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• FFmpeg memory growing in avcodec_decode_video2

  21 juillet 2015, par Wendy Pan

  I am using C# to call the ffmpeg lib.
  I use the example code to decode an video in the MP4 format.

  However, I found out that the memory grows a lot (like 10MB), when I called the avcodec_decode_video2 function.

  The memory keeps growing until I called the avcodec_close(&CodecContext) function.

  I suppose the reason may be that AVCodecContext alloc 10MB data during the call of avcodec_decode_video2 function. And this memory will not be released until the AVCodecContext is closed.

  I do not know if I am right.

  Main codes are in the following.

  private bool readNextBuffer(int index)
  
      {
  
          /// Read frames into buffer
  
          //m_codecContext->refcounted_frames = 0;
  
          int frameNumber = 0;
  
          FrameBuffer[index].Clear();
  
          GC.Collect();
  
  
  
          while (frameNumber < m_bufferSize)
  
          {
  
              AVPacket Packet; /// vedio packet 
  
              AVPacket* pPacket = &Packet;
  
              //AVFrame* pDecodedFrame = FFmpegInvoke.avcodec_alloc_frame(); 
  
              AVFrame* pDecodedFrame = FFmpegInvoke.av_frame_alloc(); 
  
              if (FFmpegInvoke.av_read_frame(m_pFormatContext, pPacket) < 0)
  
              {
  
                  Console.WriteLine("The end of the vedio.");
  
                  break;
  
              }
  
              if (pPacket->stream_index == pStream->index)
  
              {
  
                  /// Decode vedio frame
  
                  int gotPicture = 0;
  
                  int size = FFmpegInvoke.avcodec_decode_video2(m_codecContext, pDecodedFrame, &gotPicture, pPacket);
  
                  if (size < 0)
  
                  {
  
                      Console.WriteLine("End of the vedio.");
  
                      //throw new Exception(string.Format("Error while decoding frame {0}", frameNumber));
  
                      break;
  
                  }
  
  
  
                  if (gotPicture == 1)
  
                  {
  
                      /// Allocate an AVFrame structure
  
  
  
                      if (convertFrame(pDecodedFrame, index))
  
                      {
  
                          frameNumber++;
  
                      }
  
                      else
  
                      {
  
                          Console.WriteLine("Error: convert failed.");
  
                      }
  
                  }
  
              }
  
              FFmpegInvoke.av_frame_free(&pDecodedFrame);
  
              FFmpegInvoke.av_free_packet(pPacket);
  
              GC.Collect();
  
          }
  
          nowFrameIndex = 0;
  
          return FrameBuffer.Count > 0 ? true : false;
  
      }

• How to play mp4 video file with HTML5 video tag on iOS (iPhone and iPad) ?

  22 avril 2015, par Mokielas

  I want to display HTML5 video to my users using the video tag. For Firefox, Chrome and Opera WEBM works as expected. In Safari on Windows and Mac my MP4 version works, too. The only problem I’m experiencing is, that it won’t play on iPad and iPhone (Safari of course).

  Create video

  The MP4 (h.264 + acc-lc) is converted like this (with profile : baseline and level 3.0 for maximum compatibility with iOS) :

  • Stream #0:0(eng) : Video : h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x352, 198 kb/s, 17 fps, 17 tbr, 17408 tbn, 34 tbc (default)
  • Stream #0:1(eng) : Audio : aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 56 kb/s (default)

  Edit : Whole ffprobe output (slight changes in bitrate etc. to the above mentioned) :

  Metadata:
  
  major_brand     : isom
  
  minor_version   : 512
  
  compatible_brands: isomiso2avc1mp41
  
  encoder         : Lavf56.30.100
  
  Duration: 00:01:00.05, start: 0.046440, bitrate: 289 kb/s
  
  Stream #0:0(eng): Video: h264 (Constrained Baseline) 
  
  (avc1 /0x31637661), yuv420p, 640x352, 198 kb/s, 25 fps, 25 tbr, 
  
  12800 tbn, 50 tbc (default)
  
  Metadata:
  
    handler_name    : VideoHandler
  
  Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, 
  
  stereo, fltp, 85 kb/s (default)
  
  Metadata:
  
    handler_name    : SoundHandler

  I found various requirements for iOS devices like this and this, also someone mentioned to add the yuv420p pixel format when converting.

