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Regarding KLV-meta tagging with gstreamer

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akash jain

Regarding KLV-meta tagging with gstreamer

Hi all,

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?
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 ?

Do anyone know of any video player which can decode klv meta-tags?

Tim Müller

Re: Regarding KLV-meta tagging with gstreamer

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

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akash jain

Re: Regarding KLV-meta tagging with gstreamer

Thanks Tim for replying.

I have been trying to open
https://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/tests/check/elements/rtp-payloading.c#n753
since yesterday, but its not loading up. Infact https://cgit.freedesktop.org is not working.

You said that i need to create a buffer with the binary data containing sensor values, can you provide some sample example of doing this?

Thanks and Regards

Akash Dhamasia

www.sensoviz.com

Sebastian Dröge-3

Re: Regarding KLV-meta tagging with gstreamer

On Sa, 2016-02-27 at 21:53 -0800, akash jain wrote:
> Thanks Tim for replying.
>
> I have been trying to open
> https://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/tests/check/elements/rtp-payloading.c#n753
> since yesterday, but its not loading up. Infact https://cgit.freedesktop.org is not working.
>
> You said that i need to create a buffer with the binary data
> containing sensor values, can you provide some sample example of
> doing this?

That's what he did with the link. cgit.freedesktop.org is working again
it seems, but there's also a github mirror available here:
https://github.com/GStreamer/gst-plugins-good/blob/master/tests/check/elements/rtp-payloading.c#L753

And if you search with Google, you'll find many other copies of that
code. It should explain how to generate the KLV data, it's really just
the raw KLV data as defined in all those standards.
--
Sebastian Dröge, Centricular Ltd · http://www.centricular.com

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akash jain

Re: Regarding KLV-meta tagging with gstreamer

Hi Sebestian,

Thanks for replying. Surely it gave me an idea of how the klv meta-data looks like, but not getting any idea of how to generate it? Any help there would be wonderful.

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Sebastian Dröge-3

Re: Regarding KLV-meta tagging with gstreamer

On So, 2016-02-28 at 01:00 -0800, akash jain wrote:
> Hi Sebestian,
> Thanks for replying. Surely it gave me an idea of how the klv meta-
> data looks like, but not getting any idea of how to generate it? Any
> help there would be wonderful.

Check the relevant standards for this, i.e. SMPTE-336 and whatever
metadata scheme you want to use, e.g. MISB.

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Sebastian Dröge, Centricular Ltd · http://www.centricular.com

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