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design: Fix typos, indentions, and assorted improvements. Delete

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description of drain event
This commit is contained in:
ekwange 2019-08-22 14:15:43 +09:00
parent a7c41d6d3f
commit 8289d24aac
2 changed files with 27 additions and 49 deletions
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50
markdown/additional/design/element-sink.md
View file

@ -21,7 +21,7 @@ for this is that this way we can detect when the first buffer or event
arrives in the sink when the state change completes.
A sink should block on the first `EOS` event or buffer received in the
`READY→PAUSED` state before commiting the state to `PAUSED`.
`READY→PAUSED` state before committing the state to `PAUSED`.
`FLUSHING` events have to be handled out of sync with the buffer flow and
take no part in the preroll procedure.
@ -42,9 +42,9 @@ Events other than `EOS` do not complete the preroll stage.
switch (pending)
case PLAYING:
need_preroll = FALSE
break
break
case PAUSED:
break
break
case READY:
case NULL:
return FALSE
@ -178,7 +178,7 @@ Events other than `EOS` do not complete the preroll stage.
break
SEGMENT:
# the segment must be used to clip incoming
# buffers. Then then go into the queue as non-prerollable
# buffers. Then go into the queue as non-prerollable
# items used for syncing the buffers
STREAM_LOCK
PREROLL_LOCK
@ -234,50 +234,50 @@ Events other than `EOS` do not complete the preroll stage.
READY_PAUSED:
# no datapassing is going on so we always return ASYNC
ret = ASYNC
need_commit = TRUE
need_commit = TRUE
eos = FALSE
flushing = FALSE
need_preroll = TRUE
prerolled = FALSE
need_preroll = TRUE
prerolled = FALSE
break
PAUSED_PLAYING:
# we grab the preroll lock. This we can only do if the
# chain function is either doing some clock sync, we are
# waiting for preroll or the chain function is not being called.
# chain function is either doing some clock sync, we are
# waiting for preroll or the chain function is not being called.
PREROLL_LOCK
if (prerolled || eos)
if (prerolled || eos)
ret = OK
need_commit = FALSE
need_preroll = FALSE
if (eos)
post_eos
else
need_commit = FALSE
need_preroll = FALSE
if (eos)
post_eos
else
PREROLL_SIGNAL
else
need_preroll = TRUE
need_commit = TRUE
else
need_preroll = TRUE
need_commit = TRUE
ret = ASYNC
PREROLL_UNLOCK
break
PLAYING_PAUSED:
---> subclass can interrupt render
# we grab the preroll lock. This we can only do if the
# chain function is either doing some clock sync
# or the chain function is not being called.
# chain function is either doing some clock sync
# or the chain function is not being called.
PREROLL_LOCK
need_preroll = TRUE
need_preroll = TRUE
unlock_clock
if (prerolled || eos)
if (prerolled || eos)
ret = OK
else
else
ret = ASYNC
PREROLL_UNLOCK
break
PAUSED_READY:
---> subclass can interrupt render
# we grab the preroll lock. Set to flushing and unlock
# everything. This should exit the chain functions and stop
# streaming.
# everything. This should exit the chain functions and stop
# streaming.
PREROLL_LOCK
flushing = TRUE
unlock_clock

26
markdown/additional/design/events.md
View file

@ -14,7 +14,7 @@ Different types of events exist to implement various functionalities.
* `GST_EVENT_CAPS`: Format information about the following buffers
* `GST_EVENT_SEGMENT`: Timing information for the following buffers
* `GST_EVENT_TAG`: Stream metadata.
* `GST_EVENT_BUFFERSIZE`: Buffer size requirements
* `GST_EVENT_BUFFERSIZE`: Buffer size requirements. Currently not used yet.
* `GST_EVENT_SINK_MESSAGE`: An event turned into a message by sinks
* `GST_EVENT_EOS`: no more data is to be expected on a pad.
* `GST_EVENT_QOS`: A notification of the quality of service of the stream
@ -24,10 +24,6 @@ Different types of events exist to implement various functionalities.
* `GST_EVENT_STEP`: Stepping event
* `GST_EVENT_RECONFIGURE`: stream reconfigure event
- `GST_EVENT_DRAIN`: Play all data downstream before returning.
> not yet implemented, under investigation, might be needed to do
still frames in DVD.
## src pads
A `gst_pad_push_event()` on a srcpad will first store the sticky event
@ -44,7 +40,7 @@ A `gst_pad_send_event()` on a sinkpad will call the event function on
the pad. If the event function returns success, the sticky event is
stored in the sticky event array and the event is marked for update.
When the pad is flushing, the `_send_event()` function returns FALSE
When the pad is flushing, the `gst_pad_send_event()` function returns FALSE
immediately.
When the next data item is pushed, the pending events are pushed first.
@ -178,7 +174,6 @@ tagging system. A tag is serialized with buffers.
## BUFFERSIZE
> **Note**
>
> This event is not yet implemented.
An element can suggest a buffersize for downstream elements. This is
@ -263,20 +258,3 @@ value is calculated by the pipeline and distributed to all sink elements
before they are set to PLAYING. The sinks will add the configured
latency value to the timestamps of the buffer in order to delay their
presentation. (See also [latency](additional/design/latency.md)).
## DRAIN
> **Note**
>
> This event is not yet implemented.
Drain event indicates that upstream is about to perform a real-time
event, such as pausing to present an interactive menu or such, and needs
to wait for all data it has sent to be played-out in the sink.
Drain should only be used by live elements, as it may otherwise occur
during prerolling.
Usually after draining the pipeline, an element either needs to modify
timestamps, or FLUSH to prevent subsequent data being discarded at the
sinks for arriving late (only applies during playback scenarios).