KR100208004B1 - Device and method for reproducing stereo audio using upper/lower channel audio signals - Google Patents

Abstract

The present invention relates to an apparatus and method for reproducing stereo sound using upper and lower channel audio. In an audio codec supporting 5.1 channels represented by AC-3, MPEG-2 audio, DTS, and the like, 5.1 channel audio data and upper and lower channel audio are provided. To identify the data, the encoding end adds different packet identifiers (PIDs) to the 5.1 channel audio data and the upper and lower channel audio data, respectively, and provides them as an audio bit stream. The upper and lower channels according to the present invention can reproduce the three-dimensional stereoscopic sound of 7.1 channels by retrieving the 5.1 channel audio data and the upper and lower channel audio data from the audio bit stream by retrieving an identifier (PID) and playing them through the respective audio decoders. According to the device and method for stereo sound reproduction using audio However, by adding two channels of upper and lower channel audio to the conventional 5.1 channel audio without fundamentally violating the syntax of the conventional audio bit stream supporting 5.1 channels, the 7.1 channel with excellent three-dimensional stereoscopic or realism Three-dimensional stereo sound can be provided.

Description

Apparatus and method for stereo sound reproduction using up-and-down channel audio.

The present invention relates to an apparatus and method for reproducing stereo sound using top and bottom channel audio, including two channels of left and right stereo channels, two channels of left and right surround channels, and a center of a single channel. By adding two channels of upper and lower channel audio to 5.1-channel audio consisting of a center channel and a low frequency enhancement channel, three-dimensional stereoscopic sound of 7.1 channels can be provided. The present invention relates to an apparatus and method for reproducing stereo sound using upper and lower channel audio.

As interest in multi-channel audio increases, a number of multi-channel audio formats are known that add an additional channel to two-channel left and right stereo sound, which is a typical channel configuration. The common feature is to have the flexibility and the expandability of the channel to quickly adapt to changes in the taste and listening environment of the listener while pursuing the advanced quality.

The multi-channel audio format according to the prior art has a method of separating and generating four channel signals from two channels of left and right stereo signals. In recent years, each audio channel is independently coded and transmitted and then decoded to decode each audio channel. Typical methods are to implement stereoscopic sound by outputting through a sound reproducing apparatus corresponding to the above.

As described above, the latter method, which has become a technical trend in the art, has the largest number of 5.1-channel audio including two left and right stereo channels, two left and right surround channels, a single channel center channel, and a low frequency enhancement channel. The representative audio CODECs that are being discussed are the MPEG-2 Audio (Moving Picture Experts Group) from Dolby's AC-3 (Audio Compression-3) and ISO / IEC JTC1 / SC29 / WG11 audio groups. -2 Audio) and Digital Theater System Technology's Digital Theater System (DTS).

Although the audio codecs supporting 5.1 channel audio directly related to the stereoscopic sound reproducing apparatus and method using the upper and lower channel audio according to the present invention are not compatible with each other, the overall concept is similar in terms of components or headers of each channel. In order to help the understanding of the present invention, the MPEG-2 audio, which is a representative audio codec that supports 5.1-channel audio, is roughly examined in order to facilitate understanding of the present invention. 2 A description of codecs other than audio will be substituted.

MPEG-2 audio is an audio coding method established in November 1994 by the ISO / IEC JTC1 / SC29 / WG11 audio group. It is a multi-channel audio system that realizes high quality stereo sound through left and right stereo sound, left and right surround sound and center sound. An audio coding method corresponding to channel audio.

MPEG-2 audio was drafted in November 1993 by the Committee Draft (CD), in March 1994 by the Draft International Standard (DIS), and in November 1994 by the International Standard (IS). Standard) is completed.

MPEG-2 audio is collectively known as the official standard number ISO / IEC 13818-3, and can be used for audio-video encoding in combination with MPEG-2 video, as well as digital audio broadcasting (DAB) alone. In addition, it is possible to create a wide range of services for high-quality multi-channel audio transmission, digital storage means, etc. by an Integrated Service Digital Network (ISDN).

