摘要:
The objective of the present invention is to suppress deterioration of call quality caused by transcoding without interrupting a call even if a codec used by one of the terminals during communication is changed. A modification determination unit, in the case of detecting a modification of a codec used by one terminal of two terminals, determines whether or not to constrain the bandwidth of the first codec using a first codec of the other terminal and a second codec after modification by the first-mentioned one of the terminals. A signaling generation unit transmits, to the other terminal, signaling for limiting the bandwidth if the bandwidth is to be limited.
摘要:
A voice coding device capable of preventing overall quality degradation even when the bit rate for coding is lowered. The voice coding device codes a wide band signal in a first layer, and codes an extended band signal whose frequency band is located in higher frequency than the wide band signal in an extended band layer. An adaptive band selection unit (301) selects a frequency band to be excluded from a coding object in the extended band layer or a frequency band whose energy is to be attenuated in the extended band layer. A band-limited signal generation unit (302) excludes, within the frequency band of an input signal, the frequency band selected by the adaptive band selection unit (301) from the coding object, or attenuates the energy of the frequency band selected by the adaptive band selection unit (301).
摘要:
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.
摘要:
An audio decoding device capable of suppressing an information amount for a lost flame compensation process and encoding efficiency is provided. A decoded sound source generator generates a lost frame's CELP decoded sound source signal. A pitch pulse information decoder CELP decodes a pitch pulse position information and a pitch pulse amplitude information. A pitch pulse waveform learner learns a pitch pulse learning waveform in a past frame in advance from the lost frame. A convolution adjuster amplitude-adjusts the pitch pulse learning waveform according to the pitch pulse amplitude information by considering a predetermined number of waveforms peripheral to a peak position of the lost frame's CELP decoded excitation signal, and convolutes a pitch pulse waveform into a time axis which has been amplitude-adjusted according to the pitch pulse position information. A sound source signal corrector adds or replaces the pitch pulse waveform convoluted into the time axis to the lost flame decoded sound source signal.
摘要:
Fluctuation in decoded signal localization is suppressed to maintain the feel of stereo. A selection unit selects balance parameters when the balance parameters are input from a gain coefficient decoding unit, or selects balance parameters input from a gain coefficient calculation unit when there is no balance parameter input from the gain coefficient decoding unit, and outputs the selected balance parameters to a multiplication unit. The multiplication unit multiplies a gain coefficient input from the selection unit with a decoded monaural signal input from a monaural decoding unit to perform balance adjustment processing.
摘要:
Disclosed are a quantizer, encoder, and the methods thereof, wherein the computational load is reduced when the values related to the transform coefficients of the principal component analysis transform are quantized when a principal component analysis transform is applied to code stereo. A quantizer includes a power correlation calculator which calculates the power of the left channel signal, the power of the right channel signal, and the correlation between the left channel signal and the right channel signal; an intermediate value calculator which calculates the intermediate value which is the difference between left channel signal the power and the right channel signal power; a codebook which holds a plurality of sets of the coefficients related to the transform coefficients of the principal component analysis transform and the code; and a quantizer which calculates the sum of the first multiplication result obtained by multiplying the coefficient by the correlation value and the second multiplication result obtained by multiplying the coefficient by the intermediate value as the cost function E, selects the coefficients where the cost function E becomes the maximum, and fetches the code related to the selected coefficients as the quantized code.
摘要:
A scalable encoding device is capable of improving quality of a decoded signal without increasing an encoding amount and compensating data with a sufficient quality upon data loss. An extension layer bit distribution calculator calculates a bit distribution of a quality improving encoding data and compensation encoding data in the extension layer according to an audio mode of the input signal. An extension layer encoder generates quality improving encoding data according to the specified number of bits. A compensation information encoder extracts a part of core layer encoding data and makes it as compensation encoding data for the core layer. An extension layer encoded data generator multiplexes the extension layer bit distribution information, the compensation encoding data, and the quality improving encoding data so as to obtain extension layer encoding data.
摘要:
Disclosed is an audio encoding device capable of adjusting a spectrum inclination of a quantized noise without changing the Formant weight. The device includes: an HPF (131) which extracts a high-frequency component of the frequency region from an input audio signal; a high-frequency energy level calculation unit (132) which calculates an energy level of the high-frequency component in a frame unit; an LPF (133) which extracts a low-frequency component of the frequency region from the input audio signal; a low-energy level calculation unit (134) which calculates an energy level of a low-frequency component in a frame unit; an inclination correction coefficient calculation unit (141) multiplies the difference between SNR of the high-frequency component and SNR of the low-frequency component inputted from an adder (140) by a constant and adds a bias component to the product so as to calculate an inclination correction coefficient ?3. The inclination correction coefficient is used for adjusting the spectrum inclination of a quantized noise.
摘要:
A scalable decoder capable of avoiding deterioration in subjective quality of a listener. The scalable decoder for decoding core layer encoding data and extension layer encoding data including an extension layer gain coefficient, wherein a voice analysis section detects variation in power of a core layer decoding voice signal being obtained from the core layer encoding data, a gain attenuation rate calculating section (140) sets the attenuation intensity variable depending on variation in power, and a gain attenuation section (143) attenuates the extension layer gain coefficient in a second period preceding a first period according to a set attenuation intensity when extension layer encoding data in the first period is missing, thus interpolating the extension layer gain coefficient in the first period.
摘要:
A scalable decoder capable of preventing degradation of the quality of the decoded signal in a disappeared data interpolation in band scalable coding. A core layer decoding section (101) acquires a core layer decoded signal and narrow band spectrum information by decoding. A narrow band spectrum slope computing section (103) computes the slope of an attenuation line of a narrow band spectrum from the narrow band spectrum information. An extended layer disappearance detection section (104) detects whether extended layer coded data has disappeared or not. An extended layer decoding section (105) normally decodes the extended layer coded data. If the extended layer disappears, a parameter required for decoding is interpolated and synthesizes an interpolation decoded signal by the interpolated parameter. The gain of the interpolated data is controlled according to the results of the computation, by the narrow band spectrum slope computing section (103).