GstQuery

typedef struct {
  GstMiniObject mini_object;

  GstQueryType type;

  GstStructure *structure;
} GstQuery;

The GstQuery structure.

enum GstQueryType

typedef enum {
  GST_QUERY_NONE = 0,
  GST_QUERY_POSITION,
  GST_QUERY_DURATION,
  GST_QUERY_LATENCY,
  GST_QUERY_JITTER, 	/* not in draft-query, necessary? */
  GST_QUERY_RATE,
  GST_QUERY_SEEKING,
  GST_QUERY_SEGMENT,
  GST_QUERY_CONVERT,
  GST_QUERY_FORMATS,
  GST_QUERY_BUFFERING,
  GST_QUERY_CUSTOM,
  GST_QUERY_URI
} GstQueryType;

Standard predefined Query types

GST_QUERY_TYPE_NAME()

#define GST_QUERY_TYPE_NAME(query) (gst_query_type_get_name(GST_QUERY_TYPE(query)))

Get a constant string representation of the GstQueryType of the query.

Since 0.10.4

GstQueryTypeDefinition

typedef struct {
  GstQueryType   value;
  gchar  	*nick;
  gchar  	*description;
  GQuark         quark;
} GstQueryTypeDefinition;

A Query Type definition

gst_query_type_get_name ()

const gchar*        gst_query_type_get_name             (GstQueryType query);

Get a printable name for the given query type. Do not modify or free.

gst_query_type_to_quark ()

GQuark              gst_query_type_to_quark             (GstQueryType query);

Get the unique quark for the given query type.

gst_query_type_register ()

GstQueryType        gst_query_type_register             (const gchar *nick,
                                                         const gchar *description);

Create a new GstQueryType based on the nick or return an already registered query with that nick

gst_query_type_get_by_nick ()

GstQueryType        gst_query_type_get_by_nick          (const gchar *nick);

Get the query type registered with nick.

gst_query_types_contains ()

gboolean            gst_query_types_contains            (const GstQueryType *types,
                                                         GstQueryType type);

See if the given GstQueryType is inside the types query types array.

gst_query_type_get_details ()

const GstQueryTypeDefinition* gst_query_type_get_details
                                                        (GstQueryType type);

Get details about the given GstQueryType.

gst_query_type_iterate_definitions ()

GstIterator*        gst_query_type_iterate_definitions  (void);

Get a GstIterator of all the registered query types. The definitions iterated over are read only.

gst_query_ref ()

GstQuery*           gst_query_ref                       (GstQuery *q);

Increases the refcount of the given query by one.

gst_query_unref ()

void                gst_query_unref                     (GstQuery *q);

Decreases the refcount of the query. If the refcount reaches 0, the query will be freed.

gst_query_copy ()

GstQuery*           gst_query_copy                      (const GstQuery *q);

Copies the given query using the copy function of the parent GstData structure.

gst_query_make_writable()

#define         gst_query_make_writable(q)	GST_QUERY (gst_mini_object_make_writable (GST_MINI_OBJECT (q)))

Makes a writable query from the given query.

gst_query_new_application ()

GstQuery*           gst_query_new_application           (GstQueryType type,
                                                         GstStructure *structure);

Constructs a new custom application query object. Use gst_query_unref() when done with it.

gst_query_get_structure ()

GstStructure*       gst_query_get_structure             (GstQuery *query);

Get the structure of a query.

gst_query_new_convert ()

GstQuery*           gst_query_new_convert               (GstFormat src_format,
                                                         gint64 value,
                                                         GstFormat dest_format);

Constructs a new convert query object. Use gst_query_unref() when done with it. A convert query is used to ask for a conversion between one format and another.

gst_query_set_convert ()

void                gst_query_set_convert               (GstQuery *query,
                                                         GstFormat src_format,
                                                         gint64 src_value,
                                                         GstFormat dest_format,
                                                         gint64 dest_value);

Answer a convert query by setting the requested values.

gst_query_parse_convert ()

void                gst_query_parse_convert             (GstQuery *query,
                                                         GstFormat *src_format,
                                                         gint64 *src_value,
                                                         GstFormat *dest_format,
                                                         gint64 *dest_value);

