CN100588288C - Signal processing method for dual-channel stereo signal stimulant 5.1 channel surround sound - Google Patents

Abstract

The invention discloses a signal processing method to simulate 5.1 channel surround sound with dual-channel stereo. Wherein, inputting original dual-channel left and right stereo signal L0 and R0 to generate front three-channel signal L, R and C for 5.1 channel surround sound to extract environmental acoustics information S; delaying, bandpass filtering, random delaying to six sub-band, and obtaining a couple of surround sound signal LS and RS to feedback to 5.1 channel surround sound system for retransmission to generate dual-ear acoustic pressure with low correlatively on listener ears and well, natural subjective surround feeling. This invention is simple and feasible.

Description

The binary channel stereophonic signal is simulated the signal processing method of 5.1 path surround sounds

Technical field

The present invention relates to stereo and the surround sound technical field, especially relate to a kind of signal processing method from binary channel stereophonic program signal imitation 5.1 path surround sounds.

Background technology

Present 5.1 transit systems have been proposed as the international standard of surround sound, and have been widely used in sound reproductions such as DVD, home theater.It adopts a left side, the place ahead L, middle C, right R and a left side around LS, right around RS totally five independently full range band path and loud speakers, adds one tunnel selectable low-frequency effect path LFE.With the stereo comparison of common double path, 5.1 path surround sounds add a center loudspeaker forwardly, can reach the stability of improving the place ahead acoustic image, enlarge the purpose of listening area; And two around path except certain side direction and rear sound picture is provided, the prior environmental acoustics information (the subjective sensation of surrounding) that provides.

Though 5.1 paths are around stereo the having greatly improved of the more traditional binary channel of sound reproduction effect, 5.1 path surround sounds need to be specially its sound programme source of recording.Although the existing now 5.1 path surround sound recorded programs that aim in a large number, but originally recorded for the common double path is stereo in existing many sound programmes source, these binary channel stereophonic programs have very important art and historical value, and they can not be rerecorded.If they are directly retransmitted on 5.1 path surround sound equipment, have then wasted the resource of hardware device.Therefore existing binary channel stereophonic program source being converted to 5.1 path surround sound programs is the problems that realistic meaning is arranged very much.

Binary channel stereophonic program source is converted to 5.1 path surround sound programs can carry out in the program making stage, also can carry out in the sound reproduction stage.Common binary channel stereophonic signal includes the locating information of the acoustic image (as musical instrument) in the place ahead, and is mixed with the spatial information of ambient sound (as reflected sound) simultaneously.

Existing the binary channel stereophonic signal is converted to the switch technology of 5.1 path surround sound signals and studied the seventies in last century the binary channel stereophonic program is converted in the technology of quad program, simulating around the environmental acoustics information signal of path normally has following several method:

1) utilizes the method for artificial reverberation to produce environmental acoustics information, bring spatial hearing impression in the environmental acoustics of " the artificial generation " to attentive listener.But this method may make virtual environmental information of coming out not conform to actual recording condition, and may be subjected to the audition environmental impact.

2) consider in the original binary channel stereophonic signal the poor (S=L of left and right path signal ₀-R ₀) contain more environmental acoustics information, can be used as signal around path.But surround sensation in order to obtain good subjectivity, and do not influence the acoustic image location in the place ahead, need the signal around path be further processed.

3) method of researching and proposing employing Adaptive Signal Processing and Blind Signal Separation is arranged,, get the less part signal of correlation as the environmental acoustics information signal by calculating original binary channel correlation between signals.The effect of these class methods is better, but algorithm is comparatively complicated.

Summary of the invention

Purpose of the present invention is exactly the defective that exists in the above-mentioned prior art for solving, and a kind of signal processing method from binary channel stereophonic program signal imitation 5.1 path surround sounds is provided.The signal processing of this method is comparatively simple, can obtain good subjective Sensurround in repeating transmission.

