GStreamer - Revision history

Michael Murtaugh at 09:15, 1 June 2009

2009-06-01T09:15:01Z

← Older revision		Revision as of 11:15, 1 June 2009
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	[http://gstreamer.freedesktop.org GStreamer] allow you to work with media (audio/video) using pipelines. Just like standard UNIX pipeline can be used to piece different software together to manipulate / filter / transform (mainly) text, GStreamer's pipelines are designed to for instance: pull data from a camera, filter video frames (to say overlay some text), transcode formats, and ultimately either display on screen, save to a file, or stream over a network.		[http://gstreamer.freedesktop.org GStreamer] allow you to work with media (audio/video) using pipelines. Just like standard UNIX pipeline can be used to piece different software together to manipulate / filter / transform (mainly) text, GStreamer's pipelines are designed to for instance: pull data from a camera, filter video frames (to say overlay some text), transcode formats, and ultimately either display on screen, save to a file, or stream over a network.

	GStreamer provides a programming interface (bindings) in Python via [http://~~gstreamer~~.~~freedesktop~~.~~org~~/~~modules/gst-python.html~~ PyGST]. This means you can use Python to dynamically manipulate media pipelines, and make connections to other kinds of information systems (internet, email, chat, databases, etc).		GStreamer provides a programming interface (bindings) in Python via [http://pygstdocs.berlios.de/ PyGST]. This means you can use Python to dynamically manipulate media pipelines, and make connections to other kinds of information systems (internet, email, chat, databases, etc).

	GStreamer is cross-platform, with versions for Mac OSX and Windows. (don't know how capable / stable these are though)		GStreamer is cross-platform, with versions for Mac OSX and Windows. (don't know how capable / stable these are though)

Michael Murtaugh at 09:14, 1 June 2009

2009-06-01T09:14:24Z

← Older revision		Revision as of 11:14, 1 June 2009
Line 3:		Line 3:
	[http://gstreamer.freedesktop.org GStreamer] allow you to work with media (audio/video) using pipelines. Just like standard UNIX pipeline can be used to piece different software together to manipulate / filter / transform (mainly) text, GStreamer's pipelines are designed to for instance: pull data from a camera, filter video frames (to say overlay some text), transcode formats, and ultimately either display on screen, save to a file, or stream over a network.		[http://gstreamer.freedesktop.org GStreamer] allow you to work with media (audio/video) using pipelines. Just like standard UNIX pipeline can be used to piece different software together to manipulate / filter / transform (mainly) text, GStreamer's pipelines are designed to for instance: pull data from a camera, filter video frames (to say overlay some text), transcode formats, and ultimately either display on screen, save to a file, or stream over a network.

	GStreamer provides a programming interface (bindings) in Python via [http://~~pygstdocs~~.~~berlios~~.de/ [[PyGST]]]. This means you can use Python to dynamically manipulate media pipelines, and make connections to other kinds of information systems (internet, email, chat, databases, etc).		GStreamer provides a programming interface (bindings) in Python via [http://gstreamer.freedesktop.org/modules/gst-python.html PyGST]. This means you can use Python to dynamically manipulate media pipelines, and make connections to other kinds of information systems (internet, email, chat, databases, etc).

	GStreamer is cross-platform, with versions for Mac OSX and Windows. (don't know how capable / stable these are though)		GStreamer is cross-platform, with versions for Mac OSX and Windows. (don't know how capable / stable these are though)

Michael Murtaugh at 09:02, 1 June 2009

2009-06-01T09:02:57Z

← Older revision		Revision as of 11:02, 1 June 2009
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	~~= GStreamer =~~

	Programmable Media Pipelines		Programmable Media Pipelines

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	== Playing with GStreamer on the Command line ==		== Playing with GStreamer on the Command line ==