Parse a convert query answer. Any of src_format, src_value, dest_format, and dest_value may be NULL, in which case that value is omitted.

gst_query_new_position ()

GstQuery*           gst_query_new_position              (GstFormat format);

Constructs a new query stream position query object. Use gst_query_unref() when done with it. A position query is used to query the current position of playback in the streams, in some format.

gst_query_set_position ()

void                gst_query_set_position              (GstQuery *query,
                                                         GstFormat format,
                                                         gint64 cur);

Answer a position query by setting the requested value in the given format.

gst_query_parse_position ()

void                gst_query_parse_position            (GstQuery *query,
                                                         GstFormat *format,
                                                         gint64 *cur);

Parse a position query, writing the format into format, and the position into cur, if the respective parameters are non-NULL.

gst_query_new_duration ()

GstQuery*           gst_query_new_duration              (GstFormat format);

Constructs a new stream duration query object to query in the given format. Use gst_query_unref() when done with it. A duration query will give the total length of the stream.

gst_query_set_duration ()

void                gst_query_set_duration              (GstQuery *query,
                                                         GstFormat format,
                                                         gint64 duration);

Answer a duration query by setting the requested value in the given format.

gst_query_parse_duration ()

void                gst_query_parse_duration            (GstQuery *query,
                                                         GstFormat *format,
                                                         gint64 *duration);

Parse a duration query answer. Write the format of the duration into format, and the value into duration, if the respective variables are non-NULL.

gst_query_new_latency ()

GstQuery*           gst_query_new_latency               (void);

Constructs a new latency query object. Use gst_query_unref() when done with it. A latency query is usually performed by sinks to compensate for additional latency introduced by elements in the pipeline.

Since 0.10.12

gst_query_parse_latency ()

void                gst_query_parse_latency             (GstQuery *query,
                                                         gboolean *live,
                                                         GstClockTime *min_latency,
                                                         GstClockTime *max_latency);

Parse a latency query answer.

Since 0.10.12

gst_query_set_latency ()

void                gst_query_set_latency               (GstQuery *query,
                                                         gboolean live,
                                                         GstClockTime min_latency,
                                                         GstClockTime max_latency);

Answer a latency query by setting the requested values in the given format.

Since 0.10.12

gst_query_new_seeking ()

GstQuery*           gst_query_new_seeking               (GstFormat format);

Constructs a new query object for querying seeking properties of the stream.

gst_query_set_seeking ()

void                gst_query_set_seeking               (GstQuery *query,
                                                         GstFormat format,
                                                         gboolean seekable,
                                                         gint64 segment_start,
                                                         gint64 segment_end);

Set the seeking query result fields in query.

gst_query_parse_seeking ()

void                gst_query_parse_seeking             (GstQuery *query,
                                                         GstFormat *format,
                                                         gboolean *seekable,
                                                         gint64 *segment_start,
                                                         gint64 *segment_end);

Parse a seeking query, writing the format into format, and other results into the passed parameters, if the respective parameters are non-NULL

gst_query_new_formats ()

GstQuery*           gst_query_new_formats               (void);

Constructs a new query object for querying formats of the stream.

Since 0.10.4

gst_query_set_formats ()

void                gst_query_set_formats               (GstQuery *query,
                                                         gint n_formats,
                                                         ...);

Set the formats query result fields in query. The number of formats passed must be equal to n_formats.

gst_query_set_formatsv ()

void                gst_query_set_formatsv              (GstQuery *query,
                                                         gint n_formats,
                                                         GstFormat *formats);

Set the formats query result fields in query. The number of formats passed in the formats array must be equal to n_formats.

Since 0.10.4

gst_query_parse_formats_length ()

void                gst_query_parse_formats_length      (GstQuery *query,
                                                         guint *n_formats);

Parse the number of formats in the formats query.

Since 0.10.4

gst_query_parse_formats_nth ()

void                gst_query_parse_formats_nth         (GstQuery *query,
                                                         guint nth,
                                                         GstFormat *format);

Parse the format query and retrieve the nth format from it into format. If the list contains less elements than nth, format will be set to GST_FORMAT_UNDEFINED.

