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signal.go
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signal.go
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package signal
//go:generate go run gen.go
import (
"math"
"reflect"
"time"
"golang.org/x/exp/constraints"
)
const (
diffChannels string = "different number of channels"
diffCapacity string = "different buffer capacity"
)
type (
SignalTypes interface {
constraints.Float | constraints.Integer
}
)
// types for Buffer properties.
type (
bitDepth BitDepth
channels int
)
// BitDepth is the number of bits of information in each sample.
type BitDepth uint8
const (
// BitDepth4 is 4 bit depth.
BitDepth4 BitDepth = 1 << (iota + 2)
// BitDepth8 is 8 bit depth.
BitDepth8
// BitDepth16 is 16 bit depth.
BitDepth16
// BitDepth32 is 32 bit depth.
BitDepth32
// BitDepth64 is 64 bit depth.
BitDepth64
// BitDepth24 is 24 bit depth.
BitDepth24 BitDepth = 24
// MaxBitDepth is a maximum supported bit depth.
MaxBitDepth BitDepth = BitDepth64
)
// MaxSignedValue returns the maximum signed value for the bit depth.
func (b BitDepth) MaxSignedValue() int64 {
if b == 0 {
return 0
}
return 1<<(b-1) - 1
}
// MaxUnsignedValue returns the maximum unsigned value for the bit depth.
func (b BitDepth) MaxUnsignedValue() uint64 {
if b == 0 {
return 0
}
return 1<<b - 1
}
// MinSignedValue returns the minimum signed value for the bit depth.
func (b BitDepth) MinSignedValue() int64 {
if b == 0 {
return 0
}
return -1 << (b - 1)
}
// UnsignedValue clips the unsigned signal value to the given bit depth
// range.
func (b BitDepth) UnsignedValue(val uint64) uint64 {
max := b.MaxUnsignedValue()
if val > max {
return max
}
return val
}
// SignedValue clips the signed signal value to the given bit depth range.
func (b BitDepth) SignedValue(val int64) int64 {
max := b.MaxSignedValue()
min := b.MinSignedValue()
switch {
case val < min:
return min
case val > max:
return max
}
return val
}
// Scale returns scale for bit depth requantization.
func Scale[T constraints.Integer](high, low BitDepth) T {
return T(1 << (high - low))
}
// Frequency in Hertz is the number of occurrences of a repeating event per
// second. It might represent sample rate or pitch.
type Frequency float64
// Duration returns a total time duration for a number events at this
// frequency.
func (f Frequency) Duration(events int) time.Duration {
return time.Duration(math.Round(float64(time.Second) / float64(f) * float64(events)))
}
// Events returns a number of events for time duration at this frequency.
func (f Frequency) Events(d time.Duration) int {
return int(math.Round(float64(f) / float64(time.Second) * float64(d)))
}
// FloatAsFloat writes floating-point samples to the floating-point
// destination Buffer. Both buffers must have the same number of channels,
// otherwise function will panic. Returns a number of samples written per
// channel.
func FloatAsFloat[S, D constraints.Float](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
// determine the multiplier for bit depth conversion
for i := 0; i < length; i++ {
dst.SetSample(i, D(src.Sample(i)))
}
return min(src.Length(), dst.Length())
}
// FloatAsSigned converts floating-point samples into signed fixed-point
// and appends them to the destination Buffer. The floating sample range
// [-1,1] is mapped to signed [-2^(bitDepth-1), 2^(bitDepth-1)-1]. Floating
// values beyond the range will be clipped. Buffers must have the same
// number of channels, otherwise function will panic. Returns a number of
// samples written per channel.
func FloatAsSigned[S constraints.Float, D constraints.Signed](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
// determine the multiplier for bit depth conversion
msv := D(dst.BitDepth().MaxSignedValue())
for i := 0; i < length; i++ {
var sample D
if f := float64(src.Sample(i)); f > 0 {
// detect overflow
if D(f) == 0 {
sample = D(f * float64(msv))
} else {
sample = msv
}
} else {
// no overflow here
sample = D(f * (float64(msv) + 1))
}
dst.SetSample(i, sample)
}
return min(src.Length(), dst.Length())
}
// FloatAsUnsigned converts floating-point samples into unsigned
// fixed-point and appends them to the destination Buffer. The floating
// sample range [-1,1] is mapped to unsigned [0, 2^bitDepth-1]. Floating
// values beyond the range will be clipped. Buffers must have the same
// number of channels, otherwise function will panic.
func FloatAsUnsigned[S constraints.Float, D constraints.Unsigned](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
// determine the multiplier for bit depth conversion
msv := D(dst.BitDepth().MaxSignedValue())
offset := msv + 1
for i := 0; i < length; i++ {
var sample D
if f := float64(src.Sample(i)); f > 0 {
// detect overflow
if int64(f) == 0 {
sample = D(f*float64(msv)) + offset
} else {
sample = msv + offset
}
} else {
// no overflow here
sample = D(f*(float64(msv)+1)) + offset
}
dst.SetSample(i, sample)
}
return min(src.Length(), dst.Length())
}
// SignedAsFloat converts signed fixed-point samples into floating-point
// and appends them to the destination Buffer. The signed sample range
// [-2^(bitDepth-1), 2^(bitDepth-1)-1] is mapped to floating [-1,1].