Purpose of the present invention is achieved through the following technical solutions:

A kind of signal processing method from binary channel stereophonic program signal imitation 5.1 path surround sounds comprises the steps:

The first step: import the left and right stereo frequency-region signal L of original binary channel ₀, R ₀

Second step: to the left and right stereophonic signal L of original binary channel of first step input ₀, R ₀Handle, produce the place ahead three path signal L, R, the C of 5.1 path surround sounds;

The 3rd step: the extraction of environmental acoustics information signal; With the left and right stereophonic signal L of original binary channel ₀, R ₀Poor (L ₀-R ₀) through the bandpass filtering treatment of 100Hz to 2000Hz, decay following low frequency of 100Hz and the above high-frequency signal composition of 2000Hz obtain signal S _B=(L ₀-R ₀) Band (ω), then to signal S _BCarry out the delay process of 20ms, obtain representing the signal S of environmental acoustics information _WBandpass filtering treatment is with L ₀, R ₀Poor (L ₀-R ₀) difference signal and the impulse response convolution of band pass filter;

The 4th step: the decorrelation of environmental acoustics information signal is handled; With resulting S of the 3rd step _WSignal is respectively the high pass filter of 500Hz, 1000Hz, 2000Hz, 4000Hz octave band pass filter, 5600Hz respectively through low pass filter, the centre frequency of 355Hz, be decomposed into the signal S of six subbands ₁, S ₂, S ₃, S ₄, S ₅, S ₆Respectively described six subband signals are carried out the random delay processing of 0-15ms scope, each subband signal is decomposed into a pair of signal that different random is delayed time, comprise (S _1L, S _1R), (S _2L, S _2R), (S _3L, S _3R), (S _4L, S _4R), (S _5L, S _5R), (S _6L, S _6R) six pairs of signals; Again respectively with S _1L, S _2L, S _3L, S _4L, S _5L, S _6LSignal mixing addition is with S _1R, S _2R, S _3R, S _4R, S _5R, S _6RSignal mixing addition obtains a pair of decorrelation surround sound signal LS and RS, and the left and right circulating loudspeaker of feeding is respectively retransmitted.

Described second step produces the place ahead three path signal L of 5.1 path surround sounds, the method for R, C is a prior art, comprises Xu Yong, thanks the out-of-bounds stereo processing method of spinach sweet-smelling grass proposition, the virtual acoustic processing method of proposition of J.Bauck etc.

Principle of the present invention:

Difference S=(the L of the left and right stereophonic signal of original binary channel ₀-R ₀) containing more Ambient acoustic intelligence, can extract as surround sound signal.But because S=(L ₀-R ₀) the high frequency composition of signal is more, utilize adjustable bandpass filtering to carry out certain decay, thereby obtain the environmental acoustics signal S of nature acoustically high frequency (and extremely low frequency) signal _BAnd, utilize precedence effect, to environmental acoustics signal S for the effect of the acoustic image location that do not influence the place ahead _BCarry out about 20ms time-delay (in actual applications, be made as adjustable) and obtain S _WWith S _WBe divided into the signal of six subbands with band pass filter after, carrying out different random delays by the signal to each subband handles, and the signal after will handling mixes, can obtain two-way correlation low surround sound signal LS, RS, their feed a pair of loud speakers are retransmitted, can produce the low ears acoustic pressure of correlation at attentive listener ears place, surround sensation, reach the purpose of simulation surround sound thereby produce good subjectivity.

The present invention compared with prior art has following advantage and beneficial effect:

(1) the present invention is to after handling from the binary channel stereophonic signal of CD etc., be converted to 5.1 path surround sound signals, and, reach the purpose that the binary channel stereophonic signal is converted to 5.1 surround sound signals with five full range speakers (adding a selectable low-frequency effect loud speaker repeating transmission).

(2) the present invention extracts the Ambient acoustical signal from original binary channel stereophonic signal, and adopts the method for subband random delay to produce the low surround sound signal of two-way correlation.This method signal processing simple possible, and can produce good, natural subjective Sensurround effect.

(3) the present invention can adopt general dsp hardware circuit or special-purpose integrated circuit to realize, also can adopt the software of algorithmic language (as VC++) establishment to realize on multimedia computer.

(4) the present invention can be used as the making (as the DVD CD) that software is used for surround sound music program source.Also can be used as special hardware circuit and be used in the sound reproduction of aspects such as family expenses electroacoustics system, TV (comprising DTV and HDTV), home theater.

Description of drawings

Fig. 1 is the principle calcspar that the binary channel stereophonic signal is converted to 5.1 path surround sound signals.

