Running and debugging GStreamer Applications
GStreamer inspects a few of environment variables in addition to standard variables like LANG, PATH or HOME.
This environment variable can be set to a colon-separated list of paths (or semicolon-separated list on Windows). If this variable is not set, GStreamer will fill in this list for you with
plug-ins in the user's home directory, or rather the user's "data home" directory according to the xdg base dir specification. Usually this will be a directory called
.local/share/gstreamer-GST_API_VERSIONdirectory in the user's home directory by default, though this search path may change if the XDG_DATA_HOME environment variable is set.
plug-ins installed system-wide. On this system, they are stored in ``.
GStreamer will scan these paths for GStreamer plug-ins. These plug-ins
will be loaded after the plug-ins in the
below. The paths are scanned in the given order. This allows a user to
override system-installed plug-ins with his own versions.
GST_PLUGIN_SYSTEM_PATH_1_0 variant is useful if both the old
GStreamer 0.10 version and the new GStreamer 1.0 version need to be
pointed to new plugin paths. The latter will use the _1_0 variant over
the non-versioned one if it is set.
Setting this variable to an empty string will cause GStreamer not to scan any system paths at all for plug-ins. This can be useful if you're running a development environment (for development purposes) or while running testsuites.
This environment variable can be set to a colon-separated list of paths (or a semicolon-separated list on Windows). GStreamer will scan these paths for GStreamer plug-ins. These plug-ins will be loaded in addition to, and before, the plug-ins in the system paths.
The GST_PLUGIN_PATH_1_0 variant is useful if both the old GStreamer
0.10 version and the new GStreamer 1.0 version need to be pointed to new
plugin paths. The latter will use the
_1_0 variant over the
non-versioned one if it is set.
If GStreamer has been configured with
variable can be set to a list of debug options, which cause GStreamer to
print out different types of debugging information to stderr.
The variable takes a comma-separated list of
pairs to set specific levels for the individual categories. The level
value ranges from 0 (nothing) to 9 (MEMDUMP).
: Logs all fatal errors. These are errors that do not allow the core or elements to perform the requested action. The application can still recover if programmed to handle the conditions that triggered the error.
: Logs all warnings. Typically these are non-fatal, but user-visible problems are expected to happen.
: Logs all fixme messages. Fixme messages are messages that indicate that something in the executed code path is not fully implemented or handled yet. The purpose of this message is to make it easier to spot incomplete/unfinished pieces of code when reading the debug log.
: Logs all informational messages. These are typically used for events in the system that only happen once, or are important and rare enough to be logged at this level.
: Logs all debug messages. These are general debug messages for events that happen only a limited number of times during an object's lifetime; these include setup, teardown, change of parameters, ...
: Logs all log messages. These are messages for events that happen repeatedly during an object's lifetime; these include streaming and steady-state conditions.
: Logs all trace messages. These messages for events that happen repeatedly during an object's lifetime such as the ref/unref cycles.
: Log all memory dump messages. Memory dump messages are used to log (small) chunks of data as memory dumps in the log. They will be displayed as hexdump with ASCII characters.
The category_name can contain "
*" as a wildcard.
For example, setting
will cause the
GST_AUTOPLUG category to be logged at full
while all categories starting with
GST_ELEMENT_ will be logged at
To get all possible debug output, set
*:9. For debugging
*:6 debug log is usually the most useful, as it contains
all important information, but hides a lot of noise such as refs/unrefs.
For bug reporting purposes, a
*:6 log is also what will be requested
usually. It's often also worth running with
*:3 to see if there are
any non-fatal errors or warnings that might be related to the problem at
Since GStreamer 1.2 it is also possible to specify debug levels by name,
The categories and log levels are evaluated from left to right, with later
entries overriding any previously-set levels for categories, e.g.
GST_DEBUG=decodebin:LOG,*:INFO will set the decodebin category back to
INFO level whereas
GST_DEBUG=*:INFO,decodebin:LOG will log everything at
INFO level apart from decodebin which will be logged at LOG level.
Set this environment variable to any value ("1" typically) to switch
off colouring in
GST_DEBUG output. This has the same effect as
command line option to well-behaved GStreamer applications (ie. those
that pass command-line options correctly to GStreamer). This is
particularly useful to reduce the size of debug output and also allows
for the output to be compressed much better than with colours turned on.
Has the same effect as setting
variable to "off".
