| Streams |
| ------- |
| |
| This document describes the objects that are passed from element to |
| element in the streaming thread. |
| |
| |
| Stream objects |
| -------------- |
| |
| The following objects are to be expected in the streaming thread: |
| |
| - events |
| - NEW_SEGMENT (NS) |
| - EOS (EOS) * |
| - TAG (T) |
| - buffers (B) * |
| |
| Objects marked with * need to be synchronised to the clock in sinks |
| and live sources. |
| |
| |
| Typical stream |
| -------------- |
| |
| A typical stream starts with a newsegment event that marks the |
| buffer timestamp range. After that buffers are send one after the |
| other. After the last buffer an EOS marks the end of the stream. No |
| more buffer are to be processed after the EOS event. |
| |
| +--+ +-++-+ +-+ +---+ |
| |NS| |B||B| ... |B| |EOS| |
| +--+ +-++-+ +-+ +---+ |
| |
| 1) NEW_SEGMENT, rate, start/stop, time |
| - marks valid buffer timestamp range (start, stop) |
| - marks stream_time of buffers (time) |
| - marks playback rate (rate) |
| - marks applied rate (applied_rate) |
| |
| 2) N buffers |
| - displayable buffers are between start/stop of the NEW_SEGMENT |
| |
| - display_time: (B.timestamp - NS.start) * NS.abs_rate |
| * used to calculate stream_time and sync_time |
| |
| - stream_time: display_time + NS.time |
| * current position in stream between 0 and duration |
| |
| - sync_time: display_time + NS.accum + base_time |
| * used to synchronize against the clock. |
| |
| 3) EOS |
| - marks the end of data, nothing is to be expected after EOS |
| |
| |
