JP2000252976A - Method for scrambling and descrambling audio data, scrambler, recording medium and descrambler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a scramble code from being recognized in the case of applying exclusive OR to audio data and the scramble code. SOLUTION: A scrambler in the presence of audio data uses an EX-OR circuit 2 and a PN code generator 3 to apply exclusive OR to an output of the generator 3 and the audio data to scramble the audio data and uses the PN code generator 3 and EX-OR circuits 2, 2a to apply exclusive OR to the output of the generator 3 and an output of an A/D converter 1 to doubly scramble the output of the A/D converter 1 for a no sound data period or a period close to the no sound data period, a DVD audio format circuit 8 encodes the scrambled data in a way of a prescribed data structure and records the resulting data to a recording medium or the like. Thus, it is prevented that a scramble code is recognized for the no sound data period or a period close to the no sound data period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for scrambling and descrambling audio data, a scrambling device, a recording medium, and a descrambling device.

[0002]

2. Description of the Related Art Generally, in a DVD (digital video disk, digital versatile disk), video data is scrambled by a method called CSS (content scrambling system). In this CSS method, the original data and the PN code as a scrambling code are scrambled by performing an exclusive OR operation on the scrambled data. Is exclusive-ORed and descrambled.

[0003]

However, since the audio signal has a silent section, and the bits of the audio data in the silent section become all zero or close to zero, this audio data is exclusively used with the PN code. If a scoring is performed by taking a logical sum and an exclusive logical sum of the scrambled data and the PN code is taken, the PN code is output as it is, so that the PN code is known.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a method for scrambling and descrambling audio data which can prevent the scrambling code from being known when an exclusive OR of the audio data and the scrambling code is obtained. , A scrambling device, a recording medium, and a descrambling device.

[0005]

Means for Solving the Problems In order to achieve the above object, the present invention comprises the following means 1) to 4).
That is,

[0006] 1) detecting at least a silent section of audio data, and scrambling the audio data by taking an exclusive OR of the audio data and a scramble code in a section other than the silent section; Performing a multiplexed scramble by taking a logical sum of a plurality of times with the scramble code; transmitting the scrambled audio data and the multiplexed scrambled data via a medium; Detecting and descrambling the scrambled audio data by taking an exclusive OR of the scrambled audio data and the descramble code in a section that is not the silent section based on the step. And a step in audio section for descrambling the scrambled data of the multiple, the audio data having scramble, descramble process.

2) means for detecting at least a silent section of the audio data; and, in a section other than the silent section, the audio data is scrambled by taking an exclusive OR of the audio data and a scramble code. A scrambler for performing a multiplex scramble by taking a logical sum of a plurality of times with the scramble code; and a means for formatting the scrambled audio data and the multiplexed scrambled data into a data structure having a scramble key. , An audio data scrambling device.

[0008] 3) At least a silent section of the audio data is detected, and in a section other than the silent section, the audio data is scrambled by taking an exclusive OR of the audio data and a scramble code. In the silent section, the scramble is performed. A recording medium for audio data in which a logical OR is performed a plurality of times by a code and multiplex scrambling is performed, and a data structure of a predetermined format is recorded having the scrambled audio data.

4) At least a silent section of the audio data is detected, and the audio data is scrambled by taking an exclusive OR of the audio data and a scramble code in a section other than the silent section, and the scramble is performed in the silent section. An apparatus for descramble a data structure having the scrambled audio data and the multiplexed scrambled data by taking a logical sum of a plurality of times with the code and performing multiplex scrambling, wherein the section other than the silent section is used. Means for detecting, and descrambling the audio data by performing an exclusive OR operation on the scrambled audio data and the descramble code inputted in a section other than the silent section based on the detection result, Input in section And means for descrambling the multiple scrambled data, the descrambling device of the audio data having.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG.
FIG. 2 is a block diagram showing an embodiment of the scrambler according to the present invention, FIG. 2 is an explanatory diagram showing the reference data of FIG. 1 in detail, FIG. 3 is an explanatory diagram showing the format of an audio pack of a DVD audio disc, and FIG. 1 of D
FIG. 5 is a flowchart showing the processing of the VD audio formatting circuit, and FIG. 5 is a block diagram showing an embodiment of the descrambling device according to the present invention.

