KR100598602B1 - virtual sound generating system and method thereof - Google Patents

Abstract

The present invention relates to a virtual stereo sound generating apparatus and a method thereof.

In the present invention, a multichannel stereophonic signal is converted into a two channel virtual stereophonic signal. For example, a multi-channel stereo sound signal including 5.1 channels is converted into two channels of virtual stereo signals using a head-related transfer function (HRTF), and then two channels using an audio encoder. Generate an encoded virtual stereophonic signal of. As such, the generated two-channel virtual stereo signal is transmitted to a playback device such as a personal computer, a mobile terminal (cell phone, PDA, etc.) through online or offline, and reproduced in virtual stereo sound through two channels of headphones or speakers. do.

According to the present invention, the playback apparatus decodes the encoded multichannel audio signal and decodes the two-channel virtual stereophonic audio signal to reproduce the virtual stereophonic sound with headphones or speakers without decoding the two-channel virtual stereophonic sound. Can be.

Stereo sound, Virtual stereo sound, Audio, HRTF, Head transfer function

Description

Virtual sound generating system and method thereof

1 is a block diagram showing a standard playback position of a 5-channel audio source.

2 is a block diagram of an apparatus for generating a virtual stereophonic sound according to an embodiment of the present invention.

3 is a block structure diagram of a virtual stereophonic sound according to an embodiment of the present invention.

4 is a block diagram of a convolution unit of a virtual stereophonic sound system according to an exemplary embodiment of the present invention.

5 is a diagram showing a practical example of actually applying the virtual stereo sound generating apparatus according to an embodiment of the present invention.

The present invention relates to the generation and reproduction of virtual stereo sound, and more particularly, to a virtual stereo sound generating apparatus and method for reproducing virtual stereo sound through an existing media player.

With the development of storage media and audio encoding technology, various media and audio systems have emerged that provide multi-channel stereophonic sound from conventional mono sound and two-dimensional stereo sound. Dual, Dolby AC-3 surround stereophonic systems include center, front left (left), front light (right), rear left (left stereo), rear light (right stereo). And a 5.1-channel sound data consisting of five speakers and one woofer is outputted by adding a subwoofer in the center of the bass. The encoded AC-3 data can be reproduced in mono, stereo, Dolby matrix, and digital surround of 5 or 5.1 channels, depending on each decoding method. Current AC-3 recordings have become commonplace in movies, and American HDTVs and DVDs also use AC-3 recordings.

DTS stands for Digital Theater Systems and is the name of the multichannel surround encoding technology used in film and music developed in 1993. DTS has a high and flexible compression algorithm that can be quantized at 192kHz and 24bit at the maximum sampling frequency, which is more complete than linear PCM (44.1kHz, 16bit) coding, which is a compact disc recording method. The original sound can be played close to.

DVD, which is becoming popular as a representative medium that provides multi-channel stereo sound, is compressing multi-channel sound signals using PCM, Dolby AC-3, MPEG audio, etc., and recently, titles compressed by DTS are gradually increasing. to be. In addition, with the spread of home theater system, general homes can experience the three-dimensional sound full of cinema-like tension.

Recently, high-speed Internet and mobile communication terminals are widely used by the general public, and multimedia services such as audio on demand and video on demand, including broadcasting services through the Internet and wireless networks, have been introduced. It is becoming popular and a service providing 3D stereoscopic image and sound has been attempted.

The multi-channel sound system, which is getting more attention from the general public, needs as many speakers as the number of channels, which causes installation costs and space problems. In order to solve this problem, many researches have been conducted on the method of converting multi-channel stereoscopic sound into two-channel virtual stereophonic sound and then reproducing it with existing two-channel headphones and speakers. A representative method of converting multi-channel stereoscopic sound into two-channel virtual stereophonic sound is to phase-define using a head related transfer function (HRTF). It feels as if you are listening to a real multichannel speaker. At this time, the playback by the headphone has a problem that the sound source stays in the head, and the sound field control technology is used to solve this problem.

