effects

type EqualizerSections ¶ added in v1.1.0

type EqualizerSections interface {
	// contains filtered or unexported methods
}

EqualizerSections is the interfacd that is passed into NewEqualizer

type Gain ¶

type Gain struct {
	Streamer beep.Streamer
	Gain     float64
}

Gain amplifies the wrapped Streamer. The output of the wrapped Streamer gets multiplied by 1+Gain.

Note that gain is not equivalent to the human perception of volume. Human perception of volume is roughly exponential, while gain only amplifies linearly.

func (g *Gain) Err() error

func (g *Gain) Stream(samples [][2]float64) (n int, ok bool)

type MonoEqualizerSection ¶ added in v1.1.0

type MonoEqualizerSection struct {
	// F0 (center frequency) sets the mid-point of the section’s
	// frequency range and is given in Hertz [Hz].
	F0 float64

	// Bf (bandwidth) represents the width of the section across
	// frequency and is measured in Hertz [Hz]. A low bandwidth
	// corresponds to a narrow frequency range meaning that the
	// section will concentrate its operation to only the
	// frequencies close to the center frequency. On the other hand,
	// a high bandwidth yields a section of wide frequency range —
	// affecting a broader range of frequencies surrounding the
	// center frequency.
	Bf float64

	// GB (bandwidth gain) is given in decibels [dB] and represents
	// the level at which the bandwidth is measured. That is, to
	// have a meaningful measure of bandwidth, we must define the
	// level at which it is measured.
	GB float64

	// G0 (reference gain) is given in decibels [dB] and simply
	// represents the level of the section’s offset.
	G0 float64

	// G (boost/cut gain) is given in decibels [dB] and prescribes
	// the effect imposed on the audio loudness for the section’s
	// frequency range. A boost/cut level of 0 dB corresponds to
	// unity (no operation), whereas negative numbers corresponds to
	// cut (volume down) and positive numbers to boost (volume up).
	G float64
}

type MonoEqualizerSections ¶ added in v1.1.0

type MonoEqualizerSections []MonoEqualizerSection

MonoEqualizerSections implements EqualizerSections and can be passed into NewEqualizer

type Pan ¶

type Pan struct {
	Streamer beep.Streamer
	Pan      float64
}

Pan balances the wrapped Streamer between the left and the right channel. The Pan field value of -1 means that both original channels go through the left channel. The value of +1 means the same for the right channel. The value of 0 changes nothing.

func (p *Pan) Err() error

func (p *Pan) Stream(samples [][2]float64) (n int, ok bool)

type StereoEqualizerSection ¶ added in v1.1.0

type StereoEqualizerSection struct {
	Left  MonoEqualizerSection
	Right MonoEqualizerSection
}

type StereoEqualizerSections ¶ added in v1.1.0

type StereoEqualizerSections []StereoEqualizerSection

StereoEqualizerSections implements EqualizerSections and can be passed into NewEqualizer

type Volume ¶

type Volume struct {
	Streamer beep.Streamer
	Base     float64
	Volume   float64
	Silent   bool
}

Volume adjusts the volume of the wrapped Streamer in a human-natural way. Human's perception of volume is roughly logarithmic to gain and thus the natural way to adjust volume is exponential.

Natural Base for the exponentiation is somewhere around 2. In order to adjust volume along decibells, pick 10 as the Base and set Volume to dB/10. However, adjusting volume along decibells is nowhere as natural as with bases around 2.

Volume of 0 means no change. Negative Volume will decrease the perceived volume and positive will increase it.

With exponential gain it's impossible to achieve the zero volume. When Silent field is set to true, the output is muted.

func (v *Volume) Err() error

func (v *Volume) Stream(samples [][2]float64) (n int, ok bool)