.TH "GStreamer" "1" "May 2007"
.SH "NAME"
gst\-launch \- build and run a GStreamer pipeline
.SH "SYNOPSIS"
\fBgst\-launch\fR \fI[OPTION...]\fR PIPELINE\-DESCRIPTION
.SH "DESCRIPTION"
.LP 
\fIgst\-launch\fP is a tool that builds and runs basic
\fIGStreamer\fP 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 \fIproperty=value\fR.

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

Please note that \fIgst\-launch\fP 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.
.
.SH "OPTIONS"
.l
\fIgst\-launch\fP accepts the following options:
.TP 8
.B  \-\-help
Print help synopsis and available FLAGS
.TP 8
.B  \-v, \-\-verbose
Output status information
.TP 8
.B  \-m, \-\-messages
Output messages posted on the pipeline's bus
.TP 8
.B  \-t, \-\-tags
Output tags (also known as metadata)
.TP 8
.B  \-o FILE, \-\-output=FILE
Save XML representation of pipeline to FILE and exit
.TP 8
.B  \-f, \-\-no_fault
Do not install a fault handler
.TP 8
.B  \-T, \-\-trace
Print memory allocation traces. The feature must be enabled at compile time to
work.
.TP 8

.
.SH "GSTREAMER OPTIONS"
.l
\fIgst\-launch\fP also accepts the following options that are common
to all GStreamer applications:
.TP 8
.B  \-\-gst\-version
Prints the version string of the \fIGStreamer\fP core library.
.TP 8
.B  \-\-gst\-fatal\-warnings
Causes \fIGStreamer\fP to abort if a warning message occurs. This is equivalent
to setting the environment variable G_DEBUG to 'fatal_warnings' (see the
section \fIenvironment variables\fR below for further information).
.TP 8
.B  \-\-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

.TP 8
.B  \-\-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.
.TP 8
.B  \-\-gst\-debug\-no\-color
\fIGStreamer\fP 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 \fIGStreamer\fP
to print messages without color. Setting the \fBGST_DEBUG_NO_COLOR\fR
environment variable will achieve the same thing.
.TP 8
.B  \-\-gst\-disable\-debug
Disables debugging.
.TP 8
.B  \-\-gst\-debug\-help
Prints a list of available debug categories and their default debugging level.
.TP 8
.B  \-\-gst\-plugin\-spew
\fIGStreamer\fP info flags to set
Enable printout of errors while loading \fIGStreamer\fP plugins
.TP 8
.B  \-\-gst\-plugin\-path=PATH
Add directories separated with ':' to the plugin search path
.TP 8
.B  \-\-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

.SH "PIPELINE DESCRIPTION"

A pipeline consists \fIelements\fR and \fIlinks\fR. \fIElements\fR can be put 
into \fIbins\fR of different sorts. \fIElements\fR, \fIlinks\fR and \fIbins\fR
can be specified in a pipeline description in any order.

.B Elements

ELEMENTTYPE \fI[PROPERTY1 ...]\fR

Creates an element of type ELEMENTTYPE and sets the PROPERTIES.

.B Properties

PROPERTY=VALUE ...

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

.B Bins

\fI[BINTYPE.]\fR ( \fI[PROPERTY1 ...]\fR PIPELINE-DESCRIPTION )
.br

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.

.B Links

\fI[[SRCELEMENT].[PAD1,...]]\fR ! \fI[[SINKELEMENT].[PAD1,...]]\fR
\fI[[SRCELEMENT].[PAD1,...]]\fR ! CAPS ! \fI[[SINKELEMENT].[PAD1,...]]\fR

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.
.br
So the simplest link is a simple exclamation mark, that links the element to
the left of it to the element right of it.
.br

.B Caps

MIMETYPE \fI[, PROPERTY[, PROPERTY ...]]]\fR \fI[; CAPS[; CAPS ...]]\fR

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.