Since 0.10.4

gst_query_new_segment ()

GstQuery*           gst_query_new_segment               (GstFormat format);

Constructs a new segment query object. Use gst_query_unref() when done with it. A segment query is used to discover information about the currently configured segment for playback.

gst_query_set_segment ()

void                gst_query_set_segment               (GstQuery *query,
                                                         gdouble rate,
                                                         GstFormat format,
                                                         gint64 start_value,
                                                         gint64 stop_value);

Answer a segment query by setting the requested values. The normal playback segment of a pipeline is 0 to duration at the default rate of 1.0. If a seek was performed on the pipeline to play a different segment, this query will return the range specified in the last seek.

start_value and stop_value will respectively contain the configured playback range start and stop values expressed in format. The values are always between 0 and the duration of the media and start_value <= stop_value. rate will contain the playback rate. For negative rates, playback will actually happen from stop_value to start_value.

gst_query_parse_segment ()

void                gst_query_parse_segment             (GstQuery *query,
                                                         gdouble *rate,
                                                         GstFormat *format,
                                                         gint64 *start_value,
                                                         gint64 *stop_value);

Parse a segment query answer. Any of rate, format, start_value, and stop_value may be NULL, which will cause this value to be omitted.

See gst_query_set_segment() for an explanation of the function arguments.

enum GstBufferingMode

typedef enum {
  GST_BUFFERING_STREAM,
  GST_BUFFERING_DOWNLOAD,
  GST_BUFFERING_TIMESHIFT,
  GST_BUFFERING_LIVE
} GstBufferingMode;

The different types of buffering methods.

gst_query_new_buffering ()

GstQuery*           gst_query_new_buffering             (GstFormat format);

Constructs a new query object for querying the buffering status of a stream.

Since 0.10.20

gst_query_set_buffering_percent ()

void                gst_query_set_buffering_percent     (GstQuery *query,
                                                         gboolean busy,
                                                         gint percent);

Set the percentage of buffered data. This is a value between 0 and 100. The busy indicator is TRUE when the buffering is in progress.

Since 0.10.20

gst_query_parse_buffering_percent ()

void                gst_query_parse_buffering_percent   (GstQuery *query,
                                                         gboolean *busy,
                                                         gint *percent);

Get the percentage of buffered data. This is a value between 0 and 100. The busy indicator is TRUE when the buffering is in progress.

Since 0.10.20

gst_query_set_buffering_stats ()

void                gst_query_set_buffering_stats       (GstQuery *query,
                                                         GstBufferingMode mode,
                                                         gint avg_in,
                                                         gint avg_out,
                                                         gint64 buffering_left);

Configures the buffering stats values in query.

Since 0.10.20

gst_query_parse_buffering_stats ()

void                gst_query_parse_buffering_stats     (GstQuery *query,
                                                         GstBufferingMode *mode,
                                                         gint *avg_in,
                                                         gint *avg_out,
                                                         gint64 *buffering_left);

Extracts the buffering stats values from query.

Since 0.10.20

gst_query_set_buffering_range ()

void                gst_query_set_buffering_range       (GstQuery *query,
                                                         GstFormat format,
                                                         gint64 start,
                                                         gint64 stop,
                                                         gint64 estimated_total);

Set the available query result fields in query.

Since 0.10.20

gst_query_parse_buffering_range ()

void                gst_query_parse_buffering_range     (GstQuery *query,
                                                         GstFormat *format,
                                                         gint64 *start,
                                                         gint64 *stop,
                                                         gint64 *estimated_total);

Parse an available query, writing the format into format, and other results into the passed parameters, if the respective parameters are non-NULL

Since 0.10.20

gst_query_new_uri ()

GstQuery*           gst_query_new_uri                   (void);

Constructs a new query URI query object. Use gst_query_unref() when done with it. An URI query is used to query the current URI that is used by the source or sink.

Since 0.10.22

gst_query_parse_uri ()

void                gst_query_parse_uri                 (GstQuery *query,
                                                         gchar **uri);

Parse an URI query, writing the URI into uri as a newly allocated string, if the respective parameters are non-NULL. Free the string with g_free() after usage.

Since 0.10.22

gst_query_set_uri ()

void                gst_query_set_uri                   (GstQuery *query,
                                                         const gchar *uri);

Answer a URI query by setting the requested URI.

Since 0.10.22