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• Error while trying to get output from command [C++]

  8 septembre 2021, par Jilijou

  I am trying to get the duration of a video using ffmpeg in C++ and I tried using a pipe to get the output from a command. I can't compile my code, getting this error :

  


  video_concat.cpp: In function 'int main()':
video_concat.cpp:17:41: error: expected ',' or ';' before '{' token
   std::string exec(commande_duration_2) {
                                         ^
video_concat.cpp:51:1: error: expected '}' at end of input
 }
 ^


  


  And this is my code :

  


  #include <iostream>&#xA;#include <memory>&#xA;#include <stdexcept>&#xA;#include <array>&#xA;#include <cstdio>&#xA;#include &#xA;#include <string>&#xA;#include <sstream>&#xA;&#xA;using namespace std;&#xA;&#xA;int main() {&#xA;  float duration_1, duration_2, full_duration;&#xA;  duration_1 = system("ffprobe -i goal1_25.mp4 -show_entries format=duration -v quiet -of csv=\"p=0\"");&#xA;  //duration_2 = system("ffprobe -i goal2_25.mp4 -show_entries format=duration -v quiet -of csv=\"p=0\"");&#xA;  const char* command_duration_2 = "ffprobe -i goal2_25.mp4 -show_entries format=duration -v quiet -of csv=\"p=0\"";&#xA;  std::string exec(commande_duration_2) {&#xA;    std::shared_ptr<file> pipe(popen(command_duration_2, "r"), pclose);&#xA;    if (!pipe) return "ERROR";&#xA;    char buffer[128];&#xA;    std::string result = "";&#xA;    while (!feof(pipe.get())) {&#xA;        if (fgets(buffer, 128, pipe.get()) != NULL) {&#xA;            duration_2 &#x2B;= buffer;&#xA;        }&#xA;    }&#xA;    return duration_2;&#xA;  }&#xA;&#xA;&#xA;  cout &lt;&lt; duration_1 &lt;&lt; " | " &lt;&lt; duration_2;&#xA;  return 0;&#xA;}&#xA;</file></sstream></string></cstdio></array></stdexcept></memory></iostream>

  


  If I put between /.../ the pipe section, everything works fine but I don't get any result (Output : 0 | 0). Can anyone help me ? Thanks !

  


• How to rotate an image overlay in ffmpeg around the image center ?

  14 mars 2023, par ktrace

  I'm using ffmpeg to scale, rotate and overlay an image on a video. I'm able to rotate the image by the desired angle but the overlay ends up being moved both vertically and horizontally from the expected position.

  


  The commands I've tried and their corresponding outputs are shown below. Command 1 gives the expected output, 2 and 3 do not.

  


  How can I modify my commands in general, to rotate the overlay image around the image center, to get the expected output ?

  


  

  


  


  ffmpeg -i graphpaper.mp4 -i arrow.png -y -filter_complex [1:v]scale=w=364:h=370[overlay0] ;[overlay0]rotate=a=0:c=none:ow=rotw(0):oh=roth(0)[rotate0] ;[0:v][rotate0]overlay=x=419:y=168[output0] -map [output0] sample-overlay-on-graph-paper.mp4

  


  


  

  


  


  ffmpeg -i graphpaper.mp4 -i arrow.png -y -filter_complex [1:v]scale=w=364:h=370[overlay0] ;[overlay0]rotate=a=0.8017360589297406:c=none:ow=rotw(0.8017360589297406):oh=roth(0.8017360589297406)[rotate0] ;[0:v][rotate0]overlay=x=419:y=168[output0] -map [output0] sample-overlay-on-graph-paper.mp4

  


  


  

  


  


  ffmpeg -i graphpaper.mp4 -i arrow.png -y -filter_complex [1:v]scale=w=364:h=370[overlay0] ;[overlay0]rotate=a=5.493783719179012:c=none:ow=rotw(5.493783719179012):oh=roth(5.493783719179012)[rotate0] ;[0:v][rotate0]overlay=x=419:y=168[output0] -map [output0] sample-overlay-on-graph-paper.mp4

  


  


  Links to input files :

  


  

  • graphpaper.mp4 https://imgur.com/a/daHI7j0

  


  • arrow.png https://imgur.com/a/wWwnnfq

  


  


• audio dynamic range compression in php

  28 mai 2020, par monu214

  Is this possible to dynamic audio range compression in PHP. There is a lot of confusion between compression of audio, what I mean of audio compression here is described in this article.

  



  Some posts I saw here about the audio compression which only converts the audio format from wav to mp3 or other formats using FFmpeg, but what I want here is to change some audio settings like threshold, compression ratio, attack time, release time which is basic settings that can be used in audio compression.

  



  Is there any way I can do this in server-side using PHP ?