KR20070067501A - Method for mixing and detecting analog watermarking of audio - Google Patents

Abstract

A method for inserting and detecting an analog watermark of audio is provided to mix an analog signal in which a pitch and a play speed of a marking sound source of a low sound band are lowered under a reference level with corresponding contents. A watermark sound source configured by an analog signal of an audible frequency band is converted into an analog watermark of a non-audible frequency band through a watermark generator(S10). The analog watermark is mixed with contents sound source of an audible frequency band to generate audio contents(S20). The audio contents are recorded in a storing medium by a storing device(S30). The audio contents are played to confirm proprietorial rights of the audio contents stored and circulated(S40).

Description

How to insert and detect analog watermarks in audio {METHOD FOR MIXING AND DETECTING ANALOG WATERMARKING OF AUDIO}

1 illustrates a general digital watermarking system,

2 is a flowchart illustrating an analog watermark embedding and detection method of audio according to the present invention;

3 is a diagram illustrating a three-dimensional frequency graph of a circular value of a watermark sound source;

FIG. 4 is a diagram illustrating a three-dimensional frequency graph obtained by modifying a pitch value and a reproduction speed of a marking sound source.

FIG. 5 is a diagram illustrating a three-dimensional frequency graph of a content sound source applied to an analog watermark embedding and detection method of audio according to the present invention; FIG.

6 is a diagram illustrating a three-dimensional frequency graph in a mixing state of a content sound source and an analog watermark;

FIG. 7 is a diagram illustrating a three-dimensional frequency graph in which a pitch value and a playback speed of a sound source are increased in order to detect an analog watermark in audio content of the present invention. FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a watermarking technique applied to block the illegal copying and distribution of a sound source service. The present invention relates to an analog watermark embedding and detection method of audio by mixing a watermark of an analog signal into sound content. .

In general, with the development of information and communication technology, various data forms have been changed from analog forms to digital forms which are easily processed and have no deterioration in quality. Its importance is also growing in applications such as cyber magazines and audio.

Among them, audio signals stored in recording media such as cassette tapes or CDs, that is, music, can be enjoyed through MP3 files provided on the Internet, which has recently formed the whole world as an area. It is now possible to trade copyrighted materials such as audio data produced in digital form in the cyber market.

However, various media such as audio data produced in digital form are easy to store or convert information, and when placed in an open space such as the Internet, a large amount of copying is possible without restriction of space and requester, especially after copying It is likely to be copied and distributed without the author's consent as it maintains the same data as As a result, the intellectual property rights of the original authors are not protected.

The infringement of intellectual property rights through virtual space is becoming more serious due to the convenience of storing and changing digital information, mass replication, and circulation, and various security devices have been developed to protect the intellectual property rights of the original authors. It is becoming.

One of the methods of encrypting digital information is to encrypt and transmit the transmitted data, and to allow the receiving party to restore the encrypted data through the input of a public key or a secret key, thereby preventing unauthorized third parties from transmitting. Even if it is received as a method, it cannot be restored.

However, in this case, since the data may be disclosed to a third party according to the intention of the user receiving the data legally, the data itself may not protect the intellectual property rights of the original author.

Therefore, in recent years, a watermarking method has been used to detect and claim tampering and forgery of data as a method of invisibly structuring digital data and using it for authentication and property protection.

As shown in the system of FIG. 1, a digital watermark is a code that inserts a code such as ID or information that only a user can know in digital content or codes specific to a signal such as video or audio. I say technology to insert type and so on. This is also a technology to prevent piracy and to effectively protect the copyright and ownership of data owners.

This digital watermark is widely used because it is very effective at finding the source or copying path of the original without any disruption to the user's viewing images or using the software.

The watermarking is classified into visual watermarking and invisible watermarking, and in the method of inserting watermarking, the spatial method, the frequency domain method, Various methods such as using spread spectrum communication have been provided.

The spatial method is a method in which a small change in the screen pixel value is used as a watermark in terms of space, and it is easy to insert a watermark, but it is weak in image processing such as loss, compression, and filtering.

