flvdemux incorrectly determining FPS?

[Brian Dilley]

I have a process that is reading packets from an RTMP client and feeding
them into a GST pipeline via an appsrc.  It feeds them into the appsrc in
an FLV container.  From the appsrc it feeds into a decodebin, and then into
a custom element where every frame is analyzed, and then re-encoded and
sent to an RTMP server.

My problem is that the the number of frames per second that are sent to my
custom element seems to be around ~17 when I would expect it to be 30.  In
fact, if I run the pipeline for 1 minute it ends up buffering an extra
minute's worth of data and finishing that even after I've finished sending
data to the appsrc.  I'm not sure if it's exactly half (ie: ~17fps vs.
~30fps) but that's what it seems like.

As an interesting side note, I tried cutting the timestamps written to the
appsrc (in the flv container) in half and i achieved the expected ~30fps
without any latency or buffering... so I know that the software is capable
of achieving those speeds - it seems that there is an artificial slowdown
somewhere between the appsrc and my custom element.... perhaps in the
decodebin.

Has anyone experienced anything like this before?  I'm pretty certain that
the timestamps that I'm writing are correct since they are basically just a
pass-through calculation from an RTMP client.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/gstreamer-devel/attachments/20200427/838b3bfe/attachment.htm>