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371 lines
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XML
371 lines
11 KiB
XML
<?xml version="1.0"?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
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"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
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<!ENTITY % version-entities SYSTEM "version.entities">
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%version-entities;
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<!ENTITY % local.common.attrib "xmlns:xi CDATA #FIXED 'http://www.w3.org/2003/XInclude'">
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]>
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<refentry id="gst-running" revision="08 Oct 2005">
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<refmeta>
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<refentrytitle>Running GStreamer Applications</refentrytitle>
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<manvolnum>3</manvolnum>
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<refmiscinfo>GStreamer Core</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>Running GStreamer Applications</refname>
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<refpurpose>
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How to run and debug your GStreamer application
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</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Running and debugging GStreamer Applications</title>
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<refsect2>
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<title>Environment variables</title>
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<para>
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GStreamer inspects a few of environment variables in addition to standard
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variables like <envar>LANG</envar>, <envar>PATH</envar> or <envar>HOME</envar>.
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</para>
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<formalpara id="GST_PLUGIN_SYSTEM_PATH">
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<title><envar>GST_PLUGIN_SYSTEM_PATH</envar></title>
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<para>
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This environment variable can be set to a colon-separated list of paths.
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If this variable is not set, GStreamer will fill in this list for you
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with
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<itemizedlist>
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<listitem>
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<para>
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plug-ins in the user's home directory. These are stored in a directory called
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<filename>plugins</filename> inside the
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<filename>.gstreamer-&GST_API_VERSION;</filename> directory in the user's
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home directory.
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</para>
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</listitem>
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<listitem>
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<para>
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plug-ins installed system-wide. On this system, they are stored in
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<filename>&GST_PLUGINS_DIR;</filename>.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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GStreamer will scan these paths for GStreamer plug-ins. These plug-ins will
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be loaded after the plug-ins in the GST_PLUGIN_PATH variable below.
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The paths are scanned in the given order. This allows a user to override
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system-installed plug-ins with his own versions.
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</para>
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<para>
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Setting this variable to an empty string will cause GStreamer not to scan any
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system paths at all for plug-ins. This can be useful if you're running
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uninstalled (for development purposes) or while running testsuites.
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</para>
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</formalpara>
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<formalpara id="GST_PLUGIN_PATH">
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<title><envar>GST_PLUGIN_PATH</envar></title>
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<para>
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This environment variable can be set to a colon-separated list of paths.
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GStreamer will scan these paths for GStreamer plug-ins. These plug-ins will
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be loaded in addition to, and before, the plug-ins in the system paths.
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</para>
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</formalpara>
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<formalpara id="GST_DEBUG">
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<title><envar>GST_DEBUG</envar></title>
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<para>
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If GStreamer has been configured with <option>--enable-gst-debug=yes</option>,
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this variable can be set to a list of debug options, which cause GStreamer
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to print out different types of debugging information to stderr.
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</para>
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<para>
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The variable takes a comma-separated list of "category_name:level" pairs
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to set specific levels for the individual categories.
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The level value ranges from 0 (nothing) to 9 (MEMDUMP).
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<variablelist>
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<varlistentry>
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<term>1 - <option>ERROR</option></term>
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<listitem>
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<para>
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Logs all fatal errors. These are errors that do not allow the core or elements
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to perform the requested action. The application can still recover if
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programmed to handle the conditions that triggered the error.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>2 - <option>WARNING</option></term>
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<listitem>
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<para>
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Logs all warnings. Typically these are non-fatal, but user-visible problems
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are expected to happen.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>3 - <option>FIXME</option></term>
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<listitem>
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<para>
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Logs all fixme messages. Fixme messages are messages that indicate that something
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in the executed code path is not fully implemented or handled yet. The purpose
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of this message is to make it easier to spot incomplete/unfinished pieces of
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code when reading the debug log.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>4 - <option>INFO</option></term>
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<listitem>
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<para>
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Logs all informational messages. These are typically used for events in
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the system that only happen once, or are important and rare enough to be
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logged at this level.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>5 - <option>DEBUG</option></term>
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<listitem>
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<para>
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Logs all debug messages. These are general debug messages for events
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that happen only a limited number of times during an object's lifetime;
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these include setup, teardown, change of parameters, ...
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>6 - <option>LOG</option></term>
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<listitem>
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<para>
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Logs all log messages. These are messages for events
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that happen repeatedly during an object's lifetime;
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these include streaming and steady-state conditions.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>7 - <option>TRACE</option></term>
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<listitem>
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<para>
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Logs all trace messages. These messages for events
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that happen repeatedly during an object's lifetime such as the
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ref/unref cycles.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>9 - <option>MEMDUMP</option></term>
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<listitem>
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<para>
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Log all memory dump messages. Memory dump messages are used to log
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(small) chunks of data as memory dumps in the log. They will be displayed
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as hexdump with ASCII characters.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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The category_name can contain "<option>*"</option> as a wildcard.
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</para>
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<para>
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For example, setting <envar>GST_DEBUG</envar> to
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<option>GST_AUTOPLUG:6,GST_ELEMENT_*:4</option>, will cause the
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<option>GST_AUTOPLUG</option> category to be logged at full
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<option>LOG</option> level, while all categories starting with
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<option>GST_ELEMENT_</option> will be logged at <option>INFO</option> level.
