Audio encoder and audio decoder

An audio decoding method for decoding a coded signal, said method comprising:

• obtaining coded signals including a) a first coded signal obtained by coding a two- channel stereo signal downmixed from a multi-channel signal exceeding two channels,
• b) a second coded signal obtained by coding information for generating a multi-channel signal from the stereo signal and c) a signal representing a code size of the second coded signal;
• and decoding the obtained coded signal and outputting a stereo signal, wherein the decoding of the obtained coded signal further includes:
• reading the first coded signal out of the obtained coded signals via a first coded signal readout unit;
• reading a signal representing a code size of the second coded signal out of the coded signals via a code size readout unit;
• the code size readout unit configured to read the signal representing a code size of the second coded signal out of the coded signals;
• and said code size readout unit is also configured to remove or skip the second coded signal based on the code size read out by said code size readout unit.

A program stored on a computer-readable storage medium for-and used in an audio decoder which decodes a coded signal, said program causing a computer to function as the following respective units:

• an obtaining unit configured to obtain coded signals including a) a first coded signal obtained by coding a two-channel stereo signal downmixed from a multi-channel signal exceeding two channels, b) a second coded signal obtained by coding information for generating a multi-channel signal from the stereo signal, and c) a signal representing a code size of the second coded signal;
• and a decoding unit configured to decode the obtained coded signals, and outputs a stereo signal, wherein said program further causes the decoding unit to operate as:
• a first coded signal readout unit configured to read the first coded signal out of the obtained coded signals;
• a code size readout unit configured to read a signal representing a code size of the second coded signal out of the coded signals;
• and a first decoding unit configured to decode the first coded signal read out by said first coded signal readout unit, and to output the stereo signal,
• Wherein said code size readout unit is also configured to remove or skip the second coded signal based on the code size read out by said code size readout unit.