GstSegment: GStreamer 1.0 Core Reference Manual

GstSegment

GstSegment — Structure describing the configured region of interest in a media file.

Functions

gboolean	gst_segment_clip ()
void	gst_segment_init ()
GstSegment *	gst_segment_new ()
GstSegment *	gst_segment_copy ()
void	gst_segment_free ()
gboolean	gst_segment_do_seek ()
guint64	gst_segment_position_from_stream_time ()
gint	gst_segment_position_from_stream_time_full ()
guint64	gst_segment_to_running_time ()
gint	gst_segment_to_running_time_full ()
guint64	gst_segment_to_stream_time ()
gint	gst_segment_to_stream_time_full ()
guint64	gst_segment_position_from_running_time ()
gint	gst_segment_position_from_running_time_full ()
guint64	gst_segment_to_position ()
gboolean	gst_segment_set_running_time ()
void	gst_segment_copy_into ()
gboolean	gst_segment_offset_running_time ()
gboolean	gst_segment_is_equal ()

Types and Values

struct	GstSegment
enum	GstSegmentFlags

Object Hierarchy

    GBoxed
    ╰── GstSegment

Includes

#include <gst/gstprotection.h>

Description

This helper structure holds the relevant values for tracking the region of interest in a media file, called a segment.

The structure can be used for two purposes:

performing seeks (handling seek events)
tracking playback regions (handling newsegment events)

The segment is usually configured by the application with a seek event which is propagated upstream and eventually handled by an element that performs the seek.

The configured segment is then propagated back downstream with a newsegment event. This information is then used to clip media to the segment boundaries.

A segment structure is initialized with gst_segment_init(), which takes a GstFormat that will be used as the format of the segment values. The segment will be configured with a start value of 0 and a stop/duration of -1, which is undefined. The default rate and applied_rate is 1.0.

The public duration field contains the duration of the segment. When using the segment for seeking, the start and time members should normally be left to their default 0 value. The stop position is left to -1 unless explicitly configured to a different value after a seek event.

The current position in the segment should be set by changing the position member in the structure.

For elements that perform seeks, the current segment should be updated with the gst_segment_do_seek() and the values from the seek event. This method will update all the segment fields. The position field will contain the new playback position. If the start_type was different from GST_SEEK_TYPE_NONE, playback continues from the position position, possibly with updated flags or rate.

For elements that want to use GstSegment to track the playback region, update the segment fields with the information from the newsegment event. The gst_segment_clip() method can be used to check and clip the media data to the segment boundaries.

For elements that want to synchronize to the pipeline clock, gst_segment_to_running_time() can be used to convert a timestamp to a value that can be used to synchronize to the clock. This function takes into account the base as well as any rate or applied_rate conversions.

For elements that need to perform operations on media data in stream_time, gst_segment_to_stream_time() can be used to convert a timestamp and the segment info to stream time (which is always between 0 and the duration of the stream).

Functions

gst_segment_clip ()

gboolean
gst_segment_clip (const GstSegment *segment,
                  GstFormat format,
                  guint64 start,
                  guint64 stop,
                  guint64 *clip_start,
                  guint64 *clip_stop);

Clip the given start and stop values to the segment boundaries given in segment . start and stop are compared and clipped to segment start and stop values.

If the function returns FALSE, start and stop are known to fall outside of segment and clip_start and clip_stop are not updated.

When the function returns TRUE, clip_start and clip_stop will be updated. If clip_start or clip_stop are different from start or stop respectively, the region fell partially in the segment.

Note that when stop is -1, clip_stop will be set to the end of the segment. Depending on the use case, this may or may not be what you want.

Parameters

segment	a GstSegment structure.
format	the format of the segment.
start	the start position in the segment
stop	the stop position in the segment
clip_start	the clipped start position in the segment.	[out][allow-none]
clip_stop	the clipped stop position in the segment.	[out][allow-none]

Returns

TRUE if the given start and stop times fall partially or completely in segment , FALSE if the values are completely outside of the segment.

gst_segment_init ()

void
gst_segment_init (GstSegment *segment,
                  GstFormat format);

The start/position fields are set to 0 and the stop/duration fields are set to -1 (unknown). The default rate of 1.0 and no flags are set.

Initialize segment to its default values.

Parameters

segment	a GstSegment structure.
format	the format of the segment.

gst_segment_new ()

GstSegment *
gst_segment_new (void);

Allocate a new GstSegment structure and initialize it using gst_segment_init().