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</para>
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<para>
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To get all possible debug output, set
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<envar>GST_DEBUG</envar>
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to <option>*:9</option>. For debugging purposes a <option>*:6</option> debug
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log is usually the most useful, as it contains all important information, but
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hides a lot of noise such as refs/unrefs. For bug reporting purposes, a
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<option>*:6</option> log is also what will be requested usually. It's often
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also worth running with <option>*:3</option> to see if there are any
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non-fatal errors or warnings that might be related to the problem at hand.
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</para>
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</formalpara>
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<formalpara id="GST_DEBUG_NO_COLOR">
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<title><envar>GST_DEBUG_NO_COLOR</envar></title>
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<para>
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Set this environment variable to any value ("1" typically) to switch off
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colouring in GST_DEBUG output. This has the same effect as specifying the
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<option>--gst-debug-no-color</option> command line option to well-behaved
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GStreamer applications (ie. those that pass command-line options correctly to
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GStreamer).
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This is particularly useful to reduce the size of debug output and also allows
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for the output to be compressed much better than with colours turned on.
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</para>
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</formalpara>
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<formalpara id="GST_DEBUG_OPTIONS">
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<title><envar>GST_DEBUG_OPTIONS</envar></title>
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<para>
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This environment variable can be used to tweak the behaviour of the debugging
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system. Currently the only options supported are "pretty-tags" and "full-tags".
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In "pretty-tags" mode (the default), taglists in the debug log will be
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serialized so that only the first few and last few bytes of a buffer-type tag
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will be serialized into the log, to avoid dumping hundreds of lines of useless
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output into the log in case of large image tags and the like.
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</para>
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</formalpara>
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<formalpara id="GST_DEBUG_DUMP_DOT_DIR">
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<title><envar>GST_DEBUG_DUMP_DOT_DIR</envar></title>
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<para>
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Set this environment variable to a path to turn on all
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#GST_DEBUG_BIN_TO_DOT_FILE or #GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS calls
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and have the dot files in that location.
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</para>
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</formalpara>
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<formalpara id="GST_REGISTRY_FORK">
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<title><envar>GST_REGISTRY_FORK</envar></title>
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<para>
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Set this environment variable to "no" to prevent GStreamer from forking on
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startup in order to update the plugin registry. This is useful for debugging
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purposes, but should not be used under normal circumstances, since it means
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that plugins may be loaded into memory even if they are not needed by the
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application.
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</para>
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</formalpara>
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<formalpara id="GST_REGISTRY_UPDATE">
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<title><envar>GST_REGISTRY_UPDATE</envar></title>
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<para>
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Set this environment variable to "no" to prevent GStreamer from updating the
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plugin registry. This is useful for embedded device which is not updating the
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plugins frequently, it will save time when doing gst_init().
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</para>
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</formalpara>
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<formalpara id="GST_TRACE">
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<title><envar>GST_TRACE</envar></title>
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<para>
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Enable memory allocation tracing. Most GStreamer objects have support for
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tracing the number of unfreed objects and their memory pointers.
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</para>
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<para>
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The variable takes a comma-separated list of tracing options to enable.
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<variablelist>
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<varlistentry>
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<term>live</term>
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<listitem>
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<para>
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Counts all live objects and dumps an overview of the number of unfreed
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objects at program exit.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>mem-live</term>
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<listitem>
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<para>
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Keep track of the unfreed memory pointers and dump an overview of all unfreed
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memory at program exit. Together with a level 9 debug log this can be used to
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follow the lifecycle of leaked objects in order to track down where they are
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leaked. This can be useful for debugging memory leaks in situations where
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tools such as valgrind are not available, or not an option.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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Use <option>all</option> to enable all tracing flags.
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</para>
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</formalpara>
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<formalpara id="GST_DEBUG_FILE">
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<title><envar>GST_DEBUG_FILE</envar></title>
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<para>
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Set this variable to a file path to redirect all GStreamer debug
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messages to this file. If left unset, debug messages with be output
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unto the standard error.
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</para>
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</formalpara>
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<formalpara id="ORC_CODE">
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<title><envar>ORC_CODE</envar></title>
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<para>
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Useful Orc environment variable. Set ORC_CODE=debug to enable debuggers
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such as gdb to create useful backtraces from Orc-generated code. Set
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ORC_CODE=backup or ORC_CODE=emulate if you suspect Orc's SIMD code
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generator is producing incorrect code (Quite a few important
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GStreamer plugins like videotestsrc, audioconvert or audioresample use Orc).
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One can also combine flags like ORC_CODE=backup,debug.
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</para>
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</formalpara>
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<formalpara id="G_DEBUG">
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<title><envar>G_DEBUG</envar></title>
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<para>
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Useful GLib environment variable. Set G_DEBUG=fatal_warnings to make
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GStreamer programs abort when a critical warning such as an assertion failure
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occurs. This is useful if you want to find out which part of the code caused
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that warning to be triggered and under what circumstances. Simply set G_DEBUG
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as mentioned above and run the program in gdb (or let it core dump). Then get
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a stack trace in the usual way.
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</para>
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</formalpara>
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<formalpara id="G_SLICE">
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<title><envar>G_SLICE</envar></title>
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<para>
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Useful GLib environment variable. Set G_SLICE=always-malloc when running
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GStreamer programs in valgrind, or debugging memory leaks with other tools.
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See the GLib API reference for more details.
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</para>
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</formalpara>
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</refsect2>
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</refsect1>
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</refentry>
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