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• compile ffmpeg decode only without audio codecs

  28 juillet 2016, par Rob

  I work on a media manager and use ffmpeg.exe to extract screenshots.
  With the latest size of ffmpeg.exe exceeding 35MB, I am attempting to build ffmpeg without the majority of its functions, to allow only saving of a frame of video.

  I had thought disabling many of the filters, Audio Codecs etc would shrink the size of ffmpeg to something more manageable.

  Following this guide
  https://pracucci.com/compile-ffmpeg-on-windows-with-visual-studio-compiler.html
  to allow building of ffmpeg using Visual Studio 2015, I have come to the part of ./configuration and hit a wall.
  With so many options and no idea what all of them mean or do, I am asking if someone in the community can give me laymans instructions.

  I also know that I need to build x264, and possible x265 (HEVC), but am not sure if there is anything other codecs needed.
  In the end, I and am hoping to just have the one file, ffmpeg.exe for use in the media manager project.

  The code I use to get a screenshot is as follows

  Public Shared Function CreateScreenShot(ByVal FullPathAndFilename As String, ByVal SavePath As String, ByVal sec As Integer, Optional ByVal Overwrite As Boolean = False) As Boolean
  
      If Not File.Exists(SavePath) Or Overwrite Then
  
          Try
  
              IO.File.Delete(SavePath)
  
          Catch
  
              Return False
  
          End Try
  
          If IO.File.Exists(FullPathAndFilename) Then
  
              Dim myProcess As Process = New Process
  
              Try
  
                  Dim seconds As Integer = sec
  
                  myProcess.StartInfo.WindowStyle = ProcessWindowStyle.Hidden
  
                  myProcess.StartInfo.CreateNoWindow = False
  
                  myProcess.StartInfo.FileName = Utilities.applicationPath & "\Assets\ffmpeg.exe"
  
                  Dim proc_arguments As String = "-ss " & seconds.ToString & " -i """ & FullPathAndFilename & """ -vframes:v 1 -an " & """" & SavePath & """"
  
                  myProcess.StartInfo.Arguments = proc_arguments
  
                  myProcess.Start()
  
                  myProcess.WaitForExit()
  
                  If File.Exists(SavePath) Then Return True
  
              Catch ex As Exception
  
                  Throw ex
  
              Finally
  
                  myProcess.Close()
  
              End Try
  
          End If
  
      End If
  
      Return False
  
  End Function

  I hope this is sufficient information, and appreciated any help or suggestions.

• high memory & cpu usage in ffmpeg C sample when muxing audio and video

  24 juin 2016, par chandu

  I am using the muxing.c example provided with ffmpeg 3.0 version to create an MP4 file (H.264 & AAC) with VS 2013.

  The sample is working fine with default width & height for video, but when I changed the width to 1920 and height to 1080, the sample is taking nearly 400MB & 60-70% cpu usage (using task manager & in Release mode) throughout the program. I have used multi threading also.

  I tried to free the encoded packet after calling write_frame(), but to no success.
  The memory is being released only after calling avcodec_close().

  Could anybody please tell me what I am doing wrong ?

  I am adding link (https://drive.google.com/open?id=0B75_-V7se7tmWUhyM0ItS0kzUVk) to code I tested with VS 2013.

  The screenshot link https://drive.google.com/open?id=0B75_-V7se7tmVm4tUjFtSnNNSHc

  The STREAM_DURATION value in the sample is set to 120 seconds (even tested with 600 seconds) and I changed default Height & Width values of AVCodecContext in add_stream function for video type to 1080 & 1920 respectively. Through out program, it is taking 355 MB, not changing at all. I think, once frame is encoded using avcodec_encode_video2 and written to the file, the memory should be released.

  Please correct me if I am wrong.

• flush encoded packets to disk when muxing audio and video

  23 juin 2016, par chandu

  I am using muxing.c example (without any modifications) provided with ffmpeg 3.0 version to create MP4 file (H.264 & AAC) with VS 2013. The sample is working fine with default width & height for video. But when changed the width to 1920 and height to 1080, sample is taking nearly 400MB (using task manager & in Release mode) through out the program and also never writing the encoded packets to the out file. It is writing to the out file (out.mp4) only when calling avcodec_close() at the end.

  I have tried to

  1. free the encoded packet after calling write_frame().
  2. used avio_flush()
  3. used avcodec_flush_buffers()

  but no success.

  Could anybody please tell me, how can I save the every encoded packet to disk by not keeping in RAM, so the memory usage would be low ?

  Note : There is no issue with flushing the buffers after recording is over, I am doing this by calling av_interleaved_write_frame() with AVPacket NULL.