Fig. 2 is the block diagram of the present invention around the path signal handling principle

Fig. 3 is band pass filter amplitude-frequency characteristic figure

Fig. 4 is an equivalent time domain signal processing calcspar of the present invention

Fig. 5 presses schematic diagram around the ears that path produces

Fig. 6 is the signal processing flow figure of software implementation of the present invention

Embodiment

The invention will be further described below in conjunction with embodiment and accompanying drawing, but the scope of protection of present invention is not limited to the described scope of embodiment.

Fig. 1 is the functional-block diagram that the binary channel stereophonic signal is converted to 5.1 path surround sound signals.As shown in Figure 1, the binary channel stereophonic signal being converted to 5.1 path surround sound signal key problem in technology mainly comprises:

(1) generation of the place ahead three path signals (L, C, R)

Because what the place ahead mainly contained is the acoustic image locating information, thereby the stereosonic locating information of binary channel need be preserved, and is converted to the signal repetition of the place ahead three paths, promptly original binary channel stereophonic signal L ₀And R ₀, left path signal L, preceding right path signal R and center channel signal C before being converted to, utilize again be arranged in dead ahead (0 °) and about three loud speakers in left, center, right of 30 ° retransmit.It is constant that signal after the conversion must guarantee to listen attentively at the center acoustic image location of position, and can enlarge listening area.Proposed the method for several generations the place ahead three path signals in the world, just can reach comparatively ideal effect as the method for the virtual sound of the proposition of J.Bauck.

(2) around the simulation of path signal (LS, RS)

5.1 the two-way of path surround sound mainly is to retransmit environmental acoustics information around path.Thereby the binary channel stereophonic signal is converted to 5.1 path surround sound signals the environmental acoustics information of binary channel stereophonic signal need be extracted, and do suitably to handle, to obtain to be fit to two recurrent signals (LS, RS) around path.Its objective is the subjective Sensurround acoustically of increase, must be noted that simultaneously the environmental acoustics information that assurance is extracted obviously influences the place ahead acoustic image location nothing.

Fig. 2 is the block diagram of the present invention around the path signal handling principle.As shown in Figure 2, with the left and right stereophonic signal L of original binary channel ₀, R ₀Carry out signal subtraction, obtain the difference S=(L of signal ₀-R ₀), it contains more Ambient acoustic intelligence, can extract as surround sound signal; S is the adjustable bandpass filtering treatment of Band (ω) through transfer function, obtains signal S _B=(L ₀-R ₀) Band (ω), then to signal S _BThe 20ms delay process of carrying out obtains representing the signal S of environmental acoustics information _WS _WSignal is respectively the high pass filter of 500Hz, 1000Hz, 2000Hz, 4000Hz octave band pass filter, 5600Hz more respectively through low pass filter, the centre frequency of 355Hz, be decomposed into the signal S of six subbands ₁, S ₂, S ₃, S ₄, S ₅, S ₆Respectively described six subband signals are carried out the random delay processing of 0-15ms scope; Each subband signal is decomposed into a pair of signal that different random is delayed time, comprises (S _1L, S _1R), (S _2L, S _2R), (S _3L, S _3R), (S _4L, S _4R), (S _5L, S _5R), (S _6L, S _6R) six pairs of signals; Again respectively with S _1L, S _2L, S _3L, S _4L, S _5L, S _6LSignal mixing addition is with S _1R, S _2R, S _3R, S _4R, S _5R, S _6RSignal mixing addition obtains a pair of decorrelation surround sound signal LS and RS, and the left and right circulating loudspeaker of feeding is respectively retransmitted.

The key problem in technology that the binary channel stereophonic signal is converted to 5.1 path surround sound signals is the simulation around path signal.Because around path mainly is to retransmit environmental acoustics information, produces the subjective auditory effect (Sensurround) that is similar to the diffusion field, thereby must satisfy two conditions around path signal:

1) should be about equally around the acoustic pressure size of the ears that path signal produced, just binaural sound is differential approaches zero.

2) should uncorrelated as far as possible (phase place be at random) around binaural sound signal that path signal produced, so must make that binaural cross-correlation coefficient (IACC) is as far as possible little.