// Buffers must have the same number of channels, otherwise function will
// panic.
func SignedAsFloat[S constraints.Signed, D constraints.Float](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
// determine the divider for bit depth conversion.
msv := D(src.BitDepth().MaxSignedValue())
for i := 0; i < length; i++ {
if sample := src.Sample(i); sample > 0 {
dst.SetSample(i, D(sample)/msv)
} else {
dst.SetSample(i, D(sample)/(msv+1))
}
}
return min(src.Length(), dst.Length())
}
// SignedAsSigned appends signed fixed-point samples to the signed
// fixed-point destination Buffer. The samples are quantized to the
// destination bit depth. Buffers must have the same number of channels,
// otherwise function will panic.
func SignedAsSigned[S, D constraints.Signed](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
// downscale
if src.BitDepth() >= dst.BitDepth() {
scale := Scale[S](src.BitDepth(), dst.BitDepth())
for i := 0; i < length; i++ {
dst.SetSample(i, D(src.Sample(i)/scale))
}
return min(src.Length(), dst.Length())
}
// upscale
scale := Scale[D](dst.BitDepth(), src.BitDepth())
for i := 0; i < length; i++ {
if sample := src.Sample(i); sample > 0 {
dst.SetSample(i, ((D(src.Sample(i))+1)*scale)-1)
} else {
dst.SetSample(i, D(src.Sample(i))*scale)
}
}
return min(src.Length(), dst.Length())
}
// SignedAsUnsigned converts signed fixed-point samples into unsigned
// fixed-point and appends them to the destination Buffer. The samples are
// quantized to the destination bit depth. The signed sample range
// [-2^(bitDepth-1), 2^(bitDepth-1)-1] is mapped to unsigned [0,
// 2^bitDepth-1]. Buffers must have the same number of channels, otherwise
// function will panic.
func SignedAsUnsigned[S constraints.Signed, D constraints.Unsigned](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
msv := D(dst.BitDepth().MaxSignedValue())
// downscale
if src.BitDepth() >= dst.BitDepth() {
scale := Scale[S](src.BitDepth(), dst.BitDepth())
for i := 0; i < length; i++ {
dst.SetSample(i, D(src.Sample(i)/scale)+msv+1)
}
return min(src.Length(), dst.Length())
}
// upscale
scale := Scale[D](dst.BitDepth(), src.BitDepth())
for i := 0; i < length; i++ {
if sample := src.Sample(i); sample > 0 {
dst.SetSample(i, D((src.Sample(i)+1))*scale+msv)
} else {
dst.SetSample(i, D(src.Sample(i))*scale+msv+1)
}
}
return min(src.Length(), dst.Length())
}
// UnsignedAsFloat converts unsigned fixed-point samples into
// floating-point and appends them to the destination Buffer. The unsigned
// sample range [0, 2^bitDepth-1] is mapped to floating [-1,1]. Buffers
// must have the same number of channels, otherwise function will panic.
func UnsignedAsFloat[S constraints.Unsigned, D constraints.Float](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
// determine the multiplier for bit depth conversion
msv := D(src.BitDepth().MaxSignedValue())
for i := 0; i < length; i++ {
if sample := src.Sample(i); sample > 0 {
dst.SetSample(i, (D(sample)-(msv+1))/msv)
} else {
dst.SetSample(i, (D(sample)-(msv+1))/(msv+1))
}
}
return min(src.Length(), dst.Length())
}
// UnsignedAsSigned converts unsigned fixed-point samples into signed
// fixed-point and appends them to the destination Buffer. The samples are
// quantized to the destination bit depth. The unsigned sample range [0,
// 2^bitDepth-1] is mapped to signed [-2^(bitDepth-1), 2^(bitDepth-1)-1].