In addition, the frequency domain method converts digital data into analog signals of frequency components and converts and inserts watermarks through discrete cosine transform, Fourier transform, wavelet transform, or the like. This frequency domain method has the advantage that the inserted watermark coefficients are distributed over the entire area of the data, making it difficult to delete the inserted watermark, but there is a problem in that an image loss such as spots or distortions occurs depending on the coefficient value.

Lastly, the spread spectrum communication method in which the frequency domain method, which is recently studied, is applied is basically a method of converting and processing data into a frequency form. The spread spectrum communication method analyzes frequencies through discrete cosine transforms and then displays watermarks in N-high coefficients of the transform matrix, i.

The spread spectrum communication method is similar to the frequency domain method, but applies a CDMA technique that spreads the frequency of the watermark to be inserted into the original data. The spread spectrum communication method uses water for image processing such as lossy compression and filtering than the frequency domain method. Marking has a more powerful advantage, but there is a problem that it is not complete in the process of compressing data.

In addition, the digital watermarking has a disadvantage in that protection is possible only for file-level actions in common. Specifically, watermarking is a technique for planting digital markers on digital sound sources and identifying them when the files to which they are applied are distributed. The reality is that there is no way to maintain marking.

For example, re-shooting with digital cameras for image files, noise-free recordings with Speaker Out for music file play, and the like.

An object of the present invention for solving the above problems is to provide an analog watermark embedding and detection method of audio in which a watermark formed of an analog signal is inserted in a region outside the audible frequency band of the sound source content.

It is also an object of the present invention to provide an analog watermark insertion and detection method for audio in which an analog signal having a lower pitch and reproduction speed of a lower sounding marking sound source is mixed with a corresponding content.

An object as described above is an audio watermarking method, comprising: an analog watermark generating step of converting a watermark source composed of an analog signal of an audible frequency band into an analog watermark of an inaudible frequency band through a watermark generator; A mixing step of mixing the analog watermark with content original sound of an audible frequency band to generate audio content; Recording the audio content on a storage medium by a storage device; And a verification step of reproducing the audio content so as to confirm ownership of the audio content stored and distributed by the storing step.

According to the present invention, it is preferable to generate the analog watermark by slowing down the reproduction speed of the watermark original sound and lowering the pitch value in the analog watermark generating step.

In addition, according to the present invention, it is preferable that the audio content of the mixing step is recorded and generated on the recording apparatus by simultaneously playing the content original sound and the analog watermark.

In addition, according to the present invention, it is preferable that the analog watermark is engraved on the entire section of the content original sound.

According to the present invention, the audio content is preferably stored as analog data or the analog data is converted into digital data and stored.

In addition, according to the present invention, it is preferable that the verifying step reproduces the audio content at a high speed so that an analog watermark is heard in an audible frequency band.

Hereinafter, an analog watermark embedding and detection method of audio according to a preferred embodiment of the present invention will be described in detail with reference to FIGS. 2 to 7.

2 is a flowchart illustrating an analog watermark insertion and detection method of audio according to the present invention, and FIG. 3 is a diagram illustrating a three-dimensional frequency graph of a circular value of a watermark sound source.

FIG. 4 is a diagram illustrating a three-dimensional frequency graph obtained by modifying a pitch value and a playback speed of a marking sound source. FIG. 5 is a three-dimensional frequency of a content sound source applied to an analog watermark insertion and detection method of audio according to the present invention. It is a figure which shows a graph.

6 is a diagram illustrating a three-dimensional frequency graph in a mixing state of a content sound source and an analog watermark, and FIG. 7 illustrates a pitch value and a reproduction speed of a sound source in order to detect an analog watermark in the audio content of the present invention. It is a figure which shows the raised three-dimensional frequency graph.

Original sound, in a narrow sense, means that the frequencies generated by the sound waves stimulate the human auditory organs to cause hearing.

