FFmpeg fetching pictures from the video stream

The basic flow of capturing images from video: Open video stream Address---get video stream packt-> decode to picture frame--Output picture

I. Initializing FFMPEG

void Ffmpeginit ()
{
     Av_register_all ();     Avformat_network_init ();    
}

If you do not want to output log, set the log level to Av_log_panic.

Two. Open the video.

intOpen (char* URL) {
　　　　context = Avformat_alloc_context ();
Context->interrupt_callback.opaque = this; C++
Context->interrupt_callback.callback = interruptcallback;//Sets the callback function, otherwise it is possible that the ffmpeg has been suspended.
Context->start_time_realtime = Av_gettime ();
avdictionary* options = nullptr; Av_dict_set (&options,"Rtsp_transport", "UDP",0); Open UDP, if TCP is turned on to replace UDP with TCP Av_dict_set (&options,"Stimeout","3000000",0); Set timeout disconnect time int ret =Avformat_open_input (&context, URL, nullptr, &options);　　　avformat_open_input  returns 0 for open success, less than 0 for open failure 
 if (ret < 0) return ret; 
 Ret = Avformat_find_stream_info (context, options);  ///avformat_find_ stream_info  returns 0 for check Stream info success   Less than 0 indicates failure. 
     if (options!= nullptr) 
     {
      av_dict_free ( Options); 
    }　　 
  return ret; }

int INTERRUPT_CB (void *if)//10s Timeout exit    {         return  averror_eof;    }     return 0;            

Three. Read the video package:

Shared_ptr<avpacket>Readpacket () {shared_ptr<AVPacket> packet ((avpacket*) Av_malloc (sizeof(Avpacket)), [&] (Avpacket *p) {av_free_packet (P); Av_freep (&( p);}); Av_init_packet (packet.Get()); Lastframerealtime=Av_gettime (); intRET = av_read_frame (context, packet.Get()); if(Ret >=0)   {        returnpacket; }   Else    {        returnnullptr; }}

Note: You don't have to use smart pointers. I'm sure there will be no memory leaks, so do not change, the code can be written with a bug.

Four. Decoding

1. Initializing the decoder

initdecodercodec{
int ret =-1;
i < context->nb_streams; ++i)
   {       *codeccontext = context->streams[i]->codec;        if (Codeccontext->codec_type = = Avmedia_type_video)      {
//return less than 0, open decoder         failed = Avcodec_open2 (Codeccontext, Avcodec_find_decoder (codeccontext->codec_id), &options);      }
   }
  return ret;}

2. Decoding Video Packets

avframe* decodevideopacket (avcodeccontext* codeccontext)
{
    avframe* videoframe = Av_frame_alloc ();
    Auto hr = Avcodec_decode_video2 (Codeccontext, Frame, &gotframe, packet);     if 0 0)
    {
return videoframe;
    }
Else
{
　　　　Avcodec_free_frame (&videoframe);
Return nullptr
}
}

Output Image:

uint8_t *getpicturedata (int width,int height, int *buffersize)
{  
    pframeyuv= Av_frame_alloc ();        *Out_buffer;       New uint8_t[avpicture_get_size (pix_fmt_rgb32, width, height)];       *) PFRAMEYUV, Out_buffer, pix_fmt_rgb32, width, height);    Sws_scale (SWS, (constconst0
    *buffersize = width * Height * 4;
Return pframeyuv->data[0];

Context is a global variable, if there is a problem, please contact me. 350197870

FFmpeg fetching pictures from the video stream