Question about format capabilities
Francisco Velázquez
francisco.javier at me.com
Fri Nov 14 08:22:04 PST 2014
Hi,
Patrick, I was trying --gst-debug=CAPS:6 instead of --gst-debug=GST_CAPS:6.
Chuck and Patrick, yes, to link a videoconvert is a simple solution, but I want to understand how does the negotiation algorithm finds out what are the supported capabilities of the elements.
I have shown that the information registered in gst-inspect-1.0 is not complete for some elements. In the pipeline example of this thread, you can see that the accepted format of ximagesink0:sink is disclosed not before ‘gst_pad_query_accept_caps’ is called.
...
0:00:00.038159000 28278 0x7fe392cdf840 DEBUG GST_CAPS gstutils.c:2776:GstCaps *gst_pad_query_caps(GstPad *, GstCaps *):<ximagesink0:sink> query returned video/x-raw, framerate=(fraction)[ 0/1, 2147483647/1 ], width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ]
….
0:00:00.050986000 26538 0x7f80e0c28690 DEBUG GST_CAPS gstpad.c:2088:gboolean gst_pad_link_check_compatible_unlocked(GstPad *, GstPad *, GstPadLinkCheck):<ximagesink0:sink> sink caps video/x-raw, framerate=(fraction)[ 0/1, 2147483647/1 ], width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ]
…
0:00:00.052549000 26538 0x7f80e2000230 DEBUG GST_CAPS gstutils.c:2852:gboolean gst_pad_query_accept_caps(GstPad *, GstCaps *):<ximagesink0:sink> accept caps of video/x-raw, format=(string)BGRx, width=(int)320, height=(int)240, framerate=(fraction)30/1, pixel-aspect-ratio=(fraction)1/1, interlace-mode=(string)progressive
…
My motivation behind is that I want to create an automatic pipeline configurator. Therefore, I must understand the negotiation algorithm in detail.
Thank you,
Francisco.
> On 11 Nov 2014, at 15:27, Chuck Crisler <ccrisler at mutualink.net> wrote:
>
> Just for grins, what about linking directly with xvimagesink, if that fails then link videoconvert? Seems easy enough.
>
> On Mon, Nov 10, 2014 at 6:45 PM, Patrick Doyle <wpdster at gmail.com <mailto:wpdster at gmail.com>> wrote:
> Hello Francisco,
> Sorry, I misread ximagesink as xvimagesink. The
> --gst-debug=GST_CAPS:6 capability is a feature of the gstreamer
> infrastructure, not of individual plugins. When I run:
>
> $ gst-launch-1.0 --gst-debug=GST_CAPS:6 videotestsrc ! ximagesink
>
> I see
> ...
> 0:00:00.078848852 45175 0xda99e0 DEBUG GST_CAPS
> gstutils.c:2807:gst_pad_peer_query_caps:<videotestsrc0:src> get pad
> peer caps with filter video/x-raw, format=(string){ I420, YV12, YUY2,
> UYVY, AYUV, RGBx, BGRx, xRGB, xBGR, RGBA, BGRA, ARGB, ABGR, RGB, BGR,
> Y41B, Y42B, YVYU, Y444, v210, v216, NV12, NV21, NV16, NV24, GRAY8,
> GRAY16_BE, GRAY16_LE, v308, RGB16, BGR16, RGB15, BGR15, UYVP, A420,
> RGB8P, YUV9, YVU9, IYU1, ARGB64, AYUV64, r210, I420_10LE, I420_10BE,
> I422_10LE, I422_10BE, Y444_10LE, Y444_10BE, GBR, GBR_10LE, GBR_10BE },
> width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ],
> framerate=(fraction)[ 0/1, 2147483647/1 ]; video/x-bayer,
> format=(string){ bggr, rggb, grbg, gbrg }, width=(int)[ 1, 2147483647
> ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1,
> 2147483647/1 ]
> 0:00:00.078892620 45175 0xda99e0 DEBUG GST_CAPS
> gstutils.c:2814:gst_pad_peer_query_caps:<videotestsrc0:src> peer query
> returned video/x-raw, format=(string)BGRx, width=(int)[ 1, 2147483647
> ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1,
> 2147483647/1 ], pixel-aspect-ratio=(fraction)1/1
> ...
> So, (please keep in mind, I am not an expert at all in gstreamer), it
> looks to me like videotestsrc proposed a whole slew of formats to
> ximagesink and ximagesink replied "I would like BGRx". That makes
> sense, since ximagesink is "A standard X based videosink". If you
> hand it BGRx data, it probably just needs to blast the pixels into the
> framebuffer without changing them. (It might blast them one component
> at a time, if the frame buffer is 24 bits deep, or it could blast them
> 32 bits at a time into a BGRx framebuffer).
>
> Anything more than this is beyond my limited understanding. I would
> encourage you to take a peek at the source code.
>
> --wpd
>
>
> videotestsrc pr
>
> On Mon, Nov 10, 2014 at 2:46 PM, Francisco Velázquez
> <francisco.javier at me.com <mailto:francisco.javier at me.com>> wrote:
> > Hi Patrick
> >
> > In my installation I use ximagesink instead of xvimagesink. I assume that the CAPS category for debugging is declared inside the xvimagesink, because I do not get any debugging output with that option when using ximagesink. Anyway, the option “-v” of gst-launch-1.0 also shows the negotiated format between elements.