In FIG. 1, for example, stereo two-channel L and R audio signals are converted into M-bit digital data for each channel by an A / D converter 1 and then M-bit data of each channel is converted into M bits in parallel. Is applied to one input terminal of one of the EX-OR circuits 2.
The PN code generator 3 generates an M-bit PN code in which one word corresponding to the scramble key is M bits, and outputs the E-code in parallel.
The data is output to the other input terminal of the X-OR circuits 2 and 2a. Therefore, the audio data is exclusive-ORed with the PN code and scrambled. The scrambled audio data is applied to one input terminal a of the switch 4. The switch 4 is switched by the scramble change flag Fsc, and the data selected by the switch 4 is transferred to the DVD audio formatting circuit 8.
Is applied to

Further, the audio signals of the two channels L and R converted by the A / D converter 1 are applied to silence section detectors 6L and 6R, respectively, and based on the reference data 10 shown in detail in FIG. Alternatively, a section close to silence is detected. As shown in FIG. 2, the reference data 10 is a code for determining whether N pieces of M-bit data are “+0” or “−0” consecutively, and N is, for example, a serial code for scrambling. The number of words in the code is half of 64. This detection signal is supplied to the OR gate 7
Are ORed to detect a silent section or a section close to silent on either channel, and apply the result to the control terminal of the switch 4 as a scramble change flag Fsc. The switch 4 selects the output signal of the EX-OR circuit 2 in a section that is not a silent section or a section close to silent. On the other hand, in a silent section or a section close to silent, the EX-OR circuit 2 is selected.
The output signal a is selected, and the output signal subjected to double scrambling is selected.

DVD audio formatting circuit 8
Formats the scrambled audio data into a linear PCM audio pack (A pack) recorded on a DVD audio disc as shown in FIG. The A-pack of the linear PCM is composed of 2048 bytes or less, which consists of a 14-byte pack header and A
It is composed of packets. A packet is 17, 9
Or, it is composed of a 14-byte packet header, a private header, and audio data (scrambled or not scrambled linear PCM data) of 1 to 2011 bytes.

The private header includes: an 8-bit substream ID; a 4-bit reserved area in the ISRC; a 4-bit ISRC number in the ISRC; an 8-bit ISRC data in the ISRC; It is composed of an 8-bit private header length, 16-bit first access unit pointer, 6-byte audio data information (ADI), and 0 to 7 stuffing bytes.

The ADI includes: a 1-bit audio emphasis flag; a reserved area of 1 + 2 bits; a 4-bit downmix code; and a 4-bit quantization word length of group "1".
And the quantization word length “2” of the 4-bit group “2”
A 4-bit audio sampling frequency fs1 of group "1"; a 4-bit audio sampling frequency fs2 of group "2"; a 4-bit reserved area; and a 4-bit multi-channel type. , 3 bits reserved area, 5 bits channel allocation information, and 8 bits dynamic range control information.

The data of the scramble key is D
It is formatted in the lead-in area of the VD audio disc and recorded in the lead-in area of the disc. When the still image data accompanying the audio data is recorded together, the still image data is formatted into a still image pack (not shown) by the DVD audio formatting circuit 8 without being scrambled.

Next, the processing of the DVD audio formatting circuit 8 will be described with reference to FIG. First, each time data is input, it is determined whether or not it is the audio pack start time (step S1). If it is the start time, the data counter DC is set to start counting (step S1).
2) Then, the management data of the scramble change flag Fsc is reset (step S3), and the process proceeds to step S4. On the other hand, if it is not the start time in step S1, the process proceeds to step S4 to determine the scramble change flag Fsc.

In step S4, if "scramble has been changed", it is determined whether or not the count value of the data counter DC is equal to or greater than N (step S5). The management data of the scramble change flag Fsc is set (step S6), and then the process proceeds to step S7. Here, as an example, if the audio data in one channel is 2800 bits, M = 24 bits, and one pack is 1800 bytes, the data counter DC
Has a maximum value of 300, but N = 64.
On the other hand, in step S4, "there is a scramble change"
If not, in step S5 the data counter DC
If the count value is not more than N, the process directly proceeds to step S7. In step S7, it is determined whether or not the audio pack has ended. If not, the process returns to step S1. On the other hand, if the audio pack has ended, this process ends. Then, based on the management data of the scramble change flag Fsc, the scramble change flag Fsc is set in, for example, a physical information section in which management information in a read area of the DVD audio disc is recorded.

Next, the descrambling device will be described with reference to FIG. The data stream reproduced from the DVD audio disc is reformatted by the DVD audio deformatting circuit 11 to obtain scrambled audio data, double-scrambled data in a silent section or a section close to silent section, and a scramble key. Data. The PN code generator 12 generates a PN code corresponding to the scramble key data, and the scrambled audio data is output to the EX-OR circuit 1.
3, the exclusive OR is calculated with the PN code and descrambled. The descrambled audio data is applied to one input terminal a of the switch 15.

