JP4191465B2 - Multi-channel encoder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-channel coding KaSo location that can be utilized in recording apparatus or an audio reproducing device, for example, large-scale audio signal.
[0002]
[Prior art]
Conventionally, for example, when recording performances of orchestras, microphones are installed for each part of each instrument, and multi-channel acoustic signals from each microphone are appropriately adjusted and recorded. Further, it is possible to reproduce a high-fidelity musical sound by feeding the recorded multi-channel acoustic signal to the speaker system for each channel and reproducing the sound by the speaker system.
A normal multi-channel sound signal recording apparatus and multi-channel sound reproduction apparatus are configured as shown in FIG. In FIG. 5, 1A, 1B, 1C... 1N are microphones, 2A, 2B, 2C... 2N are signal transmission paths, 3A, 3B, 3C... 3N are A / D converters, and 4 is a signal. 5N is a D / A converter, 6A, 6B, 6C... 6N is a signal transmission path, 7A, 7B, 7C... 7N are speaker systems (including amplifiers). ).
[0003]
Usually, the acoustic signals captured by the microphones 1A to 1N are input to the A / D converters 3A to 3N through the signal transmission paths 2A to 2N, respectively, and converted into digital signals by the A / D converters 3A to 3N, respectively. Input to the processing device 4.
The signal processing device 4 can be constituted by, for example, a multi-channel recorder or the like, and shows a case where it is a recording device that records multi-channel musical sounds. The multi-channel acoustic signals recorded in the recording device 4 are read from the recording device 4 and supplied to the D / A converters 5A to 5N. The digital signal is converted into an analog signal by the D / A converter, and the converted analog signal is sent to the speaker systems 7A to 7N through the signal transmission paths 6A to 6N, and the sound is reproduced by the speaker systems 7A to 7N.
[0004]
In the example shown in FIG. 5, the A / D converters 3A to 3N, the D / A converters 5A to 5N, and the speaker systems 7A to 7N are supplied with power from the power supplies D1 and D2 provided separately. Show.
In the configuration shown in FIG. 5, signal transmission paths 2A to 2N interposed between the microphones 1A to 1N and the A / D converters 3A to 3N and between the D / A converters 5A to 5N and the speaker systems 7A to 7N. When 6 and 6A to 6N are long, each of the signal transmission lines 2A to 2N and 6A to 6N is an analog signal system, so that there is a drawback that noise is easily spread. Further, there is a drawback that the cost required for the A / D converters 3A to 3N and the D / A converters 5A to 5N and the cost required for amplifiers, wirings, and the like become enormous as the number of channels increases.
[0005]
In order to eliminate these drawbacks, the configuration shown in FIG. 6 can be considered. In the example shown in FIG. 6, the A / D converters 3A to 3N are arranged close to the microphones 1A to 1N, and the D / A converters 5A to 5N are arranged close to the speaker systems 7A to 7N.
According to the configuration of FIG. 6, the analog signal transmission path portion is shortened as much as possible, so that the noise fraud rate can be lowered. However, since it is necessary to provide the A / D converters 3A to 3N and the D / A converters 5A to 5N corresponding to the number of channels, an increase in cost due to an increase in the number of channels is unavoidable.
In addition, the power supply to each of the A / D converters 3A to 3N and the D / A converters 5A to 5N must be separately supplied from two power sources D1 and D2 installed at remote locations. In particular, the power source D2 shown in FIG. 6 is large because the power capacity increases because power is supplied to the D / A converters 5A to 5N and the speaker systems 7A to 7N.
[0006]
As a method for simplifying the A / D converter and the D / A converter and realizing cost reduction, there is a 1-bit encoding method based on ΣΔ modulation (Non-Patent Document 1, pages 78 to 115).
According to this 1-bit encoding method, since the A / D converter and the D / A converter can be realized with a simple configuration, the cost required for the A / D converter and the D / A converter can be reduced. An example of a high-quality audio disc using a DVD can be seen as an example of performing 1-bit quantization and recording on a medium. When the standard sampling frequency is 44.1 kHz, this high-quality audio disc samples at 2.8224 MHz, which is 64 times the standard sampling frequency, and the sample sampled at this sampling frequency is subjected to 1-bit encoding by ΣΔ modulation to the medium. It is assumed to be recorded (Patent Document 1, paragraph [0003]).
[0007]
[Patent Document 1]
JP 2001-167515 A [Non-Patent Document 1]
Toshiro Oga, Yoshio Yamazaki, Yutaka Kaneda, "Acoustic System and Digital Processing", The Institute of Electronics, Information and Communication Engineers published on March 25, 1995 [0008]
[Problems to be solved by the invention]
By using the 1-bit encoding by the above-described ΣΔ modulation, the configuration of the A / D converter and the D / A converter can be simplified, and a multi-channel audio recording apparatus and an audio reproduction apparatus can be provided at low cost. be able to.