Actual binary channel stereophonic signal recording can be divided into two types of recording studio recording and live recordings.In the recording studio recording, the place ahead acoustic image locating information is with the artificial generation by panoramic potentiometer (pan-pot) of unipath signal, and environmental acoustics information adds artificial reverberation by effect device and time-delay realizes.And in recording at the scene, be to adopt the coincidence microphone of different directive property to pick up technology acquisition the place ahead acoustic image locating information, by placing a pair of microphone in the far field to pick up the environmental acoustics information of diffusion.That a kind of signal way of recording no matter, the correlation that produces between the left and right path signal of acoustic image location is bigger, and the correlation between the relevant left and right path signal of environmental acoustics information is less.Therefore can utilize the difference S=L of the left and right path signal of original stereo ₀-R ₀The signal section that correlation is less relatively extracts.And because in common binary channel stereophonic program, speech signal is to be recorded in dead ahead (L ₀=R ₀).Add that to speech signal environmental acoustics information (reverberation) can influence the definition of language, said method can be avoided the signal of dead ahead acoustic image is entered around path.

But for high-frequency signal (particularly live recording, when a pair of when picking up distance between the microphone greater than the wavelength of sound wave), the correlation between the left and right path signal will be littler, thereby S=L ₀-R ₀Contain more high frequency composition.And in the hall of reality, if in the environmental acoustics information spinner, bass reflex sound.The following reflected sound signal of too much in addition 100Hz also can cause factitious subjective auditory effect.So in the environmental acoustics information, the medium and low frequency composition should be more than high frequency and the following signal component of 100Hz.Thereby the present invention proposes S=(L ₀-R ₀) increase by a bandpass filtering treatment, promptly get:

S _B＝(L ₀-R ₀)Band(ω) (1)

Wherein, Band (ω) is the transfer function of an adjustable band pass filter, its frequency characteristic is relevant with the type of original binary channel stereophonic signal, Fig. 3 is band pass filter amplitude-frequency characteristic figure, as shown in the figure, this filter can be decayed below the 100Hz and the above high-frequency signal of 2000Hz, makes and can satisfy the requirement of nature auditory effect according to (1) environmental acoustics information of being extracted.

For the environmental acoustics information S that (1) formula is extracted _BIn repeating transmission, do not influence the acoustic image locating effect in the place ahead, can utilize precedence effect, it is carried out certain time-delay (about 20ms, in actual applications, being made as adjustable), obtain representing the signal S of environmental acoustics information _W

To S _WMake decorrelated signals and handle, utilize method for processing signals exactly S _WBe transformed to two signals that correlation is little,,, and avoid when retransmitting, producing acoustic image around path signal with the generation Sensurround as left and right surround sound signal LS, RS.And in order to guarantee that not producing tone color when retransmitting around path signal changes, require decorrelated signals to handle and do not change signal S _WPower spectrum, i.e. the surround sound signal of decorrelation is that the all-pass filter by two out of phase characteristics produces.

The present invention proposes a kind of all-pass wave filtering implementation method that adopts the subband random delay.At first adopt a low pass filter, four 1/1 octave band pass filters, a high pass filter with S _WThe signal that is divided into six subbands, the frequency characteristic of filter is as shown in table 1, and six filters have covered the frequency band range of 20Hz-20kHz.In order to guarantee linear phase, filter is for adopting finite impulse response filter (FIR) form of Hamming window, descending slope 55dB/oct; The array at random that generates two groups every group 6 at computer is designated as (T as to the delay time of each subband signal _L1, T _L2, T _L3, T _L4, T _L5, T _L6), (T _R1, T _R2, T _R3, T _R4, T _R5, T _R6), then each subband signal is delayed time by two groups of random numbers respectively, will utilize same group of each subband signal addition after the delay time time-delay at last, obtain two-way around path signal LS, RS.Because from S _WCan regard linear all-pass process as to the transfer process of LS, RS signal, can be with two different linear all-pass transfer function (all-pass filters of two out of phase characteristics) A _L(ω), A _R(ω) expression, thereby:

LS＝A _L(ω)S _W RS＝A _R(ω)S _W (2)

So S _WAfter handling through two all-pass filters of (2) formula, just can obtain two correlations lower around path signal.(2) formula also can be write as the form of time domain convolution:

ls(t)＝a _L(t)*s _W(t) rs(t)＝a _R(t)*s _W(t) (3)

In the formula, each lowercase is represented the signal of time domain, a _L(t), a _R(t) be the impulse response of all-pass filter, they and corresponding frequency domain physical quantity be Fourier transform each other.

