question how to add own customized element between source element and decodebin2 element when using playbin2

[Christophe Oosterlynck]

Tim-Philipp, thanks for your quick and helpful reply. I'm glad I asked here
first before starting to implement something. I will try your suggestion.

I'm also not sure if inserting a queue element right after the udp source
is the right way to catch my problems with udp streaming. The actual
problem I'm having is corrupted sound on playing a raw udp stream
containing a transport stream consisting of H264 video and MPEG 1 layer 2
audio. The image is fine but the sound starts crackling after a while until
it sometimes disappears completely until it plays fine again and repeats
this in a cycle of 60 seconds.

As there is no buffering for live sources in playbin2, I'm suspecting this
to be a problem. Why is there no facility in playbin2 to delay playback of
a udp stream a bit to buffer it and handle possible packet delays?

Best regards,

Christophe


On Tue, Nov 13, 2012 at 3:09 PM, Tim-Philipp Müller <t.i.m at zen.co.uk> wrote:

> On Tue, 2012-11-13 at 05:40 -0800, Christophe Oosterlynck wrote:
>
> > I'm looking to do the same thing. Right after the source, I want to
> insert
> > another element and let playbin2 do the rest.
> >
> > From what I see I have 2 possibilities:
> > * react to "notify::source" signal, add the extra element to the bin,
> link
> > it to the source and let playbin2 continue
> > * wait until playbin2 has finished constructing the whole pipeline,
> unlink
> > source and next element and insert extra element in between.
> >
> > Can I do one of these safely or shouldn't I fiddle with the playbin2
> > pipeline behind its back?
> >
> > What I want to achieve with this: buffer a live udp source.
> > The buffering mechanism in playbin2 is not usable for live sources as you
> > cannot pause them. I want to insert a queue element right behind the
> udpsrc
> > element with min-threshold-bytes. This works when I create a custom
> pipeline
> > with gst-launch. If this is not the best way to handle this, let me know.
> > Nevertheless, I'm still interested in the answer to my question on
> fiddling
> > with the playbin2 pipeline.
>
> You should not fiddle with playbin's pipeline, and certainly not link
> elements behind its back. It won't work. Even if it does work, it might
> stop working tomorrow. And we won't even feel bad for a second if your
> app breaks doing things like that ;)
>
> The only sane way to do things like this is to write your own element,
> which could be a GstBin subclass where you add some source and whatever
> additional elements you want and then create a ghost source pad. You can
> then register a new (or existing, if you must) URI protocol for it, so
> if you do playbin uri=fooudp://a.b.c.d:port it will plug your bin.
>
> Or you could try to come up with API for playbin to add such a thing,
> but I think would need to be rather well-justified and deemed
> interesting enough to be added.
>
> (What does your "routine" element do, "BCXA" ?)
>
>  Cheers
>   -Tim
>
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