gst-launch - build and run a GStreamer pipeline




gst-launch is a tool that builds and runs basic GStreamer pipelines.

In simple form, a PIPELINE-DESCRIPTION is a list of elements separated by exclamation marks (!). Properties may be appended to elements, in the form property=value.

For a complete description of possible PIPELINE-DESCRIPTIONS see the section pipeline description below or consult the GStreamer documentation.

Please note that gst-launch is primarily a debugging tool for developers and users. You should not build applications on top of it. For applications, use the gst_parse_launch() function of the GStreamer API as an easy way to construct pipelines from pipeline descriptions.


gst-launch accepts the following options:
--help Print help synopsis and available FLAGS
-v, --verbose
 Output status information and property notifications
-v, --quiet Do not print any progress information
-m, --messages
 Output messages posted on the pipeline’s bus
-t, --tags Output tags (also known as metadata)
-o FILE, --output=FILE
 Save XML representation of pipeline to FILE and exit
-f, --no_fault
 Do not install a fault handler
-T, --trace Print memory allocation traces. The feature must be enabled at compile time to work.


gst-launch also accepts the following options that are common to all GStreamer applications:
 Prints the version string of the GStreamer core library.
 Causes GStreamer to abort if a warning message occurs. This is equivalent to setting the environment variable G_DEBUG to ’fatal_warnings’ (see the section environment variables below for further information).
 A comma separated list of category_name:level pairs to specify debugging levels for each category. Level is in the range 0-5 where 0 will show no messages, and 5 will show all messages. The wildcard * can be used to match category names.

Use --gst-debug-help to show category names

Example: GST_CAT:5,GST_ELEMENT_*:3,oggdemux:5

 Sets the threshold for printing debugging messages. A higher level will print more messages. The useful range is 0-5, with the default being 0.
 GStreamer normally prints debugging messages so that the messages are color-coded when printed to a terminal that handles ANSI escape sequences. Using this option causes GStreamer to print messages without color. Setting the GST_DEBUG_NO_COLOR environment variable will achieve the same thing.
 Disables debugging.
 Prints a list of available debug categories and their default debugging level.
 GStreamer info flags to set Enable printout of errors while loading GStreamer plugins
 Add directories separated with ’:’ to the plugin search path
 Preload plugins specified in a comma-separated list. Another way to specify plugins to preload is to use the environment variable GST_PLUGIN_PATH


A pipeline consists elements and links. Elements can be put into bins of different sorts. Elements, links and bins can be specified in a pipeline description in any order.



Creates an element of type ELEMENTTYPE and sets the PROPERTIES.



Sets the property to the specified value. You can use gst-inspect(1) to find out about properties and allowed values of different elements. Enumeration properties can be set by name, nick or value.



Specifies that a bin of type BINTYPE is created and the given properties are set. Every element between the braces is put into the bin. Please note the dot that has to be used after the BINTYPE. You will almost never need this functionality, it is only really useful for applications using the gst_launch_parse() API with ’bin’ as bintype. That way it is possible to build partial pipelines instead of a full-fledged top-level pipeline.


[[SRCELEMENT].[PAD1,...]] ! [[SINKELEMENT].[PAD1,...]] [[SRCELEMENT].[PAD1,...]] ! CAPS ! [[SINKELEMENT].[PAD1,...]]

Links the element with name SRCELEMENT to the element with name SINKELEMENT, using the caps specified in CAPS as a filter. Names can be set on elements with the name property. If the name is omitted, the element that was specified directly in front of or after the link is used. This works across bins. If a padname is given, the link is done with these pads. If no pad names are given all possibilities are tried and a matching pad is used. If multiple padnames are given, both sides must have the same number of pads specified and multiple links are done in the given order. So the simplest link is a simple exclamation mark, that links the element to the left of it to the element right of it.



Creates a capability with the given mimetype and optionally with given properties. The mimetype can be escaped using " or ’. If you want to chain caps, you can add more caps in the same format afterwards.