Korean Patent Registration No. 1002737790000, "A device and method for converting 5-channel audio data into two channels and reproducing them with headphones," is known as a technology for making multichannel stereophonic sounds using head transfer functions into two-channel virtual stereophonic sounds. It is. This technology converts the reproduced 5-channel audio data into 2-channel audio data using the head transfer function, and time-multiplexes the head transfer functions corresponding to 5 ° to 10 ° instead of 0 ° for the center channel. Method, and the remaining channels apply the head transfer function of the standard playback position of the sound source. In addition, the above technique requires a separate device for reproducing 5-channel stereophonic sound in order to reproduce 5-channel stereophonic sound and then convert it into 2-channel audio sound.

In addition to the method using the head transfer function, Korean Patent Application No. 1020000082050, "Stereo sound reproduction apparatus and method thereof" is known. This technology consists of a detector for determining the type of stereophonic sound processing, a cross talk processing unit, and the like, and outputs decoded data as it is, or after crosstalk removal or reverse crosstalk removal, thereby saving resources and playing back. Reduce the load on the player. However, this technique also requires a separate device or software to listen to the reproduced audio sound.

On the other hand, in the case of sound image positioning using a Head Related Transfer Function (HRTF) according to the prior art, a separate means for generating stereo sound is required. The head transfer function refers to the recognition characteristic that humans recognize a sound source existing at a point in space, and it is a filter coefficient modeling a path transmitted from the sound source to the eardrum of the right ear and the left ear and has different properties according to the relative positional relationship with the head. . Therefore, in order for a listener to reproduce two-channel virtual stereophonic sound with headphones or a speaker, a separate device or software is required to generate two-channel virtual stereophonic sound by performing signal processing such as stereophonic stereotype and sound field control. There is a problem.

The technical problem to be achieved by the present invention is to enable to reproduce the virtual stereo sound using an existing audio playback device without additional devices or software.

In addition, another technical problem to be achieved by the present invention is to provide a virtual stereo sound generating apparatus and method that can easily convert a multi-channel stereo signal to a two-channel stereo signal.

According to an aspect of the present invention, there is provided a virtual stereo sound generating apparatus comprising: a head transfer function DB storing left and right head transfer functions modeling a path through which a signal is transmitted from a sound source; A sound constellation unit for convolving the respective monochannel sound sources of the plurality of input channels and the left and right head transfer functions stored in the head transfer function DB; A channel generator configured to channel the sound sources output from the sound stereotactic unit into a first channel and a second channel to generate virtual stereophonic signals of the first and second channels, respectively; And an audio encoder for encoding the virtual stereophonic signals of the first and second channels.

The channel generator may include: a first channel generator configured to synthesize a virtual stereophonic signal of a first channel by synthesizing the left sound sources convolved with the left head transfer function among the sound sources output from the sound image positioning unit; A second channel generator may generate a virtual stereophonic signal of a second channel by synthesizing the right head transfer function convolved with the right head transfer function among the sound sources output from the sound image positioning unit.

The apparatus for generating a virtual stereophonic sound may further include a mono signal input unit for separating the audio signals of the plurality of channels into respective monochannel sound sources, and providing the separated monochannel sound sources to the sound phase alignment.

The apparatus may further include a first reverberator generating initial reverberation in each sound source of a plurality of channels including a low frequency effect (LFE) channel sound source, and a second reverberator generating late reverberation in each sound source of the plurality of channels. can do. In this case, the channel generator may channel the signals output from the first reverberator and the second reverberator and the signals of the sound sources output from the sound image localization unit into the first channel and the second channel, respectively. Each virtual stereo sound signal is generated.

According to another aspect of the present invention, there is provided a method for generating a virtual stereophonic sound, wherein a signal provided from a plurality of channels of sound is generated as a virtual stereophonic sound of two channels. Separating and confronting the left and right head transfer functions modeling the separated monochannel sound sources and the paths through which signals are transmitted from the sound sources; b) channeling the sound sources for sound estimation into a first channel and a second channel to generate virtual stereophonic signals of first and second channels, respectively; And c) encoding the virtual stereophonic signals of the first and second channels.

