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Functions
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] |
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.
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
gst_segment_copy ()
GstSegment *
gst_segment_copy (const GstSegment *segment
);
Create a copy of given segment
.
Free-function: gst_segment_free
gst_segment_free ()
void
gst_segment_free (GstSegment *segment
);
Free the allocated segment segment
.
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] |
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] |
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 |
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] |
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 |
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] |
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
was < 0, and the value
in the position variable 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] |
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 |
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 |
gst_segment_copy_into ()
void gst_segment_copy_into (const GstSegment *src
,GstSegment *dest
);
Copy the contents of src
into dest
.
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.
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 for this segment |
|
gdouble |
the playback rate of the segment |
|
gdouble |
the already applied rate to the segment |
|
GstFormat |
the format of the segment values |
|
guint64 |
the running time (plus elapsed time, see offset) of the segment start |
|
guint64 |
the amount (in buffer timestamps) that has already been elapsed in the segment |
|
guint64 |
the start of the segment in buffer timestamp time (PTS) |
|
guint64 |
the stop of the segment in buffer timestamp time (PTS) |
|
guint64 |
the stream time of the segment start |
|
guint64 |
the buffer timestamp position in the segment (used internally by elements such as sources, demuxers or parsers to track progress) |
|
guint64 |
the duration of the stream |
enum GstSegmentFlags
Flags for the GstSegment structure. Currently mapped to the corresponding values of the seek flags.
Members
no flags |
||
reset the pipeline running_time to the segment running_time |
||
perform skip playback (Since 1.6) |
||
Deprecated backward compatibility flag, replaced
by |
||
send SEGMENT_DONE instead of EOS |
||
Decode only keyframes, where possible (Since 1.6) |
||
Do not decode any audio, where possible (Since 1.6) |