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• ffmpeg stream videos from two cams have a same device name

  21 novembre 2020, par junsang

  There are two cameras have a same device name Microsoft® LifeCam Studio(TM).
  
ffmpeg -list_deivces true -f dshow -i dummy prints the below output.

  



  C:\Users\user>ffmpeg -list_devices true -f dshow -i dummy
ffmpeg version git-2020-02-05-e6891d1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.2.1 (GCC) 20200122
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 39.100 / 56. 39.100
  libavcodec     58. 67.101 / 58. 67.101
  libavformat    58. 37.100 / 58. 37.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 74.100 /  7. 74.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
[dshow @ 000001d5c5108dc0] DirectShow video devices (some may be both video and audio devices)
[dshow @ 000001d5c5108dc0]  "Microsoft┬« LifeCam Studio(TM)"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_pnp_\\?\usb#vid_045e&pid_0811&mi_00#8&6ae46e6&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
[dshow @ 000001d5c5108dc0]  "Microsoft┬« LifeCam Studio(TM)"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_pnp_\\?\usb#vid_045e&pid_0811&mi_00#8&e544916&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
[dshow @ 000001d5c5108dc0] DirectShow audio devices
[dshow @ 000001d5c5108dc0]  "Desktop Microphone (6- Microsoft┬« LifeCam Studio(TM))"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\wave_{D5F4881A-6E88-4563-8BA0-081CFD50E353}"
[dshow @ 000001d5c5108dc0]  "Desktop Microphone (5- Microsoft┬« LifeCam Studio(TM))"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\wave_{84674B28-DC68-4AC0-8331-D687C7B7D69C}"
[dshow @ 000001d5c5108dc0]  "Digital Audio (S/PDIF) (High Definition Audio Device)"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\wave_{CDD24485-59D2-4BED-B6FC-B7447251C7E2}"


  



  Because the two cameras have a same device name, I couldn't stream two videos using this simple command at a same time : ffplay -f dshow -i video=Microsoft® LifeCam Studio(TM).
  
So I used pin names following the ffmpeg dshow example.
The only thing I could check was Could not find video device with name [video=~~pin name~~] among source devices of type video.

  



  What ffplay command makes enable to stream both videos ?

  


• Too many FFMPEG process

  21 avril 2014, par Mrslipp3ry

  I have a list of video files and I want to convert them with ffmpeg. This is my code :

      public static void ConvertToMp3(String inputPath, String title)
  
      {
  
          String outputpath = "\"D:\\Mp3\\" + title + ".mp3\"";
  
  
  
          String _out;
  
          Process p = new Process();
  
  
  
          p.StartInfo.UseShellExecute = false;
  
          p.StartInfo.RedirectStandardInput = true;
  
          p.StartInfo.RedirectStandardOutput = true;
  
          p.StartInfo.RedirectStandardError = true;
  
          p.StartInfo.CreateNoWindow = true;
  
          p.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
  
          p.StartInfo.FileName = "ffmpeg";
  
          p.StartInfo.Arguments = " -i \"" + inputPath + "\" -vn -f mp3 -ab 192k " + outputpath;
  
  
  
          p.Start();
  
          p.StandardOutput.ReadToEnd();
  
          _out = p.StandardError.ReadToEnd();
  
          p.WaitForExit();
  
  
  
          if(!p.HasExited)
  
              p.Kill();
  
  
  
          Console.WriteLine(_out);   
  
      }

  It works fine, but when I call this function in a loop for n times, it opens too many processes. I want to open only one process at a time and when it’s done, go to the next.

• Grab frame without downloading whole file ?

  12 janvier 2012, par Writecoder

  Is this possible using php + ffmpeg ?

  ffmpeg-php has the ability to :

  Ability to grab frames from movie files and return them as images that
  can be manipulated using PHP's built-in image functions. This is great
  for automatically creating thumbnails for movie files.

  I just don't want to download the whole file before doing so.
  So lets say i want to grab a frame @ 10% of the movie :

  First lets get the size of remote file :

  $ch = curl_init(); 
  
  curl_setopt($ch, CURLOPT_HEADER, true); 
  
  curl_setopt($ch, CURLOPT_NOBODY, true);
  
  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); 
  
  curl_setopt($ch, CURLOPT_URL, $url); //specify the url
  
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); 
  
  $head = curl_exec($ch);
  
  
  
  $size = curl_getinfo($ch,CURLINFO_CONTENT_LENGTH_DOWNLOAD);

  Then it's quite easy to download only 10% of the .flv or .mov file using curl.

  But the framegrab trick using ffmpeg-php probably won't work because the file probably is corrupted ?

  Any other ideas ?