Free-function: gst_segment_free

Returns

a new GstSegment, free with gst_segment_free().

[transfer full]

gst_segment_copy ()

GstSegment *
gst_segment_copy (const GstSegment *segment);

Create a copy of given segment .

Free-function: gst_segment_free

Parameters

segment

a GstSegment.

[transfer none]

Returns

a new GstSegment, free with gst_segment_free().

[transfer full]

gst_segment_free ()

void
gst_segment_free (GstSegment *segment);

Free the allocated segment segment .

Parameters

segment

a GstSegment.

[in][transfer full]

gst_segment_do_seek ()

gboolean
gst_segment_do_seek (GstSegment *segment,
                     gdouble rate,
                     GstFormat format,
                     GstSeekFlags flags,
                     GstSeekType start_type,
                     guint64 start,
                     GstSeekType stop_type,
                     guint64 stop,
                     gboolean *update);

Update the segment structure with the field values of a seek event (see gst_event_new_seek()).

After calling this method, the segment field position and time will contain the requested new position in the segment. The new requested position in the segment depends on rate and start_type and stop_type .

For positive rate , the new position in the segment is the new segment start field when it was updated with a start_type different from GST_SEEK_TYPE_NONE. If no update was performed on segment start position (GST_SEEK_TYPE_NONE), start is ignored and segment position is unmodified.

For negative rate , the new position in the segment is the new segment stop field when it was updated with a stop_type different from GST_SEEK_TYPE_NONE. If no stop was previously configured in the segment, the duration of the segment will be used to update the stop position. If no update was performed on segment stop position (GST_SEEK_TYPE_NONE), stop is ignored and segment position is unmodified.

The applied rate of the segment will be set to 1.0 by default. If the caller can apply a rate change, it should update segment rate and applied_rate after calling this function.

update will be set to TRUE if a seek should be performed to the segment position field. This field can be FALSE if, for example, only the rate has been changed but not the playback position.

Parameters

segment	a GstSegment structure.
rate	the rate of the segment.
format	the format of the segment.
flags	the segment flags for the segment
start_type	the seek method
start	the seek start value
stop_type	the seek method
stop	the seek stop value
update	boolean holding whether position was updated.	[out][allow-none]

Returns

TRUE if the seek could be performed.

gst_segment_position_from_stream_time ()

guint64
gst_segment_position_from_stream_time (const GstSegment *segment,
                                       GstFormat format,
                                       guint64 stream_time);

Convert stream_time into a position in the segment so that gst_segment_to_stream_time() with that position returns stream_time .

Parameters

segment	a GstSegment structure.
format	the format of the segment.
stream_time	the stream_time in the segment

Returns

the position in the segment for stream_time . This function returns -1 when stream_time is -1 or when it is not inside segment .

Since: 1.8

gst_segment_position_from_stream_time_full ()

gint
gst_segment_position_from_stream_time_full
                               (const GstSegment *segment,
                                GstFormat format,
                                guint64 stream_time,
                                guint64 *position);

Translate stream_time to the segment position using the currently configured segment. Compared to gst_segment_position_from_stream_time() this function can return negative segment position.

This function is typically used by elements that need to synchronize buffers against the clock or each other.

stream_time can be any value and the result of this function for values outside of the segment is extrapolated.

When 1 is returned, stream_time resulted in a positive position returned in position .

When this function returns -1, the returned position should be negated to get the real negative segment position.

Parameters

segment	a GstSegment structure.
format	the format of the segment.
stream_time	the stream-time
position	the resulting position in the segment.	[out]

Returns

a 1 or -1 on success, 0 on failure.

Since: 1.8

gst_segment_to_running_time ()

guint64
gst_segment_to_running_time (const GstSegment *segment,
                             GstFormat format,
                             guint64 position);

Translate position to the total running time using the currently configured segment. Position is a value between segment start and stop time.

This function is typically used by elements that need to synchronize to the global clock in a pipeline. The running time is a constantly increasing value starting from 0. When gst_segment_init() is called, this value will reset to 0.

This function returns -1 if the position is outside of segment start and stop.

Parameters

segment	a GstSegment structure.
format	the format of the segment.
position	the position in the segment

Returns

the position as the total running time or -1 when an invalid position was given.

gst_segment_to_running_time_full ()

gint
gst_segment_to_running_time_full (const GstSegment *segment,
                                  GstFormat format,
                                  guint64 position,
                                  guint64 *running_time);

Translate position to the total running time using the currently configured segment. Compared to gst_segment_to_running_time() this function can return negative running-time.