Fig. 4 is that the time-domain signal corresponding with (3) formula handled calcspar, and it and Fig. 2 are of equal value fully.

As for the problem of choosing of each subband signal random delay time range, consider that the time phase difference of delay sound and direct sound wave arrival attentive listener ears surpasses 40-50ms, auditory system can be distinguished two sound sources.Therefore the resultant signal time-delay should not surpass 40ms.As previously mentioned, for fear of effect of signals the place ahead acoustic image location, to the signal S of (1) formula around path _BCarry out the time-delay of 20ms and obtained S _W, thereby the used random delay of decorrelated signals processing must be less than 20ms.

Handle the random delay time range that is adopted in order to determine decorrelated signals more accurately, in the scope of 0-5ms, 0-10ms and 0-15ms, get two groups every group each 6 random number respectively, as the random delay time of 6 subbands, see Table 1 (not selecting 20ms to be because it has arrived the edge that surpasses precedence effect, may be therefore and echogenicity) as the random delay time range.Adopt six kinds of different signal sources,

(1) 8.0KHz low pass pink noise;

(2) 3.0KHz low pass pink noise;

(3) 1.5KHz low pass pink noise;

(4) 8.0KHz low pass white noise;

(5) 3.0KHz low pass white noise;

(6) 1.5KHz low pass white noise.

The random delay time that table 1 decorrelated signals is handled

In order to check the effect of getting different random delay time scope, each signal to be done the decorrelated signals processing by Fig. 2 obtain LS, RS two signals afterwards, two of the 5.1 path surround sounds of again it being fed around path.As shown in Figure 5, at this time the frequency domain sound pressure signal of ears is:

P _L＝H _LLSLS+H _LRSRS P _R＝H _RLSLS+H _RRSRS (4)

H wherein _LLS, H _LRS, H _RLS, H _RRSFor a pair of circulating loudspeaker that is arranged in horizontal plane ± 110 ° to the transfer function of ears (HRTF, calculate adopt that the MIT Media Lab provides measure the data of gained the KEMAR dummy head).Utilize following formula again:

${\mathrm{\ψ}}_{\mathrm{LR}}\left(\mathrm{\τ}\right)=\underset{T\→\∞}{\lim }\frac{\underset{-T}{\overset{+T}{\∫}}{p}_L\left(t\right){p_R}^{*}(t+\mathrm{\τ})\mathrm{dt}}{\sqrt{\underset{-T}{\overset{+T}{\∫}}{p}_L\left(t\right){p_L}^{*}\left(t\right)\mathrm{dt}\underset{-T}{\overset{+T}{\∫}}{p}_R\left(t\right){p_R}^{*}\left(t\right)\mathrm{dt}}}---\left(5\right)$

IACC＝max|ψ _LR(τ)| |τ|≤1ms

Can calculate binaural (normalization) cross-correlation function and corresponding binaural cross-correlation coefficient IACC, wherein p _l(t), p _r(t) be the time domain form of ears acoustic pressure, with the P of (4) formula _L, P _RFourier transform each other.Can produce good subjective Sensurround with the lower corresponding random delay of the IACC time.

Two around path signal except must satisfy IACC to try one's best little, must make also that the binaural sound of following formula is differential to approach zero:

$\mathrm{\ΔP}=10\lg \frac{{\left|P_L\left(\mathrm{\ω}\right)\right|}^2{\left|f\left(\mathrm{\ω}\right)\right|}^2\mathrm{d\ω}}{{\left|P_R\left(\mathrm{\ω}\right)\right|}^2{\left|f\left(\mathrm{\ω}\right)\right|}^2\mathrm{d\ω}}---\left(6\right)$

Wherein | f (ω) | ²Be meant the power spectrum of acoustical signal.

To six kinds of different signal sources and the random delay time shown in the table 1, the differential result of calculation of IACC and binaural sound is as shown in table 2.As can be seen, if adopt the random delay time range of 0-15ms, for six kinds of signal types recited above, the IACC and the binaural sound of resultant ears acoustic pressure are differential all very low after decorrelated signals is handled, and can obtain comparatively desirable effect.Thereby the present invention just takes 0-15ms as the random delay time range.