Here, the step b) comprises the steps of synthesizing the left sound source convolved with the left head transfer function of the sound stereophonic sound source to generate a virtual stereophonic signal of the first channel; And generating a virtual stereophonic signal of a second channel by synthesizing the right head transfer function convolved with the right head transfer function among the sound-delayed sound sources.

On the other hand, step b) may further include generating an initial reverberation in each sound source of a plurality of channels including the LFE channel sound source, and additionally synthesize the generated initial reverberation when synthesizing the left and right sound sources. . In addition, the step b) may further include generating late reverberations in the sound sources of the plurality of channels, respectively, and additionally synthesizing the generated late reverberations when synthesizing the left and right sources.

In addition, the method may further include reproducing the virtual stereophonic signals of the encoded first and second channels, and the reproducing may include a decoder for decoding the virtual stereophonic signals of the encoded first and second channels. It is made in the containing terminal.

According to still another aspect of the present invention, a recording medium includes: a) a left and right head modeling a plurality of channel audio signals into respective monochannel sound sources, and modeling the paths through which the signal is transmitted from each of the separated monochannel sound sources and sound sources; Convolution of the transfer function to stereophonic; b) channeling the sound sources for sound estimation into a first channel and a second channel to generate virtual stereophonic signals of first and second channels, respectively; And c) a computer-readable recording medium having recorded thereon a program capable of executing the step of encoding the virtual stereophonic signals of the first and second channels.

In the present invention having such a feature, the plurality of channels may be five channels including center, left, right, left stereo, and right stereo channels.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In general, the ideal condition of each sound source when playing and listening to 5-channel audio data is shown in FIG. 1. 1 is a structural diagram showing a standard playback position of a 5-channel audio source recommended by the ITU International Committee.

As shown in FIG. 1, an ideal condition for a 5-channel sound source is that the left sound source L is located at an angle of 30 ° to the left of the listener (located at the center of the circle), and the right sound source R is to the right of the listener. The left stereo sound source (LS) is located at the left 110 ° angle around the listener, the right stereo sound source (RS) is located at the right 110 ° angle around the listener. The sound source C of the center channel is located at 0 ° directly in front of the listener. In this case, the ideal condition means a condition in which the stereoscopic sound can be best sensed by the 5-channel sound source from the listener's point of view.

The present invention provides a virtual stereo sound generating apparatus using ideal conditions for the 5-channel sound source recommended by the ITU International Committee. 2 illustrates a structure of an apparatus for generating a virtual stereophonic sound according to an embodiment of the present invention.

As shown in FIG. 2, the apparatus for generating a virtual stereophonic sound 100 includes a virtual stereophonic sound 110 and an audio encoder 120. The virtual stereophonic sounder 110 converts an audio signal of a plurality of channels (5.1 channel is used in this embodiment as an example, but is not limited thereto) to two-channel virtual stereophonic sound, and the audio encoder 120 converts the virtual stereophonic sounder. The virtual stereo sound converted by 110 is encoded and output.

 The virtual stereophonic sound 110 is configured as shown in FIG. 3 to convert the 5.1-channel audio signal into two-channel virtual stereophonic sound. 3 is a structural diagram of a virtual stereophonic sound according to an embodiment of the present invention.

As shown in FIG. 3, the virtual stereophonic sound receiver 110 includes an HRTF (head transfer function) DB 111, a convolution unit 112, and a mono input signal unit 113.

The HRTF DB 111 stores left and right head transfer functions calculated by modeling the positions of the ideal 5-channel sound source shown in FIG.

The mono input signal unit 113 separates the input 5.1 sound sources for each channel and provides the convolution unit 112 with a sound source of one channel, that is, a mono channel. The convolution unit 112 determines which of 5.1 channels the mono sound source input from the mono input signal unit 113 is, and then the left and right head transfer function pairs provided by the HRTF DB 111 to the mono sound source. Convolve When the mono sound source is convolved with the left and right head transfer function pairs, the mono sound source is sound-positioned to the position of the ideal sound source for the left and right sides.