	===== gst-launch =====		=== gst-launch ===

	Use can test out GStreamer media pipelines via some commandline programs: gst-launch, gst-inspect. Note that in some installs of the tools, the programs may end with a version number (as in gst-launch-0.10). The examples shown here are all using version 0.10 of GStreamer.		Use can test out GStreamer media pipelines via some commandline programs: gst-launch, gst-inspect. Note that in some installs of the tools, the programs may end with a version number (as in gst-launch-0.10). The examples shown here are all using version 0.10 of GStreamer.
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	The "hello world" of audio / video pipelines use the "videotestsrc" and "audiotestsrc" elements:		The "hello world" of audio / video pipelines use the "videotestsrc" and "audiotestsrc" elements:

	<~~pre~~>		<source lang="bash">
	gst-launch-0.10 videotestsrc ! ximagesink		gst-launch-0.10 videotestsrc ! ximagesink
	</~~pre~~>		</source>

	<~~pre~~>		<source lang="bash">
	gst-launch-0.10 audiotestsrc ! alsasink		gst-launch-0.10 audiotestsrc ! alsasink
	</~~pre~~>		</source>

	~~<!>~~ Note that GStreamer pipelines use the exclamation mark ( ! ) as their "pipe" character. If you're used to regular UNIX pipelines you ''will'' (at least once) make the mistake of typing a regular pipe ( \| ) which of course results in an error as the shell tries to interpret what you've written.		Note that GStreamer pipelines use the exclamation mark ( ! ) as their "pipe" character. If you're used to regular UNIX pipelines you ''will'' (at least once) make the mistake of typing a regular pipe ( \| ) which of course results in an error as the shell tries to interpret what you've written.

	Documentation of all available plugins is available online.		Documentation of all available plugins is available online.

	===== gst-inspect =====		=== gst-inspect ===

	gst-inspect is like the "man" command of GStreamer elements. Use gst-inspect alone to get a big list of all elements ([http://gstreamer.freedesktop.org/documentation/plugins.html plugins]) available. gst-inspect <name of plugin> will display detailed info for a particular element.		gst-inspect is like the "man" command of GStreamer elements. Use gst-inspect alone to get a big list of all elements ([http://gstreamer.freedesktop.org/documentation/plugins.html plugins]) available. gst-inspect <name of plugin> will display detailed info for a particular element.

	<~~pre~~>		<source lang="bash">
	gst-inspect-0.10 videotestsrc \| less		gst-inspect-0.10 videotestsrc \| less
	</~~pre~~>		</source>

	gst-inspect without any option will dump a list of all available elements. Combine with grep to search for a particular element:		gst-inspect without any option will dump a list of all available elements. Combine with grep to search for a particular element:

	<~~pre~~>		<source lang="bash">
	gst-inspect-0.10 \| grep crop		gst-inspect-0.10 \| grep crop
	</~~pre~~>		</source>

	On an elements inspect page, you can find out information about the available properties and their values. For instance, the change the video test pattern, you can use the 'pattern' property:		On an elements inspect page, you can find out information about the available properties and their values. For instance, the change the video test pattern, you can use the 'pattern' property:

	<~~pre~~>		<source lang="bash">
	gst-launch-0.10 videotestsrc pattern=1 ! ximagesink		gst-launch-0.10 videotestsrc pattern=1 ! ximagesink
	</~~pre~~>		</source>


Line 89:		Line 87:
	</source>		</source>

	===== building bridges =====		=== building bridges ===

	Common "bridge" elements are: audioconvert, audioresample, ffmpegcolorspace or videoscale. Often a non-functional pipeline can be fixed by plugging in the right bridge element between two conflicting pieces. Once a pipeline is working, it may be a good idea though to revist your pipeline and attempt to remove any unnecessary elements as these may slow down the processing.		Common "bridge" elements are: audioconvert, audioresample, ffmpegcolorspace or videoscale. Often a non-functional pipeline can be fixed by plugging in the right bridge element between two conflicting pieces. Once a pipeline is working, it may be a good idea though to revist your pipeline and attempt to remove any unnecessary elements as these may slow down the processing.

