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• Process videos on Azure VM

  6 March 2017, by sebastian.roibu

  I am building an application that will process uploaded video. Each uploaded video will be trimmed into multiple shorter parts and all the cuts will be concatenated to create a highlight of the original file. All the processing is done with ffmpeg.

  I am using Azure File Storage, to upload the videos and be able to access them via Samba layer.
  I also have an Azure VM where I mounted the shared folders.

  What is the best approach on the worker?

  • Should I build a console app and run it as a windows server inside an azure VM ?

  • Is there another way of doing things?

  I am looking for a way that can be scaled up in production.

  If there another way of doing everything I described above?

• Detect video frame offset to sync videos the smart way

  29 August 2018, by Fabien Biller

  When recording video, we know that it has for instance 60 fps. But do we also know, what the video offset is? We do know that the time difference between frames is 1/60 s. But when did it start as an absolute value? The problem comes into play when trying to sync two videos of the same scenery, for instance stereo with different cameras that were not frame-locked. My idea is to interpolate two - audio synced - 60 fps videos to for instance 180 fps to then change them to 60 fps again to hopefully have matching frames. This does not work, according to my test. A better solution would be to know the time difference between frames to interpolate based on difference, for instance using a deep learning algorithm.

  How can ffmpeg help me here?

• Concatenate multiple videos with a black screen loop into one video

  21 March 2016, by AHC

  I am using ffmpeg to join a bunch of videos together.
  I am using the classic join ffmpeg code:
  

  ffmpeg -f concat -i joinlist.txt -c copy joinedfile.mp4

  but the problem is that the videos are of different formats, encodings, but the same size: all 640x480. I want to join them all and put a black screen video with no sound every other video:

  video1 + black_screen_video + video2 + black_screen_video + video3 ...

  I generated a black screen video of 2 seconds duration using:

  ffmpeg -f lavfi -i color=c=black:s=640x480:d=2 black_screen_video.mp4

  so all of the videos are of the same size: 640x480, and 25 fps but different codecs. The videos have sound, except for the black screen video.
  I can’t do anything manual, because the number of videos are around several hundred. So it has got to be an automatic way to do all this.

  When I joined them together using the above code, the resulting video does not play correctly at all.

  I know that I have to re-encode them, but how to do this to all these videos at once, with one line of code?

  Update:
  I am already using with success this code to join them together, but only three, if I have more than one hundred, it is time consuming to write down one by one:

  ffmpeg -i vid1.avi -i vid2.avi -i vid3.avi -filter_complex "[0:v:0] [0:a:0] [1:v:0] [1:a:0] [2:v:0] [2:a:0] concat=n=3:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" output.mp4

  but this is joining only the videos, not looping the black screen video. When I do with black screen, ffmpeg gives me stream matching errors.

  update:

  here is the console image:
  

  2nd update:

  a very long list of errors in red, of which a screenshot here: