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• Access to motion vector's (x, y) coordinate while using libx264 encoder

  8 mars 2022, par Rockland

  I want to know if it is possible to get motion vectors values (x, y) somehwhere in the enconding process while using libx264 encoder.

  


  I have a project where I need to modify motion vectors values during encoding process.
What I want to do concretly is for exemple : motion_x = motion_x + 1 and/or motion_y = motion_y -1

  


  I want to know if it is possible to get motion vectors values (x, y) somehwhere in the enconding process while using libx264 encoder.

  


  I have a project where I need to modify motion vectors values during encoding process.
What I want to do concretly is for exemple : motion_x = motion_x + 1 and/or motion_y = motion_y -1

  


  I know that it is possible to do that while using the standards ffmpeg encoders. Precisily in the function static int encode_picture(MpegEncContext *s, int picture_number) in the file mpegvideo_enc.c located in the ffmpeg's libavcodec directory, we can get and modify motion vector's values in the struct MpegEncContext (->current_picture.motion_val).
When I use libx264 encoder, this function is not called so I don't know where and how to do that.

  


  Your help will be verry appreciated.

  


• Merging audio and video using ffmpeg in python

  11 juin 2022, par Dairop

  I am trying to merge two files (.mp3 & .mp4) to a single .mp4

  


  The videos and audio are located in the same folder as my main.py, and aren't corrupted

  


  Here is the code that seems to create the error :

  


      if (haveAudio):
        infile1 = ffmpeg.input(title+"_video.mp4")
        infile2 = ffmpeg.input(title+"_audio.mp3")

        merged  = ffmpeg.concat(infile1, infile2, v=1, a=1)
        output  = ffmpeg.output(merged[0], merged[1], title+".mp4")



  


  I am getting an error on the last line :

  


  Traceback (most recent call last):&#xA;  File "C:\Users\...\projectName\main.py", line 67, in <module>&#xA;    output  = ffmpeg.output(merged[0], merged[1], title&#x2B;".mp4")&#xA;  File "C:\Users\...\Python\Python39\lib\site-packages\ffmpeg\nodes.py", line 70, in __getitem__&#xA;    raise TypeError("Expected string index (e.g. &#x27;a&#x27;); got {!r}".format(index))&#xA;TypeError: Expected string index (e.g. &#x27;a&#x27;); got 0&#xA;</module>

  


  My guess would be that an argument is missing when calling ffmpeg.output() but based on the documentation it seems correct.

  


• Open Video Downloader Error : Postprocessing : ffmpeg not found

  11 septembre 2022, par Nick the Community Scientist

  Error Thrown :

  


  ERROR: Postprocessing: ffmpeg not found. Please install or provide the path using --ffmpeg-location


  


  Context : macOS Big Sur M1 Chip, using the open video downloader program GitHub release or Homebrew. This specifically was thrown at the end of downloading the video file and the audio file from a given URL. The two files remained separate as a result of the error, the video was playable normally, but audio was in a .webm format (unusable for most people).

  


  Analysis : It is clear that a dependency is missing, or its path cannot be located. For macOS users like me, the first step after checking the app's preferences for a path set or dependency download function is to check for the given dependency in the system. Once checking using Homebrew, it became clear that several dependencies were missing.