[gst-devel] Plugin writing problem with caps negotiation

[Wei-Di Hung]

Hi,
I’m writing a hardware video codec plugin.
For now, I am using gst-launch to test the plugin but an error occurs:

gst-launch filesrc location=xxx.avi ! ffdemux_avi ! xxxdec ! fbdevsink

ERROR: from element /pipeline0/ffdemux_avi0: Internal data stream error.
Additional debug info:
gstffmpegdemux.c(1300): gst_ffmpegdemux_loop (): /pipeline0/ffdemux_avi0:
streaming stopped, reason not-negotiated
ERROR: pipeline doesn't want to preroll.

While the last plugin is substituted by fakesink or filesink, the pipeline 
works ok.
I’ve gst-inspected the decoder and fbdevsink,
the src pad of decoder and the sink pad of fbdevsink both have the cap
GST_VIDEO_CAPS_RGB_16.
I’ve also edited the caps of decoder output buffer:
  buf->caps = GST_PAD_CAPS (filter->srcpad);

Is there something I missed or got wrong with the plugin?
Thanks in advance.
Robert