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design: decodebin: simplify non-linked handling explanation

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Additionally: fix missing markup & drop needless escaping
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Reynaldo H. Verdejo Pinochet 2017-03-20 12:54:02 -07:00
parent 8f548ae2f7
commit 5f1ce5aa5d
1 changed files with 23 additions and 17 deletions
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markdown/design/decodebin.md
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@ -43,7 +43,9 @@ 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
@ -52,7 +54,9 @@ to assist or fine-tune the process.
- **'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
@ -62,7 +66,9 @@ to assist or fine-tune the process.
- **'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
@ -92,13 +98,13 @@ By default the target caps are:
### Media chain/group handling ### Media chain/group handling
When autoplugging, all streams coming out of a demuxer will be grouped When autoplugging, all streams coming out of a demuxer will be grouped
in a DecodeGroup. in a `DecodeGroup`.
All new source pads created on that demuxer after it has emitted the All new source pads created on that demuxer after it has emitted the
'no-more-pads' signal will be put in another DecodeGroup. 'no-more-pads' signal will be put in another DecodeGroup.
Only one decodegroup can be active at any given time. If a new Only one decodegroup can be active at any given time. If a new
decodegroup is created while another one exists, that decodegroup will decodegroup is created while another one exists, that `DecodeGroup` will
be set as blocking until the existing one has drained. be set as blocking until the existing one has drained.
## DecodeGroup ## DecodeGroup
@ -118,12 +124,12 @@ The DecodeGroup contains:
### Proper group draining ### Proper group draining
The DecodeGroup takes care that all the streams in the group are The `DecodeGroup` takes care that all the streams in the group are
completely drained (EOS has come through all source ghost pads). completely drained (EOS has come through all source ghost pads).
### Pre-roll and block ### Pre-roll and block
The DecodeGroup has a global blocking feature. If enabled, all the The `DecodeGroup` has a global blocking feature. If enabled, all the
ghosted source pads for that group will be blocked. ghosted source pads for that group will be blocked.
A method is available to unblock all blocked pads for that group. A method is available to unblock all blocked pads for that group.
@ -138,11 +144,11 @@ 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.
@ -170,14 +176,12 @@ few differences:
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 returns
`GstBuffer`/`GstEvent` returns `GST_FLOW_NOT_LINKED`, then the `GST_FLOW_NOT_LINKED`, the associated queue is marked as `not-linked`.
associated queue is marked as 'not-linked'. If pushing the If pushing succeeds, the queue will no longer be marked as `not-linked`.
`GstBuffer`/`GstEvent` succeeded the queue will no longer be marked as
'not-linked'.
If pushing on all srcpads returns `GstFlowReturn` different from If pushing on all srcpads returns a `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`.
@ -216,7 +220,9 @@ Where there are multiple stream formats, parsers are usually expected to
be able to convert between the different formats. This will, if be able to convert between the different formats. This will, if
implemented correctly, work as expected in a static pipeline such as implemented correctly, work as expected in a static pipeline such as
```
... ! parser ! decoder ! sink ... ! parser ! decoder ! sink
```
where the parser can query the decoder's capabilities even before where the parser can query the decoder's capabilities even before
processing the first piece of data, and configure itself to convert processing the first piece of data, and configure itself to convert