Segment

Object Hierarchy:

Description:

public class Segment

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 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 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, 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, 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)

Namespace: Gst

Package: gstreamer-0.10

Content:

Creation methods:

public Segment ()
Allocate a new Segment structure and initialize it using init.

Methods:

public bool clip (Format format, int64 start, int64 stop, out int64 clip_start, out int64 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. completely in segment, FALSE if the values are completely outside of the segment.
public Segment copy ()
Create a copy of given segment.
public void 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.
public void set_duration (Format format, int64 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.
public void set_last_stop (Format format, int64 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.
public void set_newsegment (bool update, double rate, Format format, int64 start, int64 stop, int64 time)
Update the segment structure with the field values of a new segment event and with a default applied_rate of 1.0.
public void set_newsegment_full (bool update, double rate, double applied_rate, Format format, int64 start, int64 stop, int64 time)
Update the segment structure with the field values of a new segment event.
public bool set_running_time (Format format, int64 running_time)
Adjust the start/stop and accum values of segment such that the next valid buffer will be one with running_time. returned, running_time is -1 or not in segment.
public void set_seek (double rate, Format format, SeekFlags flags, SeekType start_type, int64 start, SeekType stop_type, int64 stop, bool update)
Update the segment structure with the field values of a seek event (see Event.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 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 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), 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. last_stop field. This field can be FALSE if, for example, only the rate has been changed but not the playback position.
public int64 to_position (Format format, int64 running_time)
Convert running_time into a position in the segment so that to_running_time with that position returns running_time. -1 when running_time is -1 or when it is not inside segment.
public int64 to_running_time (Format format, int64 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 init is called, this value will reset to 0. This function returns -1 if the position is outside of segment start and stop. was given.
public int64 to_stream_time (Format format, int64 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. was given.

Fields:

public double abs_rate
public int64 accum
public double applied_rate
public int64 duration
public SeekFlags flags
public Format format
public int64 last_stop
public double rate
public int64 start
public int64 stop
public int64 time