This function is typically used by elements that need to synchronize buffers against the clock or eachother.

position can be any value and the result of this function for values outside of the segment is extrapolated.

When 1 is returned, position resulted in a positive running-time returned in running_time .

When this function returns -1, the returned running_time should be negated to get the real negative running time.

Parameters

segment	a GstSegment structure.
format	the format of the segment.
position	the position in the segment
running_time	result running-time.	[out][allow-none]

Returns

a 1 or -1 on success, 0 on failure.

Since: 1.6

gst_segment_to_stream_time ()

guint64
gst_segment_to_stream_time (const GstSegment *segment,
                            GstFormat format,
                            guint64 position);

Translate position to stream time using the currently configured segment. The position value must be between segment start and stop value.

This function is typically used by elements that need to operate on the stream time of the buffers it receives, such as effect plugins. In those use cases, position is typically the buffer timestamp or clock time that one wants to convert to the stream time. The stream time is always between 0 and the total duration of the media stream.

Parameters

segment	a GstSegment structure.
format	the format of the segment.
position	the position in the segment

Returns

the position in stream_time or -1 when an invalid position was given.

Since: 1.8

gst_segment_to_stream_time_full ()

gint
gst_segment_to_stream_time_full (const GstSegment *segment,
                                 GstFormat format,
                                 guint64 position,
                                 guint64 *stream_time);

Translate position to the total stream time using the currently configured segment. Compared to gst_segment_to_stream_time() this function can return negative stream-time.

This function is typically used by elements that need to synchronize buffers against the clock or eachother.

position can be any value and the result of this function for values outside of the segment is extrapolated.

When 1 is returned, position resulted in a positive stream-time returned in stream_time .

When this function returns -1, the returned stream_time should be negated to get the real negative stream time.

Parameters

segment	a GstSegment structure.
format	the format of the segment.
position	the position in the segment
stream_time	result stream-time.	[out]

Returns

a 1 or -1 on success, 0 on failure.

Since: 1.8

gst_segment_position_from_running_time ()

guint64
gst_segment_position_from_running_time
                               (const GstSegment *segment,
                                GstFormat format,
                                guint64 running_time);

Convert running_time into a position in the segment so that gst_segment_to_running_time() with that position returns running_time .

Parameters

segment	a GstSegment structure.
format	the format of the segment.
running_time	the running_time in the segment

Returns

the position in the segment for running_time . This function returns -1 when running_time is -1 or when it is not inside segment .

Since: 1.8

gst_segment_position_from_running_time_full ()

gint
gst_segment_position_from_running_time_full
                               (const GstSegment *segment,
                                GstFormat format,
                                guint64 running_time,
                                guint64 *position);

Translate running_time to the segment position using the currently configured segment. Compared to gst_segment_position_from_running_time() this function can return negative segment position.

This function is typically used by elements that need to synchronize buffers against the clock or each other.

running_time can be any value and the result of this function for values outside of the segment is extrapolated.

When 1 is returned, running_time resulted in a positive position returned in position .

When this function returns -1, the returned position should be negated to get the real negative segment position.

Parameters

segment	a GstSegment structure.
format	the format of the segment.
running_time	the running-time
position	the resulting position in the segment.	[out]

Returns

a 1 or -1 on success, 0 on failure.

Since: 1.8

gst_segment_to_position ()

guint64
gst_segment_to_position (const GstSegment *segment,
                         GstFormat format,
                         guint64 running_time);

gst_segment_to_position is deprecated and should not be used in newly-written code.

Use gst_segment_position_from_running_time() instead.

Convert running_time into a position in the segment so that gst_segment_to_running_time() with that position returns running_time .

Parameters

segment	a GstSegment structure.
format	the format of the segment.
running_time	the running_time in the segment

Returns

the position in the segment for running_time . This function returns -1 when running_time is -1 or when it is not inside segment .

gst_segment_set_running_time ()

gboolean
gst_segment_set_running_time (GstSegment *segment,
                              GstFormat format,
                              guint64 running_time);

Adjust the start/stop and base values of segment such that the next valid buffer will be one with running_time .