In order to semantically distinguish the original sound of the content to be described below and the original sound of the analog watermark, the original sound of the content to be applied is referred to as 'content original sound', and the original sound for generating the analog watermark is called 'watermark original sound'. Refer.

As shown in Figure 2, the audio watermark embedding and detection method of the audio of the present invention is subjected to the analog watermark generation step (S10) of the first step.

Unlike the existing digital watermark, the analog watermark is composed of an analog signal. The analog watermark is a signal in an inaudible frequency band outside the range of an audible frequency.

In this case, the audio frequency band refers to a frequency range in which a human ear can recognize sound, and the frequency range is 20 Hz to 20 KHz, but a range in which a sound can be actually recognized by an average person falls short of this range.

In addition, the inaudible frequency of the analog signal refers to a signal of a low frequency or a high frequency region outside the audible frequency region, which can be confirmed through a special volume equipment, but is a band that cannot be heard by a human ear.

Since the watermark original sound of the analog watermark is an analog signal, it does not distinguish whether it is a sound, a machine sound, or a natural sound. The message of the watermark original sound may be any content that the content provider or the owner can prove that it is owned.

For example, if the message "This is Bon Wave" that indicates that it is owned by Bon Wave Co., Ltd. comes out of a person's mouth or speaker, the sound at this time becomes the target of the original watermark sound.

The watermark original sound is converted into an analog watermark through a watermark generator.

The watermark generator uses a transformation method using a function relationship between sound reproduction speed and sound range, and the fact that the sound moves 343.4m per second at room temperature 20 ° C (Velocity: m / sec) generates a waveform of one cycle. L = V / F, which is the relationship between the frequency (Hz) and the playback speed when the length is regarded as L (Lambda).

Due to this mathematical relationship, one period of the waveform for each frequency range (Hz)

1) L (Wavelength) at 50Hz = 343.4 / 50 = 6.86m

2) L (Wavelength) at 100Hz = 343.4 / 100 = 3.43m

3) L (Wavelength) at 440Hz = 343.4 / 440 = 0.78m

4) L (Wavelength) at 20kHz = 343.3 / 20,000 = 0.017m

You can check with

By the above process it can be seen that the length (L) and the range (Hz) of the waveform is inversely related.

By applying this principle, the sound range of the original sound can be transformed below the audible frequency by modifying the waveform period of the watermark original sound.

By using the Time Stretching function of the professional audio mixing program, you can increase the total playing time of the original sound for watermarking and convert the waveform period and sound range of the original sound.

The watermark generator slows down the reproduction speed of the watermark original sound to 1 / n speed (when the original sound reproduction speed is 1) and lowers the pitch value to 1 / m to convert the signal into an inaudible frequency band.

The reproduction speed of the converted analog water mark is at least 1/256 times the speed, and the conversion value of the pitch is preferably converted to the same ratio of 1/256 or less.

As shown in FIG. 2, the three-dimensional frequency graph of the original value of the watermark original sound is distributed in the audio frequency band.

However, as shown in FIG. 3, when the watermark original sound is converted through the watermark generator, the frequency graph is distributed in a frequency band (red) which is impossible for a person to recognize as sound.

The analog watermark generated as described above is subjected to mixing step S20 with the original sound mixed with the content original sound.

The content source sound is an original sound composed of an analog signal or a digital signal, and includes audible frequency bands such as natural sound, AR (music with singer's voice), MR (accompaniment sound without singer's voice), effect sound, sample sound, and video sound. Includes all sound sources.

In the mixing method of the content original sound and the analog watermark, a waveform of an analog watermark is inserted into a previously produced content original sound and mixed by recording the same on a recording device.

The mixing method by inserting the analog watermark waveform into the original content of the content is mixed using a professional mixing program. A new waveform is generated by audio mixing the analog watermark and the original content, and the sound range of the analog watermark is an audible frequency. Since the following, a portion conflicting with the original content of the content can be avoided.

The professional mixing program performs track mixing by integrating a track of content original sound (Stereo or Mono) and a track of analog water marking (Mono) into one 2-channel track (Stereo).