.B Properties

NAME\fI[:TYPE]\fR=VALUE
.br
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:
.br
- \fBi\fR or \fBint\fR for integer values or ranges
.br
- \fBf\fR or \fBfloat\fR for float values or ranges
.br
- \fB4\fR or \fBfourcc\fR for FOURCC values
.br
- \fBb\fR, \fBbool\fR or \fBboolean\fR for boolean values
.br
- \fBs\fR, \fBstr\fR or \fBstring\fR for strings
.br
- \fBfraction\fR for fractions (framerate, pixel-aspect-ratio)
.br
- \fBl\fR or \fBlist\fR for lists
.br
If no type was given, the following order is tried: integer, float, boolean, 
string.
.br
Integer values must be parsable by \fBstrtol()\fP, floats by \fBstrtod()\fP. FOURCC values may
either be integers or strings. Boolean values are (case insensitive) \fIyes\fR, 
\fIno\fR, \fItrue\fR or \fIfalse\fR and may like strings be escaped with " or '.
.br
Ranges are in this format:  [ PROPERTY, PROPERTY ]
.br
Lists use this format:      ( PROPERTY \fI[, PROPERTY ...]\fR )

.SH "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.
.br
There are currently no signals defined to go into the ready or pause
(GST_STATE_READY and GST_STATE_PAUSED) state explicitely.

.SH "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.

.B Audio playback

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

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

.B
        gst\-launch gnomevfssrc location=music.mp3 ! mad ! osssink
.br
.B
        gst\-launch gnomevfssrc location=http://domain.com/music.mp3 ! mad ! audioconvert ! audioresample ! osssink
.br
Play an mp3 file or an http stream using GNOME\-VFS

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

.B Format conversion

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

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

.B Other

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

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

.B
        gst\-launch cdparanoia ! lame ! filesink location=cd.mp3
.br
rips all tracks from compact disc and convert them into a single mp3 file

Using \fBgst\-inspect\fR(1), it is possible to discover settings for cdparanoia
that will tell it to rip individual tracks. Alternatively, you can use an URI
and gst-launch will find an element (such as cdparanoia) that supports that
protocol for you, e.g.:
.B
       gst\-launch cdda://5 ! lame vbr=new vbr-quality=6 ! filesink location=track5.mp3

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

.B Video

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

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

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

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

.B Network streaming

Stream video using RTP and network elements.

.B
        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
.br
Use this command on the receiver

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

.B Diagnostic

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

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

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

.B Automatic linking

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

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

.B
        gst\-launch filesrc location=videofile ! decodebin name=decoder  decoder. ! queue ! audioconvert ! audioresample ! osssink   decoder. ! ffmpegcolorspace ! xvimagesink
.br
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:

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

.B Filtered connections

These examples show you how to use filtered caps.

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

.B
        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
.br
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.


.SH "ENVIRONMENT VARIABLES"
.TP
\fBGST_DEBUG\fR
Comma-separated list of debug categories and levels, e.g.
GST_DEBUG=totem:4,typefind:5
.TP
\fBGST_DEBUG_NO_COLOR\fR
When this environment variable is set, coloured debug output is disabled.
.TP
\fBGST_REGISTRY\fR
Path of the plugin registry file. Default is
~/.gstreamer-GST_MAJORMINOR/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).
.TP
\fBGST_PLUGIN_PATH\fR
Specifies a list of directories to scan for additional plugins.
These take precedence over the system plugins.
.TP
\fBGST_PLUGIN_SYSTEM_PATH\fR
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
.TP
\fBOIL_CPU_FLAGS\fR
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).
.TP
\fBG_DEBUG\fR
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.
.
.SH FILES
.TP 8
~/.gstreamer-GST_MAJORMINOR/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.
.
.SH "SEE ALSO"
.BR gst\-feedback (1),
.BR gst\-inspect (1),
.BR gst\-typefind (1)
.SH "AUTHOR"
The GStreamer team at http://gstreamer.freedesktop.org/