JPH0481900A - Voice accumulating and reproducing device - Google Patents

Abstract

PURPOSE:To reproduce voices accumulated in always optimum sound volume by calculating the min. amplitude value at the time of decoding from input voice data and storing this value together with coded data. CONSTITUTION:An inputted voice signal S1 is coded in a coder section 1 and is converted to data X. The coded data X is stored in a memory section 3 and is inputted to a delta calculating section 2. The delta width (min. amplitude value) DELTA at the time of decoding is calculated from the coded data X in the delta calculating section 2. This value is outputted to a memory section 3. The delta width DELTA is determined by the function based on an inverse proportion from the max. value of a voice band power. The data X corresponding to the assigned voice and the delta DELTA are inputted from the memory section 3 into a decoder section 4 in the case of reproduction processing. The data X coded by this delta width DELTA is decoded and outputted as an output voice signal S0 in the decoder section 4. The magnitude of the decoded output voice signal S0 is adjusted by adjusting the delta width DELTA at this time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention stores audio input via a telephone line or the like,
The present invention relates to an audio storage and playback device that has a function of playing back stored audio as needed.

[Conventional technology]

Conventionally, this type of audio storage and playback device first converts audio input via a telephone line into mu-law (μmlaw).
Encoded using PCM as typified by coding, and in some cases encoded using an efficient high-efficiency encoding method,
Next, the encoded data is recorded on a medium such as a memory or a disk, and when reproduced, the recorded data is decoded and output as an audio signal to a telephone line or the like.

[Problem to be solved by the invention]

The conventional audio storage and playback device described above has a quantization width when encoding and a delta width (minimum amplitude value) when decoding.
is the same, but since it is at least fixed, if the volume of the input audio is unreasonably low, it will be output at an unreasonably low volume during playback, making it difficult to hear.

On the other hand, if the volume of the input audio is unreasonably high, it will be output at an unreasonably high volume during playback, which also has the disadvantage of making it difficult to hear.

To deal with this, some conventional audio storage and playback devices use an AGC (auto gain controller) amplifier before encoding the input audio, or in this case, the strength of the audio itself is lost. Therefore, it has the disadvantage that it feels unnatural and that the relationship between strengths and weaknesses cannot be faithfully reproduced.

[Means to solve the problem]

The audio storage and playback device of the present invention includes a coder unit that encodes input audio, a delta calculation unit that calculates the minimum amplitude value at the time of decoding from the encoded data, and a delta calculation unit that calculates the minimum amplitude value at the time of decoding from the encoded data. A storage unit that stores the minimum amplitude value calculated by the delta calculation unit, a decoder unit that decodes the encoded data using the minimum amplitude value, and a control unit that controls each of the units. ing.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an audio storage and playback device showing one embodiment of the present invention.

In FIG. 1, the audio storage and playback device of this embodiment includes a coder unit 1 that decodes an audio signal, and a coder unit 1 that calculates the minimum amplitude value (hereinafter referred to as delta width) at the time of decoding from the encoded data. This embodiment includes a delta calculation unit 2, a storage unit 3 that stores encoded data and the calculated delta width, and a decoder unit 4 that decodes the encoded data into audio using the delta width. The control section 5 controls the entire audio storage and playback device.

Figure 2 shows an example of the function used to calculate the delta width from the volume, Figure 3 shows an example of the quantization width, and Figure 4 shows an example of the quantization width.
Figures (a) and (b) are diagrams each showing an example of the delta width.

Next, the operation of this embodiment will be explained using FIG. 1, FIG. 2, FIG. 3, and FIGS. 4(a) and (b).

First, the case of accumulation processing of input audio signals will be explained.

In FIG. 1, an input audio signal S is encoded by a coder section 1 and converted into data X. The most basic PCM method is used as an example of this conversion method, and an example of the quantization width at that time is shown in FIG. The minimum amplitude value during quantization will be called the quantization width.

The quantization width is determined by the maximum amplitude of the input signal S1 and how many bits the encoded data X is quantized.

The encoded data X is stored in the storage section 3 and is also input to the delta calculation section 2.

The delta calculation unit 2 calculates the delta width Δ at the time of decoding from the encoded data X, and outputs this to the storage unit 3.

Calculation of the delta width Δ is realized by firmware, and various methods are possible, and an example thereof will be explained using FIG. 2.

First, short-time power is calculated from encoded data X. That is, the data X is cut out at regular length intervals (Xl, X2, . . . , X,), and the respective audio band powers (Pr, P2, . . . , Pfl) are determined.

Next, the voice band power (PI, P2, ..., p
, ) find the maximum value (P, .).

Finally, the delta width Δ is determined from the maximum value (P, , X) of the voice band power using a function based on inverse proportion as shown in FIG.

The storage unit 3 stores the encoded data X and the calculated delta width Δ. Actually, in addition to this, management numbers, addresses, length information, etc. are also stored.

Next, the operation of the playback process will be explained.

Encoded data X and delta Δ corresponding to the designated voice are input from the storage unit 3 to the decoder unit 4. The decoder section 4 decodes the encoded data X using this delta width Δ and outputs it as an output audio signal So.

FIGS. 4(a) and 4(b) are diagrams each showing an example of the delta width Δ in this case. FIG. 4(a) shows a case where the delta width Δ is relatively small, and a case where the delta width Δ is relatively large. is shown in Figure 4 (
b).

By adjusting the delta width Δ in this way, the output audio signal S is decoded. The size can be adjusted.

The series of operations of storage processing and reproduction processing is realized by the control section 5 controlling each section (coater section 1. delta calculation section 2. storage section 3. decoder section 4).

〔Effect of the invention〕

As explained above, the present invention calculates the minimum amplitude value at the time of decoding that provides the optimum volume from the data obtained by encoding the input voice when storing the input voice, and stores it together with the encoded data. By decoding the encoded data using this minimum amplitude value during playback, it is possible to always play back the stored sound at the optimal volume, and the strength relationship of the sound itself is not lost. As a result, it is possible to output audio that is easy to hear.

A block diagram of the device, Figure 2 shows an example of the function used to calculate the delta width from the volume, Figure 3 shows an example of the quantization width, and Figures 4 (a) and (b) respectively. It is a figure showing an example of delta width.

DESCRIPTION OF SYMBOLS 1... Coder section, 2... Delta calculation section, 3... Storage section, 4... Part of decoder, 5... Control section.

Claims (1)

[Claims] a coder section that encodes input audio; a delta calculation section that calculates the minimum amplitude value during decoding from the encoded data; and a delta calculation section that calculates the minimum amplitude value during decoding from the encoded data. An audio storage and playback device comprising: a storage unit that stores amplitude values; a decoder unit that decodes the encoded data using the minimum amplitude value; and a control unit that controls each of the units.