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• Concatenating multiple remote files using ffmpeg?

  8 December 2018, by May Rest in Peace

  I am trying to concatenate multiple remote files using ffmpeg but some files get skipped in the output.

  I use the command

  ffmpeg -f concat -safe 0 -protocol_whitelist "file,http,https,tcp,tls" -i mylist.txt -c copy output.m4a

  mylist.txt looks like :

  file 'http://remoteurl?fileName=20.m4a'
  
  file 'http://remoteurl?fileName=21.m4a'
  
  file 'http://remoteurl?fileName=22.m4a'
  
  file 'http://remoteurl?fileName=23.m4a'

  On running this command, the output will contain audio from only some files.

  I download the files individually from the same urls and did a local concatentation using the same command and it worked perfectly.

  Is this because concat will not work if files are not present immediately as mentioned in https://trac.ffmpeg.org/wiki/Concatenate#Automaticallyappendingtothelistfile ?

  If that’s the case then how should I proceed ? There’s a terminal script provided in the above link but I am on a Windows machine and tbh, I am not that good at bash scripting.

  All files are audio files with same bitrate and are in .m4a format.

  This is the error message I receive [mov,mp4,m4a,3gp,3g2,mj2 @ 00000278b64d4f40] stream 0, offset 0xc9b: partial file

• Adding Gapless Playback information to AAC

  13 July 2018, by StaticBR

  im currently trying to develop an Video / Audio encoding pipline.
  My goal is it to encode mp4 files containing an h264 video track and an AAC audio Track. These files should be played one after another without any gaps in between.

  Currently im converting the videos with ffmpeg.
  Unfortunately my input files are missing the gapless playback metadata, which will be needed for gapless playback of the AAC track.

  Infact im looking for a way to add the iTunSMPB udta comment, as it is needed by the Exoplayer. (See Parser for Details: GaplessInfoHolder.java )

  I could not find a way to add this via ffmpeg ( ffmpeg AAC encoder doc), did i maybe missed something?

  Even Wikipedia only lists two converters that should be able to do that: Nero Digital and Itunes. But this infomation could be outdated.

  Do anyone of you know a java library or (linux) command that can add this metadata to an mp4 file?

  I hope some of you might be able to help me.
  Thank you.

• Python VTK, how to record a video?

  15 April 2016, by Maksim Surov

  I am trying to record a video of VTK 3D animation using ffmpeg. The example I found http://www.itk.org/Wiki/VTK/Examples/Cxx/Video/FFMPEG is a bit strange for me, because it does not create a render, so it is not clear how to attach actors in this case. So, my question is how to connect vtkRenderer to vtkFFMPEGWriter? I wrote a simplified example

  import vtk
  
  
  
  # draw a plane
  
  plane_source = vtk.vtkPlaneSource()
  
  plane_source.SetCenter(0, 0, 0)
  
  plane_source.SetNormal(0, 0, 1)
  
  plane_mapper = vtk.vtkPolyDataMapper()
  
  plane_mapper.SetInput(plane_source.GetOutput())
  
  plane_actor = vtk.vtkActor()
  
  plane_actor.SetMapper(plane_mapper)
  
  
  
  # create render
  
  render = vtk.vtkRenderer()
  
  renWin = vtk.vtkRenderWindow()
  
  renWin.AddRenderer(render)
  
  renWin.SetSize(800, 600)
  
  renInter = vtk.vtkRenderWindowInteractor()
  
  renInter.SetRenderWindow(renWin)
  
  render.AddActor(plane_actor)
  
  renWin.Render()
  
  renInter.Initialize()
  
  
  
  # set callback
  
  def cb(interactor, event):
  
      global plane_actor
  
      plane_actor.RotateZ(0.1)
  
      interactor.GetRenderWindow().Render()
  
  
  
  renInter.AddObserver('TimerEvent', cb)
  
  timerId = renInter.CreateRepeatingTimer(100);
  
  
  
  # put something here?
  
  writer = vtk.vtkFFMPEGWriter()
  
  # ??? writer.SetInputConnection(...)
  
  writer.SetFileName("test.avi")
  
  writer.Start()
  
  
  
  # run
  
  renInter.Start()