	===== capsfilter =====		=== capsfilter ===

	The second element in the two pipelines above ("video/x-raw-yuv,width=320,height=240") is a special syntax that can be used in GStreamer pipeline descriptions. It sets a mime type to specify a desired video format (in this case rgb color), along with (optionally) information like frame size and rate.		The second element in the two pipelines above ("video/x-raw-yuv,width=320,height=240") is a special syntax that can be used in GStreamer pipeline descriptions. It sets a mime type to specify a desired video format (in this case rgb color), along with (optionally) information like frame size and rate.
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	== Programming GStreamer with Python ==		== Programming GStreamer with Python ==

	* ["[[PythonGStreamer]]"]		* [[PythonGStreamer]]


	== Related pages on this wiki ==		== Related pages on this wiki ==

	* ["GStreamerPlugins"]		* [[GStreamerPlugins]]
	* ["[[ListeningAndWatching]]"]		* [[ListeningAndWatching]]

	== Related / Comparable Projects ==		== Related / Comparable Projects ==
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	* [http://gstreamer.freedesktop.org GStreamer Website]		* [http://gstreamer.freedesktop.org GStreamer Website]
	* [http://pygstdocs.berlios.de/pygst-tutorial/introduction.html [[PyGST]] Tutorial]		* [http://pygstdocs.berlios.de/pygst-tutorial/introduction.html PyGST Tutorial]

	* [http://www.jonobacon.org/?p=750 GStreamer & Python Tutorial]		* [http://www.jonobacon.org/?p=750 GStreamer & Python Tutorial]
	* [http://wiki.laptop.org/go/GStreamer GStreamer on OLPC Wiki]		* [http://wiki.laptop.org/go/GStreamer GStreamer on OLPC Wiki]
	* [http://barcamp.org/DemoCampGuelph3_GStreamer barcamp presentation] with cool examples		* [http://barcamp.org/DemoCampGuelph3_GStreamer barcamp presentation] with cool examples

Michael Murtaugh at 15:25, 17 February 2009

2009-02-17T15:25:08Z

← Older revision		Revision as of 17:25, 17 February 2009
Line 83:		Line 83:
	gst-launch-0.10 v4lsrc ! video/x-raw-rgb,width=320,height=240 ! queue ! videorate ! video/x-raw-rgb,rate=15/1 ! ffmpegcolorspace ! theoraenc ! oggmux name=mux ! filesink location=foo.ogg alsasrc ! audio/x-raw-int,channels=1,rate=22025,depth=16 ! queue ! audioconvert ! vorbisenc ! mux.		gst-launch-0.10 v4lsrc ! video/x-raw-rgb,width=320,height=240 ! queue ! videorate ! video/x-raw-rgb,rate=15/1 ! ffmpegcolorspace ! theoraenc ! oggmux name=mux ! filesink location=foo.ogg alsasrc ! audio/x-raw-int,channels=1,rate=22025,depth=16 ! queue ! audioconvert ! vorbisenc ! mux.
	</pre>		</pre>

			Taking a picture (example from [http://wiki.laptop.org/go/Programming_the_camera OLPC wiki])
			<source lang="bash">
			gst-launch-0.10 v4l2src ! ffmpegcolorspace ! pngenc ! filesink location=foo.png
			</source>

	===== building bridges =====		===== building bridges =====

Michael Murtaugh: /* GStreamer Resources Online */

2008-06-05T15:15:57Z

GStreamer Resources Online

New page

= GStreamer =

Programmable Media Pipelines

[http://gstreamer.freedesktop.org GStreamer] allow you to work with media (audio/video) using pipelines. Just like standard UNIX pipeline can be used to piece different software together to manipulate / filter / transform (mainly) text, GStreamer's pipelines are designed to for instance: pull data from a camera, filter video frames (to say overlay some text), transcode formats, and ultimately either display on screen, save to a file, or stream over a network.

