chunk

Library for decoding and encoding chunked audio containers like RIFF / AIFF.

Features

• Supported formats:
  • Waveform Audio File Format (WAVE)
  • Broadcast Wave Format (BWF)
  • Audio Interchange File Format (AIFF, AIFF-C)
• Supported chunks (Decode / Encode)
  • 'fmt ' - WAVE format and PCM format
  • 'COMM' - Common
  • 'bext' - Broadcast Extension for sound metadata in BWF (version 0, 1, 2)
  • 'iXML' - Extension for sound metadata in BWF (iXML Specification Revision 2.10)
• Decode headers of unknown chunks
• Encode custom header
• Byte array presentation of known chunks for further processing

Prerequisites

Download and install chunk into your GOPATH.

go get github.com/metawav/chunk

Import the package to get started.

import "github.com/metawav/chunk"

Examples

Read headers from RIFF (.wav) file

fileName := "sample.wav"
file, err := os.Open(fileName)

if err != nil {
    panic(err)
}

defer file.Close()

reader := io.ReadSeeker(file)
container, _ := chunk.ReadRiff(file.Name(), reader)

for _, header := range container.Headers {
    fmt.Printf("%s\n", header)
}

Example output:

ID: fmt  Size: 16 FullSize: 24 StartPos: 12 HasPadding: false
ID: data Size: 88200 FullSize: 88208 StartPos: 36 HasPadding: false
ID: LIST Size: 68 FullSize: 76 StartPos: 88244 HasPadding: false
ID: JUNK Size: 10 FullSize: 18 StartPos: 88320 HasPadding: false

Find and decode format chunk

headers := container.FindHeaders("fmt ") // keep care of trailing space :)
chunkBytes := make([]byte, headers[0].FullSize())
_, err = file.ReadAt(chunkBytes, int64(headers[0].StartPos()))

if err != nil {
    //handle err
}

format, err := chunk.DecodePCMFormatChunk(chunkBytes)

if err != nil {
    //handle err
}

fmt.Printf("%s\n", format)

Example output:

Format: 1
Channels: 1
Sample rate: 44100
Byte rate: 88200
Bytes per sample: 2
Bits per sample: 16

Encode format chunk

format = chunk.EncodePCMFormatChunk(16, 1, 1, 44100, 88200, 2, 24)
fmt.Printf("%s\n", format)

Example output:

Format: 1
Channels: 1
Sample rate: 44100
Byte rate: 88200
Bytes per sample: 2
Bits per sample: 24

Get bytes representation of format chunk

format = chunk.EncodePCMFormatChunk(16, 1, 1, 44100, 88200, 2, 24)
fmt.Printf("%08b\n", format.Bytes())

Example output:

[
01100110 01101101 01110100 00100000 // ID               = "fmt "
00010000 00000000 00000000 00000000 // size             = 16
00000001 00000000                   // format           = 1
00000001 00000000                   // channels         = 1
01000100 10101100 00000000 00000000 // samples per sec  = 44100
10001000 01011000 00000001 00000000 // bytes per sec    = 88200
00000010 00000000                   // block align      = 2
00011000 00000000                   // bits per sample  = 24
]

Documentation

See package documentation:

License

chunk is released under Apache License, Version 2.0. See LICENSE.