In other words, the multi-channel audio system based on MPEG-2 audio includes CATV (CAble Television), CDAD (Cable Digital Audio Distribution), ENG (ENG) in addition to broadcasting fields such as satellite or terrestrial television broadcasting and digital audio broadcasting. Electronic News Gathering, Electronic Cinema (EC), InterPersonal Communication (IPC), Interactive Storage Media (ISM), Network DataBase service (NDB), Digital Storage Media (DSM), Home Television Theater (HTT), Integrated Service Digital Non-broadcasting media such as networks have various application areas.

MPEG-2 audio is an upgraded version of MPEG-1 audio that absorbs most of the MPEG-1 audio's ability to provide stereo sound. It supports a combination of audio input and output formats, provides multilingual function, and additionally provides a lower sampling frequency of 16 kHz, 22.05 kHz, and 24 kHz to the sampling frequency provided by MPEG-1 audio. to be.

It is clear that MPGE-2 audio shares the core algorithm with MPEG-1 audio as it supports backward compatibility. Accordingly, the main features of MPEG-1 audio shared with MPEG-2 audio will be briefly described below.

MPEG-1 audio is based on a masking-pattern universal subband integrated coding and multiplexing (MUSICAM) scheme based on subband coding. The MUSICAM system is a 16-bit uniform PCM using a subband coding scheme. Pulse Code Modulation data can be received and variably encoded from 64 kbps to 196 kbps per channel, using critical bands and masking effects, which are human hearing characteristics, according to performance and complexity. Three types of layers are defined and used.

The basic principle of the MUSICAM system is to increase the data compression efficiency by eliminating the components of the audio signal that are not perceived by the audio using human hearing characteristics.In the case of transform coding, the masking threshold is directly used by using coefficients. It is also possible to obtain a masking threshold, but in the case of subband coding, a detailed frequency analysis is required to obtain a masking threshold, so an additional fast Fourier transform (FFT) is used for the frequency characteristics of each subband. Find it.

Here, the masking threshold refers to a limit at which noise is masked by the original sound or lower than an audible limit, and thus cannot be heard. To obtain a masking threshold, the linear frequency domain must be converted to a nonlinear critical band. The masking threshold is obtained using the frequency spectrum changed in units of Bark.

The process of obtaining the masking threshold value is called psychoacoustic modeling process. If the amount of quantization noise is smaller than the masking threshold value, it is assumed that the noise is not recognized by the ear. The subband signals are encoded using Advanced Pulse Code Modulation (APCM).

In this way, MPEG-1 audio combines the concepts of subband coding and perceptual coding to achieve good sound quality even at high compression rates. Poor localization of sound source is not able to faithfully reproduce the realism, and there is a drawback that cannot provide additional services such as voice multicasting.

MPEG-2 audio is a standard that supports 5.1-channel audio by adding left and right surround channels and low-frequency enhancement channels in addition to two basic stereo channels, and basically compresses audio information in the same way as MPEG-1 audio. In order to effectively transmit the increased channel information at a lower data rate, various composite coding techniques are additionally adopted.

The 5.1 channel used in MPEG-2 audio can provide a realistic sense of reality while letting users feel the spatial stereoscopic feeling of an audio signal. In other words, directional stability can be achieved through the center channel, and vivid realism can be obtained through the left and right surround channels, so that the user can quickly cope with changes in the taste and listening environment of the listener and increase the sense of presence. Can effectively pursue the sound quality.

However, the 5.1-channel audio codec represented by AC-3, MPEG-2 audio, DTS, etc. is a two-dimensional stereo sound due to adopting a method of spatial configuration of the channel, that is, the arrangement of the channel in two dimensions. It provides excellent performance in terms of performance, but the three-dimensional stereoscopic or realism of spatial upper and lower audio, such as those generated from airplanes taking off and landing, or those from the upper and lower levels of a multi-story building. There is a fundamental problem inherent in reproducing a rather poor sound.

