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| #### RemiAudio
#### Copyright (C) 2022-2024 Remilia Scarlet <remilia@posteo.jp>
####
#### This program is free software: you can redistribute it and/or modify it
#### under the terms of the GNU Affero General Public License as published by
#### the Free Software Foundation, either version 3 of the License, or (at your
#### option) any later version.
####
#### This program is distributed in the hope that it will be useful, but WITHOUT
#### ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
#### FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
#### License for more details.
####
#### You should have received a copy of the GNU Affero General Public License
#### along with this program. If not, see <https://www.gnu.org/licenses/>.
require "../common"
module RemiAudio::DSP
# A record that is used to hold dithering state for TPDF dithering. This
# structure can be used to convert samples from one type to another.
#
# The `Ditherer` struct also contains methods for converting sample formats
# _without_ dithering.
struct Ditherer
class DitherError < RemiAudioError
end
@rnd : Random = Random.new(Time.local.to_unix_ms)
@rand1 : Int32 = 0
@rand2 : Int32 = 0
@feedback1 : Float64 = 0.0
@feedback2 : Float64 = 0.0
# :nodoc:
MAX_RAND = 2147483647i32
# Creates a new `Ditherer` instance.
def initialize
end
# Converts `sample` to a signed integer sample of `targetBitDepth` bits
# while applying TPDF dithering when needed. The format of `sample` must be
# supplied via `srcFormat`. The returned value is guaranteed to fit in
# `targetBitDepth` bits.
#
# If the sample is already an integer sample, and `targetBitDepth` is
# already greater than or equal to the current bit depth, then the sample is
# simply coerced to the appropriate integer type without dithering.
#
# Unsupported bit depths will cause this to raise an `InvalidBitDepthError`.
def dither(sample : RemiAudio::Sample, srcFormat : SampleFormat, targetBitDepth : Int,
*, useNoiseShaping = false) : Sample
if targetBitDepth < 8 || targetBitDepth > 64
raise InvalidBitDepthError.new("Unsupported bit depth: #{targetBitDepth}")
end
# Pre-convert the sample to a float64. Or possibly return if the sample
# is already an integer format and the target bit depth is >= the current
# sample bit depth.
sampleF64 : Float64 =
case srcFormat
in SampleFormat::F64
raise DitherError.new("Cannot dither a Float64 sample to an Int64 sample") unless targetBitDepth < 64
sample.to_f64!
in SampleFormat::F32
raise DitherError.new("Cannot dither a Float32 sample to a higher bit depth") unless targetBitDepth < 32
sample.to_f32!.to_f64!
in SampleFormat::I64
case targetBitDepth
when 64 then return sample.to_i64!
else int64toFloat64(sample.to_i64!)
end
in SampleFormat::I32
case targetBitDepth
when 64 then return int32toInt64(sample.to_i32!)
when 32 then return sample.to_i32!
else int32toFloat64(sample.to_i32!)
end
in SampleFormat::I24
case targetBitDepth
when 64 then return int24toInt64(sample.to_i32!)
when 32 then return int24toInt32(sample.to_i32!)
when 24 then return sample.to_i32! & 0x80FFFFFF
else int24toFloat64(sample.to_i32! & 0x80FFFFFF)
end
in SampleFormat::I16
case targetBitDepth
when 64 then return int16toInt64(sample.to_i16!)
when 32 then return int16toInt32(sample.to_i16!)
when 24 then return int16toInt24(sample.to_i16!)
when 16 then return sample.to_i16!
else int16toFloat64(sample.to_i16!)
end
# in SampleFormat::I12
# case targetBitDepth
# when 64 then return int12toInt64(sample.to_i16!)
# when 32 then return int12toInt32(sample.to_i16!)
# when 24 then return int12toInt24(sample.to_i16!)
# when 16 then return int12toInt16(sample.to_i16!)
# when 12 then return sample.to_i16! & 0x8FFF
# else int12toFloat64(sample.to_i16!)
# end
in SampleFormat::I8
case targetBitDepth
when 64 then return int8toInt64(sample.to_i8!)
when 32 then return int8toInt32(sample.to_i8!)
when 24 then return int8toInt24(sample.to_i8!)
when 16 then return int8toInt16(sample.to_i8!)
when 12 then return int8toInt12(sample.to_i8!)
when 8 then return sample.to_i8!
else raise "Unexpected bit depth"
end
in SampleFormat::U8
case targetBitDepth
when 64 then return int8toInt64((sample.to_u8!.to_i16! - 128).to_i8!)
