99, 99, 99, 99, 99, 99, 99, 99,
		99, 99, 99, 99, 99, 99, 99, 99,
		99, 99, 99, 99, 99, 99, 99, 99,
	},
}

type huffIndex int

const (
	huffIndexLuminanceDC huffIndex = iota
	huffIndexLuminanceAC
	huffIndexChrominanceDC
	huffIndexChrominanceAC
	nHuffIndex
)

// huffmanSpec specifies a Huffman encoding.
type huffmanSpec struct {
	// count[i] is the number of codes of length i bits.