JP3870816B2 - Digital audio processor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital audio processing apparatus to which a plurality of digital audio devices are connected.
[0002]
[Prior art]
Digital audio devices that process audio signals as digital signals have become widespread. Since general digital audio equipment performs input / output of audio signals as a digital audio signal of a unified standard called SPDIF, the same digital audio interface receiver can be used for any digital audio signal input from any digital audio equipment. (DIR) can be processed in common.
[0003]
For this reason, conventional analog audio devices (tuners, CD players, analog disc players, etc.) have different output audio signal levels and equalizing, so analog audio amplifiers have a dedicated input terminal (front end) for each audio device. In the case of a digital audio device, there is a higher degree of freedom that any device can be connected to any of a plurality of digital audio terminals.
[0004]
However, in the conventional digital audio amplifier, since a display for designating a device name such as CD or DVD is displayed in advance on a selector operator which is an operator for selecting a device by a user, a digital corresponding to each selector operator is displayed. If the designated device is not connected to the input terminal, there is a problem that even if the selector is operated according to the display, a device different from the display is selected.
[0005]
Therefore, digital audio amplifiers that have recently been put into practical use allow the user to set the display of the device name corresponding to the selector operator, connect any digital audio device to each digital input terminal, and support that digital input terminal. A device has been proposed in which the device name of the selector operator to be used is the name of the connected digital audio device.
[0006]
Furthermore, there is a device that can automatically display what audio device is currently receiving a signal based on the category code separated from the digital audio signal input from the digital input terminal.
[0007]
[Problems to be solved by the invention]
However, in the above conventional apparatus, even if a digital audio device can be freely connected to each digital input terminal, the name of the selector operator corresponding to the digital input terminal must be input by itself, which is troublesome. In addition, there is a problem that the correspondence may be wrong.
[0008]
Further, in the above conventional apparatus, it is possible to display what audio device is currently selected (a digital audio signal is input), but what is connected to other digital input terminals, In other words, it is impossible to know what audio device is selected when another selector operator is pressed.
[0009]
An object of the present invention is to provide a digital audio processing apparatus capable of scanning a plurality of digital input terminals and automatically detecting the type of digital audio equipment connected thereto.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, a plurality of digital input terminals to which a digital audio signal is input and a digital audio signal input from the digital input terminal are received, the digital audio signal is decoded, and audio stream data and a category code are received. A digital audio interface receiver (DIR) to be separated, a selector for selectively setting a DIR connection destination to one of the plurality of digital input terminals, and a selection for selecting one of the plurality of digital input terminals by a selection operation Means, audio data processing means for processing audio stream data, a digital input terminal selected by the selection means is connected to DIR, and audio stream data separated by DIR is input to audio data processing means Hand Stepped , Controls the lector to switch the DIR connection destination sequentially, and sequentially detects the type of digital audio equipment connected to each digital input terminal based on the category code separated from the digital audio data input from each connection destination Control means for executing the scanning process at a predetermined timing. The scan process is detected when a break in the digital audio signal from the digital input terminal selected by the selection means is detected. It is characterized by that.
[0013]
In the present invention, it is possible to detect which digital audio device is connected to which digital input terminal by scanning a plurality of digital input terminals using a DIR that decodes a digital audio signal such as the SPDIF standard. I can do it. By executing this at the break of audio signals to which null data is input, such as when the power is turned on or between CD tracks, information on which digital audio device is connected to which digital input terminal is constantly updated. can do.
[0014]
Claim 2 According to the present invention, a plurality of digital input terminals to which a digital audio signal is input, a first selection means for selecting one of the plurality of digital input terminals by a selection operation, and a first selection means are selected. A first buffer that buffers a digital audio signal input from a digital input terminal; a digital audio interface receiver (DIR) that decodes the input digital audio signal to separate audio stream data and a category code; A second buffer for buffering audio stream data obtained by decoding and separating the digital audio signal input from the first buffer; and audio data processing means for sequentially reading out and processing the audio stream data from the second buffer. A second selection means for connecting any of the plurality of digital input terminals or the first buffer to the DIR; and audio stream data is stored in the second buffer for a predetermined time, and then audio data processing is performed. The means is allowed to read the data, and the connection destination of the first selection means is sequentially switched every predetermined time, and each digital input is based on the category code separated from the digital audio data inputted from each connection destination. And a control means for executing, at a predetermined timing, scan processing for sequentially detecting the types of digital audio devices connected to the terminals.
