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385b9ee5c4
Original commit message from CVS: merge in tagging Includes: - gsttag.[ch] - The definition of GstTagList and tag registering/querying - gsttaginterface.[ch] - Interface for elements that can handle setting of tags - updates and merges to gststructure.[ch] and gstvalue.[ch] - testsuite/tags - some tests for tagging - bugfixes - updates to make make distcheck work - updates the version number to 0.7.2.1 Does not include: - including tagging stuff in docs - extensive tests
669 lines
15 KiB
Plaintext
669 lines
15 KiB
Plaintext
<!-- ##### SECTION Title ##### -->
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GstInfo
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<!-- ##### SECTION Short_Description ##### -->
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debugging subsystem
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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This file describes the debugging subsystem. The debugging subsystem works
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only after GStreamer was initilized - for example by calling #gst_init.
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</para>
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<para>
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The debugging subsystem is used to send informational strings to the debugging
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developer. Each messages has some properties attached to it. These properties
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are the debugging category, the severity (called "level" here) and an obtional
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#GObject it belongs to. Each of these messages is sent to all registered
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debugging handlers, which then handle the messages. GStreamer attaches a
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default handler on startup, which outputs requested messages to stderr.
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</para>
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<para>
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Messages are output by using shortcut macros like #GST_DEBUG,
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#GST_CAT_ERROR_OBJECT or similar. These all expand to calling #gst_debug_log
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with the right parameters.
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The only thing a developer will probably want to do is define his own
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categories. This is easily done with 3 lines. At the top of your code, declare
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the variables and set the default category.
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<informalexample>
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<programlisting>
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GST_DEBUG_CATEGORY (my_category); /* define category */
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&hash;define GST_CAT_DEFAULT my_category /* set as default */
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</programlisting>
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</informalexample>
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After that you only need to initialize the category.
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<informalexample>
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<programlisting>
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GST_DEBUG_CATEGORY_INIT (my_category, "my category", 0, "This is my very own");
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</programlisting>
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</informalexample>
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Initialization must be done before the category is used first. Plugins do this
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in their plugin_init function, libraries and applications should do that
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during their initialization.
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</para>
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<para>
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The whole debugging subsystem can be disabled at build time with passing the
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--disable-gst-debug switch to configure. If this is done, every function, macro
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and even structs described in this file evaluate to default values or nothing
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at all. So don't take addresses of these functions or use other tricks.
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If you must do that for some reason, there is still an option. If the debugging
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subsystem was compiled out, #GST_DISABLE_GST_DEBUG is defined in <gst/gst.h>,
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so you can check that before doing your trick.
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Disabling the debugging subsystem will give you a slight (read: unnoticable)
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speed increase and will reduce the size of your compiled code. The GStreamer
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library itself becomes around 10% smaller.
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</para>
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<para>
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Please note that there are naming conventions for the names of debugging
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categories. These are explained at GST_DEBUG_CATEGORY_INIT().
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</para>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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<link linkend="gstreamer-gstconfig">configuration</link>,
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<link linkend="gstreamer-gst">initialization</link> for command line parameters
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and environment variables that affect the debugging output.
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</para>
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<!-- ##### MACRO GST_STR_NULL ##### -->
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<para>
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Macro to use when a string must not be NULL, but may be NULL. If the string is
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NULL, "(NULL)" is printed instead.
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In GStreamer printf string arguments may not be NULL, because on some platforms
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(ie Solaris) the libc crashes in that case. This includes debugging strings.
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</para>
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@str: The string to check.
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@Returns: A string that is guaranteed to be not NULL.
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<!-- ##### MACRO GST_DEBUG_PAD_NAME ##### -->
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<para>
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Evaluates to 2 strings, that describe the pad. Often used in debugging
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statements.
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</para>
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@pad: The pad to debug.
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<!-- ##### MACRO GST_FUNCTION ##### -->
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<para>
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This macro should evaluate to the name of the current function and be should
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be defined when configuring your project, as it is compiler dependant. If it
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is not defined, some default value is used. It is used to provide debugging
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output with the function name of the message.