when 32 then return int8toInt32((sample.to_u8!.to_i16! - 128).to_i8!)
when 24 then return int8toInt24((sample.to_u8!.to_i16! - 128).to_i8!)
when 16 then return int8toInt16((sample.to_u8!.to_i16! - 128).to_i8!)
when 12 then return int8toInt12((sample.to_u8!.to_i16! - 128).to_i8!)
when 8 then return (sample.to_u8!.to_i16! - 128).to_i8!
else raise "Unexpected bit depth"
end
end
##
## If we've reached here, then we're good to go to apply dithering to the
## sample, which is now a 64-bit float.
##
s : Float64 = useNoiseShaping ? 0.0 : 0.5
w : Float64 = (1i64 << (targetBitDepth - 1)).to_f64!
wi : Float64 = 1.0 / w
d : Float64 = wi / MAX_RAND
o : Float64 = wi * 0.5
in2 : Float64 = 0.0
tmp : Float64 = 0.0
@rand2 = @rand1
@rand1 = @rnd.rand(MAX_RAND)
in2 = sampleF64 + (s * ((@feedback1 + @feedback2) - @feedback2))
tmp = in2 + o + (d * (@rand1 &- @rand2))
ret = case targetBitDepth
when 8 then (w * tmp).to_i8! & 0xFF
when 12 then (w * tmp).to_i16!.asBitSize(12).to_i16!
when 16 then (w * tmp).to_i16!
when 24 then (w * tmp).to_i32!.asBitSize(24).to_i32!
when 32 then (w * tmp).to_i32!
when 64 then (w * tmp).to_i64!
else raise InvalidBitDepthError.new("Unsupported bit depth: #{targetBitDepth}")
end
ret = ret &- 1 if tmp < 0.0
@feedback2 = @feedback1
@feedback1 = in2 - (wi * ret.to_i64!)
ret
end
# For each sample in `from`, this converts the sample using a `Ditherer` to
# the destination format, then yields the converted sample and its index.
def self.withDitheredSamples(from : RemiAudio::SampleData, srcFormat : SampleFormat, targetBitDepth : Int,
*, useNoiseShaping : Bool = false, & : RemiAudio::Sample, Int32 ->)
dith = Ditherer.new
from.each_with_index do |samp, i|
yield dith.dither(samp, srcFormat, targetBitDepth, useNoiseShaping: useNoiseShaping), i
end
end
# Converts `sample` from `srcFormat` to `destFormat`, applying dithering
# using `#dither` as-needed.
#
# Unlike the `#dither` method, this knows how to convert between float
# formats.
def ditherOrConvert(sample : RemiAudio::Sample, srcFormat : SampleFormat, destFormat : SampleFormat,
*, useNoiseShaping : Bool = false) : RemiAudio::Sample
# Check for simple conversions that don't require dithering.
if srcFormat == SampleFormat::F32
# Float -> Float
case destFormat
when SampleFormat::F32 then return sample.to_f32!
when SampleFormat::F64 then return sample.to_f64!
end
elsif srcFormat == SampleFormat::F64
# Float -> Float
case destFormat
when SampleFormat::F32 then return sample.to_f32!
when SampleFormat::F64 then return sample.to_f64!
end
else
# Source is an integer format
case destFormat
# Integer -> Float
when SampleFormat::F64
case srcFormat
when SampleFormat::U8 then return int8toFloat64((sample.to_u8!.to_i16! - 128).to_i8!)
when SampleFormat::I8 then return int8toFloat64(sample.to_i8!)
#when SampleFormat::I12 then return int12toFloat64(sample.to_i16!)
when SampleFormat::I16 then return int16toFloat64(sample.to_i16!)
when SampleFormat::I24 then return int24toFloat64(sample.to_i32!)
when SampleFormat::I32 then return int32toFloat64(sample.to_i32!)
when SampleFormat::I64 then return int64toFloat64(sample.to_i64!)
end
# Integer -> Float
when SampleFormat::F32
case srcFormat
when SampleFormat::U8 then return int8toFloat64((sample.to_u8!.to_i16! - 128).to_i8!).to_f32!
when SampleFormat::I8 then return int8toFloat64(sample.to_i8).to_f32!
#when SampleFormat::I12 then return int12toFloat64(sample.to_i16).to_f32!
when SampleFormat::I16 then return int16toFloat64(sample.to_i16).to_f32!
when SampleFormat::I24 then return int24toFloat64(sample.to_i32).to_f32!
when SampleFormat::I32 then return int32toFloat64(sample.to_i32).to_f32!
when SampleFormat::I64 then return int64toFloat64(sample.to_i64).to_f32!
end
end
end
# If we've reached here, then we aren't doing a simple conversion and
# instead need dithering.
if destFormat.u8?
