JPH0414676A - Digital audio recording device - Google Patents

Abstract

PURPOSE:To eliminate the need for changeover to an analog signal by manual operation by converting a digital signal whose copy is inhibited into an analog signal at a D/A converter and using it as a recording source via an A/D converter. CONSTITUTION:A digital signal inputted to a digital input terminal 1 is decoded by a decoder 2, and a detection circuit 15 detects whether or not the signal includes a copy inhibit code. A changeover control circuit 16 applies changeover control to 2nd, 4th and 5th selectors 6, 11, 14 in response to the detection output of the circuit 15. When the digital signal including the copy inhibit code is inputted to the input terminal 1, an audio data extracted by the decoder 2 depending on the changeover state of the selector 11 is fed to a D/A converter circuit 12 and an analog signal outputted from the D/A converter circuit 12 is fed to an A/D converter circuit 4 depending on the changeover state of the selector 14. On the other hand, a signal outputted from the circuit 4 is fed to a recording reproducing processing section 7 depending on the changeover state of the selector 6 and recorded on a recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a digital audio recording device that records audio information using digital signals, and in particular to a digital audio recording device that records audio information using digital signals. The present invention relates to an audio recording device.

(b) Conventional technology Recently, CD players, DAT (digital audio
Many digital audio devices that handle audio information as digital signals, such as tape recorders (tape recorders) or BS tuners (satellite broadcast reception tuners), output the audio information as analog signals as well as output the audio information as digital signals. A digital output function is provided to output the signal as is. The digital signal output from the digital audio device conforms to the format defined by the digital audio interface standard (EIAJ standard CP-340) standardized by EIAJ (Electronic Industries Association of Japan). Therefore, a digital audio recording device such as a DAT that records audio information using digital signals receives digital audio data as a recording source, which is input as an analog signal and converted to a digital signal by a built-in A/D conversion circuit. In addition to the analog input function, it is equipped with a digital input function that inputs digital signals and inputs digital audio data that has been decoded according to the standards by a built-in decoder as a recording source. Such a digital audio recording device is provided with a selection circuit so that analog input and digital input can be selected.

By the way, due to copyright issues, digital signals conforming to the above-mentioned standards have a part (bit ) are available. The digital audio recording device is provided with a detection means for detecting the digital copy prohibition code, and the digital audio recording device is configured such that digital copying is not possible when the digital copy prohibition code is detected. There is.

Recently, Philips has proposed a method called the Solo Copy method, which allows digital copying of only one generation of original software. This solo
One-way copying allows digital copying even if the original software contains a digital copy prohibition code, and also prohibits digital copying, which prohibits new digital copying of the digital signal that reproduces the software that has been completely copied by digital copying. A code is added to prevent the duplicated software from being digitally copied.

(c) Problems to be solved by the invention As mentioned above, in a digital audio recording device,
If there are restrictions on recording using digitally input digital audio data and digital copying is prohibited, it is necessary to select analog input. Since digital input is more advantageous in terms of sound quality, with conventional digital audio recording devices, you have to manually select digital input or analog input depending on the software, making the operation complicated. There was a problem.

In addition, if a single piece of software contains a mixture of sources that support digital copy M and sources that do not, it is difficult to select digital input or analog input for each source, so use analog input instead. I had selected it so that even if it was a source that could be digitally copied, analog input would be performed. In other words, a source that can be digitally copied has to be recorded using an analog input at the expense of sound quality.

(d) Means for Solving the Problems The present invention is a digital audio recording device that has been made in view of the above points, and includes a decoder that decodes a digital signal input to a digital input terminal, and an analog signal input to an analog input terminal. An A/D conversion circuit that converts a signal into a digital signal, a D/A conversion circuit that allows the reproduced digital signal and input digital signal to be output as an analog signal, and a digital signal that has been decoded by the decoder. a detection circuit for detecting a copy prohibition code that prohibits digital copy; and a first detection circuit for selectively supplying the digital audio data extracted by the decoder to the D/A conversion circuit according to the detection output of the detection circuit. The analog signal output from the supply path and the D/A conversion circuit is selectively connected to the A/A converter according to the detection output of the detection circuit.
a second supply path for supplying to the D/A conversion circuit, and when a digital signal containing a copy prohibition code is supplied to the digital input terminal, the digital audio data extracted by the decoder is transmitted to the D/A. The signal is supplied to the A/D conversion circuit via a conversion circuit.

