Abstract:
A stereo audio encoding apparatus capable of preventing degradation of the sound quality of a decoded signal, while reducing the encoding bit rate. A spatial information analyzer analyzes spatial information for each of a L channel signal and an R channel signal. A similarity raiser corrects, based on an analysis result of the spatial information analyzer, a difference between the spatial information of the L channel signal and that of the R channel signal, to raise a similarity between the L and R channel signals. A channel signal encoder uses a sound source common to the two channels to encode the L and R channel signals as raised in similarity and output the resultant single encoded information. A spatial information encoder encodes the analysis result of the spatial information analyzer to output the resultant encoded information.
Abstract:
Provided is an encoding device which improves the sound quality of a stereo signal while maintaining a low bit rate. The encoding device includes: an LP inverse filter (121) which LP-inverse-filterS a left signal L(n) by using an inverse quantization linear prediction coefficient AdM(z) of a monaural signal; a T/F conversion unit (122) which converts the left sound source signal Le(n) from a temporal region to a frequency region; an inverse quantizer (123) which inverse-quantizes encoded information Mqe; spectrum division units (124, 125) which divide a high-frequency component of the sound source signal Mde(f) and the left signal Le(f) into a plurality of bands; and scale factor calculation units (126, 127) which calculate scale factors ai and ssi by using a monaural sound source signal Mdeh,i(f), a left sound source signal Leh,i(f), Mdeh,i(f), and right sound source signal Reh,i(f) of each divided band.
Abstract:
An audio encoding apparatus and the like are disclosed which can improve the sound quality of encoded audio signals even in a case of scalable CELP encoding the audio signals in sections that vary with time. In this apparatus, an enhancement layer extended adaptive codebook generating part (102) generates an extended adaptive codebook (d_enh_ext[i]) from both one frame of core layer drive sound source signals (exc_core[n]) received from a core layer CELP encoding part (101) and past enhancement layer drive sound source signals (exc_enh[n]) received from an adder (106), and further inputs the generated extended adaptive codebook (d_enh_ext[i]) to an enhancement layer extended adaptive codebook (103) for each of sub-frames. That is, the enhancement layer extended adaptive codebook generating part (102) updates the extended adaptive codebook (d_enh_ext[i]) for each of the sub-frames.
Abstract:
Upon reception of data updating information from a server apparatus (14) in a situation in which a presentation window is “closed” or “minimized” on a display unit (24) of each of terminal apparatuses (11-13), that presentation window is displayed on the display unit (24). The user who uses each of the terminal apparatuses (11-13) can always recognize a change in situation of the presentation system.
Abstract:
An electric power source device includes a direct current voltage source 10, a capacitor 13 connected in series with direct current voltage source 10, a DC/DC converter 19 connected to supply and receive energy between direct current voltage source 10 and capacitor 13, and a high voltage load 15 connected to both ends of a series circuit of direct current voltage source 10 and capacitor 13. A control circuit 33 of DC/DC converter 19 supplies electric power from capacitor 13 to direct current voltage source 10 when electric power is supplied to high voltage load 15 so as to reduce an electric current to be output from direct current voltage source 10 and to lighten the burden imposed on the direct current voltage source.
Abstract:
Disclosed are an audio encoding device and an audio decoding device which reduce degradation of subjective quality of a decoding signal caused by power mismatch of a decoding signal which is generated by a concealing process upon disappearance of a frame. When a frame is lost, a past encoding parameter is used to obtain a concealed LPC of the current frame and a concealed sound source parameter. A normal CELP decoding is performed from the obtained concealed sound source parameter. Correction is performed by using a conceal parameter on the obtained concealed LPC and the concealed sound source signal. The power of the corrected concealed sound source signal is adjusted to match a reference sound source power. A filter gain of the synthesis filter is adjusted so as to adjust the power of a decoded sound signal to the power of a decoded sound signal during an error-free state. Moreover, a synthesis filter gain adjusting coefficient is calculated by using an estimated normalized residual power so that a filter gain of a synthesis filter formed by using a concealed LPC is a filter gain during an error-free state.
Abstract:
Disclosed is a sound decoding device capable of improving the lost frame compensation performance and improving quality of the decoded sound. In this device, a rise frame sound source compensation unit (154) generates a compensation sound source signal when the current frame is a lost frame and a rise frame. An average sound source pattern update unit (156) updates the average sound source pattern held in an average sound source pattern holding unit (157) over a plurality of frames. When a frame is lost, an LPC synthesis unit (159) performs LPC synthesis on a decoded sound source signal by using the compensation sound source signal inputted via a switching unit (158) and a decoded LPC parameter from an LPC decoding unit (152) and outputs the compensation decoded sound signal.
Abstract:
There is provided an audio encoding device for correcting the component having insufficient encoding capability in the core layer by an extended layer. In this device, a core layer encoding unit (101) encodes an audio signal, an extended layer encoding unit (150) encodes an encoding residual of the core layer encoding unit (101), a characteristic correction inverse filter (102 arranged at the pre-stage of an LPC synthesis filter (104) subjects the component having insufficient encoding capability in the core layer to the inverse characteristic correction process, and a characteristic correction filter (105) arranged at the post-stage of the LPC synthesis filter (104) performs a process for characteristic correction of the synthesis signal inputted from the LPC synthesis filter (104).
Abstract:
Disclosed is a stereo speech decoding device and others capable of reducing a stereo speech encoding bit rate and suppressing degradation of speech quality. In this device, a section 0 where only an L-channel signal SL(n) exists is identified, a monaural signal of the section 0 transmitted from the stereo speech encoding side is made to be an L-channel signal of section 0 SL(0)(n), and the L-channel signal SL(0)(n) of the section 0 is scale-adjusted so as to predict an R-channel signal SR(1)(n) of a section 1. A contribution of the R-channel signal SR(1)(n) of the predicted section 1 is subtracted from the monaural signal of the section 1 so as to isolate the L-channel signal SL(1)(n) of the section 1. This device continuously repeats the aforementioned scale adjustment and isolation process so as to obtain the L-channel signal SL(n) and the R-channel signal SR(n) of all the sections.
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.