Gst::Segment Class Reference

Gst::Segment — Class describing the configured region of interest in a media file. More...

#include <segment.h>

List of all members.

Public Member Functions

 Segment ()
 Segment (GstSegment* gobject, bool make_a_copy=true)
 Segment (const Segment& other)
Segmentoperator= (const Segment& other)
 ~Segment ()
void swap (Segment& other)
GstSegment* gobj ()
 Provides access to the underlying C instance.
const GstSegment* gobj () const
 Provides access to the underlying C instance.
GstSegment* gobj_copy () const
 Provides access to the underlying C instance. The caller is responsible for freeing it. Use when directly setting fields in structs.
bool clip (Format format, gint64 start, gint64 stop, gint64& clip_start, gint64& clip_stop)
 Clip the given start and stop values to the segment boundaries given in segment.
void init (Format format)
 The start/last_stop positions are set to 0 and the stop/duration fields are set to -1 (unknown).
void set_duration (Format format, gint64 duration)
 Set the duration of the segment to duration.
void set_last_stop (Format format, gint64 position)
 Set the last observed stop position in the segment to position.
void set_newsegment (bool update, double rate, Format format, gint64 start, gint64 stop, gint64 time)
 Update the segment structure with the field values of a new segment event and with a default applied_rate of 1.0.
void set_newsegment (bool update, double rate, double applied_rate, Format format, gint64 start, gint64 stop, gint64 time)
 Update the segment structure with the field values of a new segment event.
void set_seek (double rate, Format format, SeekFlags flags, SeekType start_type, gint64 start, SeekType stop_type, gint64 stop, bool& update)
 Update the segment structure with the field values of a seek event (see Gst::Event::new_seek()).
gint64 convert_to_running_time (Format format, gint64 position)
 Translate position to the total running time using the currently configured and previously accumulated segments.
gint64 convert_to_stream_time (Format format, gint64 position)
 Translate position to stream time using the currently configured segment.

Protected Attributes

GstSegment* gobject_

Related Functions

(Note that these are not member functions.)

void swap (Segment& lhs, Segment& rhs)
Gst::Segment wrap (GstSegment* object, bool take_copy=false)
 A Glib::wrap() method for this object.


Detailed Description

Gst::Segment — Class describing the configured region of interest in a media file.

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:

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 init(), which takes a Format 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.

If the segment is used for managing seeks, the segment duration should be set with set_duration(). 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 with the set_last_stop(). The public last_stop field contains the last set stop position in the segment.

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

For elements that want to use Gst::Segment to track the playback region, use set_newsegment() to update the segment fields with the information from the newsegment event. The 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, convert_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 all accumulated segments as well as any rate or applied_rate conversions.

For elements that need to perform operations on media data in stream_time, convert_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).

Last reviewed on 2007-05-17 (0.10.13)


Constructor & Destructor Documentation

Gst::Segment::Segment (  ) 

Gst::Segment::Segment ( GstSegment *  gobject,
bool  make_a_copy = true 
) [explicit]

Gst::Segment::Segment ( const Segment other  ) 

Gst::Segment::~Segment (  ) 


Member Function Documentation

bool Gst::Segment::clip ( Format  format,
gint64  start,
gint64  stop,
gint64 &  clip_start,
gint64 &  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:
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.
clip_stop The clipped stop position in the segment.
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.

gint64 Gst::Segment::convert_to_running_time ( Format  format,
gint64  position 
)

Translate position to the total running time using the currently configured and previously accumulated segments.

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 runnning 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:
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.

gint64 Gst::Segment::convert_to_stream_time ( Format  format,
gint64  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:
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.

const GstSegment* Gst::Segment::gobj (  )  const [inline]

Provides access to the underlying C instance.

References gobject_.

GstSegment* Gst::Segment::gobj (  )  [inline]

Provides access to the underlying C instance.

References gobject_.

GstSegment* Gst::Segment::gobj_copy (  )  const

Provides access to the underlying C instance. The caller is responsible for freeing it. Use when directly setting fields in structs.

void Gst::Segment::init ( Format  format  ) 

The start/last_stop positions 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:
format The format of the segment.

Segment& Gst::Segment::operator= ( const Segment other  ) 

void Gst::Segment::set_duration ( Format  format,
gint64  duration 
)

Set the duration of the segment to duration.

This function is mainly used by elements that perform seeking and know the total duration of the segment.

This field should be set to allow seeking requests relative to the duration.

Parameters:
format The format of the segment.
duration The duration of the segment info or -1 if unknown.

void Gst::Segment::set_last_stop ( Format  format,
gint64  position 
)

Set the last observed stop position in the segment to position.

This field should be set to allow seeking requests relative to the current playing position.

Parameters:
format The format of the segment.
position The position.

void Gst::Segment::set_newsegment ( bool  update,
double  rate,
double  applied_rate,
Format  format,
gint64  start,
gint64  stop,
gint64  time 
)

Update the segment structure with the field values of a new segment event.

Parameters:
update Flag indicating a new segment is started or updated.
rate The rate of the segment.
applied_rate The applied rate of the segment.
format The format of the segment.
start The new start value.
stop The new stop value.
time The new stream time.

void Gst::Segment::set_newsegment ( bool  update,
double  rate,
Format  format,
gint64  start,
gint64  stop,
gint64  time 
)

Update the segment structure with the field values of a new segment event and with a default applied_rate of 1.0.

Since: 0.10.6

Parameters:
update Flag indicating a new segment is started or updated.
rate The rate of the segment.
format The format of the segment.
start The new start value.
stop The new stop value.
time The new stream time.

void Gst::Segment::set_seek ( double  rate,
Format  format,
SeekFlags  flags,
SeekType  start_type,
gint64  start,
SeekType  stop_type,
gint64  stop,
bool &  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 last_stop 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 last_stop 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 last_stop 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 last_stop field. This field can be false if, for example, only the rate has been changed but not the playback position.

Parameters:
rate The rate of the segment.
format The format of the segment.
flags The seek 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 last_stop was updated.

void Gst::Segment::swap ( Segment other  ) 

Referenced by swap().


Friends And Related Function Documentation

void swap ( Segment lhs,
Segment rhs 
) [related]

Parameters:
lhs The left-hand side
rhs The right-hand side

References swap().

Gst::Segment wrap ( GstSegment *  object,
bool  take_copy = false 
) [related]

A Glib::wrap() method for this object.

Parameters:
object The C instance.
take_copy False if the result should take ownership of the C instance. True if it should take a new copy or ref.
Returns:
A C++ instance that wraps this C instance.


Member Data Documentation

GstSegment* Gst::Segment::gobject_ [protected]

Referenced by gobj().


The documentation for this class was generated from the following file:

Generated on Thu Jan 15 09:33:13 2009 for gstreamermm by  doxygen 1.5.7.1