edsp::feature::temporal Namespace Reference

Classes
class	leq
	This class estimates the Equivalent Continuous Sound Level over consecutive frames. More...

Functions
template<typename InputIt , typename OutputIt >
constexpr void	amdf (InputIt first, InputIt last, OutputIt d_first)
	Computes the AMDF (Average Magnitude Difference Function) of the contiguous elements in the range [first, last) and stores the result in another range, beginning at d_first. More...
template<typename ForwardIt , typename Numeric >
constexpr auto	duration (ForwardIt first, ForwardIt last, Numeric samplerate)
	Computes the duration of the elements in the range [first, last) More...
template<typename ForwardIt , typename Numeric >
constexpr auto	effective_duration (ForwardIt first, ForwardIt last, Numeric samplerate, Numeric threshold)
	Computes the effective duration of the elements in the range [first, last) More...
template<typename ForwardIt >
constexpr auto	energy (ForwardIt first, ForwardIt last)
	Computes the energy of the elements in the range [first, last) More...
template<typename ForwardIt , typename Numeric >
constexpr auto	lat (ForwardIt first, ForwardIt last, Numeric samplerate, Numeric start_threshold, Numeric stop_threshold)
	The laq class estimates the logarithmic attack time of an envelope signal. More...
template<typename ForwardIt >
constexpr auto	power (ForwardIt first, ForwardIt last)
	Computes the instant power of the elements in the range [first, last) More...

Function Documentation

amdf()

template<typename InputIt , typename OutputIt >

constexpr void edsp::feature::temporal::amdf	(	InputIt	first,
		InputIt	last,
		OutputIt	d_first
	)

Computes the AMDF (Average Magnitude Difference Function) of the contiguous elements in the range [first, last) and stores the result in another range, beginning at d_first.

Computes the AZCR (Average Zero Crossing Rate) of the contiguous elements in the range [first, last) and stores the result in another range, beginning at d_first.

Computes the ASDF (Average Square Difference Function) of the contiguous elements in the range [first, last) and stores the result in another range, beginning at d_first.

The definition of AMDF is:

\[ Q_x[k,n_0] \triangleq \frac{1}{N} \sum\limits_{n=0}^{N-1} \Big| x[n+n_0] - x[n+n_0+k] \Big| \]

Parameters

first	Input iterator defining the begin of the range to examine.
last	Input iterator defining the end of the range to examine.
d_first	Output iterator defining the begin of the output range.

The definition of ASDF is:

\[ Q_x[k,n_0] \triangleq \frac{1}{N} \sum\limits_{n=0}^{N-1} \big( x[n+n_0] - x[n+n_0+k] \big)^2 \]

There is a relation between the ASDF function and the ACF function:

\[ \begin{align} x[k] & \triangleq \frac{1}{N} \sum x[n] x[n+k] \\ & = \overline{x^2[n]} - \tfrac{1}{2} Q_x[k] \\ & = R_x[0] - \tfrac{1}{2} Q_x[k] \\ \end{align} \]

Parameters

first	Input iterator defining the begin of the range to examine.
last	Input iterator defining the end of the range to examine.
d_first	Output iterator defining the begin of the output range.

See also

acf, amdf

The definition of AZCR is:

\[ {\displaystyle zcr={\frac {1}{T-1}}\sum _{t=1}^{T-1}\mathbb {1} _{\mathbb {R} _{<0}}(s_{t}s_{t-1})} \]

Parameters

first	Input iterator defining the begin of the range to examine.
last	Input iterator defining the end of the range to examine.
d_first	Output iterator defining the begin of the output range.

duration()

template<typename ForwardIt , typename Numeric >

constexpr auto edsp::feature::temporal::duration	(	ForwardIt	first,
		ForwardIt	last,
		Numeric	samplerate
	)

Computes the duration of the elements in the range [first, last)

Parameters

first	Forward iterator defining the begin of the range to examine.
last	Forward iterator defining the end of the range to examine.
samplerate	Sampling frequency in Hz.

Returns

The estimated duration in seconds.

effective_duration()

template<typename ForwardIt , typename Numeric >

constexpr auto edsp::feature::temporal::effective_duration	(	ForwardIt	first,
		ForwardIt	last,
		Numeric	samplerate,
		Numeric	threshold
	)

Computes the effective duration of the elements in the range [first, last)

The effective duration is a measure of the time the signal is perceptually meaningful. It is approximated by the time the energy envelope is above a given threshold.

Parameters

first	Forward iterator defining the begin of the range to examine.
last	Forward iterator defining the end of the range to examine.
samplerate	Sampling frequency in Hz.
threshold	Numeric value in the range [0, 1] representing the active threshold.

Returns

The estimated duration in seconds.

energy()

template<typename ForwardIt >

constexpr auto edsp::feature::temporal::energy	(	ForwardIt	first,
		ForwardIt	last
	)

Computes the energy of the elements in the range [first, last)

The energy estimates the signal power at a given time, it is estimated directly from the signal frame around a given time:

\[ e = \sum\limits_{n=0}^{N-1} x^2(n) \]

Parameters

first	Forward iterator defining the begin of the range to examine.
last	Forward iterator defining the end of the range to examine.

Returns

The energy of the elements in the range.

lat()

template<typename ForwardIt , typename Numeric >

constexpr auto edsp::feature::temporal::lat	(	ForwardIt	first,
		ForwardIt	last,
		Numeric	samplerate,
		Numeric	start_threshold,
		Numeric	stop_threshold
	)

The laq class estimates the logarithmic attack time of an envelope signal.

The log-attack time is the logarithmic (decimal base) of the time duration between the time the signal to the time it reaches its stable part:

\[ lat = \log10 \left( t_{stop} - t_{start} \right) \]

Parameters

first	Forward iterator defining the begin of the range to examine.
last	Forward iterator defining the end of the range to examine.
samplerate	Sampling frequency in Hz.
start_threshold	Numeric value between [0, 1] representing the percentage of the amplitude signal representing the start of the attack time.
stop_threshold	Numeric value between [0, 1] representing the percentage of the amplitude signal representing the limit of the attack time.

Returns

Estimated attack time in seconds.

power()

template<typename ForwardIt >

constexpr auto edsp::feature::temporal::power	(	ForwardIt	first,
		ForwardIt	last
	)

Computes the instant power of the elements in the range [first, last)

The energy of signal can be computed as:

\[ P_x = \frac{1}{N} \sum\limits_{n=0}^{N-1} x^2(n) \]

Parameters

first	Forward iterator defining the begin of the range to examine.
last	Forward iterator defining the end of the range to examine.

Returns

The instant power of the elements in the range.

See also

energy