Queues empty even when stream is inactive

[Michiel Konstapel]

On 16-06-2022 19:52, Steve W via gstreamer-devel wrote:
> Hello all
>
> I’m trying to switch between two queues using input-selector:
>
> input-selector name=i sync-streams=true sync-mode=clock 
> cache-buffers=true
> … ! queue max-size-time=0 name=q1 ! i.
> … ! queue max-size-time=0 name=q2 ! i.
> i. ! fakesink
>
> I’ve added buffer probes to the sources of q1 and q2. Even when the 
> input-selector has the active pad set to one stream, both of the 
> buffer probes are triggered. Regardless of the duration rolled, 
> current-level-buffers is always 0 for both q1 and q2. It seems to 
> suggest that both queues are consumed even when the active pad is set 
> to only one stream. Does anyone know why this might be the case?
>
> Thanks

If I understand correctly, even with those properties, the 
input-selector will consume buffers from all its inputs, but drop 
everything except buffers from the active pad. `cache-buffers` only 
applies to (quoting the docs) "buffers still considered valid (after 
current running time, see sync-mode)". Even in that case, they will have 
been consumed from the queue, and when their time has passed, they'll 
still be dropped.
Michiel