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Original commit message from CVS: * docs/design/Makefile.am: * docs/design/part-synchronisation.txt: Add doc about synchronisation * docs/design/draft-latency.txt: * docs/design/part-TODO.txt: * docs/design/part-clocks.txt: * docs/design/part-events.txt: * docs/design/part-gstbus.txt: * docs/design/part-gstpipeline.txt: * docs/design/part-live-source.txt: * docs/design/part-messages.txt: * docs/design/part-overview.txt: * docs/design/part-streams.txt: * docs/design/part-trickmodes.txt: Documentation updates.
67 lines
1.9 KiB
Plaintext
67 lines
1.9 KiB
Plaintext
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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* used to synchronize against the clock (See also
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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
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