Accordingly, the present invention has been made to solve such a problem, and in order to reproduce a three-dimensional stereoscopic sound having a better sense of presence than the conventional 5.1-channel audio system, by adding two channels of upper and lower channel audio to the conventional 5.1-channel audio, An object of the present invention is to provide an apparatus and method for reproducing stereo sound using upper and lower channel audio capable of reproducing three-dimensional stereoscopic sound of 7.1 excellent channels.

1 is a block diagram showing a stereoscopic sound reproduction apparatus using the upper and lower channel audio according to the present invention;

2 is a flow chart of a stereoscopic sound reproduction method using the upper and lower channel audio according to the present invention.

〈Description of the symbols for the main parts of the drawings〉

100: audio code unit 110: packet identification unit

120: first audio decoder 130: second audio decoder

S210: Audio encoding step S220: Packet identification step

S230: first audio decoding step S240: second audio decoding step

In order to achieve the above object, an apparatus and method for reproducing stereo sound using up-and-down channel audio according to the present invention are provided in an audio codec in which up-and-down channel audio is added to 5.1-channel audio. If the audio coder adds different packet identifiers (PIDs) to the 5.1 channel audio data and the upper and lower channel audio data, respectively, to provide an audio bit stream, the audio decoder outputs the packets of the audio bit stream. By retrieving the identifier (PID), the 5.1 channel audio data and the upper and lower channel audio data are separated from the audio bit stream and reproduced through the respective audio decoders. Thus, the syntax of the conventional audio bit stream supporting the 5.1 channel is fundamental. In violation of If it is characterized standing to play a three-dimensional stereo sound in 7.1 channels.

Prior to describing the configuration and operation of the present invention in detail, a brief description of a method of producing a multi-channel audio signal is similar to the method of producing audio data in a studio or a recording studio, that is, recorded with multiple tracks in the field. In order to configure each channel using data, direct or indirect mixing between related channels is performed.

In order to clearly reproduce the spatial stereoscopic or realism through the estimation of the position of the sound source, it is very important to effectively arrange the microphone, and to relate the sound collected through the microphone to make the listener feel better than when listening to the actual sound. Artificial manipulations such as merging or subtracting sounds are applied. Currently, a technique for realizing such a realistic sound and a stereoscopic sound is known through various technical books, related papers, and patent publications.

A stereoscopic sound reproducing apparatus using upper and lower channel audio according to the present invention will be described with reference to FIG. 1.

1 is a block diagram showing an apparatus for reproducing stereo sound using up and down channel audio according to the present invention.

The stereoscopic audio reproducing apparatus using the upper and lower channel audio according to the present invention, in the audio codec supporting 5.1 channel audio, adds different packet identifiers (PIDs) to identify the upper and lower channel audio and the 5.1 channel audio. An audio encoder (not shown) for encoding an audio bit stream, and searching for the packet identifier from the audio bit stream including the 5.1 channel audio and the upper and lower channel audio, and separating the 5.1 channel audio and the upper and lower channel audio. The audio decoding unit 100 decodes and reproduces the 5.1 channel audio and the upper and lower channel audio.

The audio decoder 100 may search for a packet identifier (PID) from an audio bit stream including 5.1 channel audio data and upper and lower channel audio data, and then separate the 5.1 channel audio data and the upper and lower channel audio data. 110, a first audio decoder 120 coupled to the packet identification unit 110 to decode and reproduce the 5.1 channel audio data, and a packet identification unit 110 to connect the upper and lower channel audio data. And a second audio decoder 130 for decoding and reproducing.

Hereinafter, the operation of the stereoscopic sound reproducing apparatus using the upper and lower channel audio according to the present invention configured as described above will be described in detail with reference to FIG. 1.

First, if the audio decoder (not shown) adds different packet identifiers (PIDs) to the 5.1 channel audio data and the upper and lower channel audio data to identify the 5.1 channel audio data and the upper and lower channel audio data, and provide them as an audio bit stream. The packet identification unit 110 searches for a packet identifier (PID) from an audio bit stream including 5.1 channel audio data and upper and lower channel audio data, and separates the 5.1 channel data and the upper and lower channel audio data, respectively. And the second audio decoder 130.

