MAN page from Fedora 21 gstreamer1-1.4.5-1.fc21.x86_64.rpm


Section: Misc. Reference Manual Pages (1)
Updated: May 2007


gst-launch - build and run a GStreamer pipeline 




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

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

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

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


gst-launch accepts the following options:
Print help synopsis and available FLAGS
-v, --verbose
Output status information and property notifications
-q, --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)
-e, --eos-on-shutdown
Force an EOS event on sources before shutting the pipeline down. This isuseful to make sure muxers create readable files when a muxing pipeline isshut down forcefully via Control-C.
-i, --index
Gather and print index statistics. This is mostly useful for playback orrecording pipelines.
-f, --no-fault
Do not install a fault handler
-T, --trace
Print memory allocation traces. The feature must be enabled at compile time towork.


gst-launch also accepts the following options that are commonto all GStreamer applications:
Prints the version string of the GStreamer core library.
Causes GStreamer to abort if a warning message occurs. This is equivalentto setting the environment variable G_DEBUG to 'fatal_warnings' (see thesection environment variables below for further information).
A comma separated list of category_name:level pairs to specify debugging levelsfor each category. Level is in the range 0-9 where 0 will show no messages, and9 will show all messages. The wildcard * can be used to match category names.Note that the order of categories and levels is important, wildcards at theend may override levels set earlier. The log levels are: 1=ERROR, 2=WARNING,3=FIXME, 4=INFO, 5=DEBUG, 6=LOG, 7=TRACE, 9=MEMDUMP. Since GStreamer 1.2 onecan also use the debug level names, e.g. --gst-debug=*sink:LOG. A fulldescription of the various debug levels can be found in the GStreamer corelibrary API documentation, in the "Running GStreamer Applications" section.

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


Sets the threshold for printing debugging messages. A higher levelwill print more messages. The useful range is 0-9, with the defaultbeing 0. Level 6 (LOG level) will show all information that is usuallyrequired for debugging purposes. Higher levels are only useful in veryspecific cases. See above for the full list of levels.
GStreamer normally prints debugging messages so that themessages are color-coded when printed to a terminal that handlesANSI escape sequences. Using this option causes GStreamerto print messages without color. Setting the GST_DEBUG_NO_COLORenvironment variable will achieve the same thing.
GStreamer normally prints debugging messages so that themessages are color-coded when printed to a terminal that handlesANSI escape sequences (on *nix), or uses W32 console API to color themessages printed into a console (on W32). Using this option causesGStreamer to print messages without color ('off' or 'disable'),print messages with default colors ('on' or 'auto'), or print messagesusing ANSI escape sequences for coloring ('unix'). Setting theGST_DEBUG_COLOR_MODE 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 setEnable 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 specifyplugins to preload is to use the environment variable GST_PLUGIN_PATH



A pipeline consists elements and links. Elements can be putinto bins of different sorts. Elements, links and binscan 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) tofind 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 areset. Every element between the braces is put into the bin. Please note the dotthat has to be used after the BINTYPE. You will almost never need thisfunctionality, it is only really useful for applications using thegst_launch_parse() API with 'bin' as bintype. That way it is possible to buildpartial pipelines instead of a full-fledged top-level pipeline.



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, theelement that was specified directly in front of or after the link is used. Thisworks across bins. If a padname is given, the link is done with these pads. Ifno 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 padsspecified and multiple links are done in the given order.
So the simplest link is a simple exclamation mark, that links the element tothe left of it to the element right of it.



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


in lists and ranges: [(TYPE)]VALUE

Sets the requested property in capabilities. The name is an alphanumeric valueand 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
- 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 mayeither 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 ...] }



The examples below assume that you have the correct plug-ins available.In general, "osssink" can be substituted with another audio outputplug-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 mightaccept different formats and even the same sink might accept different formatson different machines, so you might need to add converter elements likeaudioconvert and audioresample (for audio) or videoconvert (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 andoutput 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 abovefor cdparanoiasrc that will tell it to rip the entire cd or only tracks of it.Alternatively, you can use an URI and gst-launch-1.0 will find an element (such ascdparanoia) 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 toan X display window

        gst-launch filesrc location=/flflfj.vob ! dvddemux ! mpeg2dec ! sdlvideosink

Display the video portion of a .vob file (used on DVDs), outputting toan 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 ! videoconvert ! sdlvideosink   demuxer. ! queue ! mad ! audioconvert ! audioresample ! osssink