(Main) Effect The present invention focuses on the fact that in a digital audio recording device, a D/A conversion circuit is usually provided in order to output reproduced digital signals and input digital signals as analog signals. , converts the digital signal input to the digital input terminal into an analog signal using its D/A conversion circuit, and supplies the analog signal as a recording source via the built-in A/D conversion circuit. If you install a signal path and use a digital signal whose digital copying is prohibited as a recording source, use the signal path to obtain the recording source in the same way as recording with analog input, and manually input the analog input. This eliminates the need to switch to

(v) Embodiment diagram is a circuit diagram showing an embodiment of the present invention.
) is a digital input terminal into which a digital signal conforming to the format defined by EIAJ standard CP-340 is input, and (2) is a digital input terminal that inputs a digital signal input to the digital input terminal (1) according to the format. A decoder for decoding, (3) is an analog input terminal into which an analog signal is input, and (4) is an analog input terminal for converting the analog signal input to the analog input terminal (3) into a digital signal.
a D conversion circuit; (5) a first selector for manually selecting one of the audio data extracted by the decoder (2) and the audio data output from the A/D conversion circuit (4); (6); (7) is a second selector that selects either the audio data selected by the first selector (5) or the audio data output from the A/D conversion circuit (4) as a recording source for recording; Recording that performs recording processing to record the audio data selected by the second selector (6) onto a recording medium (not shown), and performs playback processing to play back the audio data recorded on the recording medium.・The playback processing section (8) is switched according to the recording operation,
When a recording operation is performed, the audio data selected by the second selector (6) is selected, and when any other operation including a playback operation is performed, the recording/playback processing section (7) selects the audio data selected by the second selector (6). A third selector (9) selects audio data that has been played back;
8) is an encoder that converts the selected audio data into a digital signal encoded according to the format of EIAJ standard CP-340, and (10) is a digital output for deriving the digital signal output from the encoder (9). The terminal (11) is the third selector (8
) and the audio data extracted by the decoder (2>);
(1) is a D/A conversion circuit that converts the audio data of the digital signal selected by (1) into an analog signal, and (13) is an analog output terminal for deriving the analog signal output from the D/A conversion circuit (12). , (14) is the above D/
a fifth selector for selecting an analog signal to be supplied to the A/D conversion circuit (4) from among the analog signal output from the A conversion circuit (12) and the analog signal input to the analog input terminal (3); (15) is a detection circuit that detects a copy prohibition code that prohibits digital copying from the digital signal completely decoded by the decoder (2); selector (6), the fourth selector (11)
and a switching control circuit that switches the fifth selector (14).

The second selector (6) selects the A/D conversion circuit (4) when the detection circuit (15) detects the copy prohibition code.
When the copy protection code cannot be detected by the detection circuit (15), the first selector (5)
) is controlled by a switching control circuit (16) to select the audio data output from the recording source as the recording source.

On the other hand, when the detection circuit (15) detects the copy prohibition code, the fourth selector (11) selects the decoder (2).
) to select the audio data to be extracted.
When the detection circuit (15) does not detect the copy prohibition code, the switching control circuit (15) selects the audio data output from the third cell vector (8).
Switching is controlled by 6).

On the other hand, the fifth selector (14) selects the analog signal output from the D/A conversion circuit (12) when the detection circuit (15) detects the copy prohibition code, and the detection circuit When the copy prohibition code is not detected by (15), the switching control circuit (16) selects the analog signal input to the analog input terminal (3).
) is controlled by switching.

Next, the operation will be explained.

The digital signal input to the digital input terminal (1) is
Decoded by decoder (2), detection circuit (15)
It is detected whether or not a copy prohibition code is included. The switching control circuit (16) then controls the detection circuit (
The second selector, -(6), the fourth selector (11), and the fifth selector (14) are switched and controlled in accordance with the detection output of the switch 15).

Now, assume that a digital signal containing a copy prohibition code is input to the digital input terminal (1). Then, depending on the switching state of the fourth selector (11), the audio data extracted by the decoder (2) is supplied to the D/A conversion circuit (12), and the fifth selector (14)
Depending on the switching state, the analog signal output from the D/A conversion circuit (12) is supplied to the A/D conversion circuit (4). On the other hand, depending on the switching state of the second selector (6), the digital signal output from the A/D conversion circuit (4) is supplied to the recording/playback processing section (7). Therefore, in this case, the digital signal input to the digital input terminal (1) is decoded by the decoder (2>), then converted to an analog signal by the D/A conversion circuit (12), and then A/D converted. The signal is again converted into a digital signal by the circuit (4>) and supplied to the recording/playback processing section (7).

Therefore, even if a digital signal is input to the digital input terminal (1), the recording/playback processing section (7) uses an A/D conversion circuit (4) to obtain the digital signal, as in the case of recording using an analog input, which will be described later. The audio data is supplied as a recording source, and the audio data is recorded on a recording medium.

