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docs: design: fix some 0.10-isms in GstSegment docs

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1) segment.accum -> segment.base

2) Refer to GstSegment members as S.foo instead of
NS.foo, the event is now called a segment event
rather than newsegment event.

3) There's no more abs_rate field in GstSegment,
and there never was an abs_applied_rate field.

https://bugzilla.gnome.org/show_bug.cgi?id=690564
This commit is contained in:
Tim-Philipp Müller 2015-04-04 18:18:03 +01:00
parent f35ec14d33
commit 199c8ba561
2 changed files with 9 additions and 9 deletions
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12
docs/design/part-streams.txt
View file

@ -41,7 +41,7 @@ Typical stream
2) SEGMENT, rate, start/stop, time
- marks valid buffer timestamp range (start, stop)
- marks stream_time of buffers (time). This is the stream time of buffers
with a timestamp of NS.start.
with a timestamp of S.start.
- marks playback rate (rate). This is the required playback rate.
- marks applied rate (applied_rate). This is the already applied playback
rate. (See also part-trickmodes.txt)
@ -49,22 +49,22 @@ Typical stream
against the clock.
3) N buffers
- displayable buffers are between start/stop of the SEGMENT. Buffers
- displayable buffers are between start/stop of the SEGMENT (S). Buffers
outside the segment range should be dropped or clipped.
- running_time:
if (NS.rate > 0.0)
running_time = (B.timestamp - NS.start) / NS.abs_rate + NS.accum
if (S.rate > 0.0)
running_time = (B.timestamp - S.start) / ABS (S.rate) + S.base
else
running_time = (NS.stop - B.timestamp) / NS.abs_rate + NS.accum
running_time = (S.stop - B.timestamp) / ABS (S.rate) + S.base
* a monotonically increasing value that can be used to synchronize
against the clock (See also part-synchronisation.txt).
- stream_time:
stream_time = (B.timestamp - NS.start) * NS.abs_applied_rate + NS.time
stream_time = (B.timestamp - S.start) * ABS (S.applied_rate) + S.time
* current position in stream between 0 and duration.

6
docs/design/part-synchronisation.txt
View file

@ -114,8 +114,8 @@ For S.rate > 1.0, the timestamps will be scaled down to increase the playback
rate. Likewise, a rate between 0.0 and 1.0 will slow down playback.
For negative rates, timestamps are received stop S.stop to S.start so that the
first buffer received will be transformed into B.running_time of 0 (B.timestamp ==
S.stop and S.accum == 0).
first buffer received will be transformed into B.running_time of 0
(B.timestamp == S.stop and S.base == 0).
This makes it so that B.running_time is always monotonically increasing
starting from 0 with both positive and negative rates.
@ -219,7 +219,7 @@ allows us to rewrite the above formula for stream_time (and for positive rates).
filling (B.timestamp - S.start) in the above formule for stream time
=>
stream_time = (S.offset + (absolute_time - base_time - S.base) * ABS (S.rate)) * S.abs_applied_rate + S.time
stream_time = (S.offset + (absolute_time - base_time - S.base) * ABS (S.rate)) * ABS (S.applied_rate) + S.time
This last formula is typically used in sinks to report the current position in
an accurate and efficient way.