Troubleshooting GStreamer

Some application is telling me that I am missing a plug-in. What do I do ?

Well, start by checking if you really are missing the plug-in.

gst-inspect-1.0 (plug-in)
  

and replace (plug-in) with the plug-in you think is missing. If this doesn't return any result, then you either don't have it or it can't be found (which can easily happen if you have installed things from source).

If you're not sure either way, then chances are good that you don't have it. You should get the plug-in and restart the application. How to get the plug-in depends on your distribution. Many applications and distributions nowadays support automatic plugin installation of missing plugins. Mayb also try playing your file with a different application if your application does not support installation of missing plugins.

  • if you run GStreamer using packages for your distribution, you should check what packages are available for your distribution and see if any of the available packages contains the plug-in. Make sure you have the common plugin packages installed, such as gst-plugins-base, gst-plugins-good, gst-plugins-ugly, gst-plugins-bad, and gst-libav.

  • if you run GStreamer from a source install, there's a good chance the plug-in didn't get built because you are missing an external library. When you ran configure, you should have gotten output of what plug-ins are going to be built. You can re-run configure to see if it's there. If it isn't, there is a good reason why it is not getting built. The most likely is that you're missing the library you need for it. Check the README file in gst-plugins to see what library you need. Make sure to remember to re-run configure after installing the supporting library !

  • if you run GStreamer from git, the same logic applies as for a source install. Go over the reasons why the plug-in didn't get configured for build. Check output of config.log for a clue as to why it doesn't get built if you're sure you have the library needed installed in a sane place.

The GStreamer application I used stops with a segmentation fault. What can I do ?

The first point of contact for any problems with a GStreamer application should be the developers of that application. They will be able to investigate whether the problem lies with the application or with GStreamer, and will pass on any issues to GStreamer developers if needed.

There are two things you can do. If you compiled GStreamer with specific optimization compilation flags, you should try recompiling GStreamer, the application and the plug-ins without any optimization flags. This allows you to verify if the problem is due to optimization or due to bad code. Second, it will also allow you to provide a reasonable backtrace in case the segmentation fault still occurs.

The second thing you can do is look at the backtrace to get an idea of where things are going wrong, or give us an idea of what is going wrong. To provide a backtrace, you should

  1. run the application in gdb by starting it with

        gdb (gst-application)
      
    

    (If the application is in a source tree instead of installed on the system, you might want to put "libtool" before "gdb")

  2. Pass on the command line arguments to the application by typing

        set args (the arguments to the application)
      
    

    at the (gdb) prompt

  3. Type "run" at the (gdb) prompt and wait for the application to segfault. The application will run a lot slower, however.

  4. After the segfault, type "bt" to get a backtrace. This is a stack of function calls detailing the path from main () to where the code is currently at.

  5. If the application you're trying to debug contains threads, it is also useful to do

        info threads
      
    

    and get backtraces of all of the threads involved, by switching to a different thread using "thread (number)" and then again requesting a backtrace using "bt".

  6. If you can't or don't want to work out the problem yourself, a copy and paste of all this information should be included in your bug report.

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