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• 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.

• What is the best way to Stream multiple CCTV RTSP into Node.js

  1er décembre 2020, par Borneo Dev

  I am trying to start to build a node.js application that is going to receive RTSP video streams from IP CCTV cameras.

  


  I have spent considerable amount of time studying opencv and ffmpeg as the tool to listen to the cctv rtsp streams.

  


  with opencv, I am very confused if I need to use opencv.js to be included in node script or to download and install opencv build into my os.

  


  with ffmpeg, Im not sure if I can access the mat object (mat as in opencv) to be passed to a video processing module (such as tensorflow for object detection). When I look and tested ffmpeg RTSP examples, I cant seem to find a way to store the video buffer frames into Mat variable for processing. The video is either played on ffplay or is saved into file system.

  


  I know this is a general questions, as I have not started coding yet.

  


  Appreciate for some help to guide me into the right tools and methods to achieve the objective. TQ.

  


• Setting HLS segment times

  16 février 2016, par James Townsend

  I am passing a processed video from openCV to ffmpeg via a pipe here is the code

  ./OpenCV & \
  
   tail -n +0 -f out.avi  | ffmpeg -i pipe:0  -hls_time 1 -hls_list_size 0 -hls_wrap 10 -hls_segment_filename '%03d.ts' stream.m3u8 

  My issue is the output .ts files are not in a uniformed duration they change from file to file.

  These are mostly long say 60 seconds. This means the connecting client has to wait for the first stream to finish before the playlist file (.m3u8) file is created. Therefor in this example they are 60 seconds or so behind live video and if the next .ts file is larger the streaming stops until this is finished. If the client tries to play before the next .ts file is created they are played the first .ts file.

  The frame rate from openCV is 1 frame per second.

  tail changes the output file of openCV called (out.avi) to a stdout.

  Any help would be great.