Signal coding and decoding methods and devices
In a signal coding method, bits for coding allocated to different bands of a frequency domain signal obtained from an input signal are adjusted to improve the coding quality. The total available bits for coding are first allocated to the bands of the frequency domain signal according to a predetermined allocation rule. The numbers of bits allocated to the respective bands of the frequency domain signal are then adjusted when a highest frequency of the frequency domain signal to which bits are allocated is greater than a predetermined value. The frequency domain signal is coded according to the adjusted bit allocation for the bands of the frequency domain signal.
1. A signal coding method performed by a network device comprising a processor to code an input audio signal, wherein the method comprises:
obtaining a frequency domain signal of a current frame of the input audio signal, wherein the frequency domain signal has multiple bands;
allocating available bits for coding the frequency domain signal to the bands of the frequency domain signal, wherein each band either has bits or has no bit allocated thereto;
adjusting numbers of bits allocated to respective bands of the frequency domain signal when a highest index of a band with bits allocated thereto is greater than a threshold; and
coding the frequency domain signal by using the adjusted bits allocation.
2. The method according to claim 1 , wherein the adjusting comprises: decreasing the number of bits allocated to a band with more bits allocated, and increasing the number of bits allocated to the band with the highest index and a band near the band with the highest index, wherein a total number of bits decreased in the adjusting step is equal to a total number of bits increased in the adjusting step.
3. The method according to claim 1 , wherein the threshold is determined according to the number of the available bits and a resolution of the frequency domain signal.
4. The method according to claim 1 , wherein the available bits are allocated as following: more bits in the available bits are allocated to a band of the current frame with low index, and rest bits are allocated to a band of the current frame with greater energy except the low frequency band signal.
5. The method according to claim 1 , further comprising:
maintaining the bits allocated to the bands when the highest index of the band is less than the threshold.
6. A signal coding device for coding an input audio signal, comprising:
a processor; and
a non-transitory computer readable storage medium storing computer executable instructions,
the processor being configured to execute the computer executable instructions to:
obtain a frequency domain signal of a current frame of the input audio signal, wherein the frequency domain signal has multiple bands;
allocate available bits for coding the frequency domain signal to bands of the frequency domain signal, wherein each band either has bits or has no bit allocated thereto;
adjust numbers of bits allocated to respective bands of the frequency domain signal when a highest index of a band with bits allocated thereto is greater than a threshold; and
code the frequency domain signal by using the adjusted bits allocation.
7. The device according to claim 6 , wherein the adjust comprises: decrease the number of bits allocated to a band with more bits allocated, and increase the number of bits allocated to the band with the highest index and a band near the band with the highest index, wherein the number of bits decreased is equal to the number of bits increased.
8. The device according to claim 6 , wherein the threshold is determined according to the number of the available bits and a resolution of the frequency domain signal.
9. The device according to claim 6 , wherein the available bits are allocated as following: more bits in the available bits are allocated to a band of the current frame with low index, and rest bits are allocated to a band of the current frame with greater energy except the low frequency band signal.
10. The device according to claim 6 , further comprising:
maintain the bits allocated to the bands when the highest index of the band is less than the threshold.