version

#define LIBAVUTIL_VERSION_MAJOR  58

#define LIBAVUTIL_VERSION_MINOR  12

#define LIBAVUTIL_VERSION_MICRO 100

note

1.

通过*.jpg推测时，out_fmt为image2，打开*.jpg文件时，in_fmt为image2

但是out_fmt为image2时，av_write_frame调用失败

2.

指定short_name为mjpeg，out_fmt为mjpeg

av_write_frame调用成功

code

void CFfmpegOps::EncodeYUVJ420pToMJPEG(const char *infile, const char *width_str, const char *height_str)
{
    if (!infile)
    {
        return;
    }

    int32_t width = 0;
    int32_t height = 0;

    try
    {
        width = std::stoi(width_str);
        height = std::stoi(height_str);
    }
    catch (std::exception& e)
    {
        return;
    }
    
#if 0
    size_t data_bytes = width * height * 3 / 2;
    std::shared_ptr<uint8_t> data(new uint8_t[data_bytes]);
#endif
    FILE *in_fp = nullptr;
    size_t n = 0;
    AVCodecContext *encoder_ctx = nullptr;
    const AVCodec *encoder = nullptr;
    const char *outfile = nullptr;
    int ret = -1;
    AVFormatContext *out_fmt_ctx = nullptr;
    AVStream *mjpeg_stream = nullptr;
    const AVOutputFormat *out_fmt = nullptr;
    AVFrame *avframe = nullptr;
    AVPacket *avpacket = nullptr;
    int frame_bytes = 0;

    in_fp = fopen(infile, "rb");
    if (!in_fp)
    {
        printf("fopen error\n");
        goto end;
    }

    avframe = av_frame_alloc();
    if (!avframe)
    {
        printf("av_frame_alloc error\n");
        goto end;
    }
    avframe->width = width;
    avframe->height = height;
    avframe->format = AV_PIX_FMT_YUVJ420P;
    avframe->pts = 0;

    // 获取单帧yuvj420p的字节数
    frame_bytes = av_image_get_buffer_size((AVPixelFormat)(avframe->format), avframe->width, avframe->height, 1);
#if 0
    if ((int)data_bytes != frame_bytes)
    {
        printf("data_bytes != frame_bytes\n");
        goto end;
    }
#endif

    ret = av_frame_get_buffer(avframe, 0);
    if (ret < 0)
    {
        printf("av_frame_get_buffer error:%s\n", GetFfmpegERR(ret));
        goto end;
    }

    // 读取y分量
    n = fread(avframe->data[0], sizeof(uint8_t), avframe->width * avframe->height, in_fp);
    if ((int)n != (avframe->width * avframe->height))
    {
        printf("n != (avframe->width * avframe->height)\n");
        goto end;
    }

    // 读取u分量
    n = fread(avframe->data[1], sizeof(uint8_t), avframe->width * avframe->height / 4, in_fp);
    if ((int)n != (avframe->width * avframe->height / 4))
    {
        printf("n != (avframe->width * avframe->height / 4)\n");
        goto end;
    }

    // 读取v分量
    n = fread(avframe->data[2], sizeof(uint8_t), avframe->width * avframe->height / 4, in_fp);
    if ((int)n != (avframe->width * avframe->height / 4))
    {
        printf("n != (avframe->width * avframe->height / 4)\n");
        goto end;
    }

#if 0
    n = fread(data.get(), sizeof(uint8_t), data_bytes, in_fp);
    if (n != data_bytes)
    {
        printf("n != data_bytes\n");
        goto end;
    }

    ret = av_image_fill_arrays(avframe->data, avframe->linesize,
                               data.get(),
                               encoder_ctx->pix_fmt, encoder_ctx->width, encoder_ctx->height, 1);
    if (ret < 0)
    {
        printf("av_image_fill_arrays error:%s\n", GetFfmpegERR(ret));
        goto end;
    }
    else
    {
        printf("ret:%d, frame_bytes:%d\n", ret, frame_bytes);
    }
#endif

    avpacket = av_packet_alloc();
    if (!avpacket)
    {
        printf("av_packet_alloc error\n");
        goto end;
    }

    encoder = avcodec_find_encoder(AV_CODEC_ID_MJPEG);
    if (!encoder)
    {
        printf("avcodec_find_encoder error\n");
        goto end;
    }

    encoder_ctx = avcodec_alloc_context3(encoder);
    if (!encoder_ctx)
    {
        printf("avcodec_alloc_context3 error\n");
        goto end;
    }
    // encoder_ctx->colorspace = ;
    // encoder_ctx->color_range = ;
    encoder_ctx->pix_fmt = AV_PIX_FMT_YUVJ420P;
    encoder_ctx->width = width;
    encoder_ctx->height = height;
    encoder_ctx->framerate.num = 25;
    encoder_ctx->framerate.den = 1;
    encoder_ctx->time_base.num = 1;
    encoder_ctx->time_base.den = 25;
    encoder_ctx->bit_rate = frame_bytes * encoder_ctx->framerate.num * 8;

