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gst-launch
This page last changed on May 30, 2012 by xartigas.
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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 formproperty=value.
For a complete description of possible PIPELINE-DESCRIPTIONS see the sectionpipeline 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)
-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 also accepts the following options that are common to all GStreamer applications:
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,...
\[SRCELEMENTLinks 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 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 explicitely.
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 "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 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 Use this command on the receiver
gst-launch udpsrc port=5000 ! application/x-rtp, clock-rate=90000,payload=96 ! rtph263pdepay queue-delay=0 ! ffdec_h263 ! xvimagesink This command would be run on the transmitter
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.
Environment Variables
GST_DEBUG
Comma-separated list of debug categories and levels, e.g. GST_DEBUG= totem:4,typefind:5
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
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 or audioresample use liboil).
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
Document generated by Confluence on Oct 08, 2015 10:28