Sending metadata across UDP

[Nicolas Dufresne]

Le jeu. 26 sept. 2019 05 h 25, priyanka kataria <
priyanka.kataria86 at gmail.com> a écrit :

> Hello,
>
> I have an interesting problem:
> Need to transfer some kind of metadata (say frame number) with each frame
> over UDP. Receiver on the other hand, extracts he frame numebr from each
> frame and maintains it for some other work.
>
> Sample sender and receiver pipelines:
> Sender: gst-launch-1.0 -v filesrc location=file.h264  ! h264parse !
> rtph264pay ! udpsink port=5001
> Receiver: gst-launch-1.0 -v udpsrc port=5001 caps="application/x-rtp,
> media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264" !
> rtph264depay ! decodebin ! autovideosink
>

Consider adding an rtpjitterbuffer on the receiver, in future GST version,
you'll be able to use rtpsrc/rtpsink (or the rist variant) in order to get
a full feature RTP stream without complex pipeline construction.

For jpeg, consider configuring max-bitrate property on udpsink. As frames
are spread out on a lot more packet, it tend to become bursty and may
saturate the link or exhaust the udpsrc socket buffer-size.



> Things I have already tried (I am still a beginner, so some of the below
> things may look stupid):
> 1. In Sender pipeline, attaching a probe on "h264parse" element and
> assigning incremental values to "GST_BUFFER_OFFSET".
> But the set offset value is not reflected in the next element in the same
> pipeline only.
>
> 2. In Sender pipeline, attaching a probe on "h264parse" element and
> assigning incremental values to "GST_BUFFER_PTS".
> The set PTS value is reflected in the next elements in the same pipeline,
> but gets lost across UDP.
> I checked this by attaching a probe on "rtph264depay" element (src pad).
>
> 3. Using "gst_rtp_buffer_add_extension_twobytes_header()".
> This method works for H264 files, but fails with MJPEG files, and my
> solution needs to be generic.
> Here, I can provide more details with code if required.
>

That is the method I would have used. It should work with any RTP packet,
so you likely have or hit a bug.


> 4. Last thing I am trying is to mux KLV metadata into stream and send it
> across UDP.
> I refer the following link:
> https://www.aeronetworks.ca/2018/05/mpeg-2-transport-streams.html.
> This doesn't work though as written in the article but gave me an overview
> on how to use the pipeline.
> Now I want to create my custom my KLV metadata file which contains only
> frame numbers and try to mux it.
>
> Please help me in creating such file.
>
> Also please share if there are any other working approaches I should try
> to append metadata in each frame buffer.
>
> Thanks,
> Priyanka
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