audio.cpp File Reference

Definitions for audio capture and encoding. More...

#include <thread>
#include <opus/opus_multistream.h>
#include "audio.h"
#include "config.h"
#include "globals.h"
#include "logging.h"
#include "platform/common.h"
#include "thread_safe.h"
#include "utility.h"

Include dependency graph for audio.cpp:

Typedefs
using	audio::opus_t = util::safe_ptr<OpusMSEncoder, opus_multistream_encoder_destroy>
	Owning pointer for an Opus multistream encoder.
using	audio::sample_queue_t = std::shared_ptr<safe::queue_t<std::vector<float>>>
	Shared queue carrying captured PCM sample buffers to the encoder thread.

Functions
void	audio::capture (safe::mail_t mail, config_t config, void *channel_data)
	Run the capture loop for this backend.
void	audio::encodeThread (sample_queue_t samples, config_t config, void *channel_data)
	Encode captured PCM samples into Opus packets on the audio worker thread.
audio_ctx_ref_t	audio::get_audio_ctx_ref ()
	Get the reference to the audio context.
bool	audio::is_audio_ctx_sink_available (const audio_ctx_t &ctx)
	Check if the audio sink held by audio context is available.
int	audio::map_stream (int channels, bool quality)
	Select the Opus stream configuration for a channel count and quality tier.

Variables
constexpr auto	audio::SAMPLE_RATE = 48000
	Audio sample rate in hertz required by Opus.
opus_stream_config_t	audio::stream_configs [MAX_STREAM_CONFIG]
	Opus stream layouts and bitrates advertised to clients.

Detailed Description

Definitions for audio capture and encoding.

Function Documentation

capture()

void audio::capture	(	safe::mail_t	mail,
		config_t	config,
		void *	channel_data )

Run the capture loop for this backend.

Capture, encode, and publish audio packets for a stream.

Parameters

mail	Mailbox used to publish encoded audio packets.
config	Audio capture and encoder settings.
channel_data	Platform-specific capture channel pointer.

encodeThread()

void audio::encodeThread	(	sample_queue_t	samples,
		config_t	config,
		void *	channel_data )

Encode captured PCM samples into Opus packets on the audio worker thread.

Parameters

samples	Queue of captured PCM sample buffers to encode.
config	Audio stream settings negotiated with the client.
channel_data	Platform-specific audio capture context passed to packet metadata.

get_audio_ctx_ref()

audio_ctx_ref_t audio::get_audio_ctx_ref

(

)

Get the reference to the audio context.

Returns

A shared pointer reference to audio context.

Note

Aside from the configuration purposes, it can be used to extend the audio sink lifetime to capture sink earlier and restore it later.

*Examples**

audio_ctx_ref_t audio = get_audio_ctx_ref()

is_audio_ctx_sink_available()

bool audio::is_audio_ctx_sink_available

(

const audio_ctx_t &

ctx

)

Check if the audio sink held by audio context is available.

Returns

True if available (and can probably be restored), false otherwise.

Note

Useful for delaying the release of audio context shared pointer (which tries to restore original sink).

*Examples**

audio_ctx_ref_t audio = get_audio_ctx_ref()
if (audio.get()) {
    return is_audio_ctx_sink_available(*audio.get());
}
return false;

Parameters

ctx	Native context object used by the operation or callback.

map_stream()

int audio::map_stream	(	int	channels,
		bool	quality )

Select the Opus stream configuration for a channel count and quality tier.

Parameters

channels	Number of audio channels in the stream.
quality	Whether the high-quality Opus layout should be selected.

Returns

Index into stream_configs for the requested layout.