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</para>
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<!-- ##### ENUM GstDebugLevel ##### -->
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<para>
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The level defines the importance of a debugging message. The more important a
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message is, the greater the probability that the debugging system outputs it.
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</para>
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@GST_LEVEL_NONE: No debugging level specified or desired. Used to deactivate
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debugging output.
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@GST_LEVEL_ERROR: Error messages are to be used only when an error occured
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that stops the application from keeping working correctly.
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An examples is gst_element_error, which outputs a message with this priority.
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It does not mean that the application is terminating as with g_errror.
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@GST_LEVEL_WARNING: Warning messages are to inform about abnormal behaviour
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that could lead to problems or weird behaviour later on. An example of this
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would be clocking issues ("your computer is pretty slow") or broken input
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data ("Can't synchronize to stream.")
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@GST_LEVEL_INFO: Informational messages should be used to keep the developer
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updated about what is happening.
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Examples where this should be used are when a typefind function has
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successfully determined the type of the stream or when an mp3 plugin detects
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the format to be used. ("This file has mono sound.")
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@GST_LEVEL_DEBUG: Debugging messages should be used when something common
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happens that is not the expected default behavior.
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An example would be notifications about state changes or receiving/sending of
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events.
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@GST_LEVEL_LOG: Log messages are messages that are very common but might be
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useful to know. As a rule of thumb a pipeline that is iterating as expected
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should never output anzthing else but LOG messages.
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Examples for this are referencing/dereferencing of objects or cothread switches.
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@GST_LEVEL_COUNT: The number of defined debugging levels.
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<!-- ##### MACRO GST_LEVEL_DEFAULT ##### -->
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<para>
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Defines the default debugging level to be used with GStreamer. It is
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normally set to #GST_LEVEL_ERROR so only errors are printed. Developer
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builds may chose to override that though.
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You can use this as an argument to gst_debug_set_default_threshold() to
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reset the debugging output to default behaviour.
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</para>
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<!-- ##### FUNCTION gst_debug_level_get_name ##### -->
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<para>
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</para>
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@level:
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@Returns:
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<!-- ##### ENUM GstDebugColorFlags ##### -->
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<para>
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These are some terminal-oriented flags you can use when creating your debugging
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categories to make them stand out in debugging output.
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</para>
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@GST_DEBUG_FG_BLACK: Use black as foreground color.
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@GST_DEBUG_FG_RED: Use red as foreground color.
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@GST_DEBUG_FG_GREEN: Use green as foreground color.
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@GST_DEBUG_FG_YELLOW: Use yellow as foreground color.
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@GST_DEBUG_FG_BLUE: Use blue as foreground color.
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@GST_DEBUG_FG_MAGENTA: Use magenta as foreground color.
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@GST_DEBUG_FG_CYAN: Use cyan as foreground color.
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@GST_DEBUG_FG_WHITE: Use white as foreground color.
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@GST_DEBUG_BG_BLACK: Use black as background color.
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@GST_DEBUG_BG_RED: Use red as background color.
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@GST_DEBUG_BG_GREEN: Use green as background color.
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@GST_DEBUG_BG_YELLOW: Use yellow as background color.
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@GST_DEBUG_BG_BLUE: Use blue as background color.
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@GST_DEBUG_BG_MAGENTA: Use magenta as background color.
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@GST_DEBUG_BG_CYAN: Use cyan as background color.
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@GST_DEBUG_BG_WHITE: Use white as background color.
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@GST_DEBUG_BOLD: Make the output bold.
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@GST_DEBUG_UNDERLINE: Underline the output.
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<!-- ##### FUNCTION gst_debug_construct_term_color ##### -->
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<para>
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</para>
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@colorinfo:
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@Returns:
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<!-- ##### STRUCT GstDebugCategory ##### -->
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<para>
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This is the struct that describes the categories. Once initialized with
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#GST_DEBUG_CATEGORY_INIT, its values can't be changed anymore.
