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• How to batch convert mp4 files to ogg with ffmpeg using a bash command or Ruby

  3 avril 2013, par TJ Sherrill

  I am running a OSX, don't know tons about video conversions. But I have like 200 videos that are all in mp4 format and won't play in Firefox. I need to convert them to ogg to use the html5 video tag.

  These files live in a folder structure that makes it hard to do files one at a time. I would like the bash command or Ruby command to go through all child folders and find all .mp4's and convert them.

  I found one reference of how to do this with Google : http://athmasagar.wordpress.com/2011/05/12/a-bash-script-to-convert-mp4-files-to-oggogv/

  #!/bin/bash
  
  for f in $(ls *mp4 | sed ‘s/\(.*\)\..*/\1/’)
  
  do
  
  ffmpeg -i $f.mp4 -acodec vorbis -vcodec libtheora $f.ogg
  
  done

  But have no idea how to convert this from linux to osx.

• NodeJS piping with ffmpeg

  8 février 2014, par Gnap

  I wanted to do a HTTP live stream on a screen cast with using ffmpeg, nodejs and html5 . I wanted it to be as real time as possible. However, I find that my video received by the client was behind by 1 2 seconds (On Chrome/Chromium). I am using vp8/webm as my codec.

  I have eliminated the following factors as such :
  1) Network : I have tried serving and receiving the video file locally by stating the video source to be 127.0.0.1:PORT or localhost:PORT
  2) ffmpeg encoding speed:I have tried outputting the file locally, it the "delay" seems to be negligible.
  3) Chrome internal buffer. The buffer was accounted to be 0.07s 0.08s.

  On the nodeJS side, I have a child process that runs the ffmpeg command, and did a ffmpeg.stdout.pipe(res) ; <— ffmpeg is child_process.spawn(...)

  So it seems that the ffmpeg.std.pipe(res) of nodejs seems to be the one delaying the video stream. Am I correct in assuming so ? Is there anyway that I may reduce the delay ?

• ffmpeg produces bad output when called from execve in c++

  31 mai 2016, par Arheisel

  im writing a c++ program that involves ffmpeg being called from a c++ program. a couple of days ago i got it working using std::system

  std::system("ffmpeg -threads auto -y -r 1.74659 -i /mnt/ev_ramdsk/1/%05d-capture.jpg -px_fmt yuv420p -preset ultrafast -r 10 /mnt/ev_ramdsk/1/video.mp4");

  but this only worked once now this produces .mp4 videos of 8MB or so that cannot be played anywhere.. so because of a suggestion in a previous question i moved to execve.

  Here is my code

  child_pid = fork();
  
          if(child_pid < 0){
  
              syslog(LOG_ERR, "ERROR: ffmpeg forking failed");
  
              return false;
  
          }
  
          else if(child_pid > 0){
  
              syslog(LOG_DEBUG, "DEBUG: forking succeeded, pid: %d", child_pid);
  
          }
  
          else if(child_pid == 0){
  
              char *newargv[16];
  
              for(int i=0; i < 15; i++) newargv[i] = (char *)malloc(sizeof(char) * 60); //allocate the array in memory
  
              strcpy(newargv[0], "/usr/bin/ffmpeg");
  
              strcpy(newargv[1], "-threads");
  
              strcpy(newargv[2], "auto");
  
              strcpy(newargv[3], "-y");
  
              strcpy(newargv[4], "-framerate");
  
              tempSS << fps;
  
              strcpy(newargv[5], tempSS.str().c_str());
  
              tempSS.str(std::string());
  
              strcpy(newargv[6], "-i");
  
              strcpy(newargv[7], std::string(conf->dir_ram + dest + "%05d-capture.jpg").c_str());
  
              strcpy(newargv[8], "-pix_fmt");
  
              strcpy(newargv[9], "yuv420p");
  
              strcpy(newargv[10], "-preset");
  
              strcpy(newargv[11], "ultrafast");
  
              strcpy(newargv[12], "-r");
  
              strcpy(newargv[13], "25");
  
              strcpy(newargv[14], std::string(conf->dir_ram + dest + "video.mp4").c_str());
  
              newargv[15] = NULL;
  
  
  
              for(int i=0; i < 15; i++){
  
                  tempSS << "newargv[" << i << "] = \"" << newargv[i] << "\", ";
  
              }
  
              syslog(LOG_DEBUG, "DEBUG:newargv: %s", tempSS.str().c_str());
  
              tempSS.str(std::string());
  
  
  
              char *newenviron[] = { NULL };
  
  
  
              if(execve(newargv[0], newargv, newenviron) == -1){
  
                  syslog(LOG_ERR, "ERROR: execve returned -1");
  
                  exit(EXIT_SUCCESS);
  
              }
  
          }
  
  
  
          wpid = wait(&status);
  
          syslog(LOG_DEBUG, "DEBUG: ffmpeg child terminated, pid: %d, status: %d", wpid, status);

  the output of syslog is :

  May 28 00:25:03 SERVER dt_ev_maker[10471]: DEBUG: forking succeeded, pid: 10658
  
  May 28 00:25:03 SERVER dt_ev_maker[10658]: DEBUG:newargv: 
  
  newargv[0] = "/usr/bin/ffmpeg", 
  
  newargv[1] = "-threads", 
  
  newargv[2] = "auto", 
  
  newargv[3] = "-y", 
  
  newargv[4] = "-framerate", 
  
  newargv[5] = "1.45097", 
  
  newargv[6] = "-i", 
  
  newargv[7] = "/mnt/ev_ramdsk/1/%05d-capture.jpg", 
  
  newargv[8] = "-pix_fmt", 
  
  newargv[9] = "yuv420p", 
  
  newargv[10] = "-preset", 
  
  newargv[11] = "ultrafast", 
  
  newargv[12] = "-r", 
  
  newargv[13] = "25", 
  
  newargv[14] = "/mnt/ev_ramdsk/1/video.mp4",
  
  May 28 00:25:03 SERVER dt_ev_maker[10471]: DEBUG: ffmpeg child terminated, pid: 10658, status: 256

  in this case the video has about 90B size and is also corrupted.

  NOTE : if i run the same command from the command line the video can be played normally.

  what am i doing wrong ?

  Thanks in advance !

  EDIT

  Thanks to ouroborus (changes submitted above) i got it to make 18MB videos, but i cant play them.