[0015]
In the present invention, it is possible to detect which digital audio device is connected to which digital input terminal by scanning a plurality of digital input terminals using a DIR that decodes a digital audio signal such as the SPDIF standard. I can do it. A buffer is provided before and after the DIR so that the digital audio signal input while the DIR is scanning is buffered by the first buffer, and the audio stream data to be output during that time is read from the second buffer. did. Thus, even when a music audio signal (an audio signal that is not null data) is input, each digital input terminal can be scanned, and what digital audio device is connected to which digital input terminal. You can always have the latest information.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing an example of a connection form of a digital audio amplifier 1 according to an embodiment of the present invention, FIG. 2 is a diagram showing a front panel of the digital audio amplifier, and FIG. 3 is a diagram showing a rear panel of the digital audio amplifier. is there.
As shown in FIG. 3, the digital audio amplifier 1 of this embodiment has a USB terminal 20 and digital input terminals 21 to 24 (see FIG. 3) on the back surface, and a personal computer (PC) is connected to these terminals. 2 or a plurality of digital audio devices 3, 4, 5 are connected. The digital audio devices 3, 4, and 5 are, for example, an MD player, a CD player, a DVD player, a DV player, a digital broadcast tuner, and the like, and digital audio signals that conform to SPDIF are input from these devices.
[0017]
The SPDIF standard digital audio signal is obtained by framing audio stream data for each predetermined sample, and a category code indicating the type of device outputting the digital audio signal is embedded in the subcode of each frame. ing. For example, a category code “1000000x” indicates a CD player, and a category code “1001100x” indicates a DVD player. Here, “x” means don'tcare (which may be 0/1).
[0018]
As shown in FIG. 2, input selection switches 10 to 14 for selecting an external input are provided on the upper portion of the front panel. This input selection switch is a switch for selecting either the USB terminal 20 or the digital input terminals 21 to 24 and reproducing a digital audio signal input from this terminal (for outputting from a speaker). . Among these, the USB terminal 20 to which the input selection switch 10 is connected, that is, the switch for selecting the personal computer 2 is selected, and the input selection switches 11 to 14 are switches for selecting the digital input terminal.
[0019]
The input selection switches 10 to 14 are push button switches. When the user presses this button, the switch is turned on, an input terminal corresponding to the switch is selected, and an audio signal input from the input terminal is subjected to signal processing and processing. Amplified and output from the external output terminal 26 and the speaker terminal 27. The switches that are turned on are displayed by indicators 10a to 14a provided at the left ends of the input selection switches 10 to 14, respectively. The indicators 10a to 14a are constituted by LEDs, and the indicators corresponding to the switches that are turned on are lit.
[0020]
An LCD matrix display 15 is provided below the input selection switches 10 to 14 on the front panel. On the LCD matrix display 15, names of devices connected to the USB terminal 20 and the digital input terminals 21 to 24 are displayed. The display of the device name displays a list of all device names connected to the input terminals 20 to 24, and the item selected by the input selection switches 10 to 14 is highlighted or displayed in another area. indicate. The LCD matrix display 15 also displays the name of the device connected to the analog input terminal 25.
[0021]
Further, a volume encoder 16 and a power switch 17 are provided at the lower portion of the front panel.
In FIG. 3, the rear panel is provided with an analog input terminal 25, an audio output terminal 26, a speaker terminal 27 and the like in addition to the USB terminal 20 and the digital input terminals 21 to 24.
[0022]
FIG. 4 is a block diagram of the digital audio amplifier. The CPU 31 that controls the operation of the device includes a ROM 32, a RAM 33, a display device 34, an operation panel 35, a remote control receiver 36, a USB interface 37, a DIR (digital audio interface receiver) 38, selectors 39 and 41, and a DAC 42 via a bus. The amplifier 43 and the DSP 44 are connected. The ROM 32 stores a control program executed by the CPU 31, an audio signal processing program executed by the DSP 44, a device name table in which category codes in the SPDIF standard and types (names) of digital audio devices are associated with each other. A part or all of the ROM 32 may be a flash ROM so that the program (firmware) can be upgraded from the personal computer 2 connected via the USB terminal 20.
[0023]
The RAM 33 stores various setting contents by the user, and a FIFO area 33a for buffering audio stream data separated from the digital audio signal by the DIR 38 is set. The FIFO area 33a scans what devices are connected to other digital input terminals while processing the digital audio signal input from the digital input terminal selected by the input selection switch. Used for "time earning".
