Recherche avancée

Sur d’autres sites (8645)

• 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 set comma delimited values from stdout ?

  28 octobre 2017, par gregm

  I have a batch file that processes the output of an ffprobe query. It retrieves several bits of data that I use to determine some ffmpeg directives. In particular I’m converting h264 videos into h265 if the video frame height is 720 or greater. I also convert the audio stream to aac if it isn’t already and if that stream is higher than 128 kbps I convert it down to 128.

  I can do all of that by calling ffprobe a number of times and use if statements to decide what my ffmpeg command will be.

  I’d like my batch file to be more efficient so I was thinking that if I could take the output of one (maybe two) ffprobe queries and then stick that output into a for /f token=.... loop then I could set each ffprobe data point to a variable and then just check the variables to decide what the resulting ffmpeg command will be.

  Here’s what I have right now to simply check if the video stream is hevc. If it isn’t then ffmpeg converts the video to hevc and copies the audio to aac.

  for %%a in ("*.*") do (
  
  ffprobe -v quiet -show_entries stream=index,codec_name,height -of csv "%%a" 2>&1 | findstr "hevc"
  
  if errorlevel 1 (
  
      ffmpeg.exe -hwaccel cuvid -i "%%a" -pix_fmt p010le -c:v hevc_nvenc -preset slow -rc vbr_hq -b:v 4M -maxrate:v 10M -c:a aac "%%~na.h265-convert.mp4"
  
  ))

  That ffprobe query output looks like this :

  stream,0,h264,480

  I was thinking if I could tokenize that output with something like :

  for /f "tokens=1,2,3,4 delims= " %%a in ("______") do set codec=%%b&set fheight=%%d

  I don’t know what to put in the spot where I have the _______. I really don’t want to create a temp file unless that’s the only option though.

  1) Is this an efficient way to achieve what I’m trying to do ?

  2) What do I use where I have a blank line above ________ to call the output of the ffprobe query to use in my for loop ?

• How to compile ffmpeg-0.10.3 on windows with cygwin and android ndk r5

  19 avril 2014, par Vikram Mahal

  I want to compile ffmpeg on windows with cygwin and android ndk.
  I found this link very useful because there is step to step guide to compile ffmpeg.

  Does anyone find this useful ? - Compiling FFMPEG on Windows with Cywin and NDK r5

  But at last point when i am going to create .so file i got this error in cygwin bash.

  ---

  CONSOLE OUTPUT :

  vikram mahal@vikrammahal-PC ~
  
  $ cd /cygdrive/c/ffmpeg-0.10.3
  
  vikram mahal@vikrammahal-PC /cygdrive/c/ffmpeg-0.10.3
  
  $ dos2unix build_android.sh
  
  dos2unix: converting file build_android.sh to Unix format ...
  
  vikram mahal@vikrammahal-PC /cygdrive/c/ffmpeg-0.10.3
  
  $ ./build_android.sh
  
  )/configure: line 10: warning: setlocale: LC_ALL: cannot change locale (C
  
  ': not a valid identifierort: `LC_ALL
  
  ./configure: line 14: syntax error near unexpected token `$'{\r''
  
  '/configure: line 14: `try_exec(){
  
  ./build_android.sh: line 54: make: command not found
  
  ./build_android.sh: line 55: make: command not found
  
  C:\android-ndk-r5\toolchains\arm-linux-androideabi-4.4.3\prebuilt\windows\bin\ar
  
  m-linux-androideabi-ld.exe: cannot open output file ./android/armv7-a/libffmpeg.
  
  so: No such file or directory