gstreamer 手册

GStreamer(1)                                                                                                                                 GStreamer(1)


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
       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  applica‐
       tions, 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.


       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 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 insen‐
       sitive) 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 explicitly.


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 ! audio‐
       convert ! 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 ! ffmpegcol‐
       orspace ! 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  loca‐
       tion=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


       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  ini‐
              tial  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  circum‐
              stances. 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.


SEE ALSO
       gst-feedback(1), gst-inspect(1), gst-typefind(1)


AUTHOR
       The GStreamer team at http://gstreamer.freedesktop.org/