Parameters

segment	a GstSegment structure.
format	the format of the segment.
running_time	the running_time in the segment

Returns

TRUE if the segment could be updated successfully. If FALSE is returned, running_time is -1 or not in segment .

gst_segment_copy_into ()

void
gst_segment_copy_into (const GstSegment *src,
                       GstSegment *dest);

Copy the contents of src into dest .

Parameters

src	a GstSegment.	[transfer none]
dest	a GstSegment.	[transfer none]

gst_segment_offset_running_time ()

gboolean
gst_segment_offset_running_time (GstSegment *segment,
                                 GstFormat format,
                                 gint64 offset);

Adjust the values in segment so that offset is applied to all future running-time calculations.

Parameters

segment	a GstSegment structure.
format	the format of the segment.
offset	the offset to apply in the segment

Returns

TRUE if the segment could be updated successfully. If FALSE is returned, offset is not in segment .

Since: 1.2.3

gst_segment_is_equal ()

gboolean
gst_segment_is_equal (const GstSegment *s0,
                      const GstSegment *s1);

Checks for two segments being equal. Equality here is defined as perfect equality, including floating point values.

Parameters

s0	a GstSegment structure.
s1	a GstSegment structure.

Returns

TRUE if the segments are equal, FALSE otherwise.

Since: 1.6

Types and Values

struct GstSegment

struct GstSegment {
  GstSegmentFlags flags;

  gdouble         rate;
  gdouble         applied_rate;

  GstFormat       format;
  guint64         base;
  guint64         offset;
  guint64         start;
  guint64         stop;
  guint64         time;

  guint64         position;
  guint64         duration;
};

A helper structure that holds the configured region of interest in a media file.

Members

GstSegmentFlags `flags`;	flags for this segment
gdouble `rate`;	the playback rate of the segment
gdouble `applied_rate`;	the already applied rate to the segment
GstFormat `format`;	the format of the segment values
guint64 `base`;	the running time (plus elapsed time, see offset) of the segment start
guint64 `offset`;	the amount (in buffer timestamps) that has already been elapsed in the segment
guint64 `start`;	the start of the segment in buffer timestamp time (PTS)
guint64 `stop`;	the stop of the segment in buffer timestamp time (PTS)
guint64 `time`;	the stream time of the segment start
guint64 `position`;	the buffer timestamp position in the segment (used internally by elements such as sources, demuxers or parsers to track progress)
guint64 `duration`;	the duration of the stream

enum GstSegmentFlags

Flags for the GstSegment structure. Currently mapped to the corresponding values of the seek flags.

Members

GST_SEGMENT_FLAG_NONE	no flags
GST_SEGMENT_FLAG_RESET	reset the pipeline running_time to the segment running_time
GST_SEGMENT_FLAG_TRICKMODE	perform skip playback (Since 1.6)
GST_SEGMENT_FLAG_SKIP	Deprecated backward compatibility flag, replaced by `GST_SEGMENT_FLAG_TRICKMODE`
GST_SEGMENT_FLAG_SEGMENT	send SEGMENT_DONE instead of EOS
GST_SEGMENT_FLAG_TRICKMODE_KEY_UNITS	Decode only keyframes, where possible (Since 1.6)
GST_SEGMENT_FLAG_TRICKMODE_NO_AUDIO	Do not decode any audio, where possible (Since 1.6)

GstSegment

Functions

Types and Values

Object Hierarchy

Includes

Description

Functions

gst_segment_clip ()

Parameters

Returns

gst_segment_init ()

Parameters

gst_segment_new ()

Returns

gst_segment_copy ()

Parameters

Returns

gst_segment_free ()

Parameters

gst_segment_do_seek ()

Parameters

Returns

gst_segment_position_from_stream_time ()

Parameters

Returns

gst_segment_position_from_stream_time_full ()

Parameters

Returns

gst_segment_to_running_time ()

Parameters

Returns

gst_segment_to_running_time_full ()

Parameters

Returns

gst_segment_to_stream_time ()

Parameters

Returns

gst_segment_to_stream_time_full ()

Parameters

Returns

gst_segment_position_from_running_time ()

Parameters

Returns

gst_segment_position_from_running_time_full ()

Parameters

Returns

gst_segment_to_position ()

Parameters

Returns

gst_segment_set_running_time ()

Parameters

Returns

gst_segment_copy_into ()

Parameters

gst_segment_offset_running_time ()

Parameters

Returns

gst_segment_is_equal ()

Parameters

Returns

Types and Values

struct GstSegment

Members

enum GstSegmentFlags

Members

See Also