    ret = avcodec_open2(encoder_ctx, encoder, nullptr);
    if (ret < 0)
    {
        printf("avcodec_open2 error:%s\n", GetFfmpegERR(ret));
        goto end;
    }

    out_fmt_ctx = avformat_alloc_context();
    if (!out_fmt_ctx)
    {
        printf("avformat_alloc_context error\n");
        goto end;
    }

    outfile = "image_%03d.jpg";
#if 0
    /*
    通过*.jpg推测时，out_fmt为image2，打开*.jpg文件时，in_fmt为image2
    但是out_fmt为image2时，av_write_frame调用失败
    */
    out_fmt = av_guess_format(nullptr, outfile, nullptr);
    if (!out_fmt)
    {
        printf("av_guess_format error\n");
        goto end;
    }
#else
    /*
    指定short_name为mjpeg，out_fmt为mjpeg
    av_write_frame调用成功
    */
    out_fmt = av_guess_format("mjpeg", nullptr, nullptr);
    if (!out_fmt)
    {
        printf("av_guess_format error\n");
        goto end;
    }
#endif

    out_fmt_ctx->oformat = out_fmt;

    mjpeg_stream = avformat_new_stream(out_fmt_ctx, encoder);
    if (!mjpeg_stream)
    {
        printf("avformat_new_stream error\n");
        goto end;
    }

    ret = avcodec_parameters_from_context(mjpeg_stream->codecpar, encoder_ctx);
    if (ret < 0)
    {
        printf("avcodec_parameters_from_context error:%s\n", GetFfmpegERR(ret));
        goto end;
    }

#if 0
    ret = avio_open(&(out_fmt_ctx->pb), outfile, AVIO_FLAG_WRITE);
    if (ret < 0)
    {
        printf("avio_open error:%s\n", GetFfmpegERR(ret));
        goto end;
    }
#else
    ret = avio_open2(&(out_fmt_ctx->pb), outfile, AVIO_FLAG_READ_WRITE, nullptr, nullptr);
    if (ret < 0)
    {
        printf("avio_open2 error:%s\n", GetFfmpegERR(ret));
        goto end;
    }
#endif

    ret = avformat_write_header(out_fmt_ctx, nullptr);
    if (ret < 0)
    {
        printf("avformat_write_header error:%s\n", GetFfmpegERR(ret));
        goto end;
    }

    ret = avcodec_send_frame(encoder_ctx, avframe);
    if (ret < 0)
    {
        printf("avcodec_send_frame error:%s\n", GetFfmpegERR(ret));
        goto end;
    }

    while (1)
    {
        ret = avcodec_receive_packet(encoder_ctx, avpacket);
        if (ret < 0)
        {
            printf("avcodec_receive_packet error:%s\n", GetFfmpegERR(ret));
            break;
        }
        avpacket->time_base.num = encoder_ctx->time_base.num;
        avpacket->time_base.den = encoder_ctx->time_base.den;

#if 0
        ret = av_interleaved_write_frame(out_fmt_ctx, avpacket);
        if (ret < 0)
        {
            printf("av_interleaved_write_frame error:%s\n", GetFfmpegERR(ret));
            break;
        }
#else
        ret = av_write_frame(out_fmt_ctx, avpacket);
        if (ret < 0)
        {
            printf("av_write_frame error:%s\n", GetFfmpegERR(ret));
            break;
        }
#endif
    }

    // 写元数据
    ret = av_write_trailer(out_fmt_ctx);
    if (ret < 0)
    {
        printf("av_write_trailer error:%s\n", GetFfmpegERR(ret));
        goto end;
    }

end:
    if (avpacket)
    {
        av_packet_free(&avpacket);
        avpacket = nullptr;
    }

    if (avframe)
    {
        av_frame_free(&avframe);
        avframe = nullptr;
    }

    if (out_fmt_ctx->pb)
    {
        avio_close(out_fmt_ctx->pb);
        out_fmt_ctx->pb = nullptr;
    }

    if (out_fmt_ctx)
    {
        avformat_free_context(out_fmt_ctx);
        out_fmt_ctx = nullptr;
    }

    if (encoder_ctx)
    {
        avcodec_free_context(&encoder_ctx);
        encoder_ctx = nullptr;
    }

    if (in_fp)
    {
        fclose(in_fp);
        in_fp = nullptr;
    }
}

perfomance