Audio::GstreamerSimplePipeline Class Reference

Base class for gstreamer pipelines. More...

#include <gstreamplayer.h>

Inheritance diagram for Audio::GstreamerSimplePipeline:

Public Member Functions
	GstreamerSimplePipeline ()
virtual	~GstreamerSimplePipeline ()

Protected Member Functions
void	add (GstElement *element)
void	throwDeferredException (const GstreamerAudioException &exception, bool asynchronously=false) const
	"Throw" an exception from an asyncrhonous player thread. More...
void	throwAsyncException (const GstreamerAudioException &exception)
void	push (GstElement *item)
	Wire an item to the pipeline/filter graph. More...
GstElement *	createElement (const char *name, const std::string &overrides="")
	Create a gstreamer element and add it to the pipeline/bin, unwired. More...
GstState	currentPipelineState () const
	Query the pipeline's current state. More...
void	setPipelineState (GstState state)
	Set the pipeline's state. More...

Protected Attributes
GstElement *	pipeline
	Filter graph for elements. More...
GstElement *	chain_start = nullptr
	First item pushed on the stream after setup. More...
GstElement *	pipeline_last = nullptr
	Last item pushed on the stream. More...
std::recursive_mutex	state_mutex
std::unique_ptr< GstreamerAudioException >	pipeline_exception
	Asynchronous exception. More...

Detailed Description

Base class for gstreamer pipelines.

Constructor & Destructor Documentation

GstreamerSimplePipeline()

Audio::GstreamerSimplePipeline::GstreamerSimplePipeline

(

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~GstreamerSimplePipeline()

Audio::GstreamerSimplePipeline::~GstreamerSimplePipeline ( )

virtual

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Member Function Documentation

add()

void Audio::GstreamerSimplePipeline::add ( GstElement *  element )

protected

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createElement()

GstElement * Audio::GstreamerSimplePipeline::createElement ( const char *  name, const std::string &  overrides = ""  )

protected

Create a gstreamer element and add it to the pipeline/bin, unwired.

Parameters

name	The name of the element.
overrides	A user-specified alternate element to use.

Returns

Reference with constructed element.

Exceptions

GstreamerAudioException

if the element creation fails.

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currentPipelineState()

GstState Audio::GstreamerSimplePipeline::currentPipelineState ( ) const

protected

Query the pipeline's current state.

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push()

void Audio::GstreamerSimplePipeline::push ( GstElement *  item )

protected

Wire an item to the pipeline/filter graph.

Items are wired in the order they are pushed.

Parameters

item	The item to insert into to the pipeline.

Exceptions

AudioException

if the item can't be linked.

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setPipelineState()

void Audio::GstreamerSimplePipeline::setPipelineState ( GstState  state )

protected

Set the pipeline's state.

We need locking at this point, because the state may be set by a bus message or the pianod main thread. This creates a race condition where an error shuts it down, then pianod requests playback start/resume.

Furthermore, hammering state changes causes Gstreamer to become deranged and deadlock waiting on a condition variable. To avoid this, give the prior state transition a chance to complete.

But as a bonus, some elements only get to READY state; perhaps they need stream data to move on, but we're done and need to tear them down and move on. Whatever, the case, we occasionally need to go ahead with a state change, even if the last one is unfinished. Hence, we have a 1-second timeout for the last state change to finish, before proceeding recklessly with a state change.

Parameters

state

The new state.

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throwAsyncException()

void Audio::GstreamerSimplePipeline::throwAsyncException ( const GstreamerAudioException &  exception )

inlineprotected

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throwDeferredException()

void Audio::GstreamerSimplePipeline::throwDeferredException ( const GstreamerAudioException &  exception, bool  asynchronously = false  ) const

protected

"Throw" an exception from an asyncrhonous player thread.

This stores a copy of the exception for throwing later, when getting the thread's completion status.

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Member Data Documentation

chain_start

GstElement* Audio::GstreamerSimplePipeline::chain_start = nullptr

protected

First item pushed on the stream after setup.

pipeline

GstElement* Audio::GstreamerSimplePipeline::pipeline

protected

Filter graph for elements.

pipeline_exception

std::unique_ptr<GstreamerAudioException> Audio::GstreamerSimplePipeline::pipeline_exception

mutableprotected

Asynchronous exception.

pipeline_last

GstElement* Audio::GstreamerSimplePipeline::pipeline_last = nullptr

protected

Last item pushed on the stream.

state_mutex

std::recursive_mutex Audio::GstreamerSimplePipeline::state_mutex

mutableprotected

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The documentation for this class was generated from the following files:

• mediaunits/audio/gstreamplayer.h
• mediaunits/audio/gstreamplayer.cpp