[0024]
The display device 34 includes the LCD matrix display 15 and its display control circuit. The operation panel 35 includes the input selection switches 10 to 14, indicators 10 a to 14 a, the encoder 16, and the power switch 17. The remote control receiving unit 36 is a circuit unit that receives an infrared signal from the remote control device 50. The remote control device 50 is provided with an operation element that is substantially the same as the operation panel 35 of the apparatus main body, and transmits an infrared signal corresponding to the operation mode of each operation element. The remote control receiving unit 36 receives and decodes the infrared signal sent from the remote control device 50 and inputs it to the CPU 31 as operation data of the operator. When the operation data of the operation element is input from the remote control receiving unit 36, the CPU 31 executes the same process as when the operation element of the operation panel 35 is operated.
[0025]
The USB interface 37 is connected to the USB terminal 20 and controls data transmission / reception with a personal computer connected to the USB terminal 20. The DSP 44 is a processor that imparts effects such as reverberation to the audio stream data (buffered in the FIFO area 33a) input from the DIR 38. There are a plurality of types of effects that the DSP 44 can give to the audio stream data, and the effects to be given from the personal computer 2 connected to the USB terminal 20 and the degree thereof can be set. The CPU 31 transfers a program for executing the effect set to be given from the ROM 32 to the DSP 44.
[0026]
The CPU 31 executes data transfer from the DIR 38 to the FIFO area 33a and data transfer from the FIFO area 33a to the DSP 44 at a speed in accordance with the data rate of the audio stream data. However, since the DIR 38 and the DSP 44 incorporate a certain amount of buffer memory, this data transfer may be performed intermittently.
[0027]
The audio stream data provided with the effect by the DSP 44 is transferred to the DAC 42 and converted into an analog audio signal. The audio signal is amplified by the amplifier 43 and then output from the speaker terminal 27 and the audio output terminal 26.
[0028]
The digital input terminals 21 to 24 are connected to the selector 39 and the selector 41. The selector 39 connects any one of the digital input terminals 21 to 24 to the FIFO 40. The FIFO 40 is a variable-length buffer and buffers until the input SPDIF digital audio signal is read out by the DIR 38. The selector 41 connects any one of the digital input terminals 21 to 24 and the FIFO 40 to the DIR 38.
[0029]
The connection destination of the selector 39 is switched according to the operation of the input selection switches 11 to 14 (this switching is performed by the CPU 31). That is, when the input selection switch 11 is turned on, the CPU 31 inputs a selection signal for selecting the digital input terminal 21 to the selector 39 and connects the digital input terminal 21 to the FIFO 40. Similarly, when the input selection switch 12 is on, the digital input terminal 22 is connected to the FIFO 40, and when the input selection switch 13 is on, the digital input terminal 23 is connected to the FIFO 40, and the input selection switch 14 is When turned on, the digital input terminal 24 is connected to the FIFO 40.
[0030]
The connection destination of the selector 41 is switched by the CPU 31 according to the control process.
During normal audio reproduction, the CPU 31 inputs a selection signal for selecting the FIFO 40 to the selector 41 and connects the FIFO 40 to the DIR 38. The DIR 38 decodes a digital audio signal input via the digital input terminals 21 to 24 → selector 39 → FIFO 40 → selector 41 and separates audio stream data and category codes. These data are read by the CPU 31, the audio stream data is transferred to the FIFO 33a, and the category code is used as information for identifying the digital audio device connected to the digital input terminal selected at that time.
[0031]
On the other hand, at the time of input terminal scan processing, the CPU 31 controls the selector 41 to sequentially switch and select the digital input terminals 21 to 24 and sequentially supply the digital audio signals input from the digital input terminals 21 to 24 to the DIR 38. To do. The selection switching interval is about 50 ms to 100 ms, and this interval is set to a length that can capture one frame of the input digital audio signal. The DIR 38 separates and extracts the category code included in the subcode of the input digital audio signal of one frame and passes it to the CPU 31. Based on this category code, the CPU 31 detects what digital audio equipment is connected to the digital input terminal. This detection is sequentially executed for the digital input terminals 21 to 24, the connected digital audio equipment is detected for all the digital input terminals, and the input terminal scanning process is terminated.