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</para>
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<!-- ##### VARIABLE GST_CAT_DEFAULT ##### -->
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<para>
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The default category that is used when no other category is defined as the
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default. If you want to define a default category, do it like this:
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<informalexample>
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<programlisting>
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&hash;define GST_CAT_DEFAULT category_to_be_default
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</programlisting>
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</informalexample>
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</para>
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<!-- ##### USER_FUNCTION GstLogFunction ##### -->
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<para>
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</para>
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@category:
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@level:
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@file:
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@function:
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@line:
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@object:
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@message:
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@data:
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<!-- ##### FUNCTION gst_debug_log ##### -->
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<para>
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</para>
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@category:
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@level:
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@file:
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@function:
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@line:
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@object:
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@format:
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@Varargs:
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<!-- ##### FUNCTION gst_debug_log_default ##### -->
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<para>
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</para>
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@category:
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@level:
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@file:
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@function:
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@line:
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@object:
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@message:
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@unused:
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<!-- ##### FUNCTION gst_debug_add_log_function ##### -->
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<para>
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</para>
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@func:
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@data:
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<!-- ##### FUNCTION gst_debug_remove_log_function ##### -->
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<para>
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</para>
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@func:
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@Returns:
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<!-- ##### FUNCTION gst_debug_remove_log_function_by_data ##### -->
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<para>
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</para>
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@data:
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@Returns:
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<!-- ##### FUNCTION gst_debug_set_active ##### -->
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<para>
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</para>
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@active:
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<!-- ##### FUNCTION gst_debug_is_active ##### -->
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<para>
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</para>
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@Returns:
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<!-- ##### FUNCTION gst_debug_set_colored ##### -->
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<para>
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</para>
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@colored:
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<!-- ##### FUNCTION gst_debug_is_colored ##### -->
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<para>
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</para>
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@Returns:
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<!-- ##### FUNCTION gst_debug_set_default_threshold ##### -->
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<para>
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</para>
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@level:
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<!-- ##### FUNCTION gst_debug_get_default_threshold ##### -->
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<para>
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</para>
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@Returns:
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<!-- ##### FUNCTION gst_debug_set_threshold_for_name ##### -->
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<para>
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</para>
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@name:
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@level:
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<!-- ##### FUNCTION gst_debug_unset_threshold_for_name ##### -->
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<para>
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</para>
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@name:
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<!-- ##### MACRO GST_DEBUG_CATEGORY ##### -->
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<para>
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</para>
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@cat:
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<!-- ##### MACRO GST_DEBUG_CATEGORY_EXTERN ##### -->
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<para>
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</para>
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@cat:
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<!-- ##### MACRO GST_DEBUG_CATEGORY_STATIC ##### -->
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<para>
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</para>
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@cat:
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<!-- ##### MACRO GST_DEBUG_CATEGORY_INIT ##### -->
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<para>
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</para>
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@cat:
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@name:
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@color:
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@description:
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<!-- ##### FUNCTION gst_debug_category_free ##### -->
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<para>
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</para>
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@category:
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<!-- ##### FUNCTION gst_debug_category_set_threshold ##### -->
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<para>
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</para>
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@category:
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@level:
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<!-- ##### FUNCTION gst_debug_category_reset_threshold ##### -->
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<para>
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</para>
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@category:
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<!-- ##### FUNCTION gst_debug_category_get_threshold ##### -->
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<para>
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</para>
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@category:
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@Returns:
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<!-- ##### FUNCTION gst_debug_category_get_name ##### -->
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<para>
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</para>
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@category:
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@Returns:
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<!-- ##### FUNCTION gst_debug_category_get_color ##### -->
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<para>
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</para>
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@category:
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@Returns:
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<!-- ##### FUNCTION gst_debug_category_get_description ##### -->
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<para>
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</para>
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@category:
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@Returns:
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<!-- ##### FUNCTION gst_debug_get_all_categories ##### -->
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<para>
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</para>
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@Returns:
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<!-- ##### MACRO GST_CAT_LEVEL_LOG ##### -->
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<para>
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GST_CAT_LEVEL_LOG:
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Outputs a debugging message. This is the most general macro for outputting
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debugging messages. You will probably want to use one of the ones described
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below.
