Current section

Files

Jump to
wavex lib wavex.ex
Raw

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 ~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