JPH0468999A - Surround audio equipment - Google Patents

Abstract

PURPOSE:To improve the characteristic by employing a digital signal processor so as to adopt digital processing for the entire equipment. CONSTITUTION:A stereo audio signal subjected to encode processing for surround reproduction is fed to input terminals 1A-1N, converted into a digital audio signal SD by an A/D converter 42 and subjected to decode processing for surround stereo reproduction at digital signal processors 51-57 and a digital surround signal is outputted. Then D/A converters 61, 62 converts the signal into an analog surround signal and is outputted output from terminals 63-65. That is, all the surround reproduction processing is digitally processed by the digital signal processors 51-57 to output the surround stereo signal. Thus, the adjustment at assembly is not required and the best characteristic is realized with no adjustment.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a surround audio device.

[Summary of the invention]

The present invention improves the characteristics of a surround audio device by digitizing the entire device using a digital signal processor.

[Conventional technology]

As a surround audio device, there is a Dolby Pro Logic surround decoder.

FIG. 2 shows an example of such a surround decoder, in which (IA) to (IN) are plural analog input terminals, (2^) to (2M) are plural digital input terminals, (1
3) to (15) are input selector switches that are interlocked with each other, and (16) is a D/A converter.

Then, stereo audio signals encoded for surround playback are supplied to the terminals (IA) to (IN), respectively, and R is selected by the switches (13) and (14). (a signal that has not been encoded for surround audio may be supplied).

Further, similar digital audio signals are supplied to the terminals (2A) to (2M), respectively, and are selected by the switch (15). Note that the converter (16) is for converting the digital audio signals of the terminals (2A) to (2M) into analog signals, since all processing such as surround processing is performed by analog processing.

The signal R from the switch (I4) is then supplied to the Dolby Pro Logic decoder (23) through a balance adjustment circuit (21) that adjusts the balance between the sources and a switch (22).

This decoder (23) receives the signal supplied to it and R
Based on the level and phase of the signals FL, Fl?, the front left and right channel audio signals FL, Fl? and the center channel audio signal FC, and also extracts the rear left and right channel audio signals BL and BR in cooperation with a decoder (3I) to be described later.

In this case, signals FL and FR are obtained by increasing the levels of signals R and R in accordance with the level of their in-phase components. Further, the signal FC is obtained by extracting mainly the in-phase component of the signal H. Furthermore, the signal BR is obtained mainly from the difference component (LR) of the signal R.

Signals FL and FR from this decoder (23) are taken out to an output terminal (25) through a switch (24).

Furthermore, the center channel audio signal FC from the decoder (23) is taken out to the output terminal (2G).

Further, a signal is received from the decoder (23), and a difference component of R (L
-R) is taken out, and this difference component (L-R) is sequentially supplied to the decoder (31) and the delay circuit (32). In this case, the decoder (31) has level expansion characteristics and high-frequency cant characteristics, and the delay circuit (32) is for reproducing reverberation components in a hall or the like.

In this way, the rear left and right channel signals BL, BR are taken out from the delay circuit (32), and the signals BL, B
R is output to the terminal (34) through the switch (33).

Therefore, the signals FL, FR, FC, BL, 81? of terminals (25), (26), (34)? By supplying this to speakers (not shown), surround reproduction can be performed.

Note that (29) shows a test tone signal forming circuit,
When the switch (22) is connected to the forming circuit (29), the forming circuit (29) outputs a test tone signal that is localized to the front left, front cloth, center, and rear every second. Ru.

Further, when the switch (24) is connected to the switch (14) side, the audio signal R selected by the switch (14) is output directly to the terminal (25).

(Dolby Dolby Surround, etc. are registered trademarks) [Problems to be Solved by the Invention] A Dolby Pro Logic type surround decoder can be configured as described above.

However, in the surround decoder described above, the balance adjustment circuit (21), the Dolby Pro Logic decoder (
23), the test tone signal forming circuit (29), decoder (31), and delay circuit (32) are composed of analog discrete components and ICs, so adjustments were required during assembly. Moreover, even if such adjustment is made, changes over time will occur.

Furthermore, the number of parts is large and a switch is required to change the circuit, which increases the cost.

This invention attempts to eliminate these problems.

[Means to solve the problem]

For this reason, in this invention, when adapted to the embodiments described later, input terminals (IA) to (IN) to which stereo audio signals encoded for surround playback are supplied.
), an A/D converter (42) that converts the stereo audio signals supplied to the input terminals (IA) to (IN) into digital audio signals SD, and a digital audio signal S
D is subjected to decoding processing for surround stereo playback to produce digital surround signals PL, PR, FC,
Digital signal processor that outputs BL and BR (
51) to (57) and digital surround signals PL from the digital signal processors (51) to (57).
, PR, FC, BL, BR to analog surround signals FL, FRSPC, BL, BR.
A converters (61) and (62), and output terminals (63) to (65) that output analog surround signals PL, FR, FC, BL, and BR from these D/A converters (61) and (62). will be established.

[Effect]

All surround playback processing is digitally processed by a digital signal processor and a surround stereo signal is output.

〔Example〕

In Fig. 1, (71) indicates a microcomputer for system control. Various operation keys (72) are connected to this microcomputer (71), and control signals, programs, or data corresponding to the key outputs are output. Output. This control signal, program or data is transmitted to the switch circuits (41), (43) and DSP (digital signal processor) (5), which will be described later.
1) to (57).

