuvFrame->data[2], 1, y_size / 4, fp_yuv);
            LOGI("解码%d帧", framecount++);
        }
        av_free_packet(packet);
    }

    fclose(fp_yuv);
    av_frame_free(&pFrame);
    avcodec_close(pCodeCtx);
    avformat_free_context(pFormatCtx);

    (*env)->ReleaseStringUTFChars(env, input_jstr, input_cstr);
    (*env)->ReleaseStringUTFChars(env, output_jstr, output_cstr);

}

5、调用转码方法

String input = new File(Environment.getExternalStorageDirectory(), "aaaa.mp4").getAbsolutePath();
String output = new File(Environment.getExternalStorageDirectory(), "output_1280x720_yuv420p.yuv").getAbsolutePath();
VideoUtils.decode(input, output);

6、最后别忘了加入读写sd卡的权限

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

7、注意：

  

该文件来自编译FFMPEG生成的