Regarding KLV-meta tagging with gstreamer

[Tim Müller]

On Sat, 2016-02-27 at 04:37 -0800, akash jain wrote:

Hi,

> i have a few doubts regarding klv-metagging with gstreamer.
> 
> Is the actual klv-meta tagging (which is compatible with MISB) is
> different from gstreamer-klv-meta-tagging?

Not sure what you're asking here but the GStreamer KLV is the KLV
format described in the various standards (SMPTE336, MISB etc.). So no,
I don't think it's different.

> If NO then,
> 
> how the data which i am sending as meta-data is related to
> key,length,value?
> I am sending meta-data like:
> 
> const std::string meta-data = "mymetadata";
> 
> Pushing meta-data to appsrc and
> appsrc -> mpegtsmuc -> udpsink
> 
> If i want to send multiple sensor data like GPS,IMU, i thought of
> sending
> them as
> 
> meta-data << "IMUx=" << IMUx << ",IMUy=" << IMUy<< ",IMUz=" << IMUz
> <<
> ",Gpsx=" << Gpsx << ",Gpsy=" << Gpsy << ",Gpsz=" << Gpsz << ".";
> 
> but that will require decoding of these sensor value in a specific
> order and
> format which is not standard.
> 
> How to send them in a way compatible to MISB standard so that any
> klv-inspector can able to recognise it ?

Not quite sure what your code is doing here. The KLV/MISB data is in
binary form, and you have to create a buffer with the binary data
containing your values and then push that into the appsrc element.

The rtpklvpay/rtpklvdepay unit test does something like this in fact:
https://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/tests/chec
k/elements/rtp-payloading.c#n753

Cheers
 -Tim

-- 
Tim Müller, Centricular Ltd - http://www.centricular.com