Play an AVI movie with an external text subtitle stream

This example also shows how to refer to specific pads by name if an element(here: textoverlay) has multiple sink or source pads.

        gst-launch textoverlay name=overlay ! videoconvert ! videoscale !  autovideosink   filesrc location=movie.avi ! decodebin ! videoconvert ! overlay.video_sink   filesrc ! subparse ! overlay.text_sink

Play an AVI movie with an external text subtitle stream using playbin

        gst-launch playbin uri=file:///path/to/movie.avi suburi=file:///path/to/

Network streaming

Stream video using RTP and network elements.

        gst-launch v4l2src ! video/x-raw,width=128,height=96,format=UYVY ! videoconvert ! ffenc_h263 ! video/x-h263 ! rtph263ppay pt=96 ! udpsink host= port=5000

This command would be run on the transmitter

        gst-launch udpsrc port=5000 ! application/x-rtp, clock-rate=90000,payload=96 ! rtph263pdepay queue-delay=0 ! ffdec_h263 ! xvimagesink

Use this command on the receiver


        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 elementsto 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. !  videoconvert ! xvimagesink

Play any supported video format with video and audio output. Threads are usedautomatically. 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,format=YUY2;video/x-raw,format=YV12' ! xvimagesink

Show a test image and use the YUY2 or YV12 video format for this.

        gst-launch osssrc !  'audio/x-raw,rate=[32000,64000],format={S16LE,S24LE,S32LE}' ! wavenc ! filesink location=recording.wav

record audio and write it to a .wav file. Force usage of signed 16 to 32 bitsamples and a sample rate between 32kHz and 64KHz.



Comma-separated list of debug categories and levels (e.g.GST_DEBUG=totem:4,typefind:5). '*' is allowed as a wildcard as part ofdebug category names (e.g. GST_DEBUG=*sink:6,*audio*:6). Since 1.2.0 it isalso possible to specify the log level by name (1=ERROR, 2=WARN, 3=FIXME,4=INFO, 5=DEBUG, 6=LOG, 7=TRACE, 9=MEMDUMP) (e.g. GST_DEBUG=*audio*:LOG)
When this environment variable is set, coloured debug output is disabled.
When set to a filesystem path, store 'dot' files of pipeline graphs there.These can then later be converted into an image using the 'dot' utility fromthe graphviz set of tools, like this: dot -Tsvg -o foo.svg (png or jpgare also possible as output format)
Path of the plugin registry file. Default is~/.cache/gstreamer-1.0/registry-CPU.bin where CPU is themachine/cpu type GStreamer was compiled for, e.g. 'i486', 'i686', 'x86-64',
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 checkwhether a rebuild of the registry cache is required or not. This may be usefulin embedded environments where the installed plugins never change. Do notuse 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 theuser's home directory
Set this variable to a file path to redirect all GStreamer debugmessages to this file. If left unset, debug messages with be outputunto the standard error.
Useful Orc environment variable. Set ORC_CODE=debug to enable debuggerssuch as gdb to create useful backtraces from Orc-generated code. SetORC_CODE=backup or ORC_CODE=emulate if you suspect Orc's SIMD codegenerator is producing incorrect code. (Quite a few importantGStreamer plugins like videotestsrc, audioconvert or audioresample use Orc).
Useful GLib environment variable. Set G_DEBUG=fatal_warnings to makeGStreamer programs abort when a critical warning such as an assertion failureoccurs. This is useful if you want to find out which part of the code causedthat warning to be triggered and under what circumstances. Simply set G_DEBUGas mentioned above and run the program in gdb (or let it core dump). Then geta stack trace in the usual way.


The plugin cache; can be deleted at any time, will be re-createdautomatically when it does not exist yet or plugins change. Based onXDG_CACHE_DIR, so may be in a different location than the one suggested.




The GStreamer team at




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