Appsink output data

Matthew Waters ystreet00 at
Tue Oct 20 15:24:39 PDT 2015

appsink just provides data in whatever format is given to it.  Qt 5.5
(the latest) still has GStreamer 0.10 support by default which has been
unmaintained for over 3 years and the last release was over 4 years
ago.  If you're open to upgrading to GStreamer 1.0 there are a couple of
options to have a look at.

1. qmlglsink - If you write your application in QML, you can use a ready
made sink that will "Just Work".  There are some nuances to getting it
to compile on all the Qt platforms due to Qt's reliance on qmake.
2. glupload ! appsink - This will upload your data into OpenGL textures
that can be retrieved from the appsink.  appsink also now uses a
GstSample in 1.x which contains the caps (such as the format) as well as
the buffer.  You would have to be careful with object lifetimes and
OpenGL context object synchronisation though.
3. Write your own GStreamer element that renders to a
QImage/QWidget/QGLWidget - much harder than the previous options but
would still be a worthwhile exercise.

Hope that helps


On 21/10/15 05:47, Nuzut wrote:
> So I'm trying to use appsink with OpenGL. My original plan was to use Qt5 for
> displaying my video and I was able to get a video stream with QImage, but
> only when I used the Indexed8 format and this only displayed the video in
> black and white. I've discovered that OpenGL has more format options when
> displaying drawing to a texture with glteximage2d. My issue lies with my
> lack of knowledge of appsink. I'm assuming it's raw data which lacks a
> header and is why the QImage wasn't working correctly. I guess the question
> should be: What is the output format for appsink? My pipeline is: udpsrc
> port=6282 caps="application/x-rtp, media=(string)video,
> clock-rate=(int)90000, encoding-name=(string)H264" ! rtph264depay !
> h264parse ! omxh264dec ! appsink name=appsink sync=false and my platform is
> the raspberry pi2. 
> Any help on this topic would be fantastic! Thanks!!!
> --
> View this message in context:
> Sent from the GStreamer-devel mailing list archive at

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