ffmpeg android视频解码

#include "lang.h"
#include <string>
//封装格式
//解码
#include "log.h"

extern "C" {
#include <libavutil/imgutils.h>
#include <libavutil/samplefmt.h>
#include <libavutil/timestamp.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

};


static void video_decode_example(const char *outfilename, const char *filename) {
    //1.注册
    av_register_all();

    AVFormatContext *pFormatCtx = NULL;
    //2. 打开文件
    if (avformat_open_input(&pFormatCtx, filename, NULL, NULL) != 0) {
        LOGE ("打开文件失败");
        return;
    }
    //3. 获取流信息，数据封装在AVFormatContext里面
    if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
        LOGE ("获取流信息失败");
        return;
    }
    //只输出输入文件的格式信息
    av_dump_format(pFormatCtx, 0, filename, 0);
    int video_index = -1;
    //4. 从流中遍历获取video的index
    for (int i = 0; i < pFormatCtx->nb_streams; i++) {
        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_index = i;
            LOGE ("video_index = %d", video_index);
            break;
        }
    }
    if (video_index == -1) {
        LOGE ("遍历获取video_index失败");
        return;
    }
    AVCodecContext *pCodecCtxOrg = NULL;
    AVCodecContext *pCodecCtx = NULL;

    AVCodec *pCodec = NULL;
    //5. 解码器获取
    //5.1 根据video_index获取解码器上下文AVCodecContext
    pCodecCtxOrg = pFormatCtx->streams[video_index]->codec; // codec context
    //5.1 根据AVCodecContext获取解码器
    pCodec = avcodec_find_decoder(pCodecCtxOrg->codec_id);

    if (!pCodec) {
        LOGE ("解码器获取失败");
        return;
    }

    //6.获取一个AVCodecContext实例，并将第五步获取的AVCodecContext数据copy过来，解码的时候需要用这个
    pCodecCtx = avcodec_alloc_context3(pCodec);
    if (avcodec_copy_context(pCodecCtx, pCodecCtxOrg) != 0) {
        LOGE ("解码器上下文数据copy失败");
        return;
    }
    //7. 打开解码器
    if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
        LOGE ("打开解码器失败");
        return;
    }
    //原始数据帧
    AVFrame *pFrame = NULL;
    //yuv数据帧
    AVFrame *pFrameYUV = NULL;
    //内存开辟 不要忘记free
    pFrame = av_frame_alloc();
    pFrameYUV = av_frame_alloc();
    int numBytes = 0;
    uint8_t *buffer = NULL;
    //根据需要解码的类型，获取需要的buffer，不要忘记free
    numBytes = av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1);
    buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));

    //根据指定的图像参数和提供的数组设置数据指针和行数 ，数据填充到对应的pFrameYUV里面
    av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize, buffer, AV_PIX_FMT_YUV420P,
                         pCodecCtx->width,
                         pCodecCtx->height, 1);

    //获取SwsContext
    struct SwsContext *sws_ctx = NULL;
    sws_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
                             pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC,
                             NULL, NULL, NULL);

    FILE *pFile = fopen(outfilename, "wb+");
    int ret;
    AVPacket packet;
    int frameFinished = 0;
    //8. 根据AVFormatContext 读取帧数据，读取的编码数据存储到AVPacket里面
    while (av_read_frame(pFormatCtx, &packet) >= 0) {
        if (packet.stream_index == video_index) {
            //9. 将读取到的AVPacket，转换为AVFrame
            ret = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
            if (ret < 0) {
                LOGE("解码失败");
                return;
            }
            if (frameFinished) {
                //10. 将原始的AVFrame数据转换为自己需要的YUV AVFrame数据
                sws_scale(sws_ctx, (uint8_t const *const *) pFrame->data, pFrame->linesize, 0,
                          pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
                //11. 根据YUV AVFrame数据保存文件
                if (pFile == NULL)
                    return;
                int y_size = pCodecCtx->width * pCodecCtx->height;

                //yuv420 存储为4:1:1
                fwrite(pFrame->data[0], 1, static_cast<size_t>(y_size), pFile); //y
                fwrite(pFrame->data[1], 1, static_cast<size_t>(y_size / 4), pFile);//u
                fwrite(pFrame->data[2], 1, static_cast<size_t>(y_size / 4), pFile);//v
            }
        }
        av_packet_unref(&packet);
    }

    //flush decoder
    //FIX: Flush Frames remained in Codec
    //12. 刷新解码器
    while (1) {
        ret = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
        if (ret < 0)
            break;
        if (!frameFinished)
            break;
        sws_scale(sws_ctx, (const unsigned char *const *) pFrame->data, pFrame->linesize, 0,
                  pCodecCtx->height,
                  pFrameYUV->data, pFrameYUV->linesize);

        int y_size = pCodecCtx->width * pCodecCtx->height;
        fwrite(pFrameYUV->data[0], 1, static_cast<size_t>(y_size), pFile);    //Y
        fwrite(pFrameYUV->data[1], 1, static_cast<size_t>(y_size / 4), pFile);  //U
        fwrite(pFrameYUV->data[2], 1, static_cast<size_t>(y_size / 4), pFile);  //V
        LOGE("Flush Decoder: Succeed to decode 1 frame!\n");
    }
    //release resource
    sws_freeContext(sws_ctx);
    fclose(pFile);
    av_free(buffer);
    av_frame_free(&pFrameYUV);
    av_frame_free(&pFrame);
    avcodec_close(pCodecCtx);
    avcodec_close(pCodecCtxOrg);
    avformat_close_input(&pFormatCtx);

}


extern "C"
JNIEXPORT jint JNICALL
Java_zzw_com_ffmpegdemo_VideoUtils_decode(JNIEnv *env, jclass type, jstring input_,
                                          jstring output_) {
    const char *input_file_name = env->GetStringUTFChars(input_, 0);
    const char *output_file_name = env->GetStringUTFChars(output_, 0);
    
    video_decode_example(output_file_name, input_file_name);
    
    env->ReleaseStringUTFChars(input_, input_file_name);
    env->ReleaseStringUTFChars(output_, output_file_name);
    return 0;

}