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</para>
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@cat: category to use
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@level: the severity of the message
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@object: the #GObject the message belongs to or NULL if none
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@...: A printf-style message to output
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<!-- ##### MACRO GST_INFO ##### -->
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<para>
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Output an informational message in the default category.
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</para>
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@...: printf-style message to output
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<!-- ##### MACRO GST_DEBUG ##### -->
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<para>
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Output a debugging message in the default category.
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</para>
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_ERROR_OBJECT ##### -->
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<para>
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Output an error message belonging to the given object in the given category.
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</para>
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@cat: category to use
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_WARNING_OBJECT ##### -->
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<para>
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Output a warning message belonging to the given object in the given category.
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</para>
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@cat: category to use
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_INFO_OBJECT ##### -->
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<para>
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Output an informational message belonging to the given object in the given
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category.
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</para>
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@cat: category to use
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_DEBUG_OBJECT ##### -->
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<para>
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Output an debugging message belonging to the given object in the given category.
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</para>
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@cat: category to use
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_LOG_OBJECT ##### -->
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<para>
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Output an logging message belonging to the given object in the given category.
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</para>
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@cat: category to use
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_ERROR ##### -->
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<para>
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Output an error message in the given category.
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</para>
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@cat: category to use
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_WARNING ##### -->
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<para>
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Output a warning message in the given category.
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</para>
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@cat: category to use
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_LOG ##### -->
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<para>
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Output a logging message in the given category.
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</para>
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@cat: category to use
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@...: printf-style message to output
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<!-- ##### MACRO GST_ERROR_OBJECT ##### -->
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<para>
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Output an error message belonging to the given object in the default category.
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</para>
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_WARNING_OBJECT ##### -->
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<para>
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Output a warning message belonging to the given object in the default category.
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</para>
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_INFO_OBJECT ##### -->
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<para>
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Output an informational message belonging to the given object in the default
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category.
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</para>
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_DEBUG_OBJECT ##### -->
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<para>
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Output a debugging message belonging to the given object in the default
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category.
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</para>
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_LOG_OBJECT ##### -->
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<para>
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Output a logging message belonging to the given object in the default category.
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</para>
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@obj: the #GObject the message belongs to
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@...: printf-style message to output
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<!-- ##### MACRO GST_ERROR ##### -->
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<para>
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Output an error message in the default category.
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</para>
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@...: printf-style message to output
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<!-- ##### MACRO GST_WARNING ##### -->
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<para>
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|
Output a warning message in the default category.
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</para>
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@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_INFO ##### -->
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<para>
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|
Output an informational message in the given category.
|
|
</para>
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|
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@cat: category to use
|
|
@...: printf-style message to output
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<!-- ##### MACRO GST_CAT_DEBUG ##### -->
|
|
<para>
|
|
Output a debuggign message in the given category.
|
|
</para>
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|
|
|
@cat: category to use
|
|
@...: printf-style message to output
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|
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<!-- ##### MACRO GST_LOG ##### -->
|
|
<para>
|
|
Output a logging message in the default category.
|
|
</para>
|
|
|
|
@...: printf-style message to output
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|
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|
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<!-- ##### MACRO GST_DEBUG_FUNCPTR ##### -->
|
|
<para>
|
|
Register a pointer to a function with its name, so it can later be used by
|
|
GST_DEBUG_FUNCPTR_NAME().
|
|
</para>
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|
|
@ptr: The function to register
|
|
Returns: The ptr to the function.
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|
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<!-- ##### MACRO GST_DEBUG_FUNCPTR_NAME ##### -->
|
|
<para>
|
|
Retrieves the name of the function, if it was previously registered with
|
|
GST_DEBUG_FUNCPTR(). If not, it returns a description of the pointer.
|
|
<note>
|
|
<para>
|
|
Make sure you free the string after use.
|
|
</para>
|
|
</note>
|
|
</para>
|
|
|
|
@ptr: pointer to the function
|
|
Returns: The name of the function
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|
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