The first audio decoder 120 and the second audio decoder 130 are coupled to the packet identification unit 110 to decode and reproduce 5.1 channel audio data and upper and lower channel audio data, respectively. Reproduce stereoscopic sound.

Here, the upper and lower channel audio data are upper channel audio data composed of sound data generated by a sound source located relatively upward in space with respect to a local point, and a lower channel composed of sound data generated by sound sources located relatively downward. It is composed of audio data. Like the left and right stereo channel and the left and right surround channel, the upper and lower channel audio is a channel in which upper and lower channels are merged independently.

In addition, 7.1-channel audio means an audio channel formed by adding two-channel upper and lower channel audio to 5.1-channel audio including two left and right stereo channels, two left and right surround channels, a single channel center channel, and a low frequency enhancement channel. Means.

Hereinafter, a stereoscopic sound reproduction method using up-and-down channel audio according to the present invention will be described with reference to FIG. 2.

2 is a flowchart of a stereoscopic sound reproduction method using upper and lower channel audio according to the present invention.

As shown in FIG. 2, in the audio codec supporting 5.1 channels, a stereoscopic audio reproduction method using different upper and lower channel audio according to the present invention uses different packet identifiers to identify 5.1 channel audio data and upper and lower channel audio data. An audio encoding step (S210) of adding a PID) to the 5.1 channel audio data and the upper and lower channel audio data, respectively, and providing the PID as an audio bit stream, and searching for a packet identifier (PID) in the audio bit stream. When the packet identification step (S220) for identifying audio data and the packet identifier (PID) indicating the 5.1-channel audio data are detected as a result of the identification of the packet identification step (S220), the 5.1-channel audio data is decoded and reproduced. The first audio decoding step (S230) and the identification result of the packet identification step (S220), the up and down When a packet identifier (PID) indicating the channel audio data is detected, a second audio decoding step S240 of decoding and playing the upper and lower channel audio data is performed.

The procedure of the stereoscopic sound reproduction method using the upper and lower channel audio according to the present invention configured as described above will be described in detail with reference to FIG. 2.

First, in order to identify the 5.1 channel audio data and the upper and lower channel audio data in the audio encoding step S210, a different packet identifier (PID) is added to the 5.1 channel audio data and the upper and lower channel audio data, respectively, and provided as an audio bit stream. In step S220, the packet identifier PID is searched for in the audio bit stream to identify 5.1 channel audio data and upper and lower channel audio data.

If a packet identifier (PID) indicating 5.1 channel audio data is detected as a result of the identification of the packet identifying step S220, the first audio decoding step S230 decodes and reproduces the 5.1 channel audio data, and the packet As a result of the identification in the identifying step S220, if a packet identifier indicating the upper and lower channel audio data is detected, the second audio decoding step S240 decodes and reproduces the upper and lower channel audio data.

In the stereoscopic audio reproduction apparatus and method using the upper and lower channel audio according to the present invention, decoding is independently performed by assigning a first audio decoder and a second audio decoder to decode and reproduce 5.1 channel audio and upper and lower channel audio, respectively. The purpose is to maintain compatibility with audio codecs that support 5.1 channels.

That is, in the simplest embodiment to which the present invention is applied, after specifying that the data to be encoded is 7.1 channel audio data on the header of the audio bit stream, the 5.1 bit audio data and the upper and lower channel audio data are merged to make the audio bit stream. Is provided to the decoder, the decoder confirms that the audio bit stream is 7.1-channel audio data and then decodes and reproduces it. However, in this case, the compatibility with 5.1-channel audio data is destroyed.

In addition, in the present invention, a packet identifier (PID) is provided to identify 5.1 channel audio data and upper and lower channel data. In the standard of MPEG-2 audio, which is a representative codec supporting 5.1 channels, a packet identifier indicating a packet type is used. depending on the bits that 13 bits are assigned to 8192 (i.e., 2 ¹³ = 8192) different from each other and the service identity for the other packets. Accordingly, by assigning a reserved PID, which is not currently used, as a packet identifier for identifying 5.1 channel audio data and upper and lower channel data, the 7.1 channel 3 is not fundamentally violated. Can reproduce dimensional stereo sound.