A descrambled signal of data that is double-scrambled in a silent section or a section near a silent section is applied to the input terminal b. Audio data L,
R is applied to the silent section detectors 14L and 14R, and a silent section or a section close to silent is detected based on the reference data 10 shown in FIG. This detection signal is logically ORed by the OR gate 14A to detect a silent section or a section close to silent on either channel, and outputs it as a scramble change flag Fsc. Then, based on the detected scramble change flag Fsc, the switch 15 controls EX in a section other than a silent section or a section close to silent section.
The output signal of the OR circuit 13 is selected, while the output signal of the EX-OR circuit 13a is selected in a silent section or a section near a silent section, and is converted into an analog audio signal by the D / A converter 16. Although not shown, the DV
If the still image pack played from the D audio disc is D
It is separated by the VD audio reformatting circuit 11 and output as a still image via the still image generator 17.

In the above embodiment, double scrambling is applied to a silent section or a section close to silent. However, multiple scrambling may be applied more than that. Also, the determination of the silent section is not limited to the above embodiment, and “+0” may be applied to M-bit data.
It may be determined whether or not “−0”.

[0022]

As described above, according to the present invention, at least a silent section of audio data is detected and the data is scrambled multiplexly in the silent section, so that the exclusive use of the audio data and the scramble code is performed. It is possible to prevent the scrambling code from being known when performing a logical sum. Further, since the data of the scramble key for descrambling in a predetermined format is recorded together with the audio data, the management becomes easy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a scrambling device according to the present invention.

FIG. 2 is an explanatory diagram showing reference data of FIG. 1 in detail.

FIG. 3 is an explanatory diagram showing a format of an audio pack of a DVD audio disk.

FIG. 4 is a flowchart showing processing of the DVD audio formatting circuit of FIG. 1;

FIG. 5 is a block diagram showing an embodiment of a descrambling device according to the present invention.

[Explanation of symbols]

2, 2a EX-OR circuit (along with the PN code generator 3,
A scramble means based on exclusive OR is constructed. ) 3,12 PN code generator 6L, 6R, 14L, 14R
Silent section detector (constitutes silent section detecting means together with OR gate 7) 7, 14A OR gate 8 DVD audio formatting circuit (formatting means) 13, 13a EX-OR circuit (along with PN code generator 12, (Exclusive ORing constitutes a descrambling means.)

Claims (4)

[Claims] Detecting at least a silent section of the audio data; and performing an exclusive OR of the audio data and a scramble code in a section other than the silent section to scramble the audio data. Performing a multiplexed scramble by taking a logical sum of a plurality of times with the scramble code; transmitting the scrambled audio data and the multiplexed scrambled data via a medium; Detecting and descrambling the scrambled audio data by taking an exclusive OR of the scrambled audio data and the descramble code in a section that is not the silent section based on the step. And a step in audio section for descrambling the scrambled data of the multiple, the audio data having scramble, descramble process. 2. A means for detecting at least a silent section of audio data, and scrambles the audio data by taking an exclusive OR of the audio data and a scramble code in a section other than the silent section. A scrambler for performing a multiplexed scramble by taking a logical sum of a plurality of times with the scramble code; and a means for formatting the audio data scrambled and the multiplexed scrambled data into a data structure having a scramble key. , An audio data scrambling device. 3. The audio data is scrambled by detecting at least a silent section of the audio data, and performing an exclusive OR operation of the audio data and a scramble code in a section other than the silent section, and scrambling the audio data in the silent section. A recording medium for audio data in which a logical OR is performed a plurality of times by a code and multiplex scrambling is performed, and a data structure of a predetermined format is recorded having the scrambled audio data. 4. The audio data is scrambled by detecting at least a silent section of the audio data and performing an exclusive OR of the audio data and a scramble code in a section other than the silent section, and in the silent section, the scramble is performed. An apparatus for descramble a data structure having scrambled audio data and multiplexed scrambled data by taking a logical sum of a plurality of times with a code and performing multiplex scrambling, wherein the section other than the silent section is Means for detecting, and descrambling the audio data by performing an exclusive OR operation on the scrambled audio data and the descramble code inputted in a section other than the silent section based on the detection result, Entered in the interval Wherein the multiple scrambled means for descrambling data, the descrambling device of the audio data having been.