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wavex
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Read WAVE LPCM data
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lib/wavex.ex
defmodule Wavex do
@moduledoc """
Read LPCM WAVE data.
"""
alias Wavex.Chunk.{Data, Format, RIFF}
alias Wavex.Error
alias Wavex.Error.RIFFSizeMismatch
@enforce_keys [
:riff,
:format,
:data
]
defstruct [
:riff,
:format,
:data
]
@type t :: %__MODULE__{
riff: RIFF.t(),
format: Format.t(),
data: Data.t()
}
@spec verify_riff_size(non_neg_integer, binary) :: :ok | {:error, RIFFSizeMismatch.t()}
defp verify_riff_size(actual, binary) do
case byte_size(binary) - 8 do
^actual -> :ok
expected -> {:error, %RIFFSizeMismatch{expected: expected, actual: actual}}
end
end
@doc """
The duration of a wave file in seconds.
## Examples
Calculating the duration of 100000 samples at 88200b/s.
iex> Wavex.duration(%Wavex{
...> data: %Wavex.Chunk.Data{
...> data:
...> 0
...> |> List.duplicate(100_000)
...> |> List.to_string(),
...> size: 100_000
...> },
...> format: %Wavex.Chunk.Format{
...> bits_per_sample: 8,
...> block_align: 2,
...> byte_rate: 88_200,
...> channels: 2,
...> sample_rate: 44_100
...> },
...> riff: %Wavex.Chunk.RIFF{size: 100_036}
...> })
1.1337868480725624
Calculating the duration of 100000 samples at 176400b/s.
iex> Wavex.duration(%Wavex{
...> data: %Wavex.Chunk.Data{
...> data:
...> 0
...> |> List.duplicate(100_000)
...> |> List.to_string(),
...> size: 100_000
...> },
...> format: %Wavex.Chunk.Format{
...> bits_per_sample: 16,
...> block_align: 4,
...> byte_rate: 176_400,
...> channels: 2,
...> sample_rate: 44_100
...> },
...> riff: %Wavex.Chunk.RIFF{size: 100_036}
...> })
0.5668934240362812
"""
@spec duration(t) :: number
def duration(%__MODULE__{
data: %Data{size: size},
format: %Format{byte_rate: byte_rate}
}) do
size / byte_rate
end
@doc ~S"""
Map over the data of a `%Wavex{}` value.
## Examples
Mapping over an 8-bit `%Wavex{}` value.
iex> wave = %Wavex{
...> riff: %RIFF{
...> size: 60
...> },
...> format: %Format{
...> bits_per_sample: 8,
...> block_align: 2,
...> byte_rate: 88_200,
...> channels: 2,
...> sample_rate: 44_100
...> },
...> data: %Data{
...> size: 24,
...> data: <<
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00
...> >>
...> }
...> }
iex> wave = Wavex.map(wave, &(&1 + 0x12))
iex> wave.data.data
<<
0x12, 0x12, 0x12, 0x12,
0x12, 0x12, 0x12, 0x12,
0x12, 0x12, 0x12, 0x12,
0x12, 0x12, 0x12, 0x12,
0x12, 0x12, 0x12, 0x12,
0x12, 0x12, 0x12, 0x12
>>
Mapping over a 16-bit `%Wavex{}` value.
iex> wave = %Wavex{
...> riff: %RIFF{
...> size: 60
...> },
...> format: %Format{
...> bits_per_sample: 16,
...> block_align: 4,
...> byte_rate: 176_400,
...> channels: 2,
...> sample_rate: 44_100
...> },
...> data: %Data{
...> size: 24,
...> data: <<
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00
...> >>
...> }
...> }
iex> wave = Wavex.map(wave, &(&1 - 0x1234))
iex> wave.data.data
<<
-0x1234::16-signed-little, -0x1234::16-signed-little,
-0x1234::16-signed-little, -0x1234::16-signed-little,
-0x1234::16-signed-little, -0x1234::16-signed-little,
-0x1234::16-signed-little, -0x1234::16-signed-little,
-0x1234::16-signed-little, -0x1234::16-signed-little,
-0x1234::16-signed-little, -0x1234::16-signed-little
>>
Mapping over a 24-bit `%Wavex{}` value.
