Audio::LavAdapter Class Reference

Adapter to feed a ffmpeg stream to an audio output. More...

#include <ffmpegplayer.h>

Inheritance diagram for Audio::LavAdapter:

Classes
struct	FilterGraphDeleter
struct	FrameDeleter

Public Member Functions
virtual	~LavAdapter ()
bool	play (AVFrame *frame)
	Play a frame from a ffmpeg decoder. More...
void	setVolume (float level)

Static Public Member Functions
static LavAdapter *	getOutput (const AudioSettings &settings, const AVCodecContext *context, const AVStream *stream)
	Choose an output, then get an adapter for libav and set it up to match the output's format. More...

Protected Member Functions
	LavAdapter (const AVCodecContext *codec, const AVStream *stream, const AVSampleFormat output_format)
	Adapt whatever output for input from ffmpeg. More...
virtual bool	playFrame (AVFrame *frame)=0
bool	playFilteredPackets (const bool eof_return_value=true)
	Read all the resulting frames coming out of the filter stack, and push them to the outputter. More...
void	flush ()
	Play any frames buffered in the filter. More...

Private Member Functions
AVFilterContext *	pushFilter (AVFilterContext *prior_filter, const char *name, const char *optionformat=nullptr,...)
	Add a filter to the filter stack. More...

Private Attributes
AVFilterContext *	buffer_filter = nullptr
AVFilterContext *	volume_filter = nullptr
AVFilterContext *	format_filter = nullptr
AVFilterContext *	endpoint_filter = nullptr
std::unique_ptr< AVFilterGraph, FilterGraphDeleter >	filter_stack
std::unique_ptr< AVFrame, FrameDeleter >	output_frame = nullptr
std::mutex	adapter_mutex

Detailed Description

Adapter to feed a ffmpeg stream to an audio output.

Constructor & Destructor Documentation

LavAdapter()

Audio::LavAdapter::LavAdapter ( const AVCodecContext *  codec, const AVStream *  stream, const AVSampleFormat  output_format  )

protected

Adapt whatever output for input from ffmpeg.

Parameters

codec	The ffmpeg codec context.
stream	The stream from whence audio will arrive.
output_format	The format required by the outputter.

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~LavAdapter()

Audio::LavAdapter::~LavAdapter ( )

virtual

Member Function Documentation

flush()

void Audio::LavAdapter::flush ( )

protected

Play any frames buffered in the filter.

This must be invoked by subclasses during their destruction, as their specializations are gone by the time this class's destructor is called.

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getOutput()

LavAdapter * Audio::LavAdapter::getOutput ( const AudioSettings &  settings, const AVCodecContext *  codec, const AVStream *  stream  )

static

Choose an output, then get an adapter for libav and set it up to match the output's format.

Parameters

settings	Where to send the audio output.
codec	Audio format details.
stream	The stream from which audio will arrive.

Returns

A ready-to-go output stack.

Exceptions

AudioException

or a derivative if a suitable output was not located, opening/setting up the device failed, or the adapter setup failed.

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play()

bool Audio::LavAdapter::play

(

AVFrame *

frame

)

Play a frame from a ffmpeg decoder.

This involves passing it through the filter stack to adjust volume and format in accordance with the output's needs.

Parameters

frame

The audio frame to play.

Returns

True on success, false on error.

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playFilteredPackets()

bool Audio::LavAdapter::playFilteredPackets ( const bool  eof_return_value = true )

protected

Read all the resulting frames coming out of the filter stack, and push them to the outputter.

Parameters

eof_return_value

Value to return if EOF is encountered.

Returns

On error, false. On eof, up to caller. Otherwise true.

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playFrame()

virtual bool Audio::LavAdapter::playFrame ( AVFrame *  frame )

protectedpure virtual

Implemented in Audio::LavGenericAdapter.

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pushFilter()

AVFilterContext * Audio::LavAdapter::pushFilter ( AVFilterContext *  prior_filter, const char *  name, const char *  options_format = nullptr,   ...  )

private

Add a filter to the filter stack.

Parameters

prior_filter	The prior filter, or nullptr if it is the first. (used to wire the filters into sequence).
name	The ffmpeg name of the filter.
options_format	A printf-style format string (and values to follow) to create an options string for the filter.

Returns

The new filter.

Exceptions

AudioException

if anything goes wrong.

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setVolume()

void Audio::LavAdapter::setVolume

(

float

level

)

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Member Data Documentation

adapter_mutex

std::mutex Audio::LavAdapter::adapter_mutex

private

buffer_filter

AVFilterContext* Audio::LavAdapter::buffer_filter = nullptr

private

endpoint_filter

AVFilterContext* Audio::LavAdapter::endpoint_filter = nullptr

private

filter_stack

std::unique_ptr<AVFilterGraph, FilterGraphDeleter> Audio::LavAdapter::filter_stack

private

format_filter

AVFilterContext* Audio::LavAdapter::format_filter = nullptr

private

output_frame

std::unique_ptr<AVFrame, FrameDeleter> Audio::LavAdapter::output_frame = nullptr

private

volume_filter

AVFilterContext* Audio::LavAdapter::volume_filter = nullptr

private

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

• mediaunits/audio/ffmpegplayer.h
• mediaunits/audio/ffmpegadapter.cpp