Scalable encoding apparatus, scalable decoding apparatus, and methods of them
View Patent ↗A scalable encoding apparatus capable of suppressing the quality degradation of a decoded signal without increasing the bit rate. In this apparatus, a core layer encoding part ( 101 ) and an extended layer encoding part ( 102 ) encode an input signal for each of audio frames. When a replacement determining part ( 103 ) determines that a degree to which the input signal changes between a preceding frame and a current frame is equal to or greater than a predetermined value or that a degree, to which the quality of the decoded signal is improved by an extended layer encoding process in the preceding frame, is equal to less than a predetermined level, a replacing part ( 105 ) replaces a part of an extended layer encoded data of the preceding frame by a core layer encoded data of the current frame. That is, a transmitting part ( 108 ) transmits, as a backup, the core layer encoded data of the current frame to a decoding end in advance.
1. A scalable encoding apparatus that is configured with at least a lower layer and a higher layer, comprising:
a lower layer encoder that performs encoding in the lower layer to generate lower layer encoded data;
a higher layer encoder that performs encoding in the higher layer to generate higher layer encoded data;
a duplicator that generates duplicated data of the lower layer encoded data; and
a replacer that replaces part of the higher layer encoded data with the duplicated data.
2. The scalable encoding apparatus according to claim 1 , wherein the replacer replaces the higher layer encoded data of a frame that precedes a specific frame, using the duplicated data of lower layer encoded data of the specific frame.
3. The scalable encoding apparatus according to claim 2 , further comprising a determiner that determines the specific frame according to a predetermined criterion,
wherein the replacer performs the replacement using the duplicated data of the specific frame determined in the determiner.
4. The scalable encoding apparatus according to claim 3 , wherein the determiner determines a frame including one of an onset of a speech signal, a frame including an unvoiced non-stationary consonant part, and a speech frame of a non-stationary signal, as the specific frame.
5. The scalable encoding apparatus according to claim 3 , wherein the determiner determines a frame where a degree of change of a parameter showing a characteristic of an input signal is at least equal to a predetermined level, as the specific frame.
6. The scalable encoding apparatus according to claim 5 , wherein the determiner uses power of one of a speech signal, a pitch period, a pitch prediction gain and a linear prediction coefficient parameter, as the parameter.
7. The scalable encoding apparatus according to claim 3 , wherein the determiner compares coding distortion included in decoded data from the lower layer encoded data and coding distortion included in decoded data from both the lower layer encoded data and the higher layer encoded data, and determines a contribution to a decrease in the coding distortion of the higher layer encoded data, and determines a frame where the contribution is at least equal to a predetermined level as the specific frame.
8. The scalable encoding apparatus according to claim 3 , wherein the determiner calculates a ratio of a lower-band energy to a full-band energy in an input signal and determines a frame where the ratio is at least equal to a predetermined level as the specific frame.
9. The scalable encoding apparatus according to claim 2 , further comprising an extractor that extracts part of data from the lower layer encoded data of the specific frame,
wherein the duplicator generates duplicated data of the part of data.
10. The scalable encoding apparatus according to claim 9 , wherein the extractor extracts data including at least one of a linear prediction coefficient parameter, an adaptive codebook lag and a gain, as the part of data.
11. The scalable encoding apparatus according to claim 2 , wherein the replacer replaces part of data, out of the higher layer encoded data of a frame that precedes the specific frame, with the duplicated data.
12. The scalable encoding apparatus according to claim 11 , wherein the replacer selects data including none of a linear prediction coefficient parameter, an adaptive codebook lag and a gain, as the part of data.
13. A communication terminal apparatus comprising the scalable encoding apparatus according to claim 1 .
14. A base station apparatus comprising the scalable encoding apparatus according to claim 1 .
15. A scalable decoding apparatus configured with at least a lower layer and a higher layer, comprising:
a demultiplexer that demultiplexes duplicated data of a lower layer encoded data from a higher layer encoded data;
a detector that detects a loss of a frame;
a lower layer decoder that decodes the duplicated data to generate first decoded data when the loss of a frame is detected; and
a higher layer decoder that, when the loss of a frame is detected, compensates for the lost frame using the first decoded data to generate second decoded data.
16. The scalable decoding apparatus according to claim 15 , wherein the demultiplexer demultiplexes the duplicated data from the higher layer encoded data of a frame that precedes the lost frame.
17. A communication terminal apparatus comprising the scalable decoding apparatus according to claim 15 .
18. A base station apparatus comprising the scalable decoding apparatus according to claim 15 .
19. A scalable encoding method comprising using a replacer to replace part of an enhancement layer encoded data with backup data of a core layer encoded data.
20. A scalable encoding method used in a scalable encoding apparatus that is configured with at least a lower layer and a higher layer, comprising:
performing encoding, via a lower layer encoder, in the lower layer to generate lower layer encoded data;
performing encoding, via a higher layer encoder, in the high layer to generate higher layer encoded data;
generating, via a generator, duplicated data of the lower layer encoded data; and
replacing, using a replacer, part of the higher layer encoded data with the duplicated data.
21. A scalable decoding method used in a scalable decoding apparatus that is configured with at least a lower layer and a higher layer, comprising:
demultiplexing, via a demultiplexer, duplicated data of lower layer encoded data from high layer encoded data;
detecting, via a detector, a loss of a frame;
decoding, via a decoder, the duplicated data to generate first decoded data when the loss of a frame is detected; and
compensating, via a compensator, for the lost frame using the first decoded data and generating second decoded data when the loss of a frame is detected.