how to create proper HLS pipeline

[Andres Gonzalez]

Hi Chris,

Using a *tsparse* element after the udpsrc and before a hlssink2 (not
hlssink) gives this runtime error:

GStreamer-CRITICAL **: 18:42:53.362: Element splitmuxsink0 already has a
pad named video, the behaviour of  gst_element_get_request_pad() for
existing pads is undefined!

But using a *tsdemux* after udpsrc and before hlssink2 does indeed work.
This pipeline works great:

 gst-launch-1.0   udpsrc port=50000 caps="video/mpegts,systemstream=true" !
tsdemux ! hlssink2 target-duration=5 playlist-location="playlist.m3u8"
location=segment_%05d.ts

However, when I code this pipeline up in my C++ application (using
gst_element_factory_make(), gst_bin_add(), and gst_element_link()), I get
that same runtime error I got when using tsparse.

So the pipeline:     udpsrc  -->  tsdemux -->  hlssink2.    works when I
use gst-launch.  But when I code it up manually, I get that runtime error.
 So those 3 elements won't work using the typical   gst_element_link()  so
some other pad linking is going on under the covers.

How do I do the link manually so these 3 elements will link up properly?

Thanks,
-Andres

On Mon, Sep 20, 2021 at 6:41 PM Chris Wine via gstreamer-devel <
gstreamer-devel at lists.freedesktop.org> wrote:

> It might be that hlssink wants to see keyframes and durations of all the
> content so that it knows where to split... try adding a "tsparse" element
> after udpsrc. If that doesn't work, you might have to demux the individual
> audio/video streams, run them through their respective parsers, and then
> use hlssink2 to remux them.
>
> --Chris
>
> On Mon, Sep 20, 2021 at 5:45 PM Andres Gonzalez via gstreamer-devel <
> gstreamer-devel at lists.freedesktop.org> wrote:
>
>> Thanks for your response Chris.
>>
>> I tried your suggestion:
>>
>> gst-launch-1.0 udpsrc port=50000 caps="video/mpegts,systemstream=true" !
>> hlssink target-duration=5 playlist-location="playlist.m3u8"
>> location=segment.%03d.ts
>>
>> This pipeline is operational, however, it does not create the playlist
>> and just generates a single segment file, and it keeps growing and
>> growing.  I think the pipeline needs to know something about the video,
>> otherwise how does it know if it has enough video in the segment file to
>> match the specified target duration?
>>
>> In my application, I am using hlssink2 for the pipeline that is
>> generating a new video stream (with appsrc, encoder, etc). But this
>> pipeline has a udpsrc and so there isn't an encoder in the pipeline. That
>> is the reason I am using hlssink instead of hlssink2 for this pipeline.
>>
>> -Andres
>>
>>
>>
>>
>>
>>
>> On Mon, Sep 20, 2021 at 3:14 PM Chris Wine via gstreamer-devel <
>> gstreamer-devel at lists.freedesktop.org> wrote:
>>
>>> Hi Andres,
>>>
>>> I believe hlssink takes an mpeg transport stream, so you don't need to
>>> have the tsdemux element in there unless you need to do something else to
>>> the streams before remuxing them and sending them to hlssink. So maybe just
>>> "udpsrc ! hlssink" (with properties of course) will give you want you're
>>> looking for.
>>>
>>> For making sure the caps are correct, you should just be able to set the
>>> "caps" property on udpsrc:
>>> udpsrc caps="video/mpegts,systemstream=true"
>>>
>>> If you already have separate audio and video streams, I'd use hlssink2
>>> which does the mpegts muxing internally.
>>>
>>> --Chris
>>>
>>> On Mon, Sep 20, 2021 at 4:00 PM Andres Gonzalez via gstreamer-devel <
>>> gstreamer-devel at lists.freedesktop.org> wrote:
>>>
>>>> Just some additional info.  I am using gst-launch just to figure out
>>>> what the appropriate elements should be. I have a C++ app that I develop
>>>> where I code up the pipeline for my application. But since I am not even
>>>> sure which elements should be in the pipeline, I am experimenting around
>>>> with creating the pipeline with gst-launch.
>>>> Thanks,
>>>> -Andres
>>>>
>>>> On Mon, Sep 20, 2021 at 1:49 PM Andres Gonzalez <
>>>> andres.agoralabs at gmail.com> wrote:
>>>>
>>>>> Hi,
>>>>> I have a question about creating an HLS pipeline.  I am receiving a
>>>>> MPEG-TS UDP stream and I want to create a pipeline that will receive the
>>>>> UDP TS stream, and then create/publish  a corresponding HLS stream. For
>>>>> example, something like this:
>>>>>
>>>>> gst-launch-1.0 udpsrc port=50000 ! tsdemux ! hlssink playlist-root=
>>>>> http://192.168.0.100:8080 location=segment.%03d.ts
>>>>>
>>>>> This actually works and receives the UDP/TS stream and starts to
>>>>> generate the segment_000.ts file.  But it never creates the playlist file
>>>>> and keeps adding to the segment_000.ts file.
>>>>>
>>>>> I am assuming that I need to provide some caps information about the
>>>>> video coming in on the UDP/TS stream but I am not sure how to do that.  So
>>>>> could someone tell me what the pipeline should consist of to get this
>>>>> working?
>>>>>
>>>>> Thanks,
>>>>> -Andres
>>>>>
>>>>
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