  In fact the ffmpeg cmd looks like this :

  ffmpeg -i __inputfile__ -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -level 3.0 -b:v 200K -r 17 -bt 800K -c:a libfdk_aac -b:a 85k -ar 44100 -y __outputfile_lowversion__.mp4

  Display video

  With Modernizr I detect which format is "supported" and add it to the src or the video tag. Last thing is adding the right MIME type. For mp4 I add type="video/mp4". The full code for the video tag is :

  <video class="p-video" preload="auto" autoplay="" type="video/mp4" src="http://full.url/to/video_low.mp4"></video>

  I tried various ways : own implementation with own interface, controls and stuff from browser vendors and video.js just to check whether i’m too studip for this. All work in the environments listed above except for iPhone and iPad.

  I read this article on Video on the web, especially this part and only serve the "right" file with the "right" type without a posterattribute set.

  My Apache has

  AddType video/mp4                      mp4 m4v f4v f4p
  
  AddType video/ogg                      ogv
  
  AddType video/webm                     webm

  And byte-ranges are enabled. This is needed to get partial content from the server.

  Has anyone a clue what’s going on there ? Thanks in advance !

  Edit : Safari and Chrome both throw MEDIA_ERR_SRC_NOT_SUPPORTED Error on iPad. There must be an issue with the encoding.

• Process is not exiting ffmpeg.exe only for the command which detects the silences from a video

  20 juillet 2015, par Jitender Kumar

  The job of the method ExecuteCommandSync is to detect the silences from a video and return the output as string but when I run this code it never bring the value of proc.HasExited as true. If I forcefully drag the debugger to the line

  result =proc.StandardOutput.ReadToEnd()

  then it never exit the ffmpeg.exe so as a result control never returns back.

  Although the same method is working fine for a different command like creating an audio file from a video. In this case proc.HasExited also returns false but it also generates the audio file successfully.

  public static string ExecuteCommandSync(string fileName, int timeoutMilliseconds)
  
      {
  
          string result = String.Empty;
  
          string workingDirectory = Directory.GetCurrentDirectory();
  
          try
  
          {
  
              string command = string.Format("ffmpeg -i {0} -af silencedetect=noise=-20dB:d=0.2 -f null -", "\"" + fileName + "\"");                
  
              System.Diagnostics.ProcessStartInfo procStartInfo =
  
                  new System.Diagnostics.ProcessStartInfo("cmd", "/c " + command);
  
  
  
              procStartInfo.WorkingDirectory = workingDirectory;                
  
              procStartInfo.RedirectStandardOutput = true;
  
              procStartInfo.RedirectStandardError = true;
  
              procStartInfo.UseShellExecute = false;                
  
              procStartInfo.CreateNoWindow = false;                
  
              System.Diagnostics.Process proc = new System.Diagnostics.Process();
  
              proc.StartInfo = procStartInfo;
  
              proc.Start();                
  
              proc.WaitForExit(timeoutMilliseconds);
  
              // Get the output into a string 
  
              if (proc.HasExited)
  
              {
  
                  if (!proc.StandardOutput.EndOfStream)
  
                  {
  
                      result = proc.StandardOutput.ReadToEnd();
  
                  }
  
                  else if (!proc.StandardError.EndOfStream)
  
                  {
  
                      result = "Error:: " + proc.StandardError.ReadToEnd();
  
                  }
  
              }
  
          }
  
          catch (Exception)
  
          {
  
              throw;
  
          }
  
          return result;
  
      }

  So please advice.