[gst-devel] video pipeline caps negotiation problem

[Dan Taylor]

I have two pipelines, one of which negotiates caps correctly for me, and
one of which doesn't.

The analog TV pipeline comes back with a new "set caps" when I call
gst_pad_peer_accept_caps(),
but the digital pipeline doesn't.  In the following debug print clips,
you can see that set_caps()
is interleaved within my buffer_alloc(), because that's where I call
gst_pad_peer_accept_caps().

There is a video (and analog, not shown) backend that is identical for
both pipelines, and, of
course, I have had to handle the "sometimes" pads of the demuxer (and
audio decoder).  What does
NOT happen in the digital pipeline is the scaling that I want to occur,
so the image is too large
to be fully displayed.

The fbdevsink modifications are an in-progress attempt to make it more
friendly for embedded
systems, so it now has a buffer pool, "keep-aspect" handling, a bounding
box, and a few other
features.  There is still much to be done (rounding up the strides, for
example, which should
be breaking the analog, but doesn't ).

Does anyone have any ideas for why the gst_pad_peer_accept_caps() does
NOT trigger a set_caps()
in the digital pipeline?


VERSIONS:

gstreamer-0.10.22, gst-plugins-base-0.10.22, gst-plugins-good-0.10.14,
gst-plugins-bad-0.10.10,
gst-fluendo-mpegdemux-0.10.15


VIDEO BACKEND:

        gst_bin_add_many (GST_BIN (vbin), vqueue0, vscale, vfilter,
                          vqueue1, vcolor, vsink, NULL);

	vscale:     videoscale
	vfilter:    capsfilter
	vcolor:     ffmpegcolorspace
	vsink:      HIGHLY modified fbdevsink

ANALOG:

        gst_bin_add_many (GST_BIN (vbin), vsource, vqueue, vcrop,
vdelace, NULL);

	vsource:    v4l2src
	vcrop:      videocrop
	vdelace:    deinterlace2

        gst_bin_add_many (GST_BIN (video_pipeline), video_frontend,
video_backend, NULL);

gst_fbdevsink_buffer_alloc: requesting fit of 720x472 to 927x608 window
with original aspect ratio
gst_fbdevsink_buffer_alloc: peer pad accepts our desired caps; buffer
size is now 2254464 bytes
gst_fbdevsink_buffer_alloc: want buffer of size 2254464 (4,927,608)
gst_fbdevsink_buffer_alloc: buffer 0x80af6b8, fbdevsink 0x81580b0
gst_fbdevsink_set_caps: fbdevsink width 720, height 472
gst_fbdevsink_buffer_alloc: requesting fit of 720x472 to 927x608 window
with original aspect ratio
gst_fbdevsink_buffer_alloc: peer pad accepts our desired caps; buffer
size is now 2254464 bytes
gst_fbdevsink_set_caps: fbdevsink width 927, height 608
gst_fbdevsink_buffer_alloc: want buffer of size 2254464 (4,927,608)


DIGITAL:

        gst_bin_add_many (GST_BIN (digital_frontend), tsource, tqueue,
tdemux,
                          aqueue, adecode, vqueue, vdecode, NULL);

	tsource:    dvbsrc
	tdemux:     flutsdemux
	vdecode:    mpeg2dec

        gst_bin_add_many (GST_BIN (digital_pipeline), digital_frontend,
video_backend, audio_backend, NULL);

gst_fbdevsink_buffer_alloc: requesting fit of 1280x720 to 1080x608
window with original aspect ratio
gst_fbdevsink_buffer_alloc: peer pad accepts our desired caps; buffer
size is now 2626560 bytes
gst_fbdevsink_buffer_alloc: want buffer of size 2626560 (4,1080,608)
gst_fbdevsink_buffer_alloc: buffer 0x80af6b8, fbdevsink 0x816c050
gst_fbdevsink_set_caps: fbdevsink width 1280, height 720
gst_fbdevsink_buffer_alloc: requesting fit of 1280x720 to 1080x608
window with original aspect ratio
gst_fbdevsink_buffer_alloc: sending request for fit 1080x608
gst_fbdevsink_buffer_alloc: peer pad accepts our desired caps; buffer
size is now 2626560 bytes
gst_fbdevsink_buffer_alloc: requesting fit of 1280x720 to 1080x608
window with original aspect ratio
gst_fbdevsink_buffer_alloc: sending request for fit 1080x608
gst_fbdevsink_buffer_alloc: peer pad accepts our desired caps; buffer
size is now 2626560 bytes