// Buffers must have the same number of channels, otherwise function will
// panic.
func UnsignedAsSigned[S constraints.Unsigned, D constraints.Signed](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
msv := src.BitDepth().MaxSignedValue()
// downscale
if src.BitDepth() >= dst.BitDepth() {
scale := Scale[S](src.BitDepth(), dst.BitDepth())
for i := 0; i < length; i++ {
dst.SetSample(i, D((src.Sample(i)-S(msv+1))/scale))
}
return min(src.Length(), dst.Length())
}
// upscale
scale := Scale[D](dst.BitDepth(), src.BitDepth())
for i := 0; i < length; i++ {
if sample := D(src.Sample(i)) - D(msv+1); sample > 0 {
dst.SetSample(i, D((sample+1)*scale-1))
} else {
dst.SetSample(i, D(sample*scale))
}
}
return min(src.Length(), dst.Length())
}
// UnsignedAsUnsigned appends unsigned fixed-point samples to the unsigned
// fixed-point destination Buffer. The samples are quantized to the
// destination bit depth. Buffers must have the same number of channels,
// otherwise function will panic.
func UnsignedAsUnsigned[S, D constraints.Unsigned](src *Buffer[S], dst *Buffer[D]) int {
mustSame(src.Channels(), dst.Channels(), diffChannels)
// cap length to destination capacity.
length := min(src.Len(), dst.Len())
if length == 0 {
return 0
}
// downscale
if src.BitDepth() >= dst.BitDepth() {
scale := Scale[S](src.BitDepth(), dst.BitDepth())
for i := 0; i < length; i++ {
dst.SetSample(i, D(src.Sample(i)/scale))
}
return min(src.Length(), dst.Length())
}
// upscale
scale := Scale[D](dst.BitDepth(), src.BitDepth())
msv := S(src.BitDepth().MaxSignedValue())
for i := 0; i < length; i++ {
var sample S
if sample = src.Sample(i); sample > msv+1 {
dst.SetSample(i, D(sample+1)*scale-1)
} else {
dst.SetSample(i, D(sample)*scale)
}
}
return min(src.Length(), dst.Length())
}
// BitDepth returns bit depth of the Buffer.
func (bd bitDepth) BitDepth() BitDepth {
return BitDepth(bd)
}
// Channels returns number of channels in the Buffer.
func (c channels) Channels() int {
return int(c)
}
func min(v1, v2 int) int {
if v1 < v2 {
return v1
}
return v2
}
func mustSame[T comparable](a, b T, panicStr string) {
if a != b {
panic(panicStr)
}
}
// ChannelLength calculates a channel length for provided Buffer length and
// number of channels.
func ChannelLength(sliceLen, channels int) int {
return int(math.Ceil(float64(sliceLen) / float64(channels)))
}
// BufferIndex calculates sample index in the Buffer based on number of
// channels in the Buffer, channel of the sample and sample index in the
// channel.
func (c channels) BufferIndex(channel, idx int) int {
return int(c)*idx + channel
}
// ReadFloat reads values from the Buffer into provided slice.
// Returns number of samples read per channel.
func Read[S, D SignalTypes](src *Buffer[S], dst []D) int {
length := min(src.Len(), len(dst))
for i := 0; i < length; i++ {
dst[i] = D(src.Sample(i))
}
return ChannelLength(length, src.Channels())
}
// ReadStripedFloat reads values from the Buffer into provided slice. The
// length of provided slice must be equal to the number of channels,
// otherwise function will panic. Nested slices can be nil, no values for
// that channel will be read. Returns a number of samples read for the
// longest channel.
func ReadStriped[S, D SignalTypes](src *Buffer[S], dst [][]D) (read int) {
mustSame(src.Channels(), len(dst), diffChannels)
for c := 0; c < src.Channels(); c++ {
length := min(len(dst[c]), src.Length())
if length > read {
read = length
}
for i := 0; i < length; i++ {
dst[c][i] = D(src.Sample(src.BufferIndex(c, i)))
}
}
return
}
// WriteFloat writes values from provided slice into the Buffer.
// Returns a number of samples written per channel.
func Write[S, D SignalTypes](src []S, dst *Buffer[D]) int {
length := min(dst.Len(), len(src))
for i := 0; i < length; i++ {
dst.SetSample(i, D(src[i]))
}
return ChannelLength(length, dst.Channels())
}
// WriteStripedFloat64 writes values from provided slice into the Buffer.
// The length of provided slice must be equal to the number of channels,
// otherwise function will panic. Nested slices can be nil, zero values for
// that channel will be written. Returns a number of samples written for
// the longest channel.
func WriteStriped[S, D SignalTypes](src [][]S, dst *Buffer[D]) (written int) {
mustSame(dst.Channels(), len(src), diffChannels)
// determine the length of longest nested slice
for i := range src {
if len(src[i]) > written {
written = len(src[i])
}
}
// limit a number of writes to the length of the Buffer
written = min(written, dst.Length())
for c := 0; c < dst.Channels(); c++ {
for i := 0; i < written; i++ {
if i < len(src[c]) {
dst.SetSample(dst.BufferIndex(c, i), D(src[c][i]))
} else {
dst.SetSample(dst.BufferIndex(c, i), 0)
}
}
}
return
}
// alignCapacity ensures that Buffer capacity is aligned with number of
// channels.
func alignCapacity(s interface{}, channels, c int) {
reflect.ValueOf(s).Elem().SetCap(c - c%channels)
}