# Using GStreamer

Ok, I've installed GStreamer. What can I do next ?

First of all, verify that you have a working registry and that you can inspect them by typing

    $ gst-inspect fakesrc

This should print out a bunch of information about this particular element. If this tells you that there is "no such element or plugin", you haven't installed GStreamer correctly. Please check how to get GStreamer If this fails with any other message, we would appreciate a bug report.

It's time to try out a few things. Start with gst-launch and two plug-ins that you really should have : fakesrc and fakesink. They do nothing except pass empty buffers. Type this at the command-line :

    $ gst-launch fakesrc num-buffers=3 ! fakesink

This will print out output that looks similar to this :

    RUNNING pipeline
    fakesrc0: last-message = "get      ******* (fakesrc0:src)gt; (0 bytes, 0) 0x8057510"
    fakesink0: last-message = "chain   ******* (fakesink0:sink)lt; (0 bytes, 0) 0x8057510"
    fakesrc0: last-message = "get      ******* (fakesrc0:src)gt; (0 bytes, 1) 0x8057510"
    fakesink0: last-message = "chain   ******* (fakesink0:sink)lt; (0 bytes, 1) 0x8057510"
    fakesrc0: last-message = "get      ******* (fakesrc0:src)gt; (0 bytes, 2) 0x8057510"
    fakesink0: last-message = "chain   ******* (fakesink0:sink)lt; (0 bytes, 2) 0x8057510"
    execution ended after 5 iterations (sum 301479000 ns, average 60295800 ns, min 3000 ns, max 105482000 ns)

(Some parts of output have been removed for clarity) If it looks similar, then GStreamer itself is running correctly.

Can my system play sound through GStreamer ?

You can test this by trying to play a sine tone. For this, you need to link the sinesrc plug-in to an output plug-in that matches your hardware. A (non-complete) list of output plug-ins for audio is

- osssink for OSS output

- esdsink for ESound output

- artssink for aRTs output

- alsasink for ALSA output

- jacksink for JACK output

First of all, run gst-inspect on the output plug-in you want to use to make sure you have it installed. For example, if you use OSS, run

    $ gst-inspect osssink

and see if that prints out a bunch of properties for the plug-in.

Then try to play the sine tone by running

    $ gst-launch sinesrc ! osssink

and see if you hear something. Make sure your volume is turned up, but also make sure it is not too loud and you are not wearing your headphones.

How can I see what GStreamer plugins I have on my system ?

To do this you use the gst-inspect command-line tool, which comes standard with GStreamer. Invoked without any arguments,

    $ gst-inspect

will print out a listing of installed plugins. To learn more about a particular plugin, pass its name on the command line. For example,

    $ gst-inspect volume

will give you information about the volume plugin.

Also, if you install the gst-editor package, you will have a graphical plugin browser available, gst-inspect-gui.

Where should I report bugs ?

Bug management is now hosted on GNOME's Bugzilla at http://bugzilla.gnome.org, under the product GStreamer. Using bugzilla you can view past bug history, report new bugs, etc. Bugzilla requires you to make an account here, which might seem cumbersome, but allows us to at least have a chance at contacting you for further information, as we will most likely have to.

How should I report bugs ?

When doing a bug report, you should at least describe

- your distribution

- how you installed GStreamer (from cvs, source, packages, which ?)

- if you installed GStreamer before

It also is useful for us if you attach output of the gst-feedback command to your bug report. If you're having problem with a specific application (either one of ours, somebody else's, or your own), please also provide a log of gst-mask by running

    myapp --gst-mask=-1 > mask.log 2>&1
    gzip mask.log

(interrupting the program if it doesn't stop by itself) and attach mask.log.gz to your bug report.

If the application you are having problems with is segfaulting, then provide us with the necessary gdb output. See

How do I use the GStreamer command line interface ?

You access the GStreamer command line interface using the command gst-launch. To decode an mp3 and play it through OSS, you could use

    gst-launch filesrc location=thesong.mp3 ! mad ! osssink

. More examples can be found in the gst-launch man page.

To automatically detect the right codec in a pipeline, try

    gst-launch filesrc location=my-random-media-file.mpeg ! spider ! osssink

. Try replacing osssink with sdlvideosink and see what happens.

We also have a simple tool called gst-launch-ext used for debugging, which has predefined pipelines for you. This means you can just write

    gst-launch-ext (filename)

and it will play the file if the extension is supported. Note that no effort has been made for uninterrupted synchronized playback using this tool.