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segment: Enhance the GstSegment structure documentation

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Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/435>
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Thibault Saunier 2020-04-15 17:49:37 -04:00 committed by GStreamer Merge Bot
parent 416d4a13e0
commit c740c10404
1 changed files with 59 additions and 15 deletions
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74
gst/gstsegment.h
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@ -199,22 +199,66 @@ typedef enum { /*< flags >*/
/**
* GstSegment:
* @flags: flags for this segment
* @rate: the playback rate of the segment
* @applied_rate: the already applied rate to the segment
* @format: the format of the segment values
* @base: the running time (plus elapsed time, see offset) of the segment start
* @offset: the amount (in buffer timestamps) that has already been elapsed in
* the segment
* @start: the start of the segment in buffer timestamp time (PTS)
* @stop: the stop of the segment in buffer timestamp time (PTS)
* @time: the stream time of the segment start
* @position: the buffer timestamp position in the segment (used internally by
* elements such as sources, demuxers or parsers to track progress)
* @duration: the duration of the stream
* @flags: flags for this segment
* @rate: the playback rate of the segment is set in response to a seek
* event and, without any seek, the value should be `1.0`. This
* value is used by elements that synchronize buffer [running
* times](additional/design/synchronisation.md#running-time) on
* the clock (usually the sink elements), leading to consuming
* buffers faster (for a value `> 1.0`) or slower (for `0.0 <
* value < 1.0`) than normal playback speed. The rate also
* defines the playback direction, meaning that when the value is
* lower than `0.0`, the playback happens in reverse, and the
* [stream-time](additional/design/synchronisation.md#stream-time)
* is going backward. The `rate` value should never be `0.0`.
* @applied_rate: The applied rate is the rate that has been applied to the stream.
* The effective/resulting playback rate of a stream is
* `rate * applied_rate`.
* The applied rate can be set by source elements when a server is
* sending the stream with an already modified playback speed
* rate. Filter elements that modify the stream in a way that
* modifies the playback speed should also modify the applied
* rate. For example the #videorate element when its
* #videorate:rate property is set will set the applied rate of
* the segment it pushed downstream. Also #scaletempo applies the
* input segment rate to the stream and outputs a segment with
* rate=1.0 and applied_rate=<inputsegment.rate>.
* @format: the unit used for all of the segment's values.
* @base: the running time (plus elapsed time, see offset) of the
* segment [start](GstSegment.start) ([stop](GstSegment.stop) if
* rate < 0.0).
* @offset: the offset expresses the elapsed time (in buffer timestamps)
* before a seek with its start (stop if rate < 0.0) seek type
* set to #GST_SEEK_TYPE_NONE, the value is set to the position
* of the segment at the time of the seek.
* @start: the start time of the segment (in buffer timestamps)
* [(PTS)](GstBuffer.pts), that is the timestamp of the first
* buffer to output inside the segment (last one during
* reverse playback). For example decoders will
* [clip](gst_segment_clip) out the buffers before the start
* time.
* @stop: the stop time of the segment (in buffer timestamps)
* [(PTS)](GstBuffer.pts), that is the timestamp of the last
* buffer to output inside the segment (first one during
* reverse playback). For example decoders will
* [clip](gst_segment_clip) out buffers after the stop time.
* @time: the stream time of the segment [start](GstSegment.start)
* ([stop](GstSegment.stop) if rate < 0.0).
* @position: the buffer timestamp position in the segment is supposed to be
* updated by elements such as sources, demuxers or parsers to
* track progress by setting it to the last pushed buffer' end time
* ([timestamp](GstBuffer.pts) + #GstBuffer.duration) for that
* specific segment. The position is used when reconfiguring the
* segment with #gst_segment_do_seek when the seek is only
* updating the segment (see [offset](GstSegment.offset)).
* @duration: the duration of the segment is the maximum absolute difference
* between #GstSegment.start and #GstSegment.stop if stop is not
* set, otherwise it should be the difference between those
* two values. This should be set by elements that know the
* overall stream duration (like demuxers) and will be used when
* seeking with #GST_SEEK_TYPE_END.
*
* A helper structure that holds the configured region of
* interest in a media file.
* The structure that holds the configured region of interest in a media file.
*/
struct _GstSegment {
/*< public >*/