At the current state only one user with the username cat lady has added videos. Both videos are in the /cats directory ownedby cat lady. The file /cats/1.mp4 can be viewed by anyone (*), while /cats/2.mp4 has no extra sharing options, and cantherefore only be viewed by its owner, cat lady. The relationship definitions are located in thecontrib/cat-videos-example/relation-tuples directory.
Now cat lady wants to change some view permissions of /cats/1.mp4. For this, the video service application has to show allusers that are allowed to view the video. It uses Keto's expand-API to getthese data:
Next, we use the filter_complex filtergraph parameter to instruct FFmpeg from where to take the audio and video. [0:v][0:a] means FFmpeg needs to take the video and audio from the 0th video (file1.mp4). Then, you tell FFmpeg to concat three files (n=3). The v=1:a=1 implies that there is one stream for the audio and one stream for the video. 041b061a72