GPT答：

7i24.cn

作为AI语言模型，我无法直接编写代码。但是，我可以提供一些基本思路和伪代码来帮助您编写一个接收一帧的程序。

首先，您需要使用FFmpeg库来处理视频流。在这个程序中，我们只需要处理单独的一帧。

以下是一个简单的伪代码示例：

```
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

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

int main(int argc, char *argv[]) {

    AVFormatContext *pFormatCtx = NULL;
    AVCodecContext *pCodecCtxOrig = NULL, *pCodecCtx = NULL;
    AVCodec *pCodec = NULL;
    
    int videoStreamIndex = -1;

    // Open video file
   if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)
        return -1; // Couldn't open file

   // Retrieve stream information
   if(avformat_find_stream_info(pFormatCtx, NULL)<0)
        return -1; // Couldn't find stream information

   // Find the first video stream
   for(int i=0; i<pFormatCtx->nb_streams; i++)
       if(pFormatCtx->streams[i]->codecpar->codec_type==AVMEDIA_TYPE_VIDEO) {
           videoStreamIndex=i;
           break;
       }
   
   if(videoStreamIndex==-1)
        return -1; // Didn't find a video stream
   
  pCodec=avcodec_find_decoder(pCodecPar->codec_id);
  
  pCodexCtOrig= av_codec_alloc_context3(pCodecx);

  av_codec_parameters_to_context(pCodecx,CodexPar);

  av_codec_open2(PCodecx,NULL,NULL)

// Allocate an AVFrame structure
AVFrame* pFrameRGB = av_frame_alloc();
if (pFrameRGB == nullptr) {
return EXIT_FAILURE;
}

// Determine required buffer size and allocate buffer
int numBytes =
av_image_get_buffer_size(AV_PIX_FMT_RGB24,
                          pCodexCxOrig->width,
                          pCodexCxOrig->height,
                          ALIGNMENT);
uint8_t* buffer=(uint8_t*)malloc(numBytes*sizeof(uint8_t));

// Assign appropriate parts of buffer to image planes in pFrameRGB
// Note that pFrameRGB is an AVFrame struct allocated by FFmpeg.
// You need to fill it with data from your own image source.
//
// The destination data pointers should be set to the correct values:
//
//     uint8_t* destSliceY=pFramergb.data[0];
//
struct SwsContext* sws_ctx =
sws_getContext(
              Codexcxtorig.width,
              Codexcxtorig.height,
              Codexcxtorig.pix_fmt,

              Codexcxtorig.width,

            Codeccxtoig.height,

            Codeccxtoig.pix_fmt,

            SWS_BILINEAR,


NULL,NULL,NULL);

while (true) {

AVPacket packet;

if (/* receive packet */) {

int ret= av_packet_send_to_decoder(packet,pcodecx);

if(ret<0){

break;

}

ret=decode_packet_into_frame(packet,pframe,&got_picture_ptr,pcodecx);


if(got_picture_ptr){

sws_scale(sws_ctx,(const uint8_t**)Pframe.data,Pframe.linesize,0,PcodecxToig.height,PframerGB.data,Pframergb.linesize);


}


}
}

free(buffer);
return EXIT_SUCCESS;


}
```

请注意：这只是一个简单的示例，并且可能需要进行修改以适应您特定的需求和环境。