At this time, if the playback time of the content original sound is n times the time of playing the analog watermark with a general player, the analog watermark is engraved to the beginning and end of the content original sound, which means that the entire content original sound can be protected by ownership. Becomes.

In addition, when the reproduction time of the content original sound is very long, analog watermarking may be repeatedly inserted, and analog watermarking may be engraved over the entire section of the content original sound.

In FIG. 5, the frequency graph of the content original sound is distributed between the audible frequency bands, and after mixing with an analog watermark in which frequencies are distributed in the inaudible frequency band of FIG. 4, as shown in the audio content of FIG. 6. The distribution of the content of the original sound is similar to the audible frequency band.

This proves that there is no interference of sound when the audio content is played due to the insertion of the analog watermark, and even when played with a general player, only the noise of the analog watermark is not heard at all or is easily heard by human hearing. I mean.

When the audio content in which the analog watermark is engraved in the content original sound is generated in the mixing step S20 as described above, the recording process is recorded on the CD, the cassette tape, or the like by the storage device, and is recorded on the recording. Audio content can also be encoded and stored in a file format.

These encoded digital files are shared among countless Internet users on the Internet, while analog audio content stored on CDs is copied by recorders, such as CD-Rs, stored on cassette tapes for playback or broadcast on the air. Audio content that is transmitted and played is recorded in another cassette through a connecting terminal and distributed without permission.

As described above, the audio content stored and distributed by the storage step S30 is subjected to a verification step S40 for confirming ownership of the owner.

The verification step (S40) is a step of confirming the owner's watermark by playing the audio content through the fast player.

At this time, if the listening speed is increased by n times and the pitch value is increased by m times through the high speed player, the watermark original sound is distributed in the audible frequency band as shown in FIG.

Therefore, when the audio content is played at n times, the content original sound is not heard, and the sound of the original watermark 'Bone Wave' is heard.

As described in detail above, the method for embedding and detecting analog watermarks of audio according to the present invention inserts a watermark formed of an analog signal in a region outside the audio frequency band of the sound source content, thereby providing the same content as the content, not the signal separated from the content. The signal is reproduced or operated, which can prevent illegal distribution and duplication of all sound source contents to be reproduced without modification or damage to the original sound.

In addition, an object of the present invention is to increase the pitch value and the playback speed after production by mixing an analog signal having dropped the pitch and the playback speed of a low-tone marking sound below the reference level with the corresponding content, thereby creating a hidden watermark sound source. Since it is possible to hear the original ownership of the watermark can not be altered and deleted, which can be a great opportunity to further enhance the creative motivation of the music creators can contribute significantly to the cultural industry.

Although the technical idea of the analog watermark embedding and detection method of the audio of the present invention has been described above with the accompanying drawings, this is by way of example and not by way of limitation of the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (6)

In the audio watermarking method, An analog watermark generation step (S10) of converting a watermark source composed of an analog signal of an audible frequency band into an analog watermark of an inaudible frequency band through a watermark generator; A mixing step (S20) of mixing the analog watermark with the content original sound of an audible frequency band to generate audio content; A recording step (S30) in which the audio content is recorded on a storage medium by a storage device; And a verification step (S40) of reproducing the audio content so as to confirm ownership of the audio content stored and distributed by the storing step (S30). The method of claim 1, And generating the analog watermark by lowering a reproduction speed and a pitch value of the watermark original sound in the analog watermark generation step (S10). The method of claim 1, The audio content of the mixing step (S20) is an analog watermark insertion and detection method for audio, characterized in that the waveform of the watermark is inserted into the original content by the audio mixing program. The method of claim 3, wherein And an analog watermark is engraved on all sections of the content original sound. The method of claim 1, And the audio content is stored as analog data or the analog data is converted into digital data and stored. The method of claim 1, The verification step (S40) is to reproduce the audio content at high speed so that the analog watermark is heard in the audio frequency band, characterized in that the analog watermark insertion and detection method of audio.

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