GStreamer provides a programming interface (bindings) in Python via [http://pygstdocs.berlios.de/ [[PyGST]]]. This means you can use Python to dynamically manipulate media pipelines, and make connections to other kinds of information systems (internet, email, chat, databases, etc).

GStreamer is cross-platform, with versions for Mac OSX and Windows. (don't know how capable / stable these are though)

GStreamer is part of the Gnome desktop project, but is used by apps using any window manager. GStreamer is used as the "backend" in many popular linux [http://gstreamer.freedesktop.org/apps/ applications]. For instance: the Totem and Kaffeine movie players, Rhythymbox and amarok music players, and Gnash (an open source flash plugin).

== Playing with GStreamer on the Command line ==

===== gst-launch =====

Use can test out GStreamer media pipelines via some commandline programs: gst-launch, gst-inspect. Note that in some installs of the tools, the programs may end with a version number (as in gst-launch-0.10). The examples shown here are all using version 0.10 of GStreamer.

The "hello world" of audio / video pipelines use the "videotestsrc" and "audiotestsrc" elements:

<pre>
gst-launch-0.10 videotestsrc ! ximagesink
</pre>

<pre>
gst-launch-0.10 audiotestsrc ! alsasink
</pre>

<!> Note that GStreamer pipelines use the exclamation mark ( ! ) as their "pipe" character. If you're used to regular UNIX pipelines you ''will'' (at least once) make the mistake of typing a regular pipe ( | ) which of course results in an error as the shell tries to interpret what you've written.

Documentation of all available plugins is available online.

===== gst-inspect =====

gst-inspect is like the "man" command of GStreamer elements. Use gst-inspect alone to get a big list of all elements ([http://gstreamer.freedesktop.org/documentation/plugins.html plugins]) available. gst-inspect <name of plugin> will display detailed info for a particular element.

<pre>
gst-inspect-0.10 videotestsrc | less
</pre>

gst-inspect without any option will dump a list of all available elements. Combine with grep to search for a particular element:

<pre>
gst-inspect-0.10 | grep crop
</pre>

On an elements inspect page, you can find out information about the available properties and their values. For instance, the change the video test pattern, you can use the 'pattern' property:

<pre>
gst-launch-0.10 videotestsrc pattern=1 ! ximagesink
</pre>

=== Webcams (v4lsrc) ===

Webcams cam generally be accessed via the video4linux system. GStreamer has two sources for connecting to these devices, v4lsrc, and v4l2src. Use the one that works with your camera.

Viewing a USB cam (you may need v4l2src):
<pre>
gst-launch-0.10 v4lsrc ! video/x-raw-yuv,width=320,height=240 ! xvimagesink
</pre>

Alternatively, you can use the normal (non-accelerated) ximagesink, though in this case it's necessary to add the "ffmpegcolorspace" element to help negotiate the correct format that ximagesink needs to display the video.

<pre>
gst-launch-0.10 v4lsrc ! video/x-raw-yuv,width=320,height=240 ! ffmpegcolorspace ! ximagesink
</pre>

Make sure that plugging in your camera results in the creation of a "video" device (typically /dev/video0). If your camera has a different name (or for instance when using multiple cameras), set the device property of the v4lsrc element:

<pre>
gst-launch-0.10 v4lsrc device=/dev/video1 ! video/x-raw-yuv,width=320,height=240 ! xvimagesink
</pre>

Saving to file (OGG format, video only):
<pre>
gst-launch-0.10 v4lsrc ! video/x-raw-rgb,width=320,height=240 ! ffmpegcolorspace ! theoraenc ! oggmux ! filesink location=foo.ogg
</pre>

Saving to file (OGG format, audio & video):
''This example uses several tricks to adjust the rates, and queue to improve performance (and hopefully not lose any data).''
<pre>
gst-launch-0.10 v4lsrc ! video/x-raw-rgb,width=320,height=240 ! queue ! videorate ! video/x-raw-rgb,rate=15/1 ! ffmpegcolorspace ! theoraenc ! oggmux name=mux ! filesink location=foo.ogg alsasrc ! audio/x-raw-int,channels=1,rate=22025,depth=16 ! queue ! audioconvert ! vorbisenc ! mux.
</pre>

