Compatible multi-channel coding-decoding

A method of audio decoding an encoded audio signal to obtain a decoded audio signal, the method comprising:

• reading, by an input data reader, the encoded audio signal, the encoded audio signal comprising channel side information, a left downmix channel, and a right downmix channel, wherein the channel side information are calculated such that the left or the right downmix channel, when weighted using the channel side information, results in an approximation of a selected original channel;
• and
• reconstructing, by a reconstructor, the approximation of the selected original channel using the channel side information and the left or the right downmix channel to obtain the approximation of the selected original channel,
• wherein the approximation of the selected original channel represents the decoded signal and comprises at least three of an approximated left channel, an approximated left surround channel, an approximated right channel, and an approximated right surround channel,
• wherein the input data include channel side information for at least three of the approximated left channel, the approximated left surround channel, the approximated right channel, and the approximated right surround channel,
• wherein the reconstructing comprises at least three of the following:
• reconstructing the approximated left channel using channel side information for the left channel and using the left downmix channel,
• reconstructing the approximated left surround channel using channel side information for the left surround channel and using the left downmix channel,
• reconstructing the approximated right channel using channel side information for the right channel and using the right downmix channel, and
• reconstructing the approximated right surround channel using channel side information for the right surround channel and using the right downmix channel,
• wherein the method further comprises perceptually decoding, by a perceptual decoder, the left downmix channel to obtain a decoded version of the left downmix channel and perceptually decoding the right downmix channel to obtain a decoded version of the right downmix channel, wherein the perceptually decoding comprises entropy decoding, by an entropy decoder, and inverse quantizing, by an inverse quantizer, and
• wherein at least one of the input data reader, the reconstructor, the perceptual decoder, the entropy decoder, and the inverse quantizer comprises a hardware implementation.

A non-transitory storage medium having stored thereon a computer program having a program code for performing a method for audio decoding an encoded audio signal to obtain a decoded audio signal, the method comprising:

• reading the encoded audio signal, the encoded audio signal comprising channel side information, a left downmix channel, and a right downmix channel, wherein the channel side information is calculated such that the left or the right downmix channel, when weighted using the channel side information, results in an approximation of the selected original channel;
• and
• reconstructing the approximation of the selected original channel using the channel side information and the left or the right downmix channel to obtain the approximation of the selected original channel,
• wherein the approximation of the selected original channel represents the decoded signal and comprises at least three of an approximated left channel, an approximated left surround channel, an approximated right channel, and an approximated right surround channel,
• wherein the input data include channel side information for at least three of the approximated left channel, the approximated left surround channel, the approximated right channel, and the approximated right surround channel,
• wherein the reconstructing comprises at least three of the following:
• reconstructing the approximated left channel using channel side information for the left channel and using the left downmix channel,
• reconstructing the approximated left surround channel using channel side information for the left surround channel and using the left downmix channel,
• reconstructing the approximated right channel using channel side information for the right channel and using the right downmix channel, and
• reconstructing the approximated right surround channel using channel side information for the right surround channel and using the right downmix channel,
• wherein the method further comprises perceptually decoding the left downmix channel to obtain a decoded version of the left downmix channel and perceptually decoding the right downmix channel to obtain a decoded version of the right downmix channel, wherein the perceptually decoding comprises entropy decoding and inverse quantizing.