gst-launch-1.0
This content comes mostly from the Linux man page for the
gst-launch-1.0
tool. As such, it is very Linux-centric regarding path specification and plugin names. Please be patient while it is rewritten to be more generic.
Name
gst-launch-1.0
- build and run a GStreamer pipeline
Synopsis
gst-launch-1.0 [OPTIONS] PIPELINE-DESCRIPTION
Description
gst-launch-1.0
is a tool that builds and runs basic GStreamer pipelines.
In its simplest 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 more 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. 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)
-o FILE, --output=FILE
Save XML representation of pipeline to FILE and exit
-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-1.0
also accepts the following options that are common to
all GStreamer applications:
Pipeline Description
A pipeline consists of 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 its PROPERTIES
.
Element Properties
PROPERTY=VALUE ...
Sets the property to the specified value. You can use gst-inspect-1.0
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_parse_launch()
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,...]]
Links the element with name SRCELEMENT to the element with name SINKELEMENT.
Names can be set on elements using 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 using that
pad. If no pad names are given all possibilities are tried and a compatible 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. The simplest link
is a simple exclamation mark. This links the element to the left of it with the
element at its right.
The following links the element with name SRCELEMENT to the element with name SINKELEMENT, using the caps specified in CAPS as a filter:
[[SRCELEMENT].[PAD1,...]] ! CAPS ! [[SINKELEMENT].[PAD1,...]]
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.
Caps 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
orint
for integer values or ranges; -
f
orfloat
for float values or ranges; -
4
orfourcc
for FOURCC values; -
b
,bool
, orboolean
for boolean values; -
s
,str
, orstring
for strings; -
fraction
for fractions (framerate, pixel-aspect-ratio); -
l
orlist
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 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
) states explicitly.
Pipeline Examples
The examples below assume that you have the correct plugins available.
In general, osssink
can be substituted with another audio output
plugin such as directsoundsink
, esdsink
, alsasink
, osxaudiosink
, or
artsdsink
. Likewise, xvimagesink
can be substituted with d3dvideosink
,
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
in front of the sink to make things work.
Audio playback
Play the mp3 music file "music.mp3" using a libmad-based plugin and output to an OSS device:
gst-launch-1.0 filesrc location=music.mp3 ! mad ! audioconvert !
audioresample ! osssink
Play an Ogg Vorbis format file:
gst-launch-1.0 filesrc location=music.ogg ! oggdemux ! vorbisdec !
audioconvert ! audioresample ! osssink
Play an mp3 file using GNOME-VFS:
gst-launch-1.0 gnomevfssrc location=music.mp3 ! mad ! osssink
Play an HTTP stream using GNOME-VFS:
gst-launch-1.0 gnomevfssrc location=<http://domain.com/music.mp3> ! mad
! audioconvert ! audioresample ! osssink
Use GNOME-VFS to play an mp3 file located on an SMB server:
gst-launch-1.0 gnomevfssrc location=<smb://computer/music.mp3> ! mad !
audioconvert ! audioresample ! osssink
Format conversion
Convert an mp3 music file to an Ogg Vorbis file:
gst-launch-1.0 filesrc location=music.mp3 ! mad ! audioconvert ! vorbisenc !
oggmux ! filesink location=music.ogg
Convert to the FLAC format:
gst-launch-1.0 filesrc location=music.mp3 ! mad ! audioconvert ! flacenc !
filesink location=test.flac`
Other
Play a .WAV file that contains raw audio data (PCM):
gst-launch-1.0 filesrc location=music.wav ! wavparse ! audioconvert !
audioresample ! osssink
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 ! lame !
filesink location=music.mp3
Rip all tracks from CD and convert them into a single mp3 file:
gst-launch-1.0 cdparanoiasrc mode=continuous ! audioconvert ! lame !
id3v2mux ! filesink location=cd.mp3
Rip track 5 from the CD and converts it into a single mp3 file:
gst-launch-1.0 cdparanoiasrc track=5 ! audioconvert ! lame ! id3v2mux
! filesink location=track5.mp3
Using gst-inspect-1.0
, 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] ! lame vbr=new vbr-quality=6 !
filesink location=track5.mp3
Record sound from your audio input and encode it into an ogg file:
gst-launch-1.0 osssrc ! audioconvert ! vorbisenc ! oggmux !
filesink location=input.ogg
Running a pipeline using a specific user-defined latency (see gst_pipeline_set_latency()):
gst-launch-1.0 pipeline. \( latency=2000000000 videotestsrc ! jpegenc ! jpegdec ! fakevideosink \)
Video
Display only the video portion of an MPEG-1 video file, outputting to an X display window:
gst-launch-1.0 filesrc location=videofile.mpg ! dvddemux ! 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 ! 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 ! mpeg2dec ! sdlvideosink
demuxer. ! queue ! mad ! audioconvert ! audioresample ! osssink
Play an AVI movie with an external text subtitle stream:
gst-launch-1.0 filesrc location=movie.mpg ! mpegdemux name=demuxer
demuxer. ! queue ! mpeg2dec ! videoconvert ! sdlvideosink
demuxer. ! queue ! mad ! audioconvert ! audioresample ! osssink
This example 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 ! decodebin2 ! 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-yuv,width=128,height=96,format='(fourcc)'UYVY !
videoconvert ! ffenc_h263 ! video/x-h263 ! rtph263ppay pt=96 !
udpsink host=192.168.1.1 port=5000 sync=false
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 ! osssink
Generate a familiar test pattern to test the video output:
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 ! osssink
Play any supported video format with video and audio output. Threads are used automatically:
gst-launch-1.0 filesrc location=videofile ! decodebin name=decoder
decoder. ! queue ! audioconvert ! audioresample ! osssink
decoder. ! videoconvert ! xvimagesink
To make the above even easier, you can use the playbin element:
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-yuv,format=(fourcc)YUY2;video/x-raw-yuv,format=(fourcc)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 osssrc !
'audio/x-raw-int,rate=[32000,64000],width=[16,32],depth={16,24,32},signed=(boolean)true'
! 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
GST_DEBUG_NO_COLOR
: When this environment variable is set, coloured debug
output is disabled. This might come handy when saving the debug output to a
file.
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. The default is
~/.gstreamer-1.0/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, have been added or have been removed. This will make GStreamer
skip the initial check to determine 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
OIL_CPU_FLAGS
: 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
and
audioresample
use liboil.
G_DEBUG
: This is a 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 under
gdb (or let it core dump). Then get a stack trace in the usual way.
The results of the search are