FFmpeg开发实战（六）：使用 FFmpeg 将YUV数据编码为视频文件

#include "pch.h"
#include <iostream>

extern "C" {
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavcodec/avcodec.h"
#include "libswscale/swscale.h"
}

using namespace std;

int flush_encoder(AVFormatContext *fmt_ctx, unsigned int stream_index);

int main(int argc, char *argv[])
{
    AVFormatContext *pFormatCtx = nullptr;
    AVOutputFormat *fmt = nullptr;
    AVStream *video_st = nullptr;
    AVCodecContext *pCodecCtx = nullptr;
    AVCodec *pCodec = nullptr;

    uint8_t *picture_buf = nullptr;
    AVFrame *picture = nullptr;
    int size;

    //打开视频文件
    FILE *in_file = fopen("111.yuv", "rb");
    if (!in_file)
    {
        cout << "can not open file!" << endl;
        return -1;
    }

    //352x288
    int in_w = 352, in_h = 288;
    int framenum = 50;
    const char* out_file = "111.mp4";

    //[1] --注册所有ffmpeg组件
    avcodec_register_all();
    av_register_all();

    //[2] --初始化AVFormatContext结构体,根据文件名获取到合适的封装格式
    avformat_alloc_output_context2(&pFormatCtx, NULL, NULL, out_file);
    fmt = pFormatCtx->oformat;

    //[3] --打开文件
    if (avio_open(&pFormatCtx->pb, out_file, AVIO_FLAG_READ_WRITE)) {
        cout << "output file open fail!";
        return -1;
    }
    //[3]

    //[4] --初始化视频码流
    video_st = avformat_new_stream(pFormatCtx, 0);
    if (video_st == NULL)
    {
        printf("failed allocating output stram\n");
        return -1;
    }
    video_st->time_base.num = 1;
    video_st->time_base.den = 25;
    //[4]

    //[5] --编码器Context设置参数
    pCodecCtx = video_st->codec;
    pCodecCtx->codec_id = fmt->video_codec;
    pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
    pCodecCtx->pix_fmt = AV_PIX_FMT_YUV420P;
    pCodecCtx->width = in_w;
    pCodecCtx->height = in_h;
    pCodecCtx->time_base.num = 1;
    pCodecCtx->time_base.den = 25;
    pCodecCtx->bit_rate = 400000;
    pCodecCtx->gop_size = 12;

    if (pCodecCtx->codec_id == AV_CODEC_ID_H264)
    {
        pCodecCtx->qmin = 10;
        pCodecCtx->qmax = 51;
        pCodecCtx->qcompress = 0.6;
    }
    if (pCodecCtx->codec_id == AV_CODEC_ID_MPEG2VIDEO)
        pCodecCtx->max_b_frames = 2;
    if (pCodecCtx->codec_id == AV_CODEC_ID_MPEG1VIDEO)
        pCodecCtx->mb_decision = 2;
    //[5]

    //[6] --寻找编码器并打开编码器
    pCodec = avcodec_find_encoder(pCodecCtx->codec_id);
    if (!pCodec)
    {
        cout << "no right encoder!" << endl;
        return -1;
    }
    if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
    {
        cout << "open encoder fail!" << endl;
        return -1;
    }
    //[6]

    //输出格式信息
    av_dump_format(pFormatCtx, 0, out_file, 1);

    //初始化帧
    picture = av_frame_alloc();
    picture->width = pCodecCtx->width;
    picture->height = pCodecCtx->height;
    picture->format = pCodecCtx->pix_fmt;
    size = avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
    picture_buf = (uint8_t*)av_malloc(size);
    avpicture_fill((AVPicture*)picture, picture_buf, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);

    //[7] --写头文件
    avformat_write_header(pFormatCtx, NULL);
    //[7]

    AVPacket pkt; //创建已编码帧
    int y_size = pCodecCtx->width*pCodecCtx->height;
    av_new_packet(&pkt, size * 3);

    //[8] --循环编码每一帧
    for (int i = 0; i < framenum; i++)
    {
        //读入YUV
        if (fread(picture_buf, 1, y_size * 3 / 2, in_file) < 0)
        {
            cout << "read file fail!" << endl;
            return -1;
        }
        else if (feof(in_file))
            break;

        picture->data[0] = picture_buf; //亮度Y
        picture->data[1] = picture_buf + y_size; //U
        picture->data[2] = picture_buf + y_size * 5 / 4; //V
        //AVFrame PTS
        picture->pts = i;
        int got_picture = 0;

        //编码
        int ret = avcodec_encode_video2(pCodecCtx, &pkt, picture, &got_picture);
        if (ret < 0)
        {
            cout << "encoder fail!" << endl;
            return -1;
        }

        if (got_picture == 1)
        {
            cout << "encoder success!" << endl;

            // parpare packet for muxing
            pkt.stream_index = video_st->index;
            av_packet_rescale_ts(&pkt, pCodecCtx->time_base, video_st->time_base);
            pkt.pos = -1;
            ret = av_interleaved_write_frame(pFormatCtx, &pkt);
            av_free_packet(&pkt);
        }
    }
    //[8]

    //[9] --Flush encoder
    int ret = flush_encoder(pFormatCtx, 0);
    if (ret < 0)
    {
        cout << "flushing encoder failed!" << endl;
        goto end;
    }
    //[9]

    //[10] --写文件尾
    av_write_trailer(pFormatCtx);
    //[10]

end:
    //释放内存
    if (video_st)
    {
        avcodec_close(video_st->codec);
        av_free(picture);
        av_free(picture_buf);
    }
    if (pFormatCtx)
    {
        avio_close(pFormatCtx->pb);
        avformat_free_context(pFormatCtx);
    }

    fclose(in_file);

    return 0;
}

int flush_encoder(AVFormatContext *fmt_ctx, unsigned int stream_index)
{
    int ret;
    int got_frame;
    AVPacket enc_pkt;
    if (!(fmt_ctx->streams[stream_index]->codec->codec->capabilities & AV_CODEC_CAP_DELAY))
        return 0;
    while (1) {
        printf("Flushing stream #%u encoder\n", stream_index);
        enc_pkt.data = NULL;
        enc_pkt.size = 0;
        av_init_packet(&enc_pkt);
        ret = avcodec_encode_video2(fmt_ctx->streams[stream_index]->codec, &enc_pkt,
            NULL, &got_frame);
        av_frame_free(NULL);
        if (ret < 0)
            break;
        if (!got_frame)
        {
            ret = 0; break;
        }
        cout << "success encoder 1 frame" << endl;

        // parpare packet for muxing
        enc_pkt.stream_index = stream_index;
        av_packet_rescale_ts(&enc_pkt,
            fmt_ctx->streams[stream_index]->codec->time_base,
            fmt_ctx->streams[stream_index]->time_base);
        ret = av_interleaved_write_frame(fmt_ctx, &enc_pkt);
        if (ret < 0)
            break;
    }
    return ret;
}