go-fourcc

Package fourcc is a Go implementation of FOURCC (four character code) (4CC) identifiers for a video codecs, compression formats, colors, and pixel format used in media files.

Documention

Online documentation, which includes examples, can be found at: http://godoc.org/github.com/reiver/go-fourcc

Introduction

FOURCC, also sometimes written as FourCC and 4CC, are all short for “four character code”.

FOURCC, is a sequence of 4 8-bit bytes packed into an unsigned 32-bit integer which, uniquely identifies a data format.

(A character in this context is a 1 byte (i.e., 8 bit) value. Thus a FOURCC always takes up exatly 32 bits (i.e., 4 bytes).)

These data formats tend to be video codecs, compression formats, colors, and pixel format used in media files.

Samples

Here are some sample FOURCC.

Label	Hexadecimal (unsigned integer)
PAL8	0x384C4150
VP80	0x30385056
H264	0x34363248
MJPG	0x47504A4D

The way you can understand how these labels get turned in unsigned integers is, if we consider the FOURCC “PAL8”, then:

ASCII ‘P’ = hexadecimal 0x50
ASCII ‘A’ = hexadecimal 0x41
ASCII ‘L’ = hexadecimal 0x4C
ASCII ‘8’ = hexadecimal 0x38

And then these 8-bit bytes as packed into an unsigned integer in reverse order.

I.e.,:

var value uint32 = (uint32('P') | (uint32('A') << 8) | (uint32('L') << 16) | (uint32('8') << 24))

Examples

Here is an example usage:

var colorspace fourcc.Type = fourcc.FOURCC('P','A','L','8')

Here is a constant:

const (
	VP8 = fourcc.Const("VP80")
)

A fourcc.Const needs to be turned into a fourcc.Type before using it. So:

var datum fourcc.Type
var err error

datum, err = VP8.FOURCC()

Some uses of Scan:

var colorspace fourcc.Type

err := colorspace.Scan("PAL8")

And:

var p [4]byte = [4]byte{'P','A','L','8'}

var colorspace fourcc.Type

err := colorspace.Scan(p)

And:

var p []byte = []byte{'P','A','L','8'}

var colorspace fourcc.Type

err := colorspace.Scan(p)

See Also

• FOURCC.org