alsa_t< T > Class Template Reference

Our representation of one alsa device. More...

Inheritance diagram for alsa_t< T >:

Public Member Functions
	alsa_t (const alsa_dev_par_parser_t &par, unsigned int rate, unsigned int fragsize, unsigned int channels)
	Constructor receives the parameters for this device. More...
	~alsa_t ()
	Destructor closes the sound device. More...
void	start () override
	start puts alsa device in usable state More...
void	stop () override
	stop informs alsa device that we do not need any more samples / will not provide any more samples More...
bool	read (mha_wave_t **) override
	read audio samples from the device into an internal mha_wave_t buffer, then update the pointer given as parameter to point to the internal structure. More...
bool	write (mha_wave_t *) override
	write audio samples from the given waveform buffer to the sound device. More...
Public Member Functions inherited from alsa_base_t
	alsa_base_t ()
virtual	~alsa_base_t ()=default

Private Attributes
unsigned int	channels
unsigned int	fragsize
T *	buffer
std::vector< mha_real_t >	frame_data
MHASignal::waveform_t	wave
	internal buffer to store sound samples coming from the sound card. More...
const mha_real_t	gain
const mha_real_t	invgain
snd_pcm_format_t	pcm_format

Additional Inherited Members
Public Attributes inherited from alsa_base_t
snd_pcm_t *	pcm
	The underlying alsa handle to this sound card. More...

Detailed Description

template<typename T>
class alsa_t< T >

Our representation of one alsa device.

We can start and stop the device, and depending on the direction, read or write samples.

Constructor & Destructor Documentation

alsa_t()

template<typename T >

alsa_t< T >::alsa_t	(	const alsa_dev_par_parser_t &	par,
		unsigned int	rate,
		unsigned int	fragsize,
		unsigned int	channels
	)

Constructor receives the parameters for this device.

It opens the sound device using the alsa library and selects the given parameters, but does not yet start the sound device to perform real I/O.

Parameters

par	our parser variable aggregator (containing direction, device name, and number of periods to place in alsa buffer)
rate	sampling rate in Hz
fragsize	samples per block per channel
channels	number of audio channels to open

~alsa_t()

template<typename T >

alsa_t< T >::~alsa_t

Destructor closes the sound device.

Member Function Documentation

start()

template<typename T >

void alsa_t< T >::start

overridevirtual

start puts alsa device in usable state

Implements alsa_base_t.

stop()

template<typename T >

void alsa_t< T >::stop

overridevirtual

stop informs alsa device that we do not need any more samples / will not provide any more samples

Implements alsa_base_t.

read()

template<typename T >

bool alsa_t< T >::read ( mha_wave_t **  s )

overridevirtual

read audio samples from the device into an internal mha_wave_t buffer, then update the pointer given as parameter to point to the internal structure.

Converts sound samples from the integer data type provided by the sound card to floating-point values needed by the MHA in the range [-1.0,1.0]

Implements alsa_base_t.

write()

template<typename T >

bool alsa_t< T >::write ( mha_wave_t *  s )

overridevirtual

write audio samples from the given waveform buffer to the sound device.

converts the floating point values coming from the MHA to the integer samples required by the sound card.

Implements alsa_base_t.

Member Data Documentation

channels

template<typename T >

unsigned int alsa_t< T >::channels

private

fragsize

template<typename T >

unsigned int alsa_t< T >::fragsize

private

buffer

template<typename T >

T* alsa_t< T >::buffer

private

frame_data

template<typename T >

std::vector<mha_real_t> alsa_t< T >::frame_data

private

wave

template<typename T >

MHASignal::waveform_t alsa_t< T >::wave

private

internal buffer to store sound samples coming from the sound card.

gain

template<typename T >

const mha_real_t alsa_t< T >::gain

private

invgain

template<typename T >

const mha_real_t alsa_t< T >::invgain

private

pcm_format

template<typename T >

snd_pcm_format_t alsa_t< T >::pcm_format

private

---

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

• MHAIOalsa.cpp