On the other hand, assume that a digital signal that does not include a copy prohibition code is input to the digital input terminal (1). Then, depending on the switching state of the second selector (6), the audio data selected by the first selector (5) is supplied to the recording/playback processing section (7). Therefore, depending on the selection state of the first selector (5), audio data output from the decoder (2) or audio data output from the A/D conversion circuit (4) is stored in the second selector (black). is supplied. Here, the detection circuit (1
5) When the copy prohibition code is not detected,
The fifth selector (14) is configured to select the analog signal input to the analog input terminal (3).
6>, one of the first selectors (5) receives audio data obtained by converting an analog signal input to the analog input terminal (3) into a digital signal by the A/D conversion circuit (4). is supplied. Therefore, the recording/playback processing section (7) receives the audio data or the digital signal input to the digital input terminal (1) by the decoder (2) depending on the selection state of the first selector (5) by manual operation. The decoded and extracted audio data is selectively supplied as a recording source, and the audio data is selectively recorded on a recording medium.

Furthermore, the encoder (9) is connected to the digital output terminal (10).
), but when in the recording state, the third selector is used regardless of whether or not the digital signal input to the digital input terminal (1) contains a copy prohibition code. (8) is switched to a state in which the audio data selected by the second selector (6) is directly selected without going through the recording/playback processing section (7).

On the other hand, when not in recording mode, press the third selector (
8) is switched to a state where the audio data obtained from the recording/playback processing section (7>) is selected. Therefore, when the digital output terminal (10) is in the recording state, the second selector (6) ) outputs a digital signal obtained by encoding the audio data selected by the encoder (9).On the other hand, when not in the recording state, the audio data obtained via the recording/playback processing section (7) is output by the encoder (9). ) outputs the encoded digital signal.

Further, the analog signal output from the D/A conversion circuit (12) is derived from the analog output terminal (13), but the audio data input to the D/A conversion circuit (12) is It varies depending on the switching state of the selector (11), and when a digital signal containing a copy-prohibited food is input to the digital input terminal (1), the fourth selector (11) is output from the decoder (2). Select audio data and connect the digital input terminal (1
), the fourth selector (11) selects the audio data obtained via the third selector (8) when all digital signals that do not include a copy prohibition code have been input. Therefore, when a digital signal containing a copy prohibition code is input from the analog output terminal (13) to the digital input terminal (1), the decoder (
An analog signal obtained by converting the audio data output from 2) by a D/A conversion circuit (12) is output, while a digital signal that does not include a copy prohibition code is input to the digital input terminal (1). When there is a third
An analog signal obtained by converting the audio data selected by the selector (8) by the D/A conversion circuit (12) is output.

By the way, if you want to use the analog signal input to the analog input terminal (3) as the recording source, select the fifth selector (1
4), it is necessary to select the analog signal input to the analog input terminal (3). Therefore, the first
When the selector (5) selects the audio data output from the A/D conversion circuit (4), the fifth selector (14) is forced to select the analog signal input to the analog input terminal (3). A control signal is outputted from the switching control circuit (16) in order to set the state, and at the same time, a digital signal containing a copy prohibition code is input to the digital input terminal (1), and the above-mentioned This is to prevent the 5 selector (14) from switching to a state in which it selects the output of the D/A conversion circuit (12).

(G) Effects of the Invention As described above, the present invention converts a digital signal, whose digital copying is prohibited, into an analog signal using a built-in D/A conversion circuit, and also converts the analog signal into an analog signal by using a built-in D/A conversion circuit. Since it is used as a recording source via a D conversion circuit, if you give priority to digital input, you can record sources for which digital copy is prohibited in the same way as recording with analog input, and sources that can be digitally copied. This has the advantage that recording can be performed using digital input, and there is no need for complicated recording source switching operations that are performed depending on whether digital copying is possible or not.

[Brief explanation of drawings]

The figure is a configuration diagram showing an embodiment of the present invention. Explanation of main drawing numbers (1)...Digital input terminal, (2)...Decoder, (3)...Analog input terminal, (4)...A
/D conversion time, (5) (6) (8) (11) (14>
... Selector (12) ... D/A conversion circuit,
(15)...Detection circuit, 16)...Switching control circuit.

Claims (1)

[Claims] (1) D/A that records audio information using digital signals and converts digital signals to analog signals
In a digital audio recording device equipped with a conversion circuit and capable of outputting a reproduced digital signal and an input digital signal as an analog signal, a digital input terminal into which a digital signal containing audio information is input;
A decoder that decodes the digital signal input to the digital input terminal, an analog input terminal to which audio information of the analog signal is input, and an A/D that converts the analog signal input to the analog input terminal into a digital signal.
a conversion circuit; a detection circuit that detects a copy prohibition code that prohibits digital copying from the digital signal decoded by the decoder; and a detection circuit that selectively converts digital audio data extracted by the decoder according to a detection output of the detection circuit the first for supplying to the D/A conversion circuit;
The analog signal output from the supply path and the D/A conversion circuit is selectively connected to the A according to the detection output of the detection circuit.
and a second supply path for supplying the digital audio data extracted by the decoder to the D/D conversion circuit when a digital signal containing a copy prohibition code is supplied to the digital input terminal. A digital audio recording device characterized in that the signal is supplied to the A/D conversion circuit via an A conversion circuit.