webrtcbin -> videoscale results in black frames, why ?

[Michael]

Hello everybody,

I am struggling a bit with the fact that webrtcbin -> decodebin and then
scaling pipeline is not working as expected.

I get an incoming Pad (incoming_decodebin_pad)

video/x-raw, format=(string)I420, width=(int)640, height=(int)480,
interlace-mode=(string)progressive, multiview-mode=(string)mono,
multiview-flags=(GstVideoMultiviewFlagsSet)0:ffffffff:/right-view-first/left-flipped/left-flopped/right-flipped/right-flopped/half-aspect/mixed-mono,
pixel-aspect-ratio=(fraction)1/1, chroma-site=(string)jpeg,
colorimetry=(string)bt601, framerate=(fraction)0/1

which works perfectly if I do not scale it

[image: Bildschirmfoto 2020-04-15 um 16.02.06.png]

but if I add videoscale-> capsfilter between it to scale it to
"video/x-raw,width=480,height=320" I just get black frames (next I added
`method=0 add-borders=false`to videoscale same result!)and not even the
right dimension.

[image: Bildschirmfoto 2020-04-15 um 15.59.56.png]

Here is my Pipeline for the first attempt without videoscale which works

[image: Bildschirmfoto 2020-04-15 um 16.12.21.png]

And the one with videoscale

[image: Bildschirmfoto 2020-04-15 um 16.12.52.png]

Full pipelines are attached as well.

One thing to add. Even if I use the working pipeline the incoming webrtc
video goes from videoimage to blackframe back to videoimage for at least 5
sec on START.
The pipeline with videoscale never shows an image just black frame.

Pipeline with scale full: black frame
https://drive.google.com/file/d/16wMFgTs9C8cRaCGXSUvae6MS2gEISsCh/view?usp=sharing

Pipeline without scale: works
https://drive.google.com/file/d/1Gjqcmbm9x2UuepwwJ91upjf23jZJDq5U/view?usp=sharing


Thank you in advance for any clue!
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