FFMPEG encode基本流程

FFMPEG encoder流程

a)定义如下数据结构

    AVCodec *codec;

    AVCodecContext *c= NULL;

    int i, ret, x, y, got_output;

    FILE *f;

    AVFrame *frame;

    AVPacket pkt;

    uint8_t endcode[] = { 0, 0, 1, 0xb7 }; //mpeg文件结尾

b)流程

//查找编码器
codec = avcodec_find_encoder(codec_id);

//分配编码器结构体

c = avcodec_alloc_context3(codec);

/设置编码器参数
    c->bit_rate = 400000;
    c->width = 352;
    c->height = 288;
    c->time_base= (AVRational){1,25};
    c->gop_size = 10; 
    c->max_b_frames=1;
    c->pix_fmt = AV_PIX_FMT_YUV420P;

av_opt_set(c->priv_data, "preset", "slow", 0);

avcodec_open2(c, codec, NULL)

f = fopen(filename, "wb");

frame = avcodec_alloc_frame();

frame->format = c->pix_fmt;
frame->width  = c->width;
frame->height = c->height;

ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height,c->pix_fmt, 32);                         

av_init_packet(&pkt);

fflush(stdout);

ret = avcodec_encode_video2(c, &pkt, frame, &got_output);

fwrite(endcode, 1, sizeof(endcode), f);
fclose(f);
avcodec_close(c);
av_free(c);
av_freep(&frame->data[0]);
avcodec_free_frame(&frame);