US 2003/0200083 A1 · Speech decoding device and speech decoding method

Abstract

A speech decoding device is provided which is capable of reducing degradation of speech quality caused by concealment processing to be performed when a loss of a packet has occurred, in speech packet communications using a VoIP (Voice over Internet Protocol) or a like. A decoding circuit decodes speech from a packet received through an input terminal and stores an internal signal in an updating buffer circuit, the internal signal produced in the decoding process and to be used in a decoding process for a subsequent packet to be subsequently received. The decoding circuit produces, based on the internal signal stored in the updating buffer circuit, concealed speech corresponding to a packet having not been received, and outputs the produced concealed speech. At this point, the updating circuit, by regarding the concealed speech produced by the decoding circuit as being not differing greatly from an original speech and by updating the internal signal stored in the updating buffer circuit using the concealed speech, reduces mismatching of internal signals occurring due to the concealment processing between in an encoding device and in a decoding device and reduces degradation of speech quality in decoding a packet following the concealment processing.

Claims21

Dependent claims

A speech decoding device comprising:

a first circuit to receive a packet and decode speech from the received packet;
a second circuit to store an internal signal produced in the decoding process by said first circuit and to be used by said first circuit in a decoding process for a subsequent packet to be subsequently received;
a third circuit to produce concealed speech corresponding to a packet having not been received using a prior received packet;
and
a fourth circuit to update said internal signal using said concealed speech.

2 more elements

A speech decoding device comprising:

a decoding circuit to sequentially receive packets containing at least one piece of speech frame data encoded in a block unit for every specified interval in a speech encoding device on a side of a sender, to decode speech frame data in order of packets specified by a time stamp attached to a received packet, to store an internal signal produced in the decoding process and to be used in a subsequent decoding process for subsequent speech frame data in a buffer, and to produce and output concealed speech corresponding to a packet having not been received, based on said internal signal being stored in said buffer;
a loss measuring circuit to measure a length of time during which no receiving of a packet occurs continuously;
and
wherein said decoding circuit is so configured, when said length of time measured by said loss measuring circuit is longer than a predetermined length of time, as to change said internal signal being stored in said buffer for use, to decode speech from a packet received thereafter.

1 more element

A method for decoding speech comprising:

a first step of receiving a packet and decoding speech from the received packet;
a second step of storing an internal signal produced by decoding in said first step and to be used in said first step for decoding of a subsequent packet to be subsequently received;
a third step of producing concealed speech corresponding to a packet having not been received using a prior received packet;
a fourth step of measuring a length of time during which no receiving of a packet occurs continuously;
and
a fifth step of changing said internal signal, when said length of time is longer than a predetermined length of time, to decode speech from a packet received thereafter.

3 more elements

Dependencies are inferred from the claim text.

Speech decoding device and speech decoding method

Life of this patent

Speech decoding device and speech decoding method

Life of this patent

Abstract

Claims21