Patent ID: 11949817
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Digital communication (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 0:
1. A multipoint control method performed by a multipoint phone connection system comprising a multipoint control unit to which one or more first communication network terminal apparatuses and two or more second communication network terminal apparatuses are connected through a communication path, the number of points at which the one or more first communication network terminal apparatuses are located being M (M is an integer of 1 or greater), the number of points at which the two or more second communication network terminal apparatuses are located being N (N is an integer of 2 or greater), the method comprising:
a point selecting step of, for each time period, selecting, by the multipoint control unit, one point or two points from among M points at which the one or more first communication network terminal apparatuses are located and N points at which the two or more second communication network terminal apparatuses are located, a bit stream in each time period input from each first communication network terminal apparatus to the multipoint control unit through the communication path being a bit stream including, as codes representing a sound signal, a monaural code CFMm (m is an integer from 1 to M) obtained by coding a mixed signal of sound signals of two or more channels input to the first communication network terminal apparatus by a first coding scheme and an extension code CFEm including a code representing information corresponding to a difference between the input sound signals of two or more channels, and a bit stream in each time period input from each second communication network terminal apparatus to the multipoint control unit through the communication path being a bit stream including, as a code representing a sound signal, a monaural code CMMn (n is an integer from 1 to N) obtained by coding a sound signal of one channel input to the second communication network terminal apparatus by the first coding scheme;
a step of, for each time period, obtaining, by a decoding apparatus in each second communication network terminal apparatus, a decoded sound signal by decoding a monaural code in an input code representing a sound signal by a first decoding scheme corresponding to the first coding scheme,
wherein the method further comprises,
a step of, by a decoding apparatus in each first communication network terminal apparatus,
for each time period in which input codes representing a sound signal is a pair of a monaural code and an extension code corresponding to a sound signal of one point, obtaining a provisional decoded sound signal by decoding the monaural code in the pair by the first decoding scheme, obtaining decoded difference information from the extension code in the pair, and obtaining and outputting two decoded sound signals from the provisional decoded sound signal and the decoded difference information,
for each time period in which an input code representing a sound signal is one monaural code corresponding to a sound signal of one point, obtaining and outputting one decoded sound signal by decoding the one monaural code by the first decoding scheme, and
for each time period in which input codes representing a sound signal are two monaural codes corresponding to sound signals of two points, obtaining and outputting two decoded sound signals by decoding each of the two monaural codes by the first decoding scheme, and

a bit stream generating step of, if two second communication network terminal apparatuses of an N1-th point (N1 is an integer from 1 to N) and an N2-th point (N2 is an integer from 1 to N and is different from N1) are selected from the one or more first communication network terminal apparatuses and the two or more second communication network terminal apparatuses, generating and outputting, by the multipoint control unit, as a bit stream for each first communication network terminal apparatus, a bit stream including, as codes representing a sound signal, a monaural code CMMN1 that is a code representing a sound signal of the N1-th point and a monaural code CMMN2 that is a code representing a sound signal of the N2-th point.