[0032]
If one frame of the digital audio signal input from each digital input terminal is 50 ms and the number of terminals to be scanned is 4, a time of about 200 ms is required for one scanning process. During this scanning process, the DIR 38 cannot capture either the digital audio signal input from the digital audio device selected by the input selection switch or output the audio stream data to the subsequent stage. The digital audio signal is buffered in the FIFO 40, and the audio stream data output to the DSP 44 during this time is buffered in the FIFO area 33a. Note that the digital input terminal selected by the input selection switch at that time may be excluded from the scan processing target because the category code is detected in the normal audio reproduction processing. Thereby, processing time can be shortened.
[0033]
This input terminal scanning process is executed at a frequency of about once every 10 seconds to several minutes during normal audio reproduction, and also when the power is turned on. Note that the DIR 38 can be used exclusively for category code separation when the power is turned on or when any of the digital input terminals 21 to 24 is not selected by the input selection switches 11 to 14.
[0034]
The CPU 31 searches the device name table 32a with the category code of each digital input terminal detected by the input terminal scan process, finds the name of the device connected to each digital input terminal, and stores it on the LCD matrix display 15. indicate.
[0035]
FIG. 5 is a flowchart showing the operation of the digital audio amplifier. This operation starts when the power is turned on. First, before the audio reproduction process is started, the selector 41 is sequentially switched to the digital input terminals 21 to 24, and the scan process for detecting the category code of the digital audio signal input from each digital input terminal is executed ( s1). Then, the device name table 32a is searched with the category code detected in this scanning process, and the name of the digital audio device connected to each digital input terminal, that is, the name corresponding to each input selection switch is displayed (s2). Since the user refers to the input selection switch as a selector, it is referred to as a selector name here.
[0036]
After that, a steady processing loop such as scanning of an operator is executed (s3), and it is determined whether the music is being played or whether the music is being played (s4, 5). This determination is made based on whether audio stream data having a value greater than 0 (null) has been input from the digital audio device selected by the selector 39 to the DIR 38. For example, if the digital audio device selected by the selector 39 is a CD player and the CD player is not reproducing a CD or if it is between songs (between songs), this CD player The digital audio signal sent from is added with the subcode as usual, but the audio stream data is all 0, which indicates that the song is not being played. When the input audio stream data takes a value other than 0, it can be determined that reproduction has started.
[0037]
If the song is not being played and is not at the playback start timing, the selector 41 is sequentially switched to the digital input terminals 21 to 24 to execute the scanning process (s6), and the connected digital audio device is changed. Changes the display of the device name of the input selection switch corresponding to the changed digital input terminal (s7).
[0038]
On the other hand, when it is determined that the input audio stream data has a value other than 0 and the performance of the song has started, the audio stream data is first stored in the FIFO 33a for an appropriate time (500 ms in this embodiment). ) After buffering, the performance is started (s8). The start of performance is an operation of outputting data buffered in the FIFO 33a from the head to the DSP 44. At this time, a timer for measuring the scan processing interval is set (s9). In this embodiment, the timer is set to 10 seconds. Thereafter, the process proceeds to the audio reproduction process (s10 or less).
[0039]
Here, in the normal audio reproduction process, the same amount of data as that transferred from the FIFO 33a to the DSP 44 is transferred from the DIR 38 to the FIFO 33a, so that the FIFO 33a does not overflow or underrun.
[0040]
If it is determined that the performance is being performed in s5, the process proceeds to an audio reproduction process (s10 or less). In s10, it is determined whether the timer for measuring the interval of the scanning process has expired. If the time is not up, do nothing and return to s3.
[0041]
When the timer expires, it is time to scan the digital input terminal, so the DIR 38 decoding process, that is, the process of taking the digital audio signal from the FIFO 40 via the DIR 38 is interrupted and selected by the input selection switch. The digital audio signal input from the digital input terminal is buffered in the FIFO 40. Then, the connection destination of the selector 41 is sequentially switched from the FIFO 40 to the digital input terminals 21 to 24, and the DIR 38 reads the category code of the digital audio signal input from each digital input terminal (s12). When the connected digital audio device is changed, the display of the device name of the input selection switch corresponding to the changed digital input terminal is changed (s13). After that, the connection destination of the selector 41 is switched again to the FIFO 40 (s14), and a timer for measuring the scan interval is set again (s15). After this, return to s3.
[0042]
The DIR 38 reconnected to the FIFO 40 in s14 catches up with the input digital audio signal by setting the buffer amount of the FIFO 40 to 0 by reading and decoding the FIFO 40 data faster than the data rate of the digital audio signal. The buffer amount of the FIFO 33a that has been reduced by interrupting the decoding process can be replenished.