===== building bridges =====

Common "bridge" elements are: audioconvert, audioresample, ffmpegcolorspace or videoscale. Often a non-functional pipeline can be fixed by plugging in the right bridge element between two conflicting pieces. Once a pipeline is working, it may be a good idea though to revist your pipeline and attempt to remove any unnecessary elements as these may slow down the processing.

===== capsfilter =====

The second element in the two pipelines above ("video/x-raw-yuv,width=320,height=240") is a special syntax that can be used in GStreamer pipeline descriptions. It sets a mime type to specify a desired video format (in this case rgb color), along with (optionally) information like frame size and rate.

These get translated into gstreamer [http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-plugins/html/gstreamer-plugins-capsfilter.html "capsfilter"] elements that then enforce a particular format of data. In this case we request a particular framesize (as the default is typically smaller). The size requested may be limited by the capabilities of your camera (so if one size fails, try another -- 320 by 240 should be relatively safe).

=== Screencasts with Istanbul ===

Installing the Istanbul adds a special element designed to make screencasts (movies of your screen contents). (Note: built into gstreamer is the ximagesrc element; istximagesrc seems to be further developed for screencasting -- though honestly I haven't tested ximagesrc enough to know of it's shortcomings).

using istanbul's istximagesrc GStreamer module to create a screen cast (with audio):
<pre>
gst-launch-0.10 oggmux name=mux ! filesink location=foo.ogg istximagesrc name=videosource use-damage=false endx=320 endy=240 ! video/x-raw-rgb,framerate=10/1 ! videorate ! ffmpegcolorspace ! videoscale method=1 ! video/x-raw-yuv,width=512,height=384,framerate=10/1 ! theoraenc ! queue ! mux. gconfaudiosrc name=audiosource ! audioconvert ! vorbisenc ! queue ! mux.
</pre>

using istanbul's istximagesrc GStreamer module (& shout2send) to do a live screencast:
<pre>
gst-launch-0.10 oggmux name=mux ! shout2send password=mlmpass mount=live istximagesrc name=videosource use-damage=false endx=320 endy=240 ! video/x-raw-rgb,framerate=10/1 ! videorate ! ffmpegcolorspace ! videoscale method=1 ! video/x-raw-yuv,width=512,height=384,framerate=10/1 ! theoraenc ! queue ! mux. gconfaudiosrc name=audiosource ! audioconvert ! vorbisenc ! queue ! mux.
</pre>

=== Network Streaming with Icecast ===

The shout2send element allows sending the output of a audio/video stream to an icecast server.

Send a test image to a local icecast (change 'hackme' to your own icecast password):
<pre>
gst-launch-0.10 videotestsrc ! video/x-raw-yuv,width=320,height=240 ! theoraenc ! oggmux ! shout2send password=hackme mount=live
</pre>

Test it with: <pre>
vlc http://localhost:8000/live
</pre>

== Programming GStreamer with Python ==

* ["[[PythonGStreamer]]"]

== Related pages on this wiki ==

* ["GStreamerPlugins"]
* ["[[ListeningAndWatching]]"]

== Related / Comparable Projects ==

* [http://www.mltframework.org/twiki/bin/view/MLT/ MLT]

== GStreamer Resources Online ==

* [http://gstreamer.freedesktop.org GStreamer Website]
* [http://pygstdocs.berlios.de/pygst-tutorial/introduction.html [[PyGST]] Tutorial]

* [http://www.jonobacon.org/?p=750 GStreamer & Python Tutorial]
* [http://wiki.laptop.org/go/GStreamer GStreamer on OLPC Wiki]
* [http://barcamp.org/DemoCampGuelph3_GStreamer barcamp presentation] with cool examples