However, since the 1-bit encoding method has to transmit a signal serially for each channel, it is difficult to transmit a multi-channel audio signal to a remote location and simultaneously reproduce the multi-channel audio at the remote location. That is, there is an inconvenience that it costs much to transmit to a remote place with multiple channels.
[0009]
A first object of this invention to provide a multi-channel coding KaSo location that can be provided at low cost by using the over-bit low-amplitude coding.
The data encoded by the second object is oversampled coding of the present invention is transmitted at a low cost in a remote location, a multi-channel code KaSo location which can also play the multi-channel audio at low cost remote It is what we are going to propose.
[0010]
[Means for Solving the Problems]
In this invention encodes the sound signal of the multi-channel oversampled low amplitude resolution coding means each packet specifying the decoding means to be distributed to each of the encoded oversampled low amplitude resolution coded signal We propose a multi-channel encoding device that sends an identification code .
[0011]
Action D / A converter used in the A / D converters and decoding used for encoding of each channel according to the multi-channel encoding apparatus and decoding apparatus according to the present invention the configuration is simple, provides a low-cost be able to. Therefore, even if the number of channels is increased, a multi-channel recording device and a multi-channel playback device can be provided at a low cost. Since the oversampled low amplitude encoding means used in the present invention consumes little power, it is easy to supply power.
In the present invention, since the packet identification code is added to the encoded signal encoded in each channel, the encoded signal with the packet identification code can be serially transmitted to a common signal line, and can be transmitted remotely. Each channel can be distributed by a packet identification code.
Therefore, according to the present invention, a multi-channel acoustic signal can be transmitted to a remote place at low cost, and multi-channel audio can be reproduced in real time at the remote place.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows another proposed example. Parts corresponding to those in FIGS. 5 and 6 are denoted by the same reference numerals. In the present invention, oversampled low-amplitude encoding means (A / D converters) 13A to 13N are arranged in the vicinity of the microphones 1A to 1N, and decoding means (D / A converter) are provided in the vicinity of the speaker systems 7A to 7N. 15A to 15N are arranged.
The oversampled low amplitude encoding means (A / D converters) 13A to 13N include a low bit A / D converter of about 2 to 3 bits in addition to the 1 bit A / D converter.
An example of the configuration of the oversampled low amplitude encoding means 13A to 13N is shown in FIG. The oversampled low amplitude encoding means 13 shown in FIG. 2 shows the case of a 1-bit A / D converter. Since the 1-bit A / D converter is described in detail in Non-Patent Document 1 described above, it is only necessary to understand that the configuration of this 1-bit A / D converter and the configuration of the decoding means are simple. Keep on.
[0013]
The 1-bit A / D converter includes a subtractor J, an analog integrator K, and a quantizer L. As an outline of the operation, the subtracter J subtracts the analog input and the output of the quantizer L, and when the analog input changes in the increasing direction (the subtraction result of the subtractor J is positive), the quantizer L Outputs a positive pulse. When the analog input changes in the decreasing direction, the quantizer L outputs a negative pulse. When the analog input value does not change, the quantizer L alternately outputs positive and negative pulses. By setting the pulse repetition frequency to about 2 to 3 MHz, the waveform of the audio signal can be faithfully A / D converted and transmitted.
[0014]
The structure of the decoding means 15A-15N is shown in FIG. Since the 1-bit A / D converter generates a 1-bit encoded signal by the algorithm as described above, the decoding means 15A to 15N can be configured by the low-pass filter shown in FIG. .
In other words, the analog output signal to which the positive polarity pulse is continuously input rises stepwise, and when the positive and negative pulses are alternately input, the analog output signal maintains the current value, and the negative polarity polarity is negative. When the pulse is continuously input, the analog output signal decreases toward the zero value, and when the negative pulse is further input, the analog output signal becomes negative. In this way, the analog waveform is decoded.
[0015]
As described above, by using the oversampled low amplitude resolution encoding means 13A to 13N as the A / D conversion means, the A / D converter can have a simple configuration. In particular, the decoding means 15A to 15N can be configured with a low-pass filter including a resistor and a capacitor, and therefore can be provided at an extremely low cost. Further, since the decoding means 15A to 15N do not consume power, it is not necessary to provide a power supply path to the decoding means.
FIG. 4 shows another embodiment of the present invention. In this embodiment, a packet identification code is attached to an A / D converted encoded signal for each channel, and the encoded signal with the packet identification code added (hereinafter referred to as a packet signal) is multiplexed on a common transmission path. A case is shown in which a packet signal is transmitted, received at a desired destination, sorted by channel according to a packet identification code, and decoded for each channel to reproduce multi-channel sound.
