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design/context: add missing markup to function calls and gst keywords

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Reynaldo H. Verdejo Pinochet 2016-12-20 23:10:03 -08:00
parent 67fb7c7b94
commit 949c08b512
1 changed files with 12 additions and 12 deletions
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markdown/design/context.md
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@ -1,7 +1,7 @@
# Context
GstContext is a container object, containing a type string and a generic
GstStructure. It is used to store and propagate context information in a
`GstContext` is a container object, containing a type string and a generic
`GstStructure`. It is used to store and propagate context information in a
pipeline, like device handles, display server connections and other
information that should be shared between multiple elements in a
pipeline.
@ -22,40 +22,40 @@ Elements that need a specific context for their operation would do the
following steps until one succeeds:
1) Check if the element already has a context of the specific type,
i.e. it was previously set via gst_element_set_context().
i.e. it was previously set via `gst_element_set_context()`.
2) Query downstream with GST_QUERY_CONTEXT for the context and check if
2) Query downstream with `GST_QUERY_CONTEXT` for the context and check if
downstream already has a context of the specific type
3) Query upstream with GST_QUERY_CONTEXT for the context and check if
3) Query upstream with `GST_QUERY_CONTEXT` for the context and check if
upstream already has a context of the specific type
4) Post a GST_MESSAGE_NEED_CONTEXT message on the bus with the required
4) Post a `GST_MESSAGE_NEED_CONTEXT` message on the bus with the required
context types and afterwards check if a usable context was set now
as in 1). The message could be handled by the parent bins of the
element and the application.
4) Create a context by itself and post a GST_MESSAGE_HAVE_CONTEXT message
4) Create a context by itself and post a `GST_MESSAGE_HAVE_CONTEXT` message
on the bus.
Bins will propagate any context that is set on them to their child
elements via gst\_element\_set\_context(). Even to elements added after
elements via `gst_element_set_context()`. Even to elements added after
a given context has been set.
Bins can handle the GST\_MESSAGE\_NEED\_CONTEXT message, can filter both
Bins can handle the `GST_MESSAGE_NEED_CONTEXT` message, can filter both
messages and can also set different contexts for different pipeline
parts.
## Applications
Applications can set a specific context on a pipeline or elements inside
a pipeline with gst\_element\_set\_context().
a pipeline with `gst_element_set_context()`.
If an element inside the pipeline needs a specific context, it will post
a GST\_MESSAGE\_NEED\_CONTEXT message on the bus. The application can
a `GST_MESSAGE_NEED_CONTEXT` message on the bus. The application can
now create a context of the requested type or pass an already existing
context to the element (or to the complete pipeline).
Whenever an element creates a context internally it will post a
GST\_MESSAGE\_HAVE\_CONTEXT message on the bus. Bins will cache these
`GST_MESSAGE_HAVE_CONTEXT` message on the bus. Bins will cache these
contexts and pass them to any future element that requests them.