Link to this section Summary

Types

t()

Functions

Read a format chunk

Link to this section Types

t()

t() :: %Wavex.Chunk.Format{
  bits_per_sample: pos_integer(),
  block_align: pos_integer(),
  byte_rate: pos_integer(),
  channels: pos_integer(),
  sample_rate: pos_integer()
}

Link to this section Functions

read(binary)

read(binary()) ::
  {:ok, t(), binary()}
  | {:error,
     Wavex.Error.BlockAlignMismatch.t()
     | Wavex.Error.ByteRateMismatch.t()
     | Wavex.Error.UnexpectedEOF.t()
     | Wavex.Error.UnexpectedFormatSize.t()
     | Wavex.Error.UnexpectedFourCC.t()
     | Wavex.Error.UnsupportedBitsPerSample.t()
     | Wavex.Error.UnsupportedFormat.t()
     | Wavex.Error.ZeroChannels.t()}

Read a format chunk.

Examples

iex> Wavex.Chunk.Format.read(<<
...>   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
...> >>)
{:ok,
%Wavex.Chunk.Format{
  bits_per_sample: 16,
  block_align: 4,
  byte_rate: 88_200,
  channels: 2,
  sample_rate: 22_050
}, ""}

Caveats

Chunk ID

Bytes 1-4 must read "fmt " to indicate a format chunk. The following example gives an error because bytes 1-4 read "data" instead of "fmt ".

iex> Wavex.Chunk.Format.read(<<
...>   0x64, 0x61, 0x74, 0x61, #  d     a     t     a
...>   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
...> >>)
{:error, %Wavex.Error.UnexpectedFourCC{expected: "fmt ", actual: "data"}}

Format size

The format size at bytes 5-8 is expected to be 16, the default format size for the LPCM format. The following example gives an error because the format size is 18 instead of 16.

iex> Wavex.Chunk.Format.read(<<
...>   0x66, 0x6d, 0x74, 0x20, #  f     m     t     \s
...>   0x12, 0x00, 0x00, 0x00, #  18
...>   0x01, 0x00, 0x02, 0x00, #  1           2
...>   0x22, 0x56, 0x00, 0x00, #  22050
...>   0x88, 0x58, 0x01, 0x00, #  88200
...>   0x04, 0x00, 0x10, 0x00  #  4           16
...> >>)
{:error, %Wavex.Error.UnexpectedFormatSize{actual: 18}}

Format

The format at bytes 9-10 must be 0x0001 (LPCM), as other formats are not supported. The following example gives an error because the format is 0x0032 instead of 0x0001.

iex> Wavex.Chunk.Format.read(<<
...>   0x66, 0x6d, 0x74, 0x20, #  f     m     t     \s
...>   0x10, 0x00, 0x00, 0x00, #  16
...>   0x32, 0x00, 0x02, 0x00, #  50          2
...>   0x22, 0x56, 0x00, 0x00, #  22050
...>   0x88, 0x58, 0x01, 0x00, #  88200
...>   0x04, 0x00, 0x10, 0x00  #  4           16
...> >>)
{:error, %Wavex.Error.UnsupportedFormat{actual: 0x0032}}

Channels

The format at bytes 11-12 must not be 0, because there has to be at least one channel. The following example gives an error because the number of channels is 0.

iex> Wavex.Chunk.Format.read(<<
...>   0x66, 0x6d, 0x74, 0x20, #  f     m     t     \s
...>   0x10, 0x00, 0x00, 0x00, #  16
...>   0x01, 0x00, 0x00, 0x00, #  1           0
...>   0x22, 0x56, 0x00, 0x00, #  22050
...>   0x88, 0x58, 0x01, 0x00, #  88200
...>   0x04, 0x00, 0x10, 0x00  #  4           16
...> >>)
{:error, %Wavex.Error.ZeroChannels{}}

Bits per sample

The bits per second at bytes 23-24 must be 8, 16, or 24, as other bit rates are not supported. The following example gives an error because the bit rate is 32.

iex> Wavex.Chunk.Format.read(<<
...>   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, 0x20, 0x00  #  4           32
...> >>)
{:error, %Wavex.Error.UnsupportedBitsPerSample{actual: 32}}

wavex

v0.5.5

wavex v0.5.5 Wavex.Chunk.Format