GStreamer(1) User Commands GStreamer(1)

NAME

gst-launch-1.0 - build and run a GStreamer pipeline

SYNOPSIS

gst-launch-1.0 [OPTION...] PIPELINE-DESCRIPTION

DESCRIPTION

gst-launch-1.0 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. A "preset" can also be set
using the @preset=<preset name> syntax.

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

Please note that gst-launch-1.0 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-1.0 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.

--no-position
Do not print current position of pipeline. If this option is
unspecified, the position will be printed when stdout is a
TTY. To enable printing position when stdout is not a TTY,
use "force-position" option.

--force-position
Allow printing current position of pipeline even if stdout is
not a TTY. This option has no effect if the "no-position"
option is specified.

GSTREAMER OPTIONS

gst-launch-1.0 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-1.0(1) to find out about properties and allowed values of
different elements.
Enumeration properties can be set by name, nick or value.

Presets

@preset=<preset name> ...

Sets the preset on the element. you can use gst-inspect-1.0(1) to
find out what presets are available for a specific element.

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,...]]
[[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.
Linking using the : operator attempts to link all possible pads
between the elements

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, "pulsesink" can be substituted with another
audio output plug-in such as "alsasink" or "osxaudiosink" Likewise,
"xvimagesink" can be substituted with "ximagesink", "glimagesink", or
"osxvideosink". 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

Play the mp3 music file "music.mp3" using a libmpg123-based plug-in
and output to an Pulseaudio device
gst-launch-1.0 filesrc location=music.mp3 ! mpegaudioparse !
mpg123audiodec ! audioconvert ! audioresample ! pulsesink

Play an Ogg Vorbis format file
gst-launch-1.0 filesrc location=music.ogg ! oggdemux !
vorbisdec ! audioconvert ! audioresample ! pulsesink

Play an mp3 file or an http stream using GIO
gst-launch-1.0 giosrc location=music.mp3 ! mpegaudioparse !
mpg123audiodec ! audioconvert ! pulsesink
gst-launch-1.0 giosrc location=http://domain.com/music.mp3 !
mpegaudioparse ! mpg123audiodec ! audioconvert ! audioresample !
pulsesink

Use GIO to play an mp3 file located on an SMB server
gst-launch-1.0 giosrc location=smb://computer/music.mp3 !
mpegaudioparse ! mpg123audiodec ! audioconvert ! audioresample !
pulsesink

Format conversion

Convert an mp3 music file to an Ogg Vorbis file
gst-launch-1.0 filesrc location=music.mp3 ! mpegaudioparse !
mpg123audiodec ! audioconvert ! vorbisenc ! oggmux ! filesink
location=music.ogg

Convert to the FLAC format
gst-launch-1.0 filesrc location=music.mp3 ! mpegaudioparse !
mpg123audiodec ! audioconvert ! flacenc ! filesink location=test.flac

Other

Plays a .WAV file that contains raw audio data (PCM).
gst-launch-1.0 filesrc location=music.wav ! wavparse !
audioconvert ! audioresample ! pulsesink

Convert a .WAV file containing raw audio data into an Ogg Vorbis or
mp3 file
gst-launch-1.0 filesrc location=music.wav ! wavparse !
audioconvert ! vorbisenc ! oggmux ! filesink location=music.ogg
gst-launch-1.0 filesrc location=music.wav ! wavparse !
audioconvert ! lamemp3enc ! filesink location=music.mp3

Rips all tracks from compact disc and convert them into a single mp3
file
gst-launch-1.0 cdparanoiasrc mode=continuous ! audioconvert !
lamemp3enc ! mpegaudioparse ! id3v2mux ! filesink location=cd.mp3

Rips track 5 from the CD and converts it into a single mp3 file
gst-launch-1.0 cdparanoiasrc track=5 ! audioconvert !
lamemp3enc ! mpegaudioparse ! id3v2mux ! filesink location=track5.mp3

Using gst-inspect-1.0(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-1.0 cdda://5 ! lamemp3enc vbr=new vbr-quality=6 !
filesink location=track5.mp3

Records sound from your audio input and encodes it into an ogg file
gst-launch-1.0 pulsesrc ! audioconvert ! vorbisenc ! oggmux !
filesink location=input.ogg

Video

Display only the video portion of an MPEG-1 video file, outputting to
an X display window
gst-launch-1.0 filesrc location=JB_FF9_TheGravityOfLove.mpg !
dvddemux ! mpegvideoparse ! mpeg2dec ! xvimagesink

Display the video portion of a .vob file (used on DVDs), outputting
to an SDL window
gst-launch-1.0 filesrc location=/flflfj.vob ! dvddemux !
mpegvideoparse ! mpeg2dec ! sdlvideosink

Play both video and audio portions of an MPEG movie
gst-launch-1.0 filesrc location=movie.mpg ! dvddemux
name=demuxer demuxer. ! queue ! mpegvideoparse ! mpeg2dec !
sdlvideosink demuxer. ! queue ! mpegaudioparse ! mpg123audiodec !
audioconvert ! audioresample ! pulsesink

Play an AVI movie with an external text subtitle stream
gst-launch-1.0 filesrc location=movie.mpg ! mpegdemux
name=demuxer demuxer. ! queue ! mpegvideoparse ! mpeg2dec !
videoconvert ! sdlvideosink demuxer. ! queue ! mpegaudioparse !
mpg123audiodec ! audioconvert ! audioresample ! pulsesink

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-1.0 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-1.0 playbin uri=file:///path/to/movie.avi
suburi=file:///path/to/movie.srt

Network streaming

Stream video using RTP and network elements.

This command would be run on the transmitter
gst-launch-1.0 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

Use this command on the receiver
gst-launch-1.0 udpsrc port=5000 ! application/x-rtp,
clock-rate=90000,payload=96 ! rtph263pdepay queue-delay=0 !
ffdec_h263 ! xvimagesink

Diagnostic

Generate a null stream and ignore it (and print out details).
gst-launch-1.0 -v fakesrc num-buffers=16 ! fakesink

Generate a pure sine tone to test the audio output
gst-launch-1.0 audiotestsrc ! audioconvert ! audioresample !
pulsesink

Generate a familiar test pattern to test the video output
gst-launch-1.0 videotestsrc ! xvimagesink
gst-launch-1.0 videotestsrc ! ximagesink

Automatic linking

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

Play any supported audio format
gst-launch-1.0 filesrc location=musicfile ! decodebin !
audioconvert ! audioresample ! pulsesink

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-1.0 filesrc location=videofile ! decodebin
name=decoder decoder. ! queue ! audioconvert ! audioresample !
pulsesink decoder. ! videoconvert ! xvimagesink
gst-launch-1.0 playbin uri=file:///home/joe/foo.avi


Filtered connections

These examples show you how to use filtered caps.

Show a test image and use the YUY2 or YV12 video format for this.
gst-launch-1.0 videotestsrc !
'video/x-raw,format=YUY2;video/x-raw,format=YV12' ! xvimagesink

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.
gst-launch-1.0 pulsesrc !
'audio/x-raw,rate=[32000,64000],format={S16LE,S24LE,S32LE}' ! wavenc
! filesink location=recording.wav

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.
When the pipeline changes state through NULL to PLAYING and
back to NULL, a dot file is generated on each state change. To
write a snapshot of the pipeline state, send a SIGHUP to the
process.

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', 'ppc', etc. (check the output of "uname -i"
and "uname -m" for details).

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)