123 lines
2.2 KiB
Go
123 lines
2.2 KiB
Go
package player
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// Equalizer implementations based on the ffmpeg 'equalizer' filter
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import (
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"fmt"
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"math"
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"strings"
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)
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type Equalizer interface {
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IsEnabled() bool
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Preamp() float64
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Curve() EqualizerCurve
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Type() string
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// Returns the band frequencies as strings friendly for display
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BandFrequencies() []string
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}
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type ISO15BandEqualizer struct {
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Disabled bool
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EQPreamp float64
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BandGains [15]float64
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}
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var (
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iso15Bands = []string{"25", "40", "63", "100", "160", "250", "400", "630", "1k", "1.6k", "2.5k", "4k", "6.3k", "10k", "16k"}
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iso15FMult = math.Pow(2, 2./3)
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)
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var _ Equalizer = (*ISO15BandEqualizer)(nil)
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func (i *ISO15BandEqualizer) IsEnabled() bool {
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return !i.Disabled
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}
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func (i *ISO15BandEqualizer) Preamp() float64 {
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return i.EQPreamp
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}
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func (i *ISO15BandEqualizer) Curve() EqualizerCurve {
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fC := float64(25)
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curve := make([]EqualizerBand, 0, len(i.BandGains))
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for _, bandGain := range i.BandGains {
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curve = append(curve, EqualizerBand{
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Frequency: int(math.Round(fC)),
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Width: 2. / 3,
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WidthType: WidthTypeOctave,
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Gain: bandGain,
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})
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fC *= iso15FMult
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}
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return curve
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}
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func (*ISO15BandEqualizer) BandFrequencies() []string {
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ret := make([]string, len(iso15Bands))
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copy(ret, iso15Bands)
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return ret
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}
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func (*ISO15BandEqualizer) Type() string {
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return "ISO15Band"
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}
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type WidthType int
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const (
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WidthTypeHz WidthType = iota
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WidthTypeKhz
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WidthTypeQ
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WidthTypeOctave
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WidthTypeSlope
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)
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type EqualizerBand struct {
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Frequency int
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Gain float64
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Width float64
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WidthType WidthType
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}
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type EqualizerCurve []EqualizerBand
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func (e EqualizerCurve) String() string {
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var sb strings.Builder
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first := true
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for _, band := range e {
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if s := band.String(); s != "" {
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if !first {
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sb.WriteString(",")
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}
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sb.WriteString(s)
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first = false
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}
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}
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return sb.String()
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}
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func (e EqualizerBand) String() string {
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if math.Abs(e.Gain) < 0.02 {
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return ""
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}
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return fmt.Sprintf("equalizer=f=%d:g=%0.2f:t=%s:w=%0.2f",
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e.Frequency, e.Gain, e.WidthType.String(), e.Width)
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}
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func (w WidthType) String() string {
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switch w {
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case WidthTypeHz:
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return "h"
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case WidthTypeKhz:
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return "k"
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case WidthTypeQ:
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return "q"
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case WidthTypeOctave:
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return "o"
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case WidthTypeSlope:
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return "s"
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}
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return "x" // not reached
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}
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