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design/decodebin: add missing markup to gst keywords

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Fix grammar/spelling nits and drop trailing whitespace while at it.
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Reynaldo H. Verdejo Pinochet 2016-12-20 23:59:38 -08:00
parent 75d5a71617
commit 6c82899fa5
1 changed files with 38 additions and 38 deletions
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markdown/design/decodebin.md
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@ -22,8 +22,8 @@
The goal is to reach 'target' caps (by default raw media). The goal is to reach 'target' caps (by default raw media).
This is done by using the GstCaps of a source pad and finding the This is done by using the `GstCaps` of a source pad and finding the
available demuxers/decoders GstElement that can be linked to that pad. available demuxers/decoders `GstElement` that can be linked to that pad.
The process starts with the source pad of typefind and stops when no The process starts with the source pad of typefind and stops when no
more non-target caps are left. It is commonly done while pre-rolling, more non-target caps are left. It is commonly done while pre-rolling,
@ -32,28 +32,28 @@ but can also happen whenever a new pad appears on any element.
Once a target caps has been found, that pad is ghosted and the Once a target caps has been found, that pad is ghosted and the
'pad-added' signal is emitted. 'pad-added' signal is emitted.
If no compatible elements can be found for a GstCaps, the pad is ghosted If no compatible elements can be found for a `GstCaps`, the pad is ghosted
and the 'unknown-type' signal is emitted. and the 'unknown-type' signal is emitted.
### Assisted auto-plugging ### Assisted auto-plugging
When starting the auto-plugging process for a given GstCaps, two signals When starting the auto-plugging process for a given `GstCaps`, two signals
are emitted in the following way in order to allow the application/user are emitted in the following way in order to allow the application/user
to assist or fine-tune the process. to assist or fine-tune the process.
- **'autoplug-continue'**: - **'autoplug-continue'**:
gboolean user_function (GstElement * decodebin, GstPad *pad, GstCaps * caps) gboolean user_function (GstElement * decodebin, GstPad *pad, GstCaps * caps)
This signal is fired at the very beginning with the source pad GstCaps. If This signal is fired at the very beginning with the source pad `GstCaps`. If
the callback returns TRUE, the process continues normally. If the the callback returns TRUE, the process continues normally. If the
callback returns FALSE, then the GstCaps are considered as a target caps callback returns FALSE, then the `GstCaps` are considered as a target caps
and the autoplugging process stops. and the autoplugging process stops.
- **'autoplug-factories'**: - **'autoplug-factories'**:
GValueArray user_function (GstElement* decodebin, GstPad* pad, GstCaps* caps); GValueArray user_function (GstElement* decodebin, GstPad* pad, GstCaps* caps);
Get a list of elementfactories for @pad with @caps. This function is Get a list of elementfactories for @pad with @caps. This function is
used to instruct decodebin2 of the elements it should try to used to instruct decodebin2 of the elements it should try to
autoplug. The default behaviour when this function is not overriden autoplug. The default behaviour when this function is not overriden
@ -61,16 +61,16 @@ to assist or fine-tune the process.
sorted by rank. sorted by rank.
- **'autoplug-select'**: - **'autoplug-select'**:
gint user_function (GstElement* decodebin, GstPad* pad, GstCaps*caps, GValueArray* factories); gint user_function (GstElement* decodebin, GstPad* pad, GstCaps*caps, GValueArray* factories);
This signal is fired once autoplugging has got a list of compatible This signal is fired once autoplugging has got a list of compatible
GstElementFactory. The signal is emitted with the GstCaps of the `GstElementFactory`. The signal is emitted with the `GstCaps` of the
source pad and a pointer on the GValueArray of compatible factories. source pad and a pointer on the GValueArray of compatible factories.
The callback should return the index of the elementfactory in The callback should return the index of the elementfactory in
@factories that should be tried next. @factories that should be tried next.
If the callback returns -1, the autoplugging process will stop as if If the callback returns -1, the autoplugging process will stop as if
no compatible factories were found. no compatible factories were found.
@ -79,7 +79,7 @@ first factory of the list.
### Target Caps ### Target Caps
The target caps are a read/write GObject property of decodebin. The target caps are a read/write `GObject` property of decodebin.
By default the target caps are: By default the target caps are:
@ -111,7 +111,7 @@ Streams belonging to the same group/chain of a media file.
The DecodeGroup contains: The DecodeGroup contains:
- a GstMultiQueue to which all streams of a the media group are connected. - a `GstMultiQueue` to which all streams of the media group are connected.
- the eventual decoders which are autoplugged in order to produce the - the eventual decoders which are autoplugged in order to produce the
requested target pads. requested target pads.
