GstParse

GstParse — Get a pipeline from a text pipeline description

Synopsis


#include <gst/gst.h>

GQuark              gst_parse_error_quark               (void);
#define             GST_PARSE_ERROR
enum                GstParseError;
                    GstParseContext;
enum                GstParseFlags;
GstElement*         gst_parse_launch                    (const gchar *pipeline_description,
                                                         GError **error);
GstElement*         gst_parse_launch_full               (const gchar *pipeline_description,
                                                         GstParseContext *context,
                                                         GstParseFlags flags,
                                                         GError **error);
GstElement*         gst_parse_launchv                   (const gchar **argv,
                                                         GError **error);
GstElement*         gst_parse_launchv_full              (const gchar **argv,
                                                         GstParseContext *context,
                                                         GstParseFlags flags,
                                                         GError **error);
GstElement*         gst_parse_bin_from_description      (const gchar *bin_description,
                                                         gboolean ghost_unlinked_pads,
                                                         GError **err);
GstElement*         gst_parse_bin_from_description_full (const gchar *bin_description,
                                                         gboolean ghost_unlinked_pads,
                                                         GstParseContext *context,
                                                         GstParseFlags flags,
                                                         GError **err);

GstParseContext*    gst_parse_context_new               (void);
void                gst_parse_context_free              (GstParseContext *context);
gchar**             gst_parse_context_get_missing_elements
                                                        (GstParseContext *context);

Description

These function allow to create a pipeline based on the syntax used in the gst-launch utility.

Details

gst_parse_error_quark ()

GQuark              gst_parse_error_quark               (void);

Get the error quark used by the parsing subsystem.

Returns : the quark of the parse errors.

GST_PARSE_ERROR

#define GST_PARSE_ERROR gst_parse_error_quark ()

Get access to the error quark of the parse subsystem.


enum GstParseError

typedef enum
{
  GST_PARSE_ERROR_SYNTAX,
  GST_PARSE_ERROR_NO_SUCH_ELEMENT,
  GST_PARSE_ERROR_NO_SUCH_PROPERTY,
  GST_PARSE_ERROR_LINK,
  GST_PARSE_ERROR_COULD_NOT_SET_PROPERTY,
  GST_PARSE_ERROR_EMPTY_BIN,
  GST_PARSE_ERROR_EMPTY
} GstParseError;

The different parsing errors that can occur.

GST_PARSE_ERROR_SYNTAX A syntax error occured.
GST_PARSE_ERROR_NO_SUCH_ELEMENT The description contained an unknown element
GST_PARSE_ERROR_NO_SUCH_PROPERTY An element did not have a specified property
GST_PARSE_ERROR_LINK There was an error linking two pads.
GST_PARSE_ERROR_COULD_NOT_SET_PROPERTY There was an error setting a property
GST_PARSE_ERROR_EMPTY_BIN An empty bin was specified.
GST_PARSE_ERROR_EMPTY An empty description was specified

GstParseContext

typedef struct _GstParseContext GstParseContext;

Opaque structure.

Since 0.10.20


enum GstParseFlags

typedef enum
{
  GST_PARSE_FLAG_NONE = 0,
  GST_PARSE_FLAG_FATAL_ERRORS = (1 << 0)
} GstParseFlags;

Parsing options.

GST_PARSE_FLAG_NONE Do not use any special parsing options.
GST_PARSE_FLAG_FATAL_ERRORS Always return NULL when an error occurs (default behaviour is to return partially constructed bins or elements in some cases)

Since 0.10.20


gst_parse_launch ()

GstElement*         gst_parse_launch                    (const gchar *pipeline_description,
                                                         GError **error);

Create a new pipeline based on command line syntax. Please note that you might get a return value that is not NULL even though the error is set. In this case there was a recoverable parsing error and you can try to play the pipeline.

pipeline_description : the command line describing the pipeline
error : the error message in case of an erroneous pipeline.
Returns : a new element on success, NULL on failure. If more than one toplevel element is specified by the pipeline_description, all elements are put into a GstPipeline, which than is returned.

gst_parse_launch_full ()

GstElement*         gst_parse_launch_full               (const gchar *pipeline_description,
                                                         GstParseContext *context,
                                                         GstParseFlags flags,
                                                         GError **error);

Create a new pipeline based on command line syntax. Please note that you might get a return value that is not NULL even though the error is set. In this case there was a recoverable parsing error and you can try to play the pipeline.

pipeline_description : the command line describing the pipeline
context : a parse context allocated with gst_parse_context_new(), or NULL
flags : parsing options, or GST_PARSE_FLAG_NONE
error : the error message in case of an erroneous pipeline.
Returns : a new element on success, NULL on failure. If more than one toplevel element is specified by the pipeline_description, all elements are put into a GstPipeline, which then is returned.

