TWI491179B - Encoding modulation system and method - Google Patents

Description

Code modulation system and method

The present invention relates to an encoding technique, and more particularly to a coded modulation method and a system using the same.

ADPCM is an adaptive differential pulse code modulation method that compresses an audio signal by an appropriate ratio. The code modulation method generally encodes the difference between the current sample point sample data and the previous sample point sample data into a 4-bit code stream. The 4-bit code stream includes a 1-bit symbol bit and a 3-bit value bit. Since the sign bit of the difference in the above coding and modulation method needs to occupy one bit in the 4-bit code stream, and only 3 bits are used to encode the value bit of the difference value, the audio signal using the modulation coding method is guaranteed. The truth is low.

In view of this, it is necessary to provide a code modulation method with better fidelity.

In addition, it is also necessary to provide a code modulation system with better fidelity.

A code modulation method for encoding an audio signal into an L-bit code stream includes the steps of: sampling a current sample point of the audio signal to obtain sample data N, and calculating sample data N of the current sample point and sample data of the previous sample point The difference d(N) of N-1; whether the difference d(N) is greater than or equal to 0; if the difference d(N) is greater than or equal to 0, the value of the difference d(N) is quantized to M ( 2 ^{L -1} < M <2 ^L ) Quantization levels, and d(N) is encoded into one of M L-bit value streams according to the quantization level.

A coding and modulation system includes: an audio signal for encoding an L-bit code stream, comprising: a sampling unit, configured to sample sampling data of each sampling point of each sampling point of the audio signal; and a calculating unit to calculate the current sampling point The difference d(N) between the sampled data N and the sampled data N-1 of the previous sample point; a comparison unit that compares whether the difference d(N) is greater than or equal to 0 and outputs a comparison result; The code modulation system further includes: a quantization unit for quantizing the value of the difference d(N) to M(2 ^{L -1} < M <2 ^L ) quantization levels; a coding unit for comparing As a result, the difference d(N) is encoded; if the difference d(N) is greater than or equal to 0, the coding unit encodes d(N) into one of the M L-bit value streams according to the quantization level.

In the above method and system for coding and modulation, the value and the symbol corresponding to the difference d(N) of the sampled data N of the current sampling point and the sampled data N-1 of the previous sampling point are separately encoded, so that the numerical code stream can be used. The L bit indicates that the fidelity of the audio signal can be improved compared to the prior art numerical code stream represented by the L-1 bit.

201‧‧‧Sampling unit

203‧‧‧Computation unit

207‧‧‧Quantification unit

209‧‧‧ coding unit

205‧‧‧Comparative unit

S101-S109‧‧‧ Code modulation method flow steps

1 is a flow chart of a code modulation method according to a preferred embodiment.

2 is a block diagram of a code modulation system according to a preferred embodiment.

1 is a flow chart of a code modulation method according to a preferred embodiment for encoding an audio signal into an L-bit code stream, the code modulation method comprising the following steps. This embodiment will be described by taking an audio signal as a 4-bit code stream as an example.

In step S101, the current sampling point of the sampled audio signal acquires the sampled data N.

Step S103, calculating a difference d(N) between the current sample point sample data N and the previous sample point sample data N-1.

In step S105, it is determined whether the difference d(N) is greater than or equal to zero. If the difference d(N) is greater than or equal to 0, the process proceeds to step S107. If the difference d(N) is less than 0, the process proceeds to step S109.

Step S107, quantizing the value of the difference d(N) to M (2 ³ < M < 2 ⁴ ) quantization levels, and encoding d(N) into M 4-bit value streams according to the quantization level. One.

Step S109, quantizing the value of the difference d(N) to M quantization levels, and encoding d(N) into one of the M 4-bit value streams according to the quantization level, and then in the 4-bit value. The 4-bit symbol code stream P corresponding to the sign of d(N) is added before the code stream. Symbol stream number P and the value of M streams are not the same, it may take two ^24-bit code stream additionally L ²⁴ - M 4-bit code stream one. In the present embodiment, M may be 15.

In the above code modulation method, the value and the symbol corresponding to the difference d(N) between the sampled data N of the current sample point of the audio signal and the sampled data N-1 of the previous sample point are respectively The vertical coding enables the numerical code stream to be represented by L bits. Compared with the prior art, the numerical code stream is represented by L-1 bits, which can improve the fidelity of the audio signal.