NAME=[(TYPE)]VALUE in lists and ranges: [(TYPE)]VALUE

Sets the requested property in capabilities. The name is an alphanumeric value and the type can have the following case-insensitive values: - i or int for integer values or ranges - f or float for float values or ranges - 4 or fourcc for FOURCC values - b, bool or boolean for boolean values - s, str or string for strings - fraction for fractions (framerate, pixel-aspect-ratio) - l or list for lists If no type was given, the following order is tried: integer, float, boolean, string. Integer values must be parsable by strtol(), floats by strtod(). FOURCC values may either be integers or strings. Boolean values are (case insensitive) yes, no, true or false and may like strings be escaped with " or ’. Ranges are in this format: [ VALUE, VALUE ] Lists use this format: ( VALUE [, VALUE ...] )


A pipeline can be controlled by signals. SIGUSR2 will stop the pipeline (GST_STATE_NULL); SIGUSR1 will put it back to play (GST_STATE_PLAYING). By default, the pipeline will start in the playing state. There are currently no signals defined to go into the ready or pause (GST_STATE_READY and GST_STATE_PAUSED) state explicitely.


The examples below assume that you have the correct plug-ins available. In general, "osssink" can be substituted with another audio output plug-in such as "esdsink", "alsasink", "osxaudiosink", or "artsdsink". Likewise, "xvimagesink" can be substituted with "ximagesink", "sdlvideosink", "osxvideosink", or "aasink". Keep in mind though that different sinks might accept different formats and even the same sink might accept different formats on different machines, so you might need to add converter elements like audioconvert and audioresample (for audio) or ffmpegcolorspace (for video) in front of the sink to make things work.

Audio playback

gst-launch filesrc location=music.mp3 ! mad ! audioconvert ! audioresample ! osssink Play the mp3 music file "music.mp3" using a libmad-based plug-in and output to an OSS device

gst-launch filesrc location=music.ogg ! oggdemux ! vorbisdec ! audioconvert ! audioresample ! osssink Play an Ogg Vorbis format file

gst-launch gnomevfssrc location=music.mp3 ! mad ! osssink gst-launch gnomevfssrc location= ! mad ! audioconvert ! audioresample ! osssink Play an mp3 file or an http stream using GNOME-VFS

gst-launch gnomevfssrc location=smb://computer/music.mp3 ! mad ! audioconvert ! audioresample ! osssink Use GNOME-VFS to play an mp3 file located on an SMB server

Format conversion

gst-launch filesrc location=music.mp3 ! mad ! audioconvert ! vorbisenc ! oggmux ! filesink location=music.ogg Convert an mp3 music file to an Ogg Vorbis file

gst-launch filesrc location=music.mp3 ! mad ! audioconvert ! flacenc ! filesink location=test.flac Convert to the FLAC format


gst-launch filesrc location=music.wav ! wavparse ! audioconvert ! audioresample ! osssink Plays a .WAV file that contains raw audio data (PCM).

gst-launch filesrc location=music.wav ! wavparse ! audioconvert ! vorbisenc ! oggmux ! filesink location=music.ogg gst-launch filesrc location=music.wav ! wavparse ! audioconvert ! lame ! filesink location=music.mp3 Convert a .WAV file containing raw audio data into an Ogg Vorbis or mp3 file

gst-launch cdparanoiasrc mode=continuous ! audioconvert ! lame ! id3v2mux ! filesink location=cd.mp3 rips all tracks from compact disc and convert them into a single mp3 file

gst-launch cdparanoiasrc track=5 ! audioconvert ! lame ! id3v2mux ! filesink location=track5.mp3 rips track 5 from the CD and converts it into a single mp3 file

Using gst-inspect(1), it is possible to discover settings like the above for cdparanoiasrc that will tell it to rip the entire cd or only tracks of it. Alternatively, you can use an URI and gst-launch-0.10 will find an element (such as cdparanoia) that supports that protocol for you, e.g.: gst-launch cdda://5 ! lame vbr=new vbr-quality=6 ! filesink location=track5.mp3

gst-launch osssrc ! audioconvert ! vorbisenc ! oggmux ! filesink location=input.ogg records sound from your audio input and encodes it into an ogg file


gst-launch filesrc location=JB_FF9_TheGravityOfLove.mpg ! dvddemux ! mpeg2dec ! xvimagesink Display only the video portion of an MPEG-1 video file, outputting to an X display window

gst-launch filesrc location=/flflfj.vob ! dvddemux ! mpeg2dec ! sdlvideosink Display the video portion of a .vob file (used on DVDs), outputting to an SDL window

gst-launch filesrc location=movie.mpg ! dvddemux name=demuxer demuxer. ! queue ! mpeg2dec ! sdlvideosink demuxer. ! queue ! mad ! audioconvert ! audioresample ! osssink Play both video and audio portions of an MPEG movie

gst-launch filesrc location=movie.mpg ! mpegdemux name=demuxer demuxer. ! queue ! mpeg2dec ! ffmpegcolorspace ! sdlvideosink demuxer. ! queue ! mad ! audioconvert ! audioresample ! osssink Play an AVI movie