The present invention can be designed to software in computer realization, is used for the making of surround sound program source.The hardware circuit that also can utilize general signal processing chip to make is realized, also can be designed to special-purpose integrated circuit (IC) chip and realize.The present invention can be used for the making (as the DVD CD) in surround sound music program source.Also can be used as special hardware circuit and be used in the sound reproduction of aspects such as family expenses electroacoustics system, TV (comprising DTV and HDTV), home theater.

The making of embodiment one surround sound program source

Read binary channel stereophonic signal on CD or the hard disk by the CD-ROM of computer, simulate the signal processing of 5.1 path surround sounds with what computer software was carried out Fig. 6 from the binary channel stereophonic signal then, obtain five-way road surround sound signal L, R, C, LS, RS, be recorded in then on hard disk or the DVD CD, as the programme signal of 5.1 path surround sounds.

IACC and binaural sound that table 2 surround sound signal produces are differential

The application of embodiment two home theaters

With the amplifier of binary channel stereo (numeral) the signal mixing home theater of CD player output, the signal processing of Fig. 2 or Fig. 4 is as the part of functions circuit in the amplifier.Obtain five-way road surround sound signal L, R, C, LS, RS, five the external loud speakers of feeding are respectively then retransmitted.

The present invention specifically introduces with the realization of software on multimedia computer.Fig. 6 is that software is realized signal processing flow figure of the present invention.Signal processing is exactly that (from CD-ROM or hard disk) reads in original binary channel stereophonic signal, after it is handled, is converted to 5.1 path surround sound signals, and is recorded on DVD or the hard disk.

The first step: in CD-ROM, read in the stereo time-domain signal of original binary channel, be designated as l ₀, r ₀

Second step: utilize existing algorithm (as the method for the virtual sound of the proposition of J.Bauck) to convert the stereo time-domain signal of binary channel a left side, the place ahead l, right r, the center c path signal of 5.1 path surround sounds to, and deposit buffer in.

The 3rd step: with the stereo time-domain signal l of binary channel ₀, r ₀Subtract each other, obtain their difference signal s=(l ₀-r ₀), again with the impulse response h of difference signal and band pass filter _Band(t) convolution and time-delay 20ms obtain representing the time-domain signal s of ambient sound information _W

The 4th step: with signal s _WRespectively with a _L(t), a _R(t) two all-pass impulse response convolution obtain 5.1 path surround sounds left and right around path signal ls, rs of decorrelation, and deposit buffer in.

The 5th step: with the left l in the buffer, right r, middle c path signal with left and rightly write hard disk, as the program source signal of 5.1 path surround sounds around path signal ls, rs.

As mentioned above, can realize the present invention preferably.

The objective measurement experimental verification effect of the present invention, it is differential to have proved that the present invention proposes to produce low IACC and binaural sound that the method around path signal produces at attentive listener ears place.

Utilize computer software to produce (the 44.1KHz sampling of maximal-length sequence (MLS) signal, 16bit quantizes, 16384 points), it is handled generation two-way surround sound signal by the decorrelated signals that Fig. 2 carries out random delay, behind sound card (Echo Layla24) D/A conversion and power amplifier, the loud speaker of feeding is retransmitted.Loudspeaker arrangement is the garden of 2.0m on week at a radius, two circulating loudspeaker position consistency in the standard arrangement of azimuth and 5.1 path surround sounds.With dummy head (KEMAR dummy head, the DB60/61 auricular concha) position is listened attentively at the center of being placed on, micro microphone (Core Sound 4060) is placed on dummy head's duct porch and picks up binaural sound signal (measurement of ear canal method), its output (B﹠amp after modification amplifier amplifies; K 2690A-OS4) the A/D converter by sound card is input to computer.Carry out deconvolution to picking up the binaural sound signal that obtains, can obtain ears impulse response, they are added time window after, can eliminate the influence of room reflections.With ears impulse response respectively with the low pass pink noise convolution of 1.5KHz and 3.0KHz, can obtain corresponding ears acoustic pressure, and by (5)) formula calculates binaural cross-correlation coefficient (IACC).Experimental result shows that the IACC of the pink noise signal of 1.5KHz low pass is 0.339, and binaural sound is differential to be 1.1dB.3.0KHz the IACC of the pink noise signal of low pass is 0.256, binaural sound is differential to be 0.7dB.So the IACC of two kinds of signals is lower, and binaural sound is differential also lower, can obtain good Ambience.