Since 0.10.20


gst_parse_launchv ()

GstElement*         gst_parse_launchv                   (const gchar **argv,
                                                         GError **error);

Create a new element based on command line syntax. error will contain an error message if an erroneuos pipeline is specified. An error does not mean that the pipeline could not be constructed.

argv : null-terminated array of arguments
error : pointer to a GError
Returns : a new element on success and NULL on failure.

gst_parse_launchv_full ()

GstElement*         gst_parse_launchv_full              (const gchar **argv,
                                                         GstParseContext *context,
                                                         GstParseFlags flags,
                                                         GError **error);

Create a new element based on command line syntax. error will contain an error message if an erroneous pipeline is specified. An error does not mean that the pipeline could not be constructed.

argv : null-terminated array of arguments
context : a parse context allocated with gst_parse_context_new(), or NULL
flags : parsing options, or GST_PARSE_FLAG_NONE
error : pointer to a GError (which must be initialised to NULL)
Returns : a new element on success; on failure, either NULL or a partially-constructed bin or element will be returned and error will be set (unless you passed GST_PARSE_FLAG_FATAL_ERRORS in flags, then NULL will always be returned on failure)

Since 0.10.20


gst_parse_bin_from_description ()

GstElement*         gst_parse_bin_from_description      (const gchar *bin_description,
                                                         gboolean ghost_unlinked_pads,
                                                         GError **err);

This is a convenience wrapper around gst_parse_launch() to create a GstBin from a gst-launch-style pipeline description. See gst_parse_launch() and the gst-launch man page for details about the syntax. Ghost pads on the bin for unlinked source or sink pads within the bin can automatically be created (but only a maximum of one ghost pad for each direction will be created; if you expect multiple unlinked source pads or multiple unlinked sink pads and want them all ghosted, you will have to create the ghost pads yourself).

bin_description : command line describing the bin
ghost_unlinked_pads : whether to automatically create ghost pads for unlinked source or sink pads within the bin
err : where to store the error message in case of an error, or NULL
Returns : a newly-created bin, or NULL if an error occurred.

Since 0.10.3


gst_parse_bin_from_description_full ()

GstElement*         gst_parse_bin_from_description_full (const gchar *bin_description,
                                                         gboolean ghost_unlinked_pads,
                                                         GstParseContext *context,
                                                         GstParseFlags flags,
                                                         GError **err);

This is a convenience wrapper around gst_parse_launch() to create a GstBin from a gst-launch-style pipeline description. See gst_parse_launch() and the gst-launch man page for details about the syntax. Ghost pads on the bin for unlinked source or sink pads within the bin can automatically be created (but only a maximum of one ghost pad for each direction will be created; if you expect multiple unlinked source pads or multiple unlinked sink pads and want them all ghosted, you will have to create the ghost pads yourself).

bin_description : command line describing the bin
ghost_unlinked_pads : whether to automatically create ghost pads for unlinked source or sink pads within the bin
context : a parse context allocated with gst_parse_context_new(), or NULL
flags : parsing options, or GST_PARSE_FLAG_NONE
err : where to store the error message in case of an error, or NULL
Returns : a newly-created bin, or NULL if an error occurred.

Since 0.10.20


gst_parse_context_new ()

GstParseContext*    gst_parse_context_new               (void);

Allocates a parse context for use with gst_parse_launch_full() or gst_parse_launchv_full().

Returns : a newly-allocated parse context. Free with gst_parse_context_free() when no longer needed.

Since 0.10.20


gst_parse_context_free ()

void                gst_parse_context_free              (GstParseContext *context);

Frees a parse context previously allocated with gst_parse_context_new().

context : a GstParseContext

Since 0.10.20


gst_parse_context_get_missing_elements ()

gchar**             gst_parse_context_get_missing_elements
                                                        (GstParseContext *context);

Retrieve missing elements from a previous run of gst_parse_launch_full() or gst_parse_launchv_full(). Will only return results if an error code of GST_PARSE_ERROR_NO_SUCH_ELEMENT was returned.

context : a GstParseContext
Returns : a NULL-terminated array of element factory name strings of missing elements. Free with g_strfreev() when no longer needed.

Since 0.10.20