Methods and apparatuses for encoding and decoding object-based audio signals
Provided are an audio encoding method and apparatus and an audio decoding method and apparatus in which audio signals can be encoded or decoded so that sound images can be localized at any desired position for each object audio signal. The audio decoding method includes extracting a downmix signal and object-based side information from an audio signal; generating channel-based side information based on object-based side information and control information for rendering the downmix signal; processing the downmix signal using a decorrelated channel signal; and generating a multi-channel audio signal using the processed downmix signal and the channel-based side information.
1. An audio decoding method comprising:
receiving, by an audio decoding apparatus, a downmix signal comprising at least one object signal, and object-based side information generated when the at least one object signal is downmixed into the downmix signal, wherein the downmix signal is a stereo signal consisting of a left channel signal and a right channel signal;
receiving, by an audio decoding apparatus, control information for controlling position or level of at least one object signal;
generating, by an audio decoding apparatus, channel-based side information based on the object-based side information and the control information;
generating, by an audio decoding apparatus, parameter information using the object-based side information and the control information;
generating, by an audio decoding apparatus, a processed downmix signal by modifying the downmix signal using the parameter information wherein a position or level of at least one object signal is controlled based at least in part on the control information, and wherein the processed downmix signal is a stereo signal consisting of a left channel signal and a right channel signal; and
generating, by an audio decoding apparatus, a multi-channel audio signal using the processed downmix signal and the channel-based side information
wherein:
the downmix signal is modified in a frequency domain,
a number of channels of the processed downmix signal is equal to a number of channels of the downmix signal,
a number of channels of the multi-channel audio signal is larger than the number of channels of the processed downmix signal, and
the channel-based side information is used to generate a multi-channel signal from a mono signal or a stereo signal.
2. The audio decoding method of claim 1 , wherein the downmix signal is modified by performing at least one of level adjustment, sound image processing and effect addition on the downmix signal.
3. The audio decoding method of claim 1 , wherein the processed downmix signal is generated using a decorrelated channel signal.
4. The method of claim 1 , where in the audio decoding apparatus processes a plurality of object signals as a single sound source according to the position or level specified in the control information.
5. The audio decoding method of claim 1 , wherein the object-based side information comprises at least one of object level difference information, inter object cross correlation information, downmix gain information, downmix channel level difference information, and absolute object energy information.
6. The audio decoding method of claim 1 , wherein the channel-based side information comprises at least one of channel level differences information, inter-channel correlation information, and channel prediction coefficient information.
7. An audio decoding apparatus comprising:
a demultiplexer receiving a downmix signal comprising at least one object signal, and object-based side information generated when the at least one object signal is downmixed into the downmix signal, wherein the downmix signal is a stereo signal consisting of a left channel signal and a right channel signal;
a parameter converter configured to:
receive control information for controlling position or level of at least one object signal,
generate parameter information using the object based side information and the control information, and,
generate channel-based side information based on the object-based side information and the control information;
a downmix processor generating a processed downmix signal by modifying the downmix signal using the parameter information wherein a position or level of at least one object signal is controlled based at least in part on the control information, and wherein the processed downmix signal is a stereo signal consisting of a left channel signal and a right channel signal; and
a multi-channel decoder generating a multi-channel audio signal using the processed downmix signal and the channel-based side information,
wherein:
the downmix signal is modified in a frequency domain,
a number of channels of the processed downmix signal is equal to a number of channels of the downmix signal,
a number of channels of the multi-channel audio signal is larger than the number of channels of the processed downmix signal, and
the channel-based side information is used to generate a multi-channel signal from a mono signal or a stereo signal.
8. The audio decoding apparatus of claim 7 , wherein the downmix signal is modified by performing at least one of level adjustment, sound image processing and effect addition on the downmix signal.
9. The audio decoding apparatus of claim 7 , wherein the processed downmix signal is generated using a decorrelated channel signal.
10. The audio decoding apparatus of claim 7 , where in the audio decoding apparatus processes a plurality of object signals as a single sound source according to the position or level specified in the control information.