Why send seeks to sinks?

[Nicolas Dufresne]

Le lundi 27 juin 2022 à 10:38 -0700, amindfv--- via gstreamer-devel a écrit :
> As a novice, it's quite unintuitive to send seek events to the sinks of a
> pipeline.
> 
> For example, say I'd like to have two video files, each playing from a a
> different point in the file. I'd then like to play them simultaneously, mix
> them together (e.g. give them each opacity 0.5 and overlay them) and then send
> the combined data stream to e.g. an autovideosink. Intuitively, I'd imagine:

As a novice, you should use GStreamer Edition Service API for the purpose, this
problem have been solve inside that library.

> 
>   a) I'd send a seek event to the source, not the sink, to cause the source to
> jump to a different point in its file, and
>   b) the autovideosink wouldn't know or care what seeking had happened
> upstream
> 
> But I think both of my intuitive guesses are very wrong. My sense it that
> there's a deep reason for why things are the way they are, and understanding
> it will uncover some misconceptions I have about how GStreamer works
> (something about clocks, maybe?)
> 
> If anyone could help me understand, or point me towards a resource that'll
> help, it'd be much appreciated.
> 
> Thanks,
> Tom