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• get UTC time of every video frame using ffmepg

  22 septembre 2015, par MathxH Chen

  I just read a RTSP stream from my IP Camera using FFMPEG. I need to display UTC time of every frame and video frame synchronously. The player GUI I created by Qt.

  At very first, I just use libVLC to implement my requirement. Then, I just found out that LibVLC cannot get UTC timestamp of every frame(https://forum.videolan.org/viewtopic.php?f=4&t=128403), So I was out to move from libvlc to ffmepg. I code a Demo read RTSP using ffmpeg library and print the presentation time of every frame . but I find the presentation time is relative , It start from zero up to end. How I can convert the time to UTC ? RTP Packet’s timestamp is relative, It only need RTCP sender report’s absolute timestamp to calculate the UTC. How can I get the UTC time of every frame using FFMPEG ??

  In FFPMEG every frame has own pts in struct AVFrame, the pts just copied from AVPacket, the struct AVStream has time_base this field, UTC time is equal to time_base*pts ?

  my code snippet as follows :

  //SDL End----------------------
  
  while(av_read_frame(pFormatCtx, packet)>=0){
  
  
  
  
  
      if(packet->stream_index==videoindex){
  
          ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
  
          if(ret < 0){
  
              printf("Decode Error.\n");
  
              return -1;
  
          }
  
  
  
          int64_t utc = packet->pts * av_q2d(pStream->time_base);
  
          printf("UTC is :%I64d\n", utc);

  What’s Wrong ?

• How to convert multiple files with ffmpeg to GIFs [closed]

  26 juillet 2020, par mriisa

  I found in this forum Convert-mp4-to-gif at good batch-code for converting videos to GIF-files by just dragging and dropping the files onto the batch files. The problem is I can only drop one file at the time, whereas I have maybe hundres of files, which I just want my computer to work on.

  



  The code is as seen here :

  



  @echo off
::** create animated GIF w/ optimized palette
::
:: https://ffmpeg.org/ffmpeg-all.html#gif-2
:: http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html
:: http://superuser.com/questions/556029/how-do-i-convert-a-video-to-gif-using-ffmpeg-with-reasonable-quality

if not exist "%~dpnx1" goto :EOF
cd "%~dp1" 

::** generate palette
@echo on
@echo.
"c:\program files\ffmpeg\bin\ffmpeg.exe" ^
 -v warning -i "%~nx1" ^
 -vf "palettegen" ^
 -y tmp-palette.png

::** generate GIF
@echo.
"c:\program files\ffmpeg\bin\ffmpeg.exe" ^
 -v warning -i "%~nx1" ^
 -i tmp-palette.png ^
 -lavfi "[0][1:v] paletteuse" ^
 "%~n1.gif"
@echo off

del /q tmp-palette.png

if errorlevel 1 pause
goto :eof


  



  I have absolutely no idea how to program batch files, and this code was just something I found online which worked for me. Can anybody help me adding the needed code for making me able to drag and drop multiple files ?

  


• Révision 20697 : Micro-modif dans la page de contrôle des forums :

  3 juillet 2013, par esj -
  • mettre un ancre vers le message de forum même dans le cas interne ;
    * prendre en compte les noms de site de longueur 3 ;
    * decouper en 2 la fonction principale afin de permettre facilement une surcharge, notamment l’argument "type".