Network streaming

Stream video using RTP and network elements.

gst-launch v4l2src ! video/x-raw-yuv,width=128,height=96,format=’(fourcc)’UYVY ! ffmpegcolorspace ! ffenc_h263 ! video/x-h263 ! rtph263ppay pt=96 ! udpsink host= port=5000 sync=false Use this command on the receiver

gst-launch udpsrc port=5000 ! application/x-rtp, clock-rate=90000,payload=96 ! rtph263pdepay queue-delay=0 ! ffdec_h263 ! xvimagesink This command would be run on the transmitter


gst-launch -v fakesrc num-buffers=16 ! fakesink Generate a null stream and ignore it (and print out details).

gst-launch audiotestsrc ! audioconvert ! audioresample ! osssink Generate a pure sine tone to test the audio output

gst-launch videotestsrc ! xvimagesink gst-launch videotestsrc ! ximagesink Generate a familiar test pattern to test the video output

Automatic linking

You can use the decodebin element to automatically select the right elements to get a working pipeline.

gst-launch filesrc location=musicfile ! decodebin ! audioconvert ! audioresample ! osssink Play any supported audio format

gst-launch filesrc location=videofile ! decodebin name=decoder decoder. ! queue ! audioconvert ! audioresample ! osssink decoder. ! ffmpegcolorspace ! xvimagesink Play any supported video format with video and audio output. Threads are used automatically. To make this even easier, you can use the playbin element:

gst-launch playbin uri=file:///home/joe/foo.avi

Filtered connections

These examples show you how to use filtered caps.

gst-launch videotestsrc ! ’video/x-raw-yuv,format=(fourcc)YUY2;video/x-raw-yuv,format=(fourcc)YV12’ ! xvimagesink Show a test image and use the YUY2 or YV12 video format for this.

gst-launch osssrc ! ’audio/x-raw-int,rate=[32000,64000],width=[16,32],depth={16,24,32},signed=(boolean)true’ ! wavenc ! filesink location=recording.wav record audio and write it to a .wav file. Force usage of signed 16 to 32 bit samples and a sample rate between 32kHz and 64KHz.


 Comma-separated list of debug categories and levels, e.g. GST_DEBUG=totem:4,typefind:5
 When this environment variable is set, coloured debug output is disabled.
 When set to a filesystem path, store dot files of pipeline graphs there.
 Path of the plugin registry file. Default is ~/.gstreamer-0.10/registry-CPU.xml where CPU is the machine/cpu type GStreamer was compiled for, e.g. ’i486’, ’i686’, ’x86-64’, ’ppc’, etc. (check the output of "uname -i" and "uname -m" for details).
 Set to "no" to force GStreamer to assume that no plugins have changed, been added or been removed. This will make GStreamer skip the initial check whether a rebuild of the registry cache is required or not. This may be useful in embedded environments where the installed plugins never change. Do not use this option in any other setup.
 Specifies a list of directories to scan for additional plugins. These take precedence over the system plugins.
 Specifies a list of plugins that are always loaded by default. If not set, this defaults to the system-installed path, and the plugins installed in the user’s home directory
 Useful liboil environment variable. Set OIL_CPU_FLAGS=0 when valgrind or other debugging tools trip over liboil’s CPU detection (quite a few important GStreamer plugins like videotestsrc, audioconvert or audioresample use liboil).
G_DEBUG Useful GLib environment variable. Set G_DEBUG=fatal_warnings to make GStreamer programs abort when a critical warning such as an assertion failure occurs. This is useful if you want to find out which part of the code caused that warning to be triggered and under what circumstances. Simply set G_DEBUG as mentioned above and run the program in gdb (or let it core dump). Then get a stack trace in the usual way.


 The xml plugin database; can be deleted at any time, will be re-created automatically when it does not exist yet or plugins change.


gst-feedback(1), gst-inspect(1), gst-typefind(1)


The GStreamer team at

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