The present invention can be applied to a 5.1-channel audio codec represented by AC-3, MPEG-2 audio, DTS, etc., and in the description of the present invention in the detailed description of the present invention, it is attributed to the fact that MPEG-2 audio is added as a reference. Therefore, it is obvious that the scope of the present invention is not limited to the MPEG-2 TS scheme.

As described in detail above, in an audio codec supporting 5.1 channels, the encoder determines different packet identifiers (PIDs) for the 5.1 channel audio data and the upper and lower channel audio data so as to identify the 5.1 channel audio data and the upper and lower channel audio data. ) Is added to provide an audio bit stream, and the decoding end separates 5.1 channel audio data and upper and lower channel audio data from the audio bit stream by searching for a packet identifier (PID) of the audio bit stream. According to the apparatus and method for reproducing stereoscopic audio using upper and lower channel audio according to the present invention capable of reproducing 7.1-channel three-dimensional stereophonic sound by reproducing through each audio decoding unit, the syntax of a conventional audio bit stream supporting 5.1 channel is provided. fundamentally above (syntax) By adding two channels of upper and lower channel audio to the conventional 5.1 channel audio, it is possible to provide 7.1-channel three-dimensional stereo sound with excellent three-dimensional stereoscopic or realism.

Claims (5)

For a 5.1 channel audio CODEC that supports 5.1 channel audio, including at least one left and right stereo channel, left and right surround channel, a center channel, and a low frequency enhancement channel: Upper and lower channel audio and at least one upper channel audio generated by a sound source located relatively upward in space and at least one lower channel audio generated by a sound source located relatively downward and the 5.1 channel audio An audio encoder which adds different packet identifiers (PIDs) to encode the audio bit streams to identify the audio bit streams; And Searching for the packet identifier from an audio bit stream including the 5.1 channel audio and the upper and lower channel audio, separating the 5.1 channel audio and the upper and lower channel audio, and decoding and playing the 5.1 channel audio and the upper and lower channel audio. Stereo reproduction apparatus using the upper and lower channel audio, characterized in that it comprises an audio decoder. The audio decoding unit of claim 1, A packet identification unit for retrieving a packet identifier from the audio bit stream and separating the 5.1 channel audio and the upper and lower channel audio; A first audio decoder coupled to the packet identification unit to decode and reproduce the 5.1 channel audio; And And a second audio decoder coupled to the packet identification unit to decode and reproduce the upper and lower channel audio. The method of claim 1, wherein the 5.1-channel audio codec is any one of AC-3 (Audio Compression-3), MPEG-2 audio (Moving Picture Experts Group-2 Audio), DTS (Digital Theater System) Stereo playback device using up-and-down channel audio. For a 5.1 channel audio CODEC that supports 5.1 channel audio, including at least one left and right stereo channel, left and right surround channel, a center channel, and a low frequency enhancement channel: Upper and lower channel audio and at least one upper channel audio generated by a sound source located relatively upward in space and at least one lower channel audio generated by a sound source located relatively downward and the 5.1 channel audio Encoding an audio bit stream by adding different packet identifiers (PIDs) to identify a PDU; Identifying a packet identifier in the audio bit stream to identify the 5.1 channel audio and the upper and lower channel audio; A first audio decoding step of decoding and reproducing the 5.1 channel audio when the packet identifier indicating the 5.1 channel audio is detected as a result of the identification of the packet identifying step; And And a second audio decoding step of decoding and reproducing the upper and lower channel audio when the packet identifier indicating the upper and lower channel audio is detected as a result of the identification of the packet identification step. How to play. The method of claim 4, wherein the 5.1-channel audio codec is any one of AC-3 (Audio Compression-3), MPEG-2 Audio (Moving Picture Experts Group-2 Audio), and Digital Theater System (DTS). Stereo playback method using up-and-down channel audio.