Set this environment variable to change log colouring in
on: Enables debug log output coloring. Uses default coloring method for
current platform. This is the default.
off: Disables debug log output coloring. This has the same effect as
--gst-debug-color-mode=off command line option to well-behaved
GStreamer applications (ie. those that pass command-line options correctly to
GStreamer). This is particularly useful to reduce the size of debug output and
also allows for the output to be compressed much better than with colours turned
on. Has the same effect as setting
GST_DEBUG_NO_COLOR environment variable to
auto: Same as
disable: Same as
unix: Enables debug log output coloring and forces the use of UNIX termial
codes for coloring, even if this method is not normally used on current
platform. This has the same effect as specifying the
--gst-debug-color-mode=unix command line option to well-behaved GStreamer
applications (ie. those that pass command-line options correctly to GStreamer).
This is particularly useful to dump debug output into a file on non-UNIX
platforms to be sent to developers who have viewers that support UNIX terminal
This environment variable can be used to tweak the behaviour of the debugging system. Currently the only options supported are "pretty-tags" and "full-tags". In "pretty-tags" mode (the default), taglists in the debug log will be serialized so that only the first few and last few bytes of a buffer-type tag will be serialized into the log, to avoid dumping hundreds of lines of useless output into the log in case of large image tags and the like.
Set this environment variable to a path to turn on all
GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS calls and
have the dot files in that location.
This will only work if the application in question makes these calls in
strategic places (like when the pipeline state changes or an error
gst-launch-1,0 is one such application.
gst-launch-1.0 changes state through NULL to PLAYING
and back to NULL, a dot file is generated on each state change. To have
gst-launch-1.0 write a snapshot of the pipeline state,
send a SIGHUP to the
These .dot files can then be turned into images using the 'dot'
utility from the graphviz set of tools, like this:
dot foo.dot -Tsvg -o foo.svg or
dot foo.dot -Tpng -o foo.png or
dot foo.dot -Tjpg -o foo.jpg.
There is also a utility called
xdot which allows you to view the dot
file directly without converting it first.
Set this environment variable to make GStreamer use a different file for the plugin cache / registry than the default one. This is useful when operating in a separate environment which should not affect the default cache in the user's home directory.
Set this environment variable to "no" to prevent GStreamer from forking on startup in order to update the plugin registry. This is useful for debugging purposes, but should not be used under normal circumstances, since it means that plugins may be loaded into memory even if they are not needed by the application.
Set this environment variable to "no" to prevent GStreamer from
updating the plugin registry. This is useful for embedded device which
is not updating the plugins frequently, it will save time when doing
GST_REGISTRY_MODE. (Since: 1.20)
Set this environment variable to make Gstreamer change the file permissions of the plugin cache / registry. If not set, default is to limit read / write permissions to current user only. Set mode shall be from one to four octal digits as used in chmod.
Enable memory allocation tracing. Most GStreamer objects have support for tracing the number of unfreed objects and their memory pointers.
The variable takes a comma-separated list of tracing options to enable.
: Counts all live objects and dumps an overview of the number of unfreed objects at program exit.
: Keep track of the unfreed memory pointers and dump an overview of all unfreed memory at program exit. Together with a level 9 debug log this can be used to follow the lifecycle of leaked objects in order to track down where they are leaked. This can be useful for debugging memory leaks in situations where tools such as valgrind are not available, or not an option.
all to enable all tracing flags.
Set this variable to a file path to redirect all GStreamer debug messages to this file. If left unset, debug messages with be output unto the standard error.
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=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). One
can also combine flags like
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.
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.
Useful GLib environment variable. Set
running GStreamer programs in valgrind, or debugging memory leaks with
other tools. See the GLib API reference for more details.
Try this character encoding first for tag-related strings where the encoding is not defined and which are not UTF-8 already. By default the current locale will be tried (if not UTF-8).
Try this character encoding first for ID3 tag-related strings where the encoding is not defined and which are not UTF-8 already. By default the current locale will be tried (if not UTF-8).
Try this character encoding first for ID3v1 tag-related strings where the encoding does not look like UTF-8.
Influences the window system to use by the GStreamer OpenGL library. Common values are 'x11', 'wayland', 'win32' or 'cocoa'.
Influences the OpenGL platform to use by the GStreamer OpenGL library. Common values are 'egl', 'glx', 'wgl' or 'cgl'.
Influences the OpenGL API requested by the OpenGL platform. Common values are 'opengl' or 'gles2'.
GST_PLUGIN_FEATURE_RANK. (Since: 1.18)
This environment variable can be used to adjust rank of each plugin feature.
The variable takes a comma-separated list of
pairs to set specific ranks for the individual plugin features.
The rank can be an arbitrary numerical value or one of pre-defined rank values
PRIMARY(256) in case-insensitive manner.
In addition to the pre-defined rank values,
MAX is an acceptable value to set
higher rank than the rank of other existing plugin features.
As a result of the above example,
bar plugin feature rank values are
SECONDARY(128) rank value will be assigned to
The results of the search are