gstreamer-python and playbin

[Charles Ulrich-2]

Hi,

I freely admit to still having much to learn about gstreamer (and its
python bindings), but I was wondering if someone can give me any advice
on a simple prototype script I'm working on.

Basically, I'm trying to write a script in Python using gsteamer. The
goal of this script is to capture the data from a uri source and save it
to a file on disk. Because I want to be able to support many types of
sources automatically (file, http, mms, rstp), I thought the playbin
would be the best and simplest way to go. But I'm having a hard time
plugging the filesrc plugin into it.

#!/usr/bin/python

import pygst
pygst.require("0.10")
import gst
import gobject

srcuri='http://r1.scenesat.com:8000/scenesat'
#srcuri='mms://71.127.77.19/wadml'
#srcuri='rtsp://archmp3.wfmu.org/broadcast/wfmu_live.rm'

class Main:
     def __init__(self):
         # Create a pipline object
         self.pipeline = gst.Pipeline("mypipeline")

         # Create the playbin object
         self.streambin = gst.element_factory_make("playbin", "stream")

         # Set the uri property so playbin knows where to fetch from
         self.streambin.set_property('uri', srcuri)

         # Add our playbin to the pipeline
         self.pipeline.add(self.streambin)

         # Create filesink, set location, and configure filesink as playbin
         # audio sink
         self.audiosink = gst.element_factory_make('filesink', 'audiosink')
         self.audiosink.set_property('location', 'foo.dump')
         self.streambin.set_property('audio-sink', self.audiosink)

         # Create fakesink for playbin video sink
         self.videosink = gst.element_factory_make('fakesink', 'videosink')
         self.streambin.set_property('video-sink', self.videosink)

         # Set the pipeline state to playing
         self.pipeline.set_state(gst.STATE_PLAYING)

start=Main()

mainloop = gobject.MainLoop()
mainloop.run()

Basically, what happens is that gstreamer appears to be correctly
fetching the stream and saving _something_ to disk, but what's saved
does not appear to be either audio or video. Mplayer won't play the file
but identifies it as DVSD (video) and ffdv (audio). I thought that
specifying fakesink for the video sink would make a difference, but it
does not.

What I'd like to do is construct is a pipeline that can (ideally) detect
the media given to it via some uri and save that media as it is
streamed, without any audio conversion or encoding. Any tips on how I
can accomplish that?

Charles


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[Christian Fredrik Kalager Schaller]

Hi,
playbin (or uridecodebin) will automatically decode the incoming stream
unless you specifically tells it not to. uridecodebin and playbin2 got a
property called 'caps' which you can use to tell it to stop autopluggin
on certain caps. If you create a list of possible container formats caps
there, it will not try to demux and decode and you can save it directly
to disk.

Here is an example that should work (haven't tested though):

self.remuxcaps = gst.Caps()
self.remuxcaps.append_structure(gst.Structure("video/quicktime"))
self.remuxcaps.append_structure(gst.Structure("video/x-ms-asf"))
self.uridecoder.set_property("caps", self.remuxcaps)

Hope this helps,
Christian


On Sat, 2009-08-01 at 20:40 -0400, Charles Ulrich wrote:

> Hi,
>
> I freely admit to still having much to learn about gstreamer (and its
> python bindings), but I was wondering if someone can give me any advice
> on a simple prototype script I'm working on.
>
> Basically, I'm trying to write a script in Python using gsteamer. The
> goal of this script is to capture the data from a uri source and save it
> to a file on disk. Because I want to be able to support many types of
> sources automatically (file, http, mms, rstp), I thought the playbin
> would be the best and simplest way to go. But I'm having a hard time
> plugging the filesrc plugin into it.
>
> #!/usr/bin/python
>
> import pygst
> pygst.require("0.10")
> import gst
> import gobject
>
> srcuri='http://r1.scenesat.com:8000/scenesat'
> #srcuri='mms://71.127.77.19/wadml'
> #srcuri='rtsp://archmp3.wfmu.org/broadcast/wfmu_live.rm'
>
> class Main:
>      def __init__(self):
>          # Create a pipline object
>          self.pipeline = gst.Pipeline("mypipeline")
>
>          # Create the playbin object
>          self.streambin = gst.element_factory_make("playbin", "stream")
>
>          # Set the uri property so playbin knows where to fetch from
>          self.streambin.set_property('uri', srcuri)
>
>          # Add our playbin to the pipeline
>          self.pipeline.add(self.streambin)
>
>          # Create filesink, set location, and configure filesink as playbin
>          # audio sink
>          self.audiosink = gst.element_factory_make('filesink', 'audiosink')
>          self.audiosink.set_property('location', 'foo.dump')
>          self.streambin.set_property('audio-sink', self.audiosink)
>
>          # Create fakesink for playbin video sink
>          self.videosink = gst.element_factory_make('fakesink', 'videosink')
>          self.streambin.set_property('video-sink', self.videosink)
>
>          # Set the pipeline state to playing
>          self.pipeline.set_state(gst.STATE_PLAYING)
>
> start=Main()
>
> mainloop = gobject.MainLoop()
> mainloop.run()
>
> Basically, what happens is that gstreamer appears to be correctly
> fetching the stream and saving _something_ to disk, but what's saved
> does not appear to be either audio or video. Mplayer won't play the file
> but identifies it as DVSD (video) and ffdv (audio). I thought that
> specifying fakesink for the video sink would make a difference, but it
> does not.
>
> What I'd like to do is construct is a pipeline that can (ideally) detect
> the media given to it via some uri and save that media as it is
> streamed, without any audio conversion or encoding. Any tips on how I
> can accomplish that?
>
> Charles
>
>
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> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
> trial. Simplify your report design, integration and deployment - and focus on
> what you do best, core application coding. Discover what's new with
> Crystal Reports now.  http://p.sf.net/sfu/bobj-july
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel

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[Charles Ulrich-2]

Christian Fredrik Kalager Schaller wrote:

> Hi,
> playbin (or uridecodebin) will automatically decode the incoming stream
> unless you specifically tells it not to. uridecodebin and playbin2 got a
> property called 'caps' which you can use to tell it to stop autopluggin
> on certain caps. If you create a list of possible container formats caps
> there, it will not try to demux and decode and you can save it directly
> to disk.
>
> Here is an example that should work (haven't tested though):
>
> self.remuxcaps = gst.Caps()
> self.remuxcaps.append_structure(gst.Structure("video/quicktime"))
> self.remuxcaps.append_structure(gst.Structure("video/x-ms-asf"))
> self.uridecoder.set_property("caps", self.remuxcaps)
>
> Hope this helps,
> Christian

Thanks, Christian. I was hoping to not have to explicitly list the media
type (or other properties of the stream), but maybe this will get me
headed in the right direction.

Charles
--
http://bityard.net

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