videorate doesn't drop or duplicate frames in live stream?

[Nicolas Dufresne]

Le vendredi 24 juillet 2020 à 20:15 -0500, gotsring a écrit :
> I'm using gstreamer 1.16.2 and C++ to process a IP cam video feed. I use the
> videorate element to even out the live stream which averages ~30 FPS. I need
> a smooth 20 FPS, so videorate should duplicate frames during the occasional
> dropouts and drop the excess frames, so I have a pipeline as follows:
> 
> souphttpsrc location=http://192.168.1.145/mjpeg is-live=true ! queue !
> jpegdec ! videorate ! 'video/x-raw, framerate=20/1' ! d3dvideosink
> 
> All this seems to do is re-timestamp all frames with a duration of 50ms, so
> nothing is ever dropped or duplicated, messing up anything I do downstream.
> I'm guessing this is probably because the incoming frames have no
> timestamps. 
> 
> Adding the do-timestamp option in souphttpsrc causes jpegdec to fail (messes
> with jpeg data header? still looking into this)
> 
> Inserting a timecodestamper element in front of videorate spams a bunch of
> gst_time_code_is_valid assertion fails. Desite the messages, the pipeline
> still runs, but the behavior is the same as the original pipeline, i.e. the
> timestamps are altered, but no frames are duplicated or dropped.
> 
> Is there a property in videorate that I'm missing that can perform
> rate-smoothing based on an internal clock with no reliance on frame
> timestamps, or some other way to add timestamps to frames before they enter
> videorate? 

videorate does not have a live mode implemented atm. In fact, it does
not have the needed thread to allow this. So even if you where usinging
a proper container with timestamp, it would bursts frames on the next
buffer after the gap.

I've heard some folks have managed to workaround using compositor
element, with a single pad. In live mode, it produces data on the
clock. The only issue I see is how it behaves on gaps (it renders the
background rather then repeating last image). I think it's wrong
default, I would need to discuss this.

gst-launch-1.0 videotestsrc is-live=1 ! video/x-raw,framerate=10/1 ! compositor ! video/x-raw,framerate=30/1 ! fpsdisplaysink video-sink=glimagesink

> 
> 
> 
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