When the convolution unit 112 phase-aligns the sound sources of 5 channels except the LFE channel among the 5.1 channels to an ideal position, the left channel is made by collecting the 5 channel sources convolved with the left head transfer function among the sound sources, and the right head is transferred. It collects the sound sources of 5 channels convolved with the function and makes them into the right channel.

The operation of the convolution unit 112 described above will be readily understood through FIG. 4 showing the detailed configuration of the convolution unit 112. 4 is a block diagram of a convolution unit of a virtual stereophonic sound system according to an exemplary embodiment of the present invention.

As shown in FIG. 4, the convolution unit 112 transmits five channel sound sources C, FR, FL, RR, and RL input from the mono input signal unit 113 to the left and right head transfer functions of the HRTF DB 111. Each sound source of multiple channels (5.1 channels) including five sound stereo phases 112a to 112e for stereotactic positioning in pairs, and a Low Frequency Effect (LFE) channel, which is 0.1 channel occupying about 1/10 the bandwidth of other channels. A first reverberant 112f for generating reverberation in the second channel; a second reverberator 112g for generating late reverberation in the sound source of the 5.1-channel; five sound stereotactic parts 112a to 112e; Convolutional results of the left and right head transfer functions output from the reverberators 112f and 112g collect the first and second channel generators 112h and 112i into the left and right channels according to respective directions. Include. The output generated by the first and second channel generators 112h and 112i is virtual stereophonic sound.

The mono sound source convolved by the left and right head transfer functions has directivity and synaesthesia is given by the early and late reverberators. The first and second channel generators 112h and 112i output the generated left and right channel sound sources to the audio encoder 120.

The audio encoder 120 stores the Dolby AC-3 and MPEG-2 AAC (Dolby AC-3 and MPEG-2 AAC) to easily store two-channel virtual stereophonic signals generated by the first and second channel generators 112h and 112i and to reduce the transmission load. Advanced Audio Coding), MPEG-4 AAC, etc. are encoded and compressed into digital data.

Hereinafter, an example of practical use of the two-channel virtual stereo sound generated by the apparatus of the present invention will be described with reference to FIG. 5 is a view showing a practical example of applying the virtual stereo sound generating apparatus according to an embodiment of the present invention.

According to the present invention, since the multi-channel audio signal can be made into digital compressed data for two-channel virtual stereophonic sound, the producer can use the virtual stereophonic sound generating apparatus according to an embodiment of the present invention for a plurality of multichannel audio. The song is converted into virtual stereophonic contents C1 to Cn, respectively, and the virtual stereophonic contents C1 to Cn are stored in a remote audio server 200 (or a storage medium). Alternatively, the audio server 200 may include a virtual stereo sound generating device.

The audio server 200 is built in a network-enabled environment, so that the user can access the corresponding stereo sound contents C1 to Cn stored in the audio server 200 using an internet network or a wireless network. That is, it can be downloaded to a client 300 such as a computer or a mobile communication terminal or a PDA.

Here, the terminal 300 of the user has a built-in audio decoder 310 that can decode the data encoded by the audio encoder 120 of the virtual stereo sound generating apparatus 100, from the audio server 200 The downloaded virtual stereo sound content is decoded and reproduced as two channel data. The two-channel data decoded in this manner is reproduced through a speaker (headphone or the like).

As a result, according to the present invention, a multi-channel audio signal is converted into a general two-channel signal and a general digital compressed data format that can be stored in a storage medium, so that a user can easily listen to the multi-channel audio signal through a mobile phone, headphones or a computer. To be able.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, according to the present invention, the virtual stereo sound can be reproduced using an existing audio reproducing apparatus without any additional device or software.

In addition, a stereoscopic sound reproduction effect can be obtained with a data amount corresponding to two audio signals.

