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16ce2d4ea4
Unify the ad-hoc markup to be asciidoc style in many places. Add a "html" target to Makefile to generate the output.
68 lines
2 KiB
Text
68 lines
2 KiB
Text
Streams
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-------
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This document describes the objects that are passed from element to
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element in the streaming thread.
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Stream objects
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~~~~~~~~~~~~~~
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The following objects are to be expected in the streaming thread:
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- events
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- NEW_SEGMENT (NS)
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- EOS (EOS) *
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- TAG (T)
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- buffers (B) *
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Objects marked with * need to be synchronised to the clock in sinks
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and live sources.
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Typical stream
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~~~~~~~~~~~~~~
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A typical stream starts with a newsegment event that marks the
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buffer timestamp range. After that buffers are send one after the
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other. After the last buffer an EOS marks the end of the stream. No
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more buffer are to be processed after the EOS event.
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+--+ +-++-+ +-+ +---+
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|NS| |B||B| ... |B| |EOS|
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+--+ +-++-+ +-+ +---+
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1) NEW_SEGMENT, rate, start/stop, time
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- marks valid buffer timestamp range (start, stop)
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- marks stream_time of buffers (time). This is the stream time of buffers
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with a timestamp of NS.start.
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- marks playback rate (rate). This is the required playback rate.
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- marks applied rate (applied_rate). This is the already applied playback
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rate. (See also part-trickmodes.txt)
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2) N buffers
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- displayable buffers are between start/stop of the NEW_SEGMENT. Buffers
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outside the segment range should be dropped or clipped.
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- running_time:
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if (NS.rate > 0.0)
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running_time = (B.timestamp - NS.start) / NS.abs_rate + NS.accum
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else
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running_time = (NS.stop - B.timestamp) / NS.abs_rate + NS.accum
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* a monotonically increasing value that can be used to synchronize
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against the clock (See also part-synchronisation.txt).
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- stream_time:
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stream_time = (B.timestamp - NS.start) * NS.abs_applied_rate + NS.time
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* current position in stream between 0 and duration.
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3) EOS
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- marks the end of data, nothing is to be expected after EOS, elements
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should refuse more data and return GST_FLOW_UNEXPECTED. A FLUSH_STOP
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event clears the EOS state of an element.
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