Further, (74) indicates a remote control transmitter, and from this transmitter (74) a remote control signal corresponding to the key operation,
For example, if it is an infrared remote control, infrared light is output. This infrared light is then received by the light receiving element (73) and a remote control signal is supplied to the microcomputer (71).

In this way, when the key of the transmitter (74) is operated, the same processing as when the key (72) is operated is performed.

Furthermore, stereo audio signals R and R that have been encoded for surround playback are supplied to analog input terminals (IA) to (IN), respectively.

These signals, R, are supplied to the switch circuit (41), and the switch circuit (41) is controlled by a control signal from the microcomputer (71) to output a signal, R is selected, and the selected signal is Then, R is supplied to an A/D converter (42) and converted into a digital audio signal SD, and this signal SD is supplied to a switch circuit (43).

Furthermore, similar digital audio signals SD are supplied to the digital input terminals (2A) to (2M), respectively, and these signals SD are supplied to the switch circuit (43).

This switch circuit (43) is connected to the microcomputer (71)
The terminals (IA) to (IN
), (2^) to (2M) one signal SD is selected from the audio signals (digital audio signals), and this signal SD is supplied to DSP (51) to (57).

These DSPs (51) to (57) are microcomputers dedicated to digital audio signal processing, and are each implemented as a 1-chip IC. These DSPs (51) to (57) are operated by a microcomputer (7).
1) According to the program or data sent from the DSP, predetermined signal processing is performed on the digital audio signal passing through the DSP.

That is, for example, when the user operates the key (72),
Microcomputer (71) to DSP (51) to (57)
The processing program or data is loaded into the
DSP (51) to (57) process digital audio signals according to the loaded program or data.

At this time, these D S P (51) to (5
7) cooperate to form circuits (21) to (24) in FIG.
, (29), (31) to (33).

That is, the DSP (51) mainly includes a balance adjustment circuit (21) and a test tone signal forming circuit (29).
and a switch (22) for manual adjustment of the level balance between sources.
It is used to form automatic adjustment test tone signals, etc. Note that this balance adjustment and the formation of the test tone signal are performed using the key (72) as described above.
When the DSP (51) is operated, the program or data of the DSP (51) is changed and the switch is made.

Further, the DSPs (52) to (55) mainly function as Dolby Pro Logic decoders (23), and are used to extract front signals FL and FR1 difference components (LR).

In addition, D S P (56) mainly uses the front signal F
This is for reproducing the acoustic characteristics in a hall etc. for L and FR.

Furthermore, the D S P (57) is mainly a decoder (
3I), which functions as a delay circuit (32) and a switch (33), and performs level expansion, high-frequency cut, addition of reverberation, etc. to the difference component (LR), thereby increasing the rear signal BL, This is to take out the BR. The center channel signal FC is also extracted from this DSP (57).

Then, the signals PL and FR from the DSP (56)
are supplied to a D/A converter (61) and converted into analog signals PL and PR, and these signals PL and FR are taken out to a terminal (63).

In addition, the signals FC, BL from the D S P (57),
BR is supplied to the D/A converter (62) and converted into analog signals FC, BL, and BR, and the signal FC
is taken out to the terminal (64), and signals BL and BR are taken out to the terminal (65).

Note that the passing characteristics of the D S P (51) to (57) are controlled by the microcomputer (71) and are controlled by the switch (24).
), the digital signal SD from the switch circuit (43) is supplied as is to the D/A converter (61), and the audio signal without any surround processing is output to the terminal (63). Or, DSP
At (57), the signal line is turned off and the switch circuit (33) is realized.

Further, the D S P (51) functions as a forming circuit (29) and a switch (22), and a test tone signal is output.

〔Effect of the invention〕

In this way, according to the present invention, surround processing can be performed, but in this case, especially according to the present invention, all surround processing is realized by digital processing, so there is no need for adjustment during assembly. The best characteristics can be obtained without adjustment.

Moreover, no change occurs over time.

The surround processing is performed by DSPs (51) to (57) dedicated to processing digital audio signals, so just by changing the program or data,
Predetermined signal processing can be performed, and detailed and various processing can be performed.

Furthermore, the number of parts is small, and D S P (51),
Since it is shared by the balance adjustment circuit (21) and the test tone signal forming circuit (29), it is advantageous in terms of cost.

In addition, since all operations other than signal selection in the switch circuit (41) are digitally processed, signal deterioration, such as S/
Excellent sound quality can be maintained without a decrease in N or an increase in distortion.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an example of the present invention, and FIG. 2 is a system diagram of a conventional example. (IA) to (IN) are analog input terminals, (2A) to (
21) is a digital input terminal, (42) is an A/D converter, (51) to (S7) are DSPs, (61), (62)
is a D/A converter, (63) to (65) are output terminals,
(71) is a microcomputer, (72) is an operation key, and (74) is a remote control transmitter.

Claims (1)

[Claims] An input terminal to which a stereo audio signal that has been encoded for surround playback is supplied, and an A/D converter that converts the stereo audio signal supplied to the input terminal into a digital audio signal. and a digital signal processor that performs decoding processing for surround stereo playback on the digital audio signal converted by the A/D converter and outputs a digital surround signal, and the digital surround signal from the digital signal processor. D to convert into an analog surround signal
A surround audio device comprising: a /A converter; and an output terminal for outputting the analog surround signal from the D/A converter.