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• How to extract frames from a video with transparency ?

  10 août 2017, par Ahtsham Abbasi

  How do I extract frames from a video (.mov Apple ProRes 4444) with the alpha channel ?

  I need the PNG images so transparency is not lost.

  I have 23 videos so I would prefer to automate the process.

• FFMpeg outputs empty stream/file in C#

  15 juin 2017, par Dark0Matter

  I’m making a bot for discord, and I’m currently trying to use ffmpeg to stream an audio file through voice chat. (Which, many other people succeeded in doing it)

  So basically, I’m using libsodium.dll + opus.dll + ffmpeg.exe to turn an mp3 file into a stream using ffmpeg, and output it.

  This is my "CreateStream" function which starts ffmpeg and turns the mp3 file into a stream/pipe.

      private Process CreateStream(string path)
  
      {
  
          var ffmpeg = new ProcessStartInfo
  
          {
  
              FileName = "ffmpeg.exe",
  
              //Arguments = $"-hide_banner -loglevel panic -i \"{path}\" -ac 2 -f s16le -ar 48000 pipe:1",
  
              Arguments = $"-i {path} -ac 2 -f s16le -ar 48000 pipe:1",
  
              //Arguments = $"-i {path} -ac 2 -f s16le -ar 48000 testingtesting.mp3",
  
              UseShellExecute = false,
  
              RedirectStandardOutput = true,
  
          };
  
          return Process.Start(ffmpeg);
  
      }

  The commented arguments are the other arguments that I’ve tried. (e.g. the last commented arguments line was an attempt to output it to a file instead of a stream, and the file turned out to be empty)

  So basically, my current arguments are

  Arguments = $"-i {path} -ac 2 -f s16le -ar 48000 pipe:1"

  (where pipe:1 is replaceable by any filename such as test.wav)

  and here’s my problem in case you didn’t catch it :

  ffmpeg always outputs empty streams/files.

  Here’s the output that I got in the console.
  https://pastebin.com/zvGgsZZ6

  So my question is,

  Am I using the wrong arguments ?

  And if so, what other arguments can I try to get it fixed ?

  Tl ;dr : ffmpeg outputs empty data to a stream, and it does the same thing when the pipe is replaced by a .wav/.mp3 file.

  EDIT1 : After some time of waiting, I got this : https://pastebin.com/y8rjnsMb

  EDIT2 : I searched for more argument combinations that worked for other people and stumbled upon Arguments = $"-i \"path\" -ab 48000 -f mp3 test.mp3",
  when I tried writing to test.mp3, it worked, but the quality was low.
  Then I tried replacing test.mp3 with pipe:1, but that didn’t work. Help ?

• ffmpeg rtmp streaming process exit

  12 août 2013, par Samson

  I'm using ffmpeg to capture jpeg images from an rtmp stream. Here is the command I use :

  /usr/local/bin/ffmpeg -threads 4 -i rtmp://..../chat/mp4:<variable>.mp4 
  
  -q:v 0.6 -r 15 -s 320x240 /frames/10021237_data/frame-%0999d.jpg
  
  
  
  ffmpeg version N-55388-g9386f33 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Aug  8 2013 14:07:38 with gcc 4.7 (Ubuntu/Linaro 4.7.2-2ubuntu1)
  
    configuration: 
  
    libavutil      52. 41.100 / 52. 41.100
  
    libavcodec     55. 24.100 / 55. 24.100
  
    libavformat    55. 13.102 / 55. 13.102
  
    libavdevice    55.  3.100 / 55.  3.100
  
    libavfilter     3. 82.100 /  3. 82.100
  
    libswscale      2.  4.100 /  2.  4.100
  
    libswresample   0. 17.103 /  0. 17.103
  
  Input #0, flv, from &#39;rtmp://......./mp4:10021237.mp4&#39;:
  
    Duration: N/A, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: h264 (Main), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 1.92 tbr, 1k tbn, 40 tbc
  
      Stream #0:1: Audio: nellymoser, 44100 Hz, mono, flt
  
  [swscaler @ 0x1910000] deprecated pixel format used, make sure you did set range correctly
  
  Output #0, image2, to &#39;/frames/10021237_data/frame-%0999d.jpg&#39;:
  
    Metadata:
  
      encoder         : Lavf55.13.102
  
      Stream #0:0: Video: mjpeg, yuvj420p, 320x240 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 90k tbn, 15 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 -> mjpeg)
  
  Press [q] to stop, [?] for help
  
  </variable>

  However after a few minutes I get this line (before the process exits) :

  video:5264kB audio:0kB subtitle:0 global headers:0kB muxing overhead -100.000408%

  What exactly is the "muxing overhead" and why is it causing a crash ? Can I solve this or get it some other way (by restarting the process when it exits) ?

  EDIT :

  Actually it's not a crash. I'm running this command from a PHP CLI when a stream starts :

   $command = "/usr/local/bin/ffmpeg -i ".$rtmp." -q:v 0.6 -r 12 -s 320x240 ".__DIR__."/".$dir."/".$naming." >/dev/null 2>/dev/null &";
  
  shell_exec($command);

  but when one stops streaming all the ffmpeg processes end. Is there a way to make them independent ?

  Even opening 2 terminals and running the command (with different rtmp s)in each (for different streams), killing one of them closes the other one also.

  Bottom line is : How can I make 2 ffmpeg instances independent so as killing one does not kill the other. Is this behaviour expected ?