2 is a block diagram of a coded modulation system according to a preferred embodiment. The code modulation system 200 includes a sampling unit 201, a calculation unit 203, a comparison unit 205, a quantization unit 207, and an encoding unit 209.

The sampling unit 201 is configured to sample sampling points of the audio signal to obtain sampling data of each sampling point to convert the continuous analog signal into a discrete digital signal.

The calculating unit 203 is configured to calculate a difference d(N) between the sampling data N of the current sampling point and the sampling data N-1 of the previous sampling point.

The comparison unit 205 is for comparing whether the difference d(N) is greater than or equal to 0 and outputting the comparison result.

The quantization unit 207 is for quantizing the value of the difference d(N) to M (2 ³ < M < 2 ⁴ ) quantization levels.

The encoding unit 209 is connected to the comparison unit 205 and the quantization unit 207 for encoding the difference d(N) calculated by the quantization unit 207 according to the comparison result of the comparison unit 205. If the difference between the sampled data N and the previous sampled data N-1 is greater than or equal to 0, the value of d(N) is encoded as one of the M 4-bit valued code streams according to the quantization level. If the difference between the sampled data N and the previous sampled data N-1 is less than 0, the value of d(N) is encoded into one of the M 4-bit value streams according to the quantization level, and then the 4-digit value code is used. The 4-bit symbol code stream P corresponding to the sign of d(N) is added before the stream. Symbol stream number P and the value of M streams are not the same, it may take ²⁴ 4-bit code stream addition ²⁴ - M 4-bit code stream one. In the present embodiment, M may be 15.

In the above code modulation system 200, the value and the symbol corresponding to the difference d(N) of the sampled data N of the current sampling point and the sampled data N-1 of the previous sampling point are independently encoded, so that the numerical code stream can use the L bit. It is indicated that the fidelity of the audio signal can be improved compared with the L-1 bit of the numerical code stream in the prior art.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above description is only the preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and equivalent modifications or variations made by those skilled in the art in light of the spirit of the present invention are It should be covered by the following patent application.

S101-S109‧‧‧ Code modulation method flow steps

Claims (6)

A code modulation method for encoding an audio signal into an L-bit code stream includes the steps of: sampling a current sample point of the audio signal to obtain sample data N; calculating sample data N of the current sample point and sample data of the previous sample point The difference d(N) of N-1; whether the difference d(N) is greater than or equal to 0; if the difference d(N) is greater than or equal to 0, the value of the difference d(N) is quantized to M ( 2 ^{L -1} < M <2 ^L ) quantization levels, and d(N) is encoded into one of M L-bit value streams according to the quantization level; if d(N) is less than 0, the difference is The value of d(N) is quantized to M(2 ^{L -1} < M <2 ^L ) quantization levels, and d(N) is encoded into one of M L-bit value streams according to the quantization level, and then An L-bit symbol code stream P corresponding to the symbol of d(N) is added before the L-bit value code stream, wherein the symbol code stream P and the M L-value code streams are different. If the application code modulation method according to item 1 of the scope of the patent, wherein stream number P takes the symbol ^L 2 L-bit code stream additional 2 ^L - M L-stream one byte code. The code modulation method according to claim 1, wherein the L is 4 and the M is 15. A code modulation system for encoding an audio signal into an L-bit code stream, comprising: a sampling unit for sampling sampling points of an audio signal to obtain sampling data of each sampling point; and a calculating unit for calculating a current sampling point a difference d(N) between the sampled data N and the sampled data N-1 of the previous sample point; a comparison unit that compares whether the difference d(N) is greater than or equal to 0 and outputs a comparison result; The code modulation system further includes: a quantization unit for quantizing the value of the difference d(N) to M(2 ^{L -1} < M <2 ^L ) quantization levels; a coding unit for comparing results Encoding the difference d(N); if the difference d(N) is greater than or equal to 0, the coding unit encodes d(N) into one of the M L-bit value streams according to the quantization level; d(N) If it is less than 0, the coding unit encodes d(N) into one of the M L-bit value code streams according to the quantization level, and then adds L corresponding to the symbol of d(N) before the L-bit value code stream. The bit symbol code stream P, and the symbol code stream P and the M L numbers are different from each other. If the application code modulation system as recited in item 4 patentable scope, wherein the symbol code stream P 2 taken ^L L-bit code stream additional 2 ^L - M L-bit code stream one. The code modulation system of claim 4, wherein the L is 4 and the M is 15.