# Unsigned 8-bit is handled slightly differently. Silence is at 128,
# not 0.
(dither(sample, srcFormat, destFormat.getBits, useNoiseShaping: useNoiseShaping).to_i16! + 128).to_u8!
else
dither(sample, srcFormat, destFormat.getBits, useNoiseShaping: useNoiseShaping)
end
end
# For each sample in `from`, this converts the sample using a `Ditherer` to
# the destination format, then yields the converted sample and its index.
# Unlike `Ditherer.withDitheredSamples`, this uses the `#ditherOrConvert`
# method internally.
def self.withConvertedSamples(from : SampleData, srcFormat : SampleFormat, destFormat : SampleFormat,
*, useNoiseShaping : Bool = false, & : Sample, Int32 ->)
dith = Ditherer.new
from.each_with_index do |samp, i|
yield dith.ditherOrConvert(samp, srcFormat, destFormat, useNoiseShaping: useNoiseShaping), i
end
end
############################################################################
private macro defineIntUpConvFn(name, srcType, srcMask, srcBits, destType, destMask, convFn)
private def {{name.id}}(sample : {{srcType}}) : {{destType}}
{% den = (1 << (srcBits - 1)) %}
{% if srcMask == nil %}
{% if destMask == nil %}
((sample / {{den}}_f64) * {{destType}}::MAX).{{convFn.id}}
{% else %}
((sample / {{den}}_f64) * {{destType}}::MAX).{{convFn.id}} & {{destMask}}
{% end %}
{% else %}
{% if destMask == nil %}
(((sample & {{srcMask}}) / {{den}}_f64) * {{destType}}::MAX).{{convFn.id}}
{% else %}
(((sample & {{srcMask}}) / {{den}}_f64) * {{destType}}::MAX).{{convFn.id}} & {{destMask}}
{% end %}
{% end %}
end
end
defineIntUpConvFn(int8toInt64, Int8, nil, 8, Int64, nil, :to_i64!)
defineIntUpConvFn(int12toInt64, Int16, 0x8FFF, 12, Int64, nil, :to_i64!)
defineIntUpConvFn(int16toInt64, Int16, nil, 16, Int64, nil, :to_i64!)
defineIntUpConvFn(int24toInt64, Int32, 0x80FFFFFF, 24, Int64, nil, :to_i64!)
defineIntUpConvFn(int32toInt64, Int32, nil, 32, Int64, nil, :to_i64!)
defineIntUpConvFn(int8toInt32, Int8, nil, 8, Int32, nil, :to_i32!)
defineIntUpConvFn(int12toInt32, Int16, 0x8FFF, 12, Int32, nil, :to_i32!)
defineIntUpConvFn(int16toInt32, Int16, nil, 16, Int32, nil, :to_i32!)
defineIntUpConvFn(int24toInt32, Int32, 0x80FFFFFF, 24, Int32, nil, :to_i32!)
defineIntUpConvFn(int8toInt24, Int8, nil, 8, Int32, 0x80FFFFFF, :to_i32!)
defineIntUpConvFn(int12toInt24, Int16, 0x8FFF, 12, Int32, 0x80FFFFFF, :to_i32!)
defineIntUpConvFn(int16toInt24, Int16, nil, 16, Int32, 0x80FFFFFF, :to_i32!)
defineIntUpConvFn(int8toInt16, Int8, nil, 8, Int16, nil, :to_i16!)
defineIntUpConvFn(int12toInt16, Int16, 0x8FFF, 12, Int16, nil, :to_i16!)
defineIntUpConvFn(int8toInt12, Int8, nil, 8, Int16, 0x8FFF, :to_i16!)
private macro defineIntToFloat64Fn(name, srcType)
private def {{name.id}}(sample : {{srcType}}) : Float64
sample / {{srcType}}::MAX.to_f64!
end
end
defineIntToFloat64Fn(int8toFloat64, Int8)
defineIntToFloat64Fn(int16toFloat64, Int16)
defineIntToFloat64Fn(int32toFloat64, Int32)
defineIntToFloat64Fn(int64toFloat64, Int64)
private def int12toFloat64(sample : Int16) : Float64
sample / 2048.0
end
private def int24toFloat64(sample : Int32) : Float64
sample / 8388608.0
end
end
end
|