gst-launch-0.10
build and run a GStreamer pipeline
Synopsis
gst-launch
[OPTION...] PIPELINE-DESCRIPTION
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examples
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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.
-o FILE,
--output=FILE
Save XML representation of
pipeline to FILE and exit (DEPRECATED, DO NOT USE)
-f,
--no-fault
Do not install a fault
handler
--no-sigusr-handler
Do not install signal handlers
for SIGUSR1 (play) and SIGUSR2 (stop)
-T,
--trace
Print memory allocation traces.
The feature must be enabled at compile time to work.
environment variables
GST_DEBUG
Comma-separated list of debug categories and levels, e.g.
GST_DEBUG=totem:4,typefind:5
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.
GST_REGISTRY
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).
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
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
~/.gstreamer-0.10/registry-*.xml
The xml plugin database; can be deleted at any time, will be
re-created automatically when it does not exist yet or plugins
change.
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 0-5
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
--gst-debug-level=LEVEL
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.
--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-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 control
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 explicitly.
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
MIMETYPE [, PROPERTY[, PROPERTY ...]]] [; CAPS[; CAPS
...]]
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.
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
- 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 ...] )
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
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=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-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
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 ! ffmpegcolorspace ! 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 ! ffmpegcolorspace !
videoscale ! autovideosink filesrc location=movie.avi !
decodebin2 ! ffmpegcolorspace ! overlay.video_sink filesrc
location=movie.srt ! subparse ! overlay.text_sink
Play an AVI movie with an external text subtitle stream using
playbin2
gst-launch playbin2 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-yuv,width=128,height=96,format=’(fourcc)’UYVY !
ffmpegcolorspace ! ffenc_h263 ! video/x-h263 ! rtph263ppay pt=96
! udpsink host=192.168.1.1 port=5000 sync=false
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. ! 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.
see also
gst-feedback,
gst-inspect,
gst-typefind
author
The GStreamer
team at http://gstreamer.freedesktop.org/