将mat编码为h264流, 使用ffmpeg, cpp代码

以下是使用FFmpeg将Mat编码为H.264流的示例C++代码：

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

void encodeMatToH264(cv::Mat& frame, AVFormatContext* formatContext, AVStream* stream, AVCodecContext* codecContext) {
    AVFrame* avFrame = nullptr;
    uint8_t* buffer = nullptr;
    int bufferLength = 0;

    // Allocate an AVFrame structure
    avFrame = av_frame_alloc();
    if (!avFrame) {
        throw std::runtime_error("Failed to allocate AVFrame");
    }

    // Fill the AVFrame with the input frame data
    avFrame->width = frame.cols;
    avFrame->height = frame.rows;
    avFrame->format = AV_PIX_FMT_BGR24;
    av_frame_get_buffer(avFrame, 0);

    // Convert the input frame to the required pixel format
    SwsContext* swsContext = sws_getContext(
        frame.cols, frame.rows, AV_PIX_FMT_BGR24,
        frame.cols, frame.rows, AV_PIX_FMT_YUV420P,
        SWS_BILINEAR, nullptr, nullptr, nullptr);

    sws_scale(swsContext, frame.data, frame.step, 0, frame.rows, avFrame->data, avFrame->linesize);

    // Allocate a buffer for the output data
    bufferLength = av_image_get_buffer_size(codecContext->pix_fmt, codecContext->width, codecContext->height, 1);
    buffer = (uint8_t*)av_malloc(bufferLength);

    // Allocate an output packet
    AVPacket packet;
    av_init_packet(&packet);
    packet.data = nullptr;
    packet.size = 0;

    // Encode the frame
    int ret = avcodec_send_frame(codecContext, avFrame);
    if (ret < 0) {
        throw std::runtime_error("Failed to send frame for encoding");
    }

    while (ret >= 0) {
        ret = avcodec_receive_packet(codecContext, &packet);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
            break;
        }
        else if (ret < 0) {
            throw std::runtime_error("Error during encoding");
        }

        // Write the encoded data to the output stream
        av_packet_rescale_ts(&packet, codecContext->time_base, stream->time_base);
        packet.stream_index = stream->index;
        av_interleaved_write_frame(formatContext, &packet);
    }

    // Free resources
    av_frame_free(&avFrame);
    av_free(buffer);
    av_packet_unref(&packet);
    sws_freeContext(swsContext);
}

此代码使用FFmpeg将输入的cv::Mat转换为YUV420P格式，然后使用H.264编码器进行编码，并将编码的数据写入输出流中。