iex> wave = %Wavex{
...> riff: %RIFF{
...> size: 60
...> },
...> format: %Format{
...> bits_per_sample: 24,
...> block_align: 4,
...> byte_rate: 176_400,
...> channels: 2,
...> sample_rate: 44_100
...> },
...> data: %Data{
...> size: 24,
...> data: <<
...> 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
...> 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
...> >>
...> }
...> }
iex> wave = Wavex.map(wave, &(&1 + 0x123456))
iex> wave.data.data
<<
0x123456::24-signed-little, 0x123456::24-signed-little,
0x123456::24-signed-little, 0x123456::24-signed-little,
0x123456::24-signed-little, 0x123456::24-signed-little,
0x123456::24-signed-little, 0x123456::24-signed-little
>>
"""
@spec map(t, (integer -> integer)) :: t
def map(
%__MODULE__{
data: %Data{data: data} = data_chunk,
format: %Format{bits_per_sample: bits_per_sample}
} = wave,
function
) do
data =
case bits_per_sample do
8 -> map8(data, function)
16 -> map16(data, function)
24 -> map24(data, function)
end
%__MODULE__{wave | data: %Data{data_chunk | data: data}}
end
@spec map8(binary, (integer -> integer), binary) :: binary
defp map8(binary, function, acc \\ <<>>)
defp map8(<<sample, etc::binary>>, function, acc) do
map8(etc, function, <<function.(sample)>> <> acc)
end
defp map8(<<>>, _, acc), do: String.reverse(acc)
@spec map16(binary, (integer -> integer), binary) :: binary
defp map16(binary, function, acc \\ <<>>)
defp map16(<<sample::16-signed-little, etc::binary>>, function, acc) do
map16(etc, function, <<function.(sample)::16-signed-big>> <> acc)
end
defp map16(<<>>, _, acc), do: String.reverse(acc)
@spec map24(binary, (integer -> integer), binary) :: binary
defp map24(binary, function, acc \\ <<>>)
defp map24(<<sample::24-signed-little, etc::binary>>, function, acc) do
map24(etc, function, <<function.(sample)::24-signed-big>> <> acc)
end
defp map24(<<>>, _, acc), do: String.reverse(acc)
@doc ~S"""
Read LPCM WAVE data.
For more details, see `Wavex.Chunk.RIFF.read/1`, `Wavex.Chunk.Format.read/1`,
and `Wavex.Chunk.Data.read/1`.
## Examples
Reading a 16-bit stereo 88200b/s LPCM file:
iex> Wavex.read(<<
...> 0x52, 0x49, 0x46, 0x46, # R I F F
...> 0x2C, 0x00, 0x00, 0x00, # 44
...> 0x57, 0x41, 0x56, 0x45, # W A V E
...> 0x66, 0x6D, 0x74, 0x20, # f m t \s
...> 0x10, 0x00, 0x00, 0x00, # 16
...> 0x01, 0x00, 0x02, 0x00, # 1 2
...> 0x22, 0x56, 0x00, 0x00, # 22050
...> 0x88, 0x58, 0x01, 0x00, # 88200
...> 0x04, 0x00, 0x10, 0x00, # 4 16
...> 0x64, 0x61, 0x74, 0x61, # d a t a
...> 0x08, 0x00, 0x00, 0x00, # 8
...> 0x00, 0x00, 0x00, 0x00, # 0
...> 0x00, 0x00, 0x00, 0x00 # 0
...> >>)
{:ok,
%Wavex{
data: %Wavex.Chunk.Data{
data: <<0, 0, 0, 0, 0, 0, 0, 0>>,
size: 8
},
format: %Wavex.Chunk.Format{
bits_per_sample: 16,
block_align: 4,
byte_rate: 88_200,
channels: 2,
sample_rate: 22_050
},
riff: %Wavex.Chunk.RIFF{size: 44}
}}
Reading a 16-bit mono 22050/s LPCM file:
iex> Wavex.read(<<
...> 0x52, 0x49, 0x46, 0x46, # R I F F
...> 0x28, 0x00, 0x00, 0x00, # 40
...> 0x57, 0x41, 0x56, 0x45, # W A V E
...> 0x66, 0x6D, 0x74, 0x20, # f m t \s
...> 0x10, 0x00, 0x00, 0x00, # 16
...> 0x01, 0x00, 0x01, 0x00, # 1 1
...> 0x11, 0x2B, 0x00, 0x00, # 11025
...> 0x22, 0x56, 0x00, 0x00, # 22050
...> 0x02, 0x00, 0x10, 0x00, # 2 16
...> 0x64, 0x61, 0x74, 0x61, # d a t a
...> 0x04, 0x00, 0x00, 0x00, # 4
...> 0x00, 0x00, 0xFE, 0xFF # 0 0 254 255
...> >>)
{:ok,
%Wavex{
data: %Wavex.Chunk.Data{data: <<0, 0, 254, 255>>, size: 4},
format: %Wavex.Chunk.Format{
bits_per_sample: 16,
block_align: 2,
byte_rate: 22_050,
channels: 1,
sample_rate: 11_025
},
riff: %Wavex.Chunk.RIFF{size: 40}
}}
"""
@spec read(binary) :: {:ok, t} | {:error, Error.t()}
def read(binary) when is_binary(binary) do
with {:ok, %RIFF{size: riff_size} = riff, etc} <- RIFF.read(binary),
:ok <- verify_riff_size(riff_size, binary),
{:ok, %Format{} = format, etc} <- Format.read(etc),
{:ok, %Data{} = data} <- Data.read(etc) do
{:ok, %Wavex{riff: riff, format: format, data: data}}
end
end
end