Provided by: gstreamer1.0-tools_1.8.3-1~ubuntu0.1_amd64 
NAME
gst-launch - build and run a GStreamer pipeline
SYNOPSIS
gst-launch [OPTION...] PIPELINE-DESCRIPTION
DESCRIPTION
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.
OPTIONS
gst-launch accepts the following options:
--help 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 is useful to make sure
muxers create readable files when a muxing pipeline is shut down forcefully via Control-C.
-i, --index
Gather and print index statistics. This is mostly useful for playback or recording pipelines.
-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.
GSTREAMER OPTIONS
gst-launch also accepts the following options that are common to all GStreamer applications:
--gst-version
Prints the version string of the GStreamer core library.
--gst-fatal-warnings
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).
--gst-debug=STRING
A comma separated list of category_name:level pairs to specify debugging levels for each
category. Level is in the range 0-9 where 0 will show no messages, and 9 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 the end 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 one can also
use the debug level names, e.g. --gst-debug=*sink:LOG. A full description of the various debug
levels can be found in the GStreamer core library API documentation, in the "Running GStreamer
Applications" section.
Use --gst-debug-help to show category names
Example: GST_CAT:5,GST_ELEMENT_*:3,oggdemux:5
--gst-debug-level=LEVEL
Sets the threshold for printing debugging messages. A higher level will print more messages.
The useful range is 0-9, with the default being 0. Level 6 (LOG level) will show all information
that is usually required for debugging purposes. Higher levels are only useful in very specific
cases. See above for the full list of levels.
--gst-debug-no-color
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.
--gst-debug-color-mode
GStreamer normally prints debugging messages so that the messages are color-coded when printed to
a terminal that handles ANSI escape sequences (on *nix), or uses W32 console API to color the
messages printed into a console (on W32). Using this option causes GStreamer to print messages
without color ('off' or 'disable'), print messages with default colors ('on' or 'auto'), or print
messages using ANSI escape sequences for coloring ('unix'). Setting the GST_DEBUG_COLOR_MODE
environment variable will achieve the same thing.
--gst-debug-disable
Disables debugging.
--gst-debug-help
Prints a list of available debug categories and their default debugging level.
--gst-plugin-spew
GStreamer info flags to set Enable printout of errors while loading GStreamer plugins
--gst-plugin-path=PATH
Add directories separated with ':' to the plugin search path
--gst-plugin-load=PLUGINS
Preload plugins specified in a comma-separated list. Another way to specify plugins to preload is
to use the environment variable GST_PLUGIN_PATH
PIPELINE DESCRIPTION
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.
Elements
ELEMENTTYPE [PROPERTY1 ...]
Creates an element of type ELEMENTTYPE and sets the PROPERTIES.
Properties
PROPERTY=VALUE ...
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.
Bins
[BINTYPE.] ( [PROPERTY1 ...] PIPELINE-DESCRIPTION )
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.
Links
[[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.
Caps
MEDIATYPE [, PROPERTY[, PROPERTY ...]]] [; CAPS[; CAPS ...]]
Creates a capability with the given media type and optionally with given properties. The media type can
be escaped using " or '. If you want to chain caps, you can add more caps in the same format afterwards.
Properties
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
- 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 ...] }
PIPELINE EXAMPLES
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 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 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=http://domain.com/music.mp3 ! 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
Other
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-1.0 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
Video
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 !
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 location=movie.srt !
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/movie.srt
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=192.168.1.1 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
Diagnostic
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. ! videoconvert ! 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,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 bit samples and a sample rate
between 32kHz and 64KHz.
ENVIRONMENT VARIABLES
GST_DEBUG
Comma-separated list of debug categories and levels (e.g. GST_DEBUG=totem:4,typefind:5). '*' is
allowed as a wildcard as part of debug category names (e.g. GST_DEBUG=*sink:6,*audio*:6). Since
1.2.0 it is also 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)
GST_DEBUG_NO_COLOR
When this environment variable is set, coloured debug output is disabled.
GST_DEBUG_DUMP_DOT_DIR
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 from the graphviz set of tools, like this: dot
foo.dot -Tsvg -o foo.svg (png or jpg are also possible as output format). There is also a utility
called 'xdot' which allows you to view the .dot file directly without converting it first.
GST_REGISTRY
Path of the plugin registry file. Default is ~/.cache/gstreamer-1.0/registry-CPU.bin where CPU is
the machine/cpu type GStreamer was compiled for, e.g. 'i486', 'i686', 'x86-64',
GST_REGISTRY_UPDATE
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.
GST_PLUGIN_PATH
Specifies a list of directories to scan for additional plugins. These take precedence over the
system plugins.
GST_PLUGIN_SYSTEM_PATH
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
GST_DEBUG_FILE
Set this variable to a file path to redirect all GStreamer debug messages to this file. If left
unset, debug messages with be output unto the standard error.
ORC_CODE
Useful Orc environment variable. Set ORC_CODE=debug to enable debuggers such as gdb to create
useful backtraces from Orc-generated code. Set ORC_CODE=backup or ORC_CODE=emulate if you suspect
Orc's SIMD code generator is producing incorrect code. (Quite a few important GStreamer plugins
like videotestsrc, audioconvert or audioresample use Orc).
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.
FILES
~/.cache/gstreamer-1.0/registry-*.bin
The plugin cache; can be deleted at any time, will be re-created automatically when it does not
exist yet or plugins change. Based on XDG_CACHE_DIR, so may be in a different location than the
one suggested.
SEE ALSO
gst-inspect-1.0(1), gst-launch-1.0(1),
AUTHOR
The GStreamer team at http://gstreamer.freedesktop.org/
May 2007 GStreamer(1)