STEREO ENCODING DEVICE, STEREO DECODING DEVICE, AND STEREO ENCODING METHOD

• US 20090262945A1
• Filed: 08/30/2006
• Published: 10/22/2009
• Est. Priority Date: 08/31/2005
• Status: Active Grant

• Current Assignee: III Holdings 12, LLC (Intellectual Ventures LLC)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Yoshida, Koji, Goto, Michiyo, Neo, Sua Hong, Teo, Chun Woei
• Granted Patent: US 8,457,319 B2
• Time in Patent Office: Days
• US Class Current: 381/2
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding

Abstract

There is disclosed a stereo encoding device capable of accurately encoding a stereo signal at a low bit rate and suppressing delay in audio communication. The device performs monaural encoding in its first layer (110). In a second layer (120), a filtering unit (103) generates an LPC (Linear Predictive Coding) coefficient and generates a left channel drive sound source signal. A time region evaluation unit (104) and a frequency region evaluation unit (105) perform signal evaluation and prediction in both of their regions. A residual encoding unit (106) encodes a residual signal. A bit distribution control unit (107) adaptively distributes bits to the time region evaluation unit (104), the frequency region evaluation unit (105), and the residual encoding unit (106) according to a condition of the audio signal.

Claims

1. A stereo coding apparatus comprising:

a time domain estimating section that estimates a first channel signal of a stereo signal in a time domain and encodes the estimation result; and

a frequency domain estimating section that partitions a frequency band of the first channel signal into a plurality of subbands, estimates the first channel signal in each subband in a frequency domain, and encodes the estimation result.

2. The stereo coding apparatus according to claim 1 that performs scalable coding, further comprising:

a first layer coding section that encodes a mono signal generated from the stereo signal; and

a second layer coding section that comprises the time domain estimating section and the frequency domain estimating section.

3. The stereo coding apparatus according to claim 2, wherein:

the time domain estimating section performs time domain estimation using the mono signal and generates a time domain estimated signal similar to the first channel signal; and

the frequency domain estimating section partitions a frequency band of the time domain estimated signal into a plurality of subbands in the same way as the first channel signal, performs frequency domain estimation using the time domain estimated signal in each subband and generates a frequency domain estimated signal similar to the first channel signal.

4. The stereo coding apparatus according to claim 2, further comprising a bit allocating section that allocates bits to the time domain estimating section and the frequency domain estimating section according to a degree of similarities between the first channel signal and the mono signal.

5. The stereo coding apparatus according to claim 4, wherein, when the degree of similarities between the first channel signal and the mono signal is equal to or greater than a predetermined threshold, the bit allocating section allocates more bits to the frequency domain estimating section.

6. The stereo coding apparatus according to claim 4, wherein, when the degree of similarities between the first channel signal and the mono signal is less than the predetermined threshold, the bit allocating section allocates bits to the time domain estimating section and the frequency domain estimating section equally.

7. The stereo coding apparatus according to claim 3, further comprising a residual coding section that encodes a residual signal between the first channel signal and the frequency domain estimated signal.

8. The stereo coding apparatus according to claim 3, wherein:

the time domain estimating section calculates spatial information between the first channel signal and the mono signal in the time domain estimation; and

the frequency domain estimating section calculates spatial information between the first channel signal and the time domain estimated signal in the frequency domain estimation.

9. A stereo decoding apparatus comprising:

a time domain decoding section that decodes encoded information that is an encoded result of time domain estimation of a first channel signal of a stereo signal; and

a frequency domain decoding apparatus that decodes encoded information that is an encoded result of frequency domain estimation of the first channel signal in a plurality of subbands partitioned from a frequency band of the first channel signal.

10. A stereo coding method comprising the steps of:

estimating a first channel signal of a stereo signal in a time domain;

encoding the estimation result in the time domain;

partitioning a frequency band of the first channel signal into a plurality of subbands;

estimating the first channel signal in each partitioned subband in a frequency domain; and

encoding the estimation result in the frequency domain.