[0043]
Thus, by providing the buffer FIFOs 40 and 33a before and after the DIR 38, it is possible to periodically scan the input device with one DIR even during audio reproduction.
[0044]
Even when the buffer is not provided before and after the DIR 38, it is possible to periodically execute the scanning process while the selected digital audio device does not start playing the song.
[0045]
Also, as shown in FIG. 6, two DIRs may be provided, one used for audio reproduction and the other used exclusively for category code detection of digital audio signals input from each digital input terminal. The category codes can be detected and the names of the digital audio devices connected to the respective digital input terminals can be displayed in a list.
[0046]
In this embodiment, a digital audio amplifier has been described as an example. However, the present invention can be applied to any device provided with a plurality of digital input terminals. Although the number of digital input terminals is four, the number of digital input terminals is not limited to this.
[0047]
【The invention's effect】
As described above, according to the present invention, even if a user freely connects a digital audio device to a plurality of digital input terminals, the digital audio input device automatically determines which device is connected to which digital input terminal. Since it detects and displays the list, it is not necessary for the user to be aware of the connection destination of each device, and it is easy to understand which device is connected to which device after the connection.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a connection form of a digital audio amplifier according to an embodiment of the present invention.
FIG. 2 is a diagram showing a front panel of the digital audio amplifier
FIG. 3 is a view showing a rear panel of the digital audio amplifier.
FIG. 4 is a block diagram of the digital audio amplifier.
FIG. 5 is a flowchart showing the operation of the digital audio amplifier.
FIG. 6 is a diagram showing another embodiment of the digital audio amplifier.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Digital audio amplifier, 2 ... Personal computer, 3 ... MD player, 4 ... CD player, 5 ... DVD player,
10-14 ... Input selection switch, 10a-14a ... Indicator, 15 ... CLD display, 16 ... Volume encoder, 17 ... Power switch,
20 ... USB terminal, 21-24 ... digital input terminal, 25 ... analog input terminal, 26 ... audio signal terminal, 27 ... speaker terminal,
31 ... CPU, 32 ... ROM, 32a ... device name table, 33 ... RAM, 33a ... FIFO area, 34 ... display device, 35 ... operation panel, 36 ... remote receiver, 37 ... USB interface, 38 ... DIR (digital audio) Interface receiver), 39 ... selector, 40 ... FIFO, 41 ... selector, 42 ... DAC, 43 ... amplifier, 44 ... DSP, 50 ... remote control device

Claims (2)

A plurality of digital input terminals to which digital audio signals are input;
A digital audio interface receiver (DIR) that receives a digital audio signal input from a digital input terminal and decodes the digital audio signal to separate audio stream data and a category code;
A selector for selectively setting a connection destination of DIR to any of the plurality of digital input terminals;
Selecting means for selecting one from the plurality of digital input terminals by a selection operation;
Audio data processing means for processing audio stream data;
The digital input terminal selected by the selection means is connected to the DIR, and the audio stream data separated by the DIR is input to the audio data processing means. The selector is controlled to switch the connection destination of the DIR sequentially. Control means for executing, at a predetermined timing, scan processing for sequentially detecting the type of digital audio equipment connected to each digital input terminal based on a category code separated from digital audio data input from a connection destination; ,
And the control means detects the break of the digital audio signal from the digital input terminal selected by the selection means, and executes the scan process at that time . A plurality of digital input terminals to which digital audio signals are input;
First selection means for selecting one of the plurality of digital input terminals by a selection operation;
A first buffer for buffering a digital audio signal input from the digital input terminal selected by the first selection means;
A digital audio interface receiver (DIR) that decodes an input digital audio signal to separate audio stream data and category codes;
A second buffer for buffering audio stream data obtained by decoding and separating the digital audio signal input from the first buffer;
Audio data processing means for sequentially reading and processing the audio stream data from the second buffer;
Second selection means for connecting either the plurality of digital input terminals or the first buffer to the DIR;
After the audio stream data is accumulated for a predetermined time in the second buffer, the audio data processing means is allowed to read it, and the connection destination of the first selection means is sequentially switched every predetermined time, Control means for executing scan processing for sequentially detecting the type of digital audio equipment connected to each digital input terminal based on a category code separated from digital audio data input in advance at a predetermined timing;
A digital audio processing apparatus.

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