Comments on: GStreamer Dynamic Pads, Explained

By: GStreamer, RTP and live streaming — Alexandre Bourget

GStreamer, RTP and live streaming — Alexandre Bourget — Fri, 19 Jun 2009 07:05:13 +0000

[...] http://www.jonobacon.org/2006/11/03/gstreamer-dynamic-pads-explained/ [...]

By: Christian Schaller

Christian Schaller — Wed, 18 Mar 2009 11:12:21 +0000

Hi Jono, I am actually using your tutorials to teach myself some basic python/gstreamer hacking. One thing you might want to change in your example is naming your alsasink element ‘sink’ as it confused the hell out of me when I then saw ‘sink’ again in the pad.link argument.

By: GroteBozeWolf

GroteBozeWolf — Sat, 14 Jul 2007 15:47:07 +0000

I would like to create a never stopping stream of data (to send to an icecast server, with shout2send..). In my case, i want to play files, using a playlist. But i don't understand how to make gstreamer aware of loading the next file, if the other one is ended. I understand i have to change something in the pipeline.

The pipeline for one file is: filesrc file1.mp3 ! decodebin ! audioconvert ! lame ! etc.

After file1.mp3 is finished, i have to make filesrc aware to load a new file, or i have to cut filesrc file1 from the pipeline and reconnect anew filesrc element. But how do i do that?

By: Kyle

Kyle — Tue, 19 Jun 2007 00:35:50 +0000

How would you set up a queue to play many files sequentially or randomly? Would you have a pipeline in your play pipeline or just have a boolean test after it is done playing and if it isn’t the last in the a queue list and then play that file? Thanks for nay response.

By: Lone Wolves - Web, game, and open source development

Lone Wolves - Web, game, and open source development — Sat, 27 Jan 2007 16:56:59 +0000

[...] Anoher thing I wanted an excuse for was learning gstreamer, so naturally I picked python-gstreamer. Sadly there’s a huge lack of documentation for it. There are only a few good tutorials around, first and foremost Jona Bacon’s excellent tutorials [1][2][3]. I wanted my hack to work over TCP as well, because I have multiple music libraries. One on my home server, one on my desktop, a bit more on my laptop, etcetera. I want to be able to stream from other machines to my server which I’ll hook up to my stereo. I could not find any tutorials on using tcpserversource and tcpclientsink elements, so honoring Jona’s request that everyone “should write an article about something that you have discovered that isn’t particularly well documented”, here’s mine about tcpserversource and tcpclientsink. [...]

By: jonobacon@home » Using Gnonlin with GStreamer and Python

jonobacon@home » Using Gnonlin with GStreamer and Python — Wed, 27 Dec 2006 20:03:24 +0000

[...] In GStreamer there is a concept called Dynamic Pads. What this means is that with some objects in GStreamer, pads only get added when other things have been processed, and one such item is the gnlcomposition. Before the gnlcomposition can know what pads should be added, it needs to check which gnlfilesources it has and automatically figure out which elements are required to process the media that you want to play. All of this happens automatically, but it means that you cannot assume that it will have a pad – once the gnlcomposition has figured out what it is doing with its gnlfilesources it will then provide a pad. See GStreamer Dynamic Pads, Explained for more details on this. [...]

By: Tristan

Tristan — Wed, 22 Nov 2006 00:30:55 +0000

David,

I see where you’re coming from.

Here, self.filesrc is a GStreamer filesrc element, which is a Python object. This object has various properties, one of which is a “name” field, which in this case is equal to “source”. This name is how GStreamer refers to the element.

I agree that it’s a bit confusing, that an element can have a (Python) object name that’s different from its GStreamer name; I tend to set them to be the same whenever I create an element, so I don’t get mixed up

By: Kushal Das

Kushal Das — Sun, 19 Nov 2006 03:53:15 +0000

while running the above example follwing error is coming:

python: Python/ceval.c:2531: PyEval_EvalCodeEx: Assertion `tstate != ((void *)0)' failed. Aborted

By: David Nielsen

David Nielsen — Sun, 05 Nov 2006 02:50:01 +0000

well at least we are all learning from this.. I had never touched GStreamer code before but now I’m getting into it by reading Jono’ examples..

By: Jonathan Hitchcock

Jonathan Hitchcock — Sat, 04 Nov 2006 15:04:16 +0000

Insert "not a gstreamer fundi" disclaimer here, but doesn't your decodebin element want to link to the 'convert' element, and not to the 'sink' element?

In other words, your callback:

def OnDynamicPad(self, dbin, pad, islast): print "OnDynamicPad Called!" pad.link(self.convert.get_pad("sink"))

Should be, if I'm right: def OnDynamicPad(self, dbin, pad, islast): print "OnDynamicPad Called!" pad.link(self.convert.get_pad("convert"))

Not so?

Still, we get the point - thanks for the explanation!