Subjective experiment has been verified the subjective auditory effect that the present invention produced.

The original binary channel stereophonic program source that experiment is adopted is: (1) Beethovan's D turns violin concerto the 3rd movement fragment greatly down; (2) orchestral music, the William of Luo Xini moves back your overture fragment; (3) piano recital: Beethovan's enthusiasm sonata fragment; (4) opera: male and female voice duet, Weir younger brother's camellia woman fragment.

Utilize above-mentioned method, generate 5.1 path surround sound signals (framing signal of 3 the place ahead loud speakers wherein, 2 rear circulating loudspeakers around signal), the 5.1 path ambiophonic systems of feeding from binary channel stereophonic program source and retransmit.And with original binary channel stereophonic program relatively.

Experiment is to carry out in the listening room of a reverberation time 0.15s, and five loudspeaker arrangement are on the circumference of 2.0m at radius, and the azimuth is arranged with reference to Fig. 1.Attentive listener is positioned at the center of circle, totally 8 attentive listener, four male four woman.

Informal subjective experiment result shows: for various signals, generate in the repeating transmission of 5.1 path surround sound signals for binary channel stereophonic program source, the surround channel signal can not influence the location of the place ahead acoustic image; With the stereo comparison of original binary channel, generating has better Sensurround when 5.1 path surround sound signals are retransmitted.

Research of the present invention obtains " Guangzhou plan of science and technology project, numbering: 200523-D0071 " and subsidizes.

Claims (2)

1, the signal processing method of the stereo simulation 5.1 path surround sounds of binary channel is characterized in that comprising the steps:

The first step: import the left and right stereo frequency-region signal L of original binary channel ₀, R ₀

Second step: to the left and right stereophonic signal L of original binary channel of first step input ₀, R ₀Handle, produce the place ahead three path signal L, R, the C of 5.1 path surround sounds;

The 3rd step: the extraction of environmental acoustics information signal; With the left and right stereophonic signal L of original binary channel ₀, R ₀Poor (L ₀-R ₀) through the bandpass filtering treatment of 100Hz to 2000Hz, decay following low frequency of 100Hz and the above high-frequency signal composition of 2000Hz obtain signal S _B=(L ₀-R ₀) Band (ω), then to signal S _BCarry out the delay process of 20ms, obtain representing the signal S of environmental acoustics information _WBandpass filtering treatment is with L ₀, R ₀Poor (L ₀-R ₀) difference signal and the impulse response convolution of band pass filter;

The 4th step: the decorrelation of environmental acoustics information signal is handled; With resulting S of the 3rd step _WSignal is respectively the high pass filter of 500Hz, 1000Hz, 2000Hz, 4000Hz octave band pass filter, 5600Hz respectively through low pass filter, the centre frequency of 355Hz, be decomposed into the signal S of six subbands ₁, S ₂, S ₃, S ₄, S ₅, 8 ₆Respectively described six subband signals are carried out the random delay processing of 0-15ms scope, each subband signal is decomposed into a pair of signal that different random is delayed time, comprise (S _1L, S _1R), (S _2L, S _2R), (S _3L, S _3R), (S _4L, S _4R), (S _5L, S _5R), (S _6L, S _6R) six pairs of signals; Again respectively with S _1L, S _2L, S _3L, S _4L, S _5L, S _6LSignal mixing addition is with S _1R, S _2R, S _3R, S _4R, S _5R, S _6RSignal mixing addition obtains a pair of decorrelation surround sound signal LS and RS, and the left and right circulating loudspeaker of feeding is respectively retransmitted.

2, the signal processing method of the stereo simulation 5.1 path surround sounds of binary channel according to claim 1, it is characterized in that described second step produces the place ahead three path signal L of 5.1 path surround sounds, the method for R, C comprises out-of-bounds stereo processing method or virtual acoustic processing method.

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