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• Can't get the right formula to set frame pts for a stream using libav

  4 avril 2022, par user1365836

  I'm trying to save a stream of frames as mp4.
Source framerate is not fixed and it stay in the range [15,30]

  


  Encoder params :

  


  ...
eCodec.time_base = AVRational(1,3000);
eCodec.framerate = AVRational(30, 1);
...


  


  Stream params :

  


  eStream = avformat_new_stream(eFormat, null);                
eStream.codecpar = codecParams;
eStream.time_base = eCodec.time_base;


  


  Decoder time_base is 0/1 and it marks each frame with a pts like :

  


  480000
528000
576000
...


  


  PTS(f) is always == PTS(f-1)+48000

  


  Encoding (dFrame is the received frame, micro the elapsed time in microseconds) :

  


  av_frame_copy(eFrame, dFrame);
eFrame.pts = micro*3/1000;


  


  This make the video playing too fast.
I can't understand why, but changing micro*3/1000 to micro*3*4/1000 make the video play at the correct speed (checked against a clock after many minutes of varying fps)

  


  What am I missing ?

  


• Merge commit ’b36bc81ccaa2fc85dc4bae7dc546c71e8833573d’

  10 février 2014, par Michael Niedermayer

  Merge commit ’b36bc81ccaa2fc85dc4bae7dc546c71e8833573d’
  * commit ’b36bc81ccaa2fc85dc4bae7dc546c71e8833573d’ :
  
    avplay : add support for seeking to chapter marks
  Conflicts :
  
  	doc/ffplay.texi
  
  	ffplay.c
  ffplay uses pageup/down for seeking by +-10min
  
  thus this use of the keys conflicts.
  
  The merge thus uses them to seek to chapters when there are some or
  
  +-10min when there are not
  Merged-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] doc/ffplay.texi
  • [DH] ffplay.c

• FFmpeg drawtext not working on filter complex with watermark on php

  14 octobre 2018, par Groovekingg

  After I made a question of this topic i got a great answer from LordNeckbeard and appreciate for the help, but still the drawtext isn’t working, and can’t figure out what could possibly be wrong. So everything works if I omit drawtext=text=’hello’ on both of these lines, but once i add drawtext, no output.gif is created.

  $cmd1 = "$ffmpeg -ss 00:00:02 -t 00:00:02 -i $file_full_path -i $watermark -filter_complex '[0]fps=15,scale=200:113:flags=lanczos[bg];[bg][1]overlay=5:5,drawtext=text='hello',palettegen' $palette";
  
  $cmd2 = "$ffmpeg -ss 00:00:02 -t 00:00:02 -i $file_full_path -i $watermark -i $palette -filter_complex '[0]fps=15,scale=200:113:flags=lanczos[bg];[bg][1]overlay=5:5,drawtext=text='hello'[x];[x][2]paletteuse=dither=bayer:bayer_scale=3' -loop -1 output.gif";
  
  shell_exec($cmd1);
  
  shell_exec($cmd2);

  i have tried changing the single quotation marks to double, but nothing change. Also tried with exec(). Or is it possible that my server has a library missing and drawtext isn’t working because of this ?
  So I have tried to break down to check where it is wrong by simplifying the cmd to :

  $cmd1 = "$ffmpeg -i $file_full_path -ss 00:00:02 -t 00:00:02 -r 20 -vf scale=200:113,drawtext=text='hello' output.gif";

  and an output.gif file is created but 0bytes. what could it be ?

  Thanks to LordNeckbeard again for his answered on my previous post. Any answer would be of great help.