摘要:
A device (1) is arranged for synthesizing sound represented by sets of parameters, each set comprising noise parameters (NP) representing noise components of the sound and optionally also other parameters representing other components, such as transients and sinusoids. Each set of parameters may correspond with a sound channel, such as a MIDI voice. In order to reduce the computational load, the device comprises a selection unit (2) for selecting a limited number of sets from the total number of sets on the basis of a perceptual relevance value, such as the amplitude or energy. The device further comprises a synthesizing unit (3) for synthesizing the noise components using the noise parameters of the selected sets only.
摘要:
Encoding (2) a signal (A) is provided, wherein frequency and amplitude information of at least one sinusoidal component in the signal (A) is determined (20), and sinusoidal parameters (f,a) representing the frequency and amplitude information are transmitted (22), and wherein further a phase jitter parameter (p) is transmitted, which represents an amount of phase jitter that should be added during restoring the sinusoidal component from the transmitted sinusoidal parameters (f,a).
摘要:
Coding (1) of an audio signal is provided including estimating (110) a position of a transient signal component in the audio signal, matching (111,112) a shape function on the transient signal component in case the transient signal component is gradually declining after an initial increase, which shape function has a substantially exponential initial behavior and a substantially logarithmic declining behavior; and including (15) the position and shape parameters describing the shape function in an audio stream (AS).
摘要:
In a sinusoidal audio encoder it is known to use different time scales for analyzing different parts of the frequency spectrum. In prior art encoders sub-band filtering is used to split the input signal into a number of sub bands. By splitting the input signal into sub-bands, it can happen that a signal component at the boundary of two sub-bands results in a representation in both sub-band signals. This double representation of signal components can lead to several problems when coding these components. According to the present invention it is proposed to use preventing means (46, 48, 58, 68; 88, 92, 96) to avoid signal components to have multiple representations.
摘要:
The invention relates to a linking unit 100, a parametric encoder 400 and a method for generating linking information L indicating components of consecutive extended segments sp and sc which may be linked together in order to form a sinusoidal track. The segments sp and sc approximate consecutive segments of a sinusoidal audio or speech signal s. The linking unit comprises a calculating unit 120 for generating a similarity matrix S(m,n) in response to received sinusoidal code data and an evaluating unit 140 for receiving and evaluating said similarity matrix S in order to generate said linking information by selecting those pairs of components m,n the similarity of which is maximal. According to the invention the calculating unit 120 is adapted to calculate the similarity matrix S by additionally considering information about the phase consistency between the components of the extended previous segment sp and the extended current segment sc. In that way the selection of components suitable for being linked together is improved resulting in the definition of correct tracks.
摘要:
Coding (1) of an audio signal is provided including estimating (110) a position of a transient signal component in the audio signal, matching (111,112) a shape function on the transient signal component in case the transient signal component is gradually declining after an initial increase, which shape function has a substantially exponential initial behavior and a substantially logarithmic declining behavior; and including (15) the position and shape parameters describing the shape function in an audio stream (AS).
摘要:
An audio encoding device (100) comprises first encoding means (101, 111) for encoding transient signal components and/or sinusoidal signal components of an audio signal (x(n)) and producing a residual signal (z(n)), and second encoding means for encoding the residual signal. The second encoding means comprise filter means (122) for selecting at least two frequency bands of the residual signal. The selected frequency bands (LF, HF) of the residual signal (z(n)) are encoded by a first encoding unit (123) and a second encoding unit (124) respectively. The first encoding unit (123) may comprise a waveform encoder, such as a time-domain encoder, while the second encoding unit (124) may comprise a noise encoder.
摘要:
Coding of an audio signal is provided where an indicator of the frequency variation of sinusoidal components of the signal is used in the tracking algorithm of a sinusoidal coder where sinusoidal parameters from appropriate sinusoids from consecutive segments are linked. By applying an indicator such as a warp factor or polynomial fitting, more accurate tracks are obtained. As a result, the sinusoids can be encoded more efficiently. Furthermore, a better audio quality can be obtained by improved phase continuation.
摘要:
In a sinusoidal audio encoder a number of sinusoids are estimated per audio segment. A sinusoid is represented y frequency, amplitude and phase. Normally, phase is quantised independent of frequency The invention uses a frequency dependent quantisation of phase, and in particular the low frequencies are quantised using smaller quantisation intervals than at higher frequencies. Thus, the unwrapped phases of the lower frequencies are quantised more accurately, possibly with a smaller quantisation range, than the phases of the higher frequencies. The invention gives a significant improvement in decoded signal quality, especially for low bit-rate quantisers.
摘要:
The method creates an audio stream comprising tracks of sinusoidal components linked across a plurality of sequential time segments. Segments in each track are weighted with a normal window (WI, W2, W3), and consecutive segments have a normal period of overlap (0) of their trailing edges and leading edges. Segments in which a transient5 component is determined are weighted with a first modified window (WIm) having a modified trailing edge, and the following segment in the track is weighted with a second modified window (W2m) having a modified leading edge, so that the modified trailing edge and the modified leading edge have a modified period of overlap (0m) that comprises the transient component and that is shorter than the normal period of overlap (0), and wherein the audio stream includes sinusoidal codes representing the frequency and the transient. According to the invention, the modified period of overlap (0m) depends on the frequency value (f).