/
filter.go
82 lines (73 loc) · 1.75 KB
/
filter.go
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// Filters take samples as an input and produce samples as an output.
package filters
import (
"github.com/bspaans/bleep/audio"
)
type Filter interface {
Filter(cfg *audio.AudioConfig, samples []float64) []float64
}
type BaseFilter struct {
FilterFunc func(cfg *audio.AudioConfig, samples []float64) []float64
}
func NewBaseFilter(f func(cfg *audio.AudioConfig, samples []float64) []float64) Filter {
return &BaseFilter{
FilterFunc: f,
}
}
func (f *BaseFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64 {
if f.FilterFunc != nil {
return f.FilterFunc(cfg, samples)
}
return samples
}
func ComposedFilter(f1 Filter, f2 Filter) Filter {
if f1 == nil {
return f2
}
if f2 == nil {
return f1
}
return NewBaseFilter(
func(cfg *audio.AudioConfig, samples []float64) []float64 {
s1 := f2.Filter(cfg, samples)
return f1.Filter(cfg, s1)
},
)
}
func SumFilter(filters ...Filter) Filter {
return NewBaseFilter(
func(cfg *audio.AudioConfig, samples []float64) []float64 {
if filters == nil || len(filters) == 0 {
return samples
}
s := make([]float64, len(samples))
for _, f := range filters {
filteredSamples := f.Filter(cfg, samples)
for i, sample := range filteredSamples {
s[i] += sample
}
}
return s
},
)
}
func AverageFilter(filters ...Filter) Filter {
return NewBaseFilter(
func(cfg *audio.AudioConfig, samples []float64) []float64 {
if filters == nil || len(filters) == 0 {
return samples
}
s := make([]float64, len(samples))
for _, f := range filters {
filteredSamples := f.Filter(cfg, samples)
for i, sample := range filteredSamples {
s[i] += sample
}
}
for i, sample := range s {
s[i] = sample / float64(len(filters))
}
return s
},
)
}