gst-rtsp-server share v4l2src accross several mounting points

[Nicolas Dufresne]

Le jeu. 10 oct. 2019 06 h 41, jean-philippe <jean_philippe_arnaud at yahoo.fr>
a écrit :

> Hi,
>
> I'm trying to use gst-rtsp-server to implement an RTSP server for an IP
> camera.
>
> Here is what I need to do but have not found a way to implement:
> - I am looking for a way to have several video streams running at the same
> time, streaming video captured from my one v4l2 camera, but with different
> encodings.
> - I need to be able to add new stream/mounting points without interrupting
> the streaming that may already be ongoing.
> - I need to be able to capture snapshots (still images) from the camera
> when
> 0 or more RTP stream(s) are live, without interrupting the streams that may
> already be live.
>
> The v4l2src cannot be reopened, so creating individual pipelines, one for
> each RTSP mounting point is not an option. So the following, based on the
> GstRTSPMediaFactory does not work:
> for (int i = 0; i < 2; ++i) {
>    std::string s = "test_" + std::to_string(i);
>    factory = gst_rtsp_media_factory_new();
>    gst_rtsp_mount_points_add_factory(mounts, s.c_str(), factory)
>    gst_rtsp_media_factory_set_launch(factory, "v4l2src ! vpuenc_h264 !
> rtph264pay name=pay0 pt96");
>    gst_rtsp_media_factory_set_shared (factory, TRUE);
> }
>
> With this sort of code, I can stream from test_1 or test_2, but not both.
> The reason is that the v4l2src cannot be reopened.
>
> The following pipeline would work for my requirements, but according to
> this link
> <
> http://gstreamer-devel.966125.n4.nabble.com/RTSP-Server-Can-t-get-multiple-streams-per-URI-to-work-td4672194.html>
>
> all streams would be sent once a client connects to the aggregate URI as
> each stream does not have its own URI and must instead by filtered on the
> client side based on the payload type.
> This would be too inefficient for my used case and having to filter on the
> payload type on the client side does not fit my requirement.
>
>                   --> q --> fakesink (used for snapshots via last-sample)
> v4l2src --> t --> q --> vpuenc_h264 --> rtph264pay name=pay0 pt=96
>                   --> q --> vpuenc_h264 --> rtph264pay name=pay1 pt=97
>
> I'm currently contemplating removing the v4l2src from the pipeline used by
> the RTSP server and place it into a separate pipeline. I will then need to
> somehow forward samples from that v4l2src pipeline to the pipelines used by
> the RTSP server.
>
> So something like the following:
>
> Pipelines in my app:
>    v4l2src --> appsink
>    appsrc --> jpenenc --> filesink (for snapshot)
>
> RTSP mount / pipelines:
>    mount_1: appsrc --> vpuenc_h264 --> rtph264pay
>    mount_2: appsrc --> vpuenc_h264 --> rtph264pay
>    etc...
>
> Then in my app, manually push samples into the appsrc elements for each
> mounting points.
> This approach seems too hacky to be the right way to proceed and I am
> concerned it will introduce inefficiencies (will the data be memcpy-ed when
> push into the appsrc?).
>

Splitting it into its own pipeline is quite common. Though for raw video,
it's also a bit challenging. You have to advertise support for VideoMeta to
prevent random memcpy (for realignment purpose).


> So am I missing something here? Is there a simpler way to implement this?
>

They might not be all super efficient, it depends on the context. But
intervideosink/src is extremely simple. There is also some other proxies
which I forgot the name, was is pipesrc/sink ? There is also something
called proxysrc/sink, they all have a slight difference, I'm under the
impression the last one does not do multiplexing, so you'd need to combine
with a tee, which is more programming.


> Thanks
> JP
>
>
>
>
>
> --
> Sent from: http://gstreamer-devel.966125.n4.nabble.com/
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