User:אפונה/sandbox

[0000 0000] [..........]

The prefix is one byte long, containing two parts: the first nibble represents how many zeroes precede the AC coefficient being encoded, and the second nibble represents the length (in bits) of the binary representation of the coefficient that will follow the prefix. The coefficient is represented as a

Each non-zero AC coefficient is encoded as a special prefix followed by a binary representation of the coefficient. The prefix is a Huffman code that can be used to look up a 1-byte value in the Huffman table. This corresponding byte has two components - the first nibble (4 bits) represents how many zero-value AC coefficients directly precede the AC coefficient being encoded, and the second nibble represents the length (in bits) of the coefficient value that will follow the prefix. The coefficient value itself is encoded in binary form with any leading zeroes trimmed. If the value is negative, it is decremented by one and encoded with any leading 1's trimmed (negative numbers always have at least one or more consecutive 1-bits starting from the most significant bit).

The AC coefficient is encoded in binary form with any leading zeroes trimmed. If the value is negative, it is decremented by one and encoded with any leading 1's trimmed (see Two's complement). This value is prefixed by a Huffman code that can be used to look up a 1-byte value in the Huffman table. This corresponding byte has two components - the first nibble (4 bits) represents how many zero-value AC coefficients directly precede the AC coefficient being encoded, and the second nibble represents the length (in bits) of the coefficient value that follows the prefix.