@ -136,57 +136,57 @@ Multiple input-output data queue.
few differences: few differences:
- Multiple streams handling. - Multiple streams handling.
The element handles queueing data on more than one stream at once. The element handles queueing data on more than one stream at once.
To achieve such a feature it has request sink pads (sink\_%u) and To achieve such a feature it has request sink pads (sink\_%u) and
'sometimes' src pads (src\_%u). 'sometimes' src pads (src\_%u).
When requesting a given sinkpad, the associated srcpad for that When requesting a given sinkpad, the associated srcpad for that
stream will be created. Ex: requesting sink\_1 will generate src\_1. stream will be created. Ex: requesting sink\_1 will generate src\_1.
- Non-starvation on multiple streams. - Non-starvation on multiple streams.
If more than one stream is used with the element, the streams' If more than one stream is used with the element, the streams'
queues will be dynamically grown (up to a limit), in order to ensure queues will be dynamically grown (up to a limit), in order to ensure
that no stream is risking data starvation. This guarantees that at that no stream is risking data starvation. This guarantees that at
any given time there are at least N bytes queued and available for any given time there are at least N bytes queued and available for
each individual stream. each individual stream.
If an EOS event comes through a srcpad, the associated queue should If an EOS event comes through a srcpad, the associated queue should
be considered as 'not-empty' in the queue-size-growing algorithm. be considered as 'not-empty' in the queue-size-growing algorithm.
- Non-linked srcpads graceful handling. - Non-linked srcpads graceful handling.
A GstTask is started for all srcpads when going to A `GstTask` is started for all srcpads when going to
GST\_STATE\_PAUSED. `GST_STATE_PAUSED`.
The task are blocking against a GCondition which will be fired in The task are blocking against a GCondition which will be fired in
two different cases: two different cases:
- When the associated queue has received a buffer. - When the associated queue has received a buffer.
- When the associated queue was previously declared as 'not-linked' - When the associated queue was previously declared as 'not-linked'
and the first buffer of the queue is scheduled to be pushed and the first buffer of the queue is scheduled to be pushed
synchronously in relation to the order in which it arrived globally synchronously in relation to the order in which it arrived globally
in the element (see 'Synchronous data pushing' below). in the element (see 'Synchronous data pushing' below).
When woken up by the GCondition, the GstTask will try to push the When woken up by the GCondition, the `GstTask` will try to push the
next GstBuffer/GstEvent on the queue. If pushing the next `GstBuffer`/`GstEvent` on the queue. If pushing the
GstBuffer/GstEvent returns GST\_FLOW\_NOT\_LINKED, then the `GstBuffer`/`GstEvent` returns `GST_FLOW_NOT_LINKED`, then the
associated queue is marked as 'not-linked'. If pushing the associated queue is marked as 'not-linked'. If pushing the
GstBuffer/GstEvent succeeded the queue will no longer be marked as `GstBuffer`/`GstEvent` succeeded the queue will no longer be marked as
'not-linked'. 'not-linked'.
If pushing on all srcpads returns GstFlowReturn different from If pushing on all srcpads returns `GstFlowReturn` different from
GST\_FLOW\_OK, then all the srcpads' tasks are stopped and `GST_FLOW_OK`, then all the srcpads' tasks are stopped and
subsequent pushes on sinkpads will return GST\_FLOW\_NOT\_LINKED. subsequent pushes on sinkpads will return `GST_FLOW_NOT_LINKED`.
- Synchronous data pushing for non-linked pads. - Synchronous data pushing for non-linked pads.
In order to better support dynamic switching between streams, the In order to better support dynamic switching between streams, the
multiqueue (unlike the current GStreamer queue) continues to push multiqueue (unlike the current GStreamer queue) continues to push
buffers on non-linked pads rather than shutting down. buffers on non-linked pads rather than shutting down.
In addition, to prevent a non-linked stream from very quickly In addition, to prevent a non-linked stream from very quickly
consuming all available buffers and thus 'racing ahead' of the other consuming all available buffers and thus 'racing ahead' of the other
streams, the element must ensure that buffers and inlined events for streams, the element must ensure that buffers and inlined events for
@ -224,7 +224,7 @@ accordingly, if conversion is needed at all.
In an auto-plugging context this is not so straight-forward though, In an auto-plugging context this is not so straight-forward though,
because elements are plugged incrementally and not before the previous because elements are plugged incrementally and not before the previous
element has processes some data and decided what it will output exactly element has processed some data and decided what it will output exactly
(unless the template caps are completely fixed, then it can continue (unless the template caps are completely fixed, then it can continue
right away, this is not always the case here though, see below). A right away, this is not always the case here though, see below). A
parser will thus have to decide on *some* output format so auto-plugging parser will thus have to decide on *some* output format so auto-plugging