Renegotiate GstVaapiDecode src caps

Danny Cullen Danny.Cullen at
Tue Nov 21 13:46:53 UTC 2017


I am using a GstURIDecodeBin to access an HTTP MJPEG IP video source.  The source sends the first few frames as 800x600 (a black splash screen) JPEG images and then sends the live data as 352x288.

When the first frame is decoded I link a GstVaapiPostproc element with the GstURIDecodeBin and the vaapipostproc sink caps are negotiated with the vaapidecode elements src caps as 800x600.

When the JPEG images change size, the sink caps of the vaapidecode element receive a GST_EVENT but this does not propagate to any of the downstream elements.

I’m assuming that the sink of the vaapipostproc element would need to renegotiate with the src of the vaapidecode element?  Is that correct?

I have connected a notify::caps signal handler to the sink pad of the vaapidecode element however I’m not sure of the best way of getting the downstream elements to renegotiate.  What is the best way of achieving this?

Thanks in advance,


Danny Cullen
Software Team Leader
Bemrose House, Bemrose Park, Wayzgoose Drive, Derby, DE21 6XQ, United Kingdom
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Datapath Ltd.  Registered Number: 1609392.  Registered in England at Bemrose House, Bemrose Park, Wayzgoose Drive, Derby. DE21 6XQ.

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