In addition, by converting a signal of a plurality of channels to two channels to be transmitted to the user terminal, it is possible to reduce the capacity and transmission traffic of the storage medium.

Claims (14)

In the virtual stereo sound generating apparatus for processing a sound source of a plurality of channels to provide a sound reproduction device, A virtual stereo sounder which processes a sound source of each mono channel of the plurality of input channels and outputs the virtual stereo sound signal of the first and second channels; And An audio encoder which encodes the virtual stereophonic signals of the first and second channels and outputs them to the sound reproduction autonomy Including; The virtual stereo sounder A head transfer function DB for storing left and right head transfer functions modeling a path from which a signal is transmitted from a sound source; A sound image convolution unit for convolving the left and right head transfer functions stored in the head transfer function DB with each sound source of the input multiple channels; And A channel generation unit for generating virtual stereo sound signals of the first and second channels by channeling the sound sources output from the sound image positioning unit into a first channel and a second channel, respectively. Virtual stereo sound generating device comprising a. The method of claim 1 The channel generator A first channel generator configured to synthesize a virtual stereophonic signal of a first channel by synthesizing the left sound source convolved with the left head transfer function among the sound sources output from the sound phase alignment unit; And A second channel generator configured to synthesize a virtual stereophonic signal of a second channel by synthesizing the right head transfer function convolved with the right head transfer function among the sound sources output from the sound image positioning unit; Virtual stereo sound generating device comprising a. The method of claim 1 And a mono signal input unit for separating the plurality of channels of audio signals into respective mono channel sound sources and providing the separated mono channel sound sources to the sound stereoposition. The method of claim 1 And a first reverberator configured to generate initial reverberation in each of a plurality of sound sources including a low frequency effect (LFE) channel. The method of claim 4, wherein And a second reverberator configured to generate late reverberations in the sound sources of the plurality of channels, respectively. The method according to claim 4 or 5 The channel generator Generating the virtual stereophonic signals of the first and second channels by channeling the signals output from the first and second reverberators and the signals of the sound sources output from the sound localization to the first and second channels, respectively. Virtual stereo sound generating device. The method of claim 1 And the audio encoder encodes the virtual stereophonic signals of the first and second channels into one of Dolby AC-3, MPEG-2 Advanced Audio Coding (AAC), and MPEG-4 AAC. The method of claim 1 And the audio encoder compresses the encoded virtual stereophonic signal. The method of claim 1 And the plurality of channels are five channels including center, left, right, left stereo, and right stereo channels. Claims [1] A method for processing an audio signal provided from sound sources of multiple channels and providing the same to a sound reproducing apparatus. a) separating audio signals of a plurality of channels into respective monochannel sound sources and convoluting each of the separated monochannel sound sources with left and right head transfer functions modeling a path from which the signal is transmitted; b) channeling the sound sources for sound estimation into a first channel and a second channel to generate virtual stereophonic signals of first and second channels, respectively; And c) encoding virtual stereo sound signals of the first and second channels and outputting the encoded stereoscopic sound signals to the sound reproducing apparatus; Virtual stereo sound generation method comprising a. The method of claim 10 Step b) Generating a virtual stereophonic signal of a first channel by synthesizing the left head transfer function convolved with the left head transfer function among the sound localized sound sources; Generating a virtual stereophonic signal of a second channel by synthesizing the right head transfer function convolved with the right head transfer function among the sound displaced sound sources; Virtual stereo sound generation method comprising a. The method of claim 11, The step a) further comprises the step of generating the initial reverberation to each of the sound sources of the plurality of channels including the LFE channel, and additionally synthesize the generated initial reverberation during synthesis of the left and right sound sources. The method of claim 12, The step b) further comprises the step of generating late reverberation in the sound source of the plurality of channels, respectively, and further synthesized during synthesis of the left and right sound sources. The method of claim 10 Reproducing the virtual stereophonic signals of the encoded first and second channels; And the reproducing step is performed in the sound reproducing apparatus including a decoder which decodes the encoded virtual stereophonic signals of the first and second channels.

Images