> >
> > Yes, the negotiation process selects the first capability that matches between two linked elements. In the case of video formats, a solution is to insert a videoconvert element to ensure that capabilities match. This solution, however, introduces an overhead that sometimes is unnecessary. Therefore I would like to find out how to know what are the supported formats by elements even when their description does not state it. That is the case of the ximagesink element.
> >
> > Some output snippets:
> >
> > $gst-inspect-1.0 ximagesink
> > …
> > Pad Templates:
> > SINK template: 'sink'
> > Availability: Always
> > Capabilities:
> > video/x-raw
> > framerate: [ 0/1, 2147483647/1 ]
> > width: [ 1, 2147483647 ]
> > height: [ 1, 2147483647 ]
> > …
> >
> >
> >
> > $gst-launch-1.0 -v videotestsrc ! opencvtextoverlay text="Hello" ! videoconvert ! ximagesink
> > …
> > /GstPipeline:pipeline0/GstOpencvTextOverlay:opencvtextoverlay0.GstPad:src: caps = "video/x-raw\,\ format\=\(string\)RGB\,\ width\=\(int\)320\,\ height\=\(int\)240\,\ framerate\=\(fraction\)30/1\,\ pixel-aspect-ratio\=\(fraction\)1/1\,\ interlace-mode\=\(string\)progressive"
> > /GstPipeline:pipeline0/GstVideoConvert:videoconvert0.GstPad:src: caps = "video/x-raw\,\ width\=\(int\)320\,\ height\=\(int\)240\,\ framerate\=\(fraction\)30/1\,\ pixel-aspect-ratio\=\(fraction\)1/1\,\ interlace-mode\=\(string\)progressive\,\ format\=\(string\)BGRx”
> > …
> > Note that the videoconverter changes the format from RGB to BGRx. Otherwise:
> >
> > $ gst-launch-1.0 -v videotestsrc ! opencvtextoverlay text="Hello" ! ximagesink
> > Setting pipeline to PAUSED ...
> > Pipeline is PREROLLING ...
> > ERROR: from element /GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0: Internal data flow error.
> > Additional debug info:
> > gstbasesrc.c(2933): void gst_base_src_loop(GstPad *) (): /GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0:
> > streaming task paused, reason not-negotiated (-4)
> > …
> >
> > How to know what are the supported formats by ximagesink?
> >
> > Thank you.
> >
> > Francisco
> >
> >> On 10 Nov 2014, at 15:25, Patrick Doyle <wpdster at gmail.com <mailto:wpdster at gmail.com>> wrote:
> >>
> >> When I run 'gst-inspect-1.0 ximagesink', I see the following:
> >> ...
> >> Pad Templates:
> >> SINK template: 'sink'
> >> Availability: Always
> >> Capabilities:
> >> video/x-raw
> >> framerate: [ 0/1, 2147483647 <tel:2147483647>/1 ]
> >> width: [ 1, 2147483647 ]
> >> height: [ 1, 2147483647 ]
> >> ...
> >>
> >> This tells me that xvimagesink takes video/x-raw frames at
> >> (effectively) any frame rate and framesize. But (as you note) that
> >> doesn't tell me what specific image formats are support. So I have
> >> learned to do somthing like:
> >>
> >> $ gst-launch-1.0 --gst-debug=CAPS:6 videotestsrc ! xvimagesink
> >>
> >> When I look through the debug output produced by that, I see that
> >> xvimagesink reports same set of capabilities (not surprisingly) and
> >> that it doesn't restrict the image formats (which is what I learned
> >> from gst-inspect-1.0). Continuing through the debug output, I see
> >> that videotestsrc and xvimagesink negotiate a UVYV format. My
> >> (limited) understanding of this negotiation process is that each side
> >> is free to suggest the formats it supports and to choose from the
> >> other side's list the format it would prefer to see.
> >>
> >> --wpd
> >>
> >>
> >> On Mon, Nov 10, 2014 at 9:02 AM, Francisco Velázquez
> >> <francisco.javier at me.com <mailto:francisco.javier at me.com>> wrote:
> >>> Dear GStreamer community,
> >>>
> >>> I am trying to figure out how to know what are the supported formats of
> >>> ximagesink.
> >>>
> >>> I have GStreamer 1.4.3 in Mac OS X 10.10.
> >>>
> >>> `gst-inspect-1.0 ximagesink` shows no format information.
> >>>
> >>> You can see that
> >>> http://cgit.freedesktop.org/gstreamer/gst-plugins-base/tree/sys/ximage/ximagesink.c:931 <http://cgit.freedesktop.org/gstreamer/gst-plugins-base/tree/sys/ximage/ximagesink.c:931>
> >>> does have a "format" descriptor, but that “format descriptor” is missing in
> >>> http://cgit.freedesktop.org/gstreamer/gst-plugins-base/tree/docs/plugins/inspect/plugin-ximagesink.xml <http://cgit.freedesktop.org/gstreamer/gst-plugins-base/tree/docs/plugins/inspect/plugin-ximagesink.xml>.
> >>>
> >>> Is the lack of format in the XML file intentional?
> >>>
> >>> How can one determine what are the supported formats of ximagesink without
> >>> such description?
> >>>
> >>> Thank you,
> >>>
> >>> Francisco
> >>>
> >>>
> >>> _______________________________________________
> >>> gstreamer-devel mailing list
> >>> gstreamer-devel at lists.freedesktop.org <mailto:gstreamer-devel at lists.freedesktop.org>
> >>> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel <http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel>
> >>>
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> >
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