[0016]
For this reason, in this embodiment, the encoded signals output from the oversampled low amplitude resolution encoding means 13A to 13N are collected in the packet multiplexing means 16A, and the packet multiplexing means 16A converts the encoded signals into the encoded signals of each channel. A packet identification code for identifying each channel is attached, converted into a high-speed packet signal, and the high-speed packet signal is time-division multiplexed and sent to a common transmission system 17A. As the transmission system 17A, a LAN using an IP packet, a wireless LAN, a power supply line LAN using a power supply line, or the like can be used. Also, multiplexing by spread spectrum can be used in a wireless LAN or power line LAN.
[0017]
A packet receiving unit 18A is provided in the signal processing unit 4, and the packet receiving unit 18A receives a packet signal. The received packet signal is sorted for each channel according to the packet identification code, converted into a low-speed signal, and signal processed (for example, recorded for each channel).
The signal processing 4 is further provided with packet multiplexing means 16B. The packet multiplexing means 16B adds a packet identification code to the multi-channel signal transmitted from the signal processing section 4 again to convert it into a high-speed packet signal. It is time-division multiplexed and sent to the transmission system 17B.
[0018]
A packet receiving means 18B is provided in association with a speaker system provided at a remote location. The packet receiving means 18B receives the packet signal, sorts each channel signal into a low-speed signal, and decodes the low-speed signal. The decoding means 15A to 15N decode the analog signals, input the decoded signals to the speaker systems 7A to 7N, and reproduce multi-channel sounds. If the signal processor 4 is not required in this embodiment, the packet receiving means 18A, the packet multiplexing means 16B, and the transmission system 18B may be omitted, and the packet receiving means 18B may be directly connected to the transmission system 17A.
In addition, as a packet identification method, a packet identification code for simultaneous broadcast or a bucket identification code assigned for each group and a packet identification code for individual use are prepared, and broadcast information or information to be transmitted for each group, A large amount of information can be transmitted within a short time if it is transmitted using the specified timing in the time slot, and this information is received and reproduced by all speaker systems or speaker systems belonging to a specified group. . In addition, if the remaining timing in the time slot is used, individual information for each speaker can be transmitted.
[0019]
【The invention's effect】
As described above, according to the present invention, since oversampled low-amplitude resolution encoding is used as the A / D conversion means, this A / D conversion means has a simple configuration as described with reference to FIG. In addition, since the power consumption is small, it is cheap and can easily supply power. In particular, when a 1-bit encoding means is used, this effect is remarkably obtained. Further, when the oversampled low amplitude resolution encoding means is used, the decoding means can be constituted by a low-pass filter as shown in FIG. As a result, the cost required for the decoding means can be extremely reduced, and even if the number of channels is increased, the overall cost can be greatly reduced. Furthermore, since the decoding means does not involve power consumption, it is possible only to supply power to the speaker systems 7A to 7N, and the cost for power supply can be reduced.
Further, when a method of packetizing and transmitting using a common transmission system is adopted, an advantage that a multi-channel signal can be distributed to a remote place at a low cost is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram for explaining another proposal example.
FIG. 2 is a block diagram for explaining the configuration and operation of oversampled low amplitude resolution encoding means used in the proposed example shown in FIG. 1;
FIG. 3 is a block diagram for explaining the configuration and operation of decoding means used in the proposed example shown in FIG. 1;
FIG. 4 is a block diagram for explaining an embodiment of the present invention in which the above proposed example is applied to a packet transmission system .
FIG. 5 is a block diagram for explaining a conventional technique.
FIG. 6 is a block diagram for explaining another example of the prior art.
[Explanation of symbols]
1A to 1N Microphone 7A to 7N Speaker system 2A to 2N Signal transmission path 15A to 15N Decoding means 3A to 3N A / D converters 16A and 16B Packet multiplexing means
4 Signal processor 17A, 17B Transmission system 5A-5N D / A converter 18A, 18B Packet receiving means 6A-6N Signal transmission path 13A-13N Oversampled low amplitude resolution encoding means

Claims (1)

Multi-channel acoustic signals are individually encoded by oversampled low amplitude resolution encoding means, and packets for individual identification that specify the decoding means to be distributed to each of the encoded oversampled low amplitude resolution encoded signals Add identification code to make individual information for each speaker,
Add a packet identification code for simultaneous broadcast or a packet identification code assigned to each group to the above oversampled low-amplitude resolution encoded signal to make broadcast information for all speakers or group broadcast information for each group,
Storing the individual information and the simultaneous broadcast information or the group broadcast information at a specific timing in a timing slot;
Said the broadcast information to all of the speaker system, or multi-channel encoding apparatus, characterized by sending in pairs to a speaker system of the group specified above the multicast information.

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