Source: http://www.patentsencyclopedia.com/app/20100250259
Timestamp: 2017-11-22 09:23:16
Document Index: 579819205

Matched Legal Cases: ['art 2240', 'art 2240', 'art 2240', 'art 2240', 'art 2240', 'art 2240', 'art 2240']

Patent application number: 20100250259
1. An apparatus for decoding an audio signal, comprising:an audio signal receiving unit receiving the audio signal having a plurality of channel signals including an ambient component signal and a source component signal;an ambient component signal extracting unit extracting the ambient component signal of each of the channels based on correlation between the channel signals;an ambient component signal modifying unit modifying the ambient component signal using surround effect information;a source component signal extracting unit extracting the source component signal of each of the channels based on the correlation between the channel signals;a first signal output unit outputting the modified ambient component signal and the source component signal; anda second signal output unit outputting the audio signal or the source component signal.
14. A method of decoding an audio signal, comprising:receiving the audio signal having a plurality of channel signals including an ambient component signal and a source component signal;extracting the ambient component signal and the source component signal of each of the channels based on correlation between the channel signals;modifying the ambient component signal using surround effect information; andoutputting the modified ambient component signal and the source component signal via different output units, respectively.
[0019]FIG. 8 is a graph of a post-scaling factor for weights ω3, ω4 and {circumflex over (N)}1' according to one embodiment of the present invention;
[0020]FIG. 9 is a graph of a post-scaling factor for weights ω5, ω6 and {circumflex over (N)}2' according to one embodiment of the present invention;
[0037]According to the present invention, the ambient component signal is a signal having low correlation between component signals included in each of the channels.
[0063]The terminology `front` used in this disclosure indicates a front side or a fore side. For instance, a front of a device (or unit) indicates a fore side seen by a screen part of the device (or unit). Disposing an output device (or unit) in a lateral rear side means that the output device (or unit) is disposed to have an output direction of 45°˜135° with reference to a plane in which a screen part of a decoding device of an audio signal exists. And, disposing an output unit in a lateral front side means that the output device (or unit) is disposed to have an output direction of 0°˜45° or 135°˜180° with reference to a plane in which a screen part of a decoding device of an audio signal exists.
X1(i,k)=S(i,k)+N(i,k)
x L = i = 1 N h head_Li * S i + i = 1 N h tail_Li * S i + n L x L = i = 1 N h head_Ri * S i + i = 1 N h tail_Ri * S i + n R [ Formula 3 ] ##EQU00001##
[0076]In this case, h_head_Li and h_head_Ri correspond to head parts of a transfer function indicating a relation that an ith entity is included in channels L and R. h_tail_Li and h_tail_Ri correspond to tail parts of the transfer function and include reverberant components of s_i introduced into the respective channels. And, `*` indicates convolution. In this case, the ambient component signal corresponds to
i = 1 N h tail_Xi * S i + n X ##EQU00002##
PX1(j,k)=E{X12(i,k)} [Formula 4]
[0079]In Formula 4, E{.} indicates an average.
[0080]Assume that powers of N1 and N2 are equal to each other. And, assume that the dependent signals having external influence have the same power in left and right channels of a stereo channel (PN=PN1=N2).
[0081]Besides PN=PN1=PN2, it is able to use such assumption as A2PN1=PN2 and the like for example.
φ ( i k ) = E { X 1 ( i , k ) X 2 ( i , k ) } E { X 1 1 ( i , k ) } E { X 2 2 ( i , k ) } [ Formula 5 ] ##EQU00003##
[0083]It is able to determine A, PS, PN using PX1, PX2, φ. And, the relation formula for the PX1, PX2, φ can be represented as Formula 6.
[0084]Formula 6 is summarized for A, PS, PN into Formula 7.
E=(1-ω1-ω2A)S-ω1N1ω2N.sub- .2 [Formula 10]
(1=ω1-ω2A)PS-ω1PN=0
E=(-ω3-ω4A)S-(1-ω3)N1-ωN2 [Formula 15]
[0093]The weights ω1 and ω2 are calculated into Formula 16 in a manner that the estimation error E is orthogonal to X1 and X2.
N ^ 2 = ω 5 X 1 ω 6 X 2 = ω 2 ( S + N 1 ) + ω 6 ( AS + N 2 ) [ Formula 17 ] ω 5 = - AP S P N ( A 2 + 1 ) P S P N + P N 2 ω 6 = P S P N + P N 2 ( A 2 + 1 ) P S P N + P N 2 [ Formula 18 ] ##EQU00008##
PS=(ω1+αω2)2PS+(ω1.s- up.2+ω22)PN [Formula 19]
[0097]In the same manner for S', {circumflex over (N)}1' and {circumflex over (N)}2' can be scaled as Formula 21 and Formula 22.
[0098]Meanwhile, FIGS. 6 to 10 are graphs of relations of various variables calculated until the S', {circumflex over (N)}1', and {circumflex over (N)}2' are obtained. First of all, the normalized power of the gain factors A, S and AS ca be represented as a function of the level difference of stereo signal and the normalized cross-correlation Φ. This is shown in FIG. 6.
[0100]In FIG. 8, weights ω3 and ω4 for calculating minimum square estimation value of N1 are represented as a function of the level difference of stereo signal and the normalized cross-correlation Φ and are shown on the two upper graphs, respectively. And, a post-scaling factor for {circumflex over (N)}1' in Formula 19 is represented as a lower graph in FIG. 8.
[0101]In FIG. 9, weights ω5 and ω6 for calculating minimum square estimation value of N2 are represented as a function of the level difference of stereo signal and the normalized cross-correlation Φ and are shown on the two upper graphs, respectively. And, a post-scaling factor for {circumflex over (N)}2' in Formula 19 is represented as a lower graph in FIG. 9.
[0111]A signal output unit 1150 outputs a stereo signal to an external environment of the audio signal decoding apparatus by receiving and combining the source component signal extracted by the source component signal extracting unit 1140 and the ambient component signal modified by the ambient component signal modifying unit 1130 together. The signal output unit 1150 is able to output the audios signal received by the audio signal receiving unit 1110, i.e., a channel signal instead of the source component signal extracted by the source component signal extracting unit 1140 and is also able to output the source component signal and the received audio signal together with the ambient component signal. And, the audio signal received by the audio signal receiving unit 1110 can include flag information indicating whether the signal output unit 1150 outputs at least one of the source component signal and the audio signal. The signal output unit 1150 can include a single output unit or can include at least two output units. In case that the signal output unit 1150 includes the at least two output units, functions and configurations of the output units may differ from each other and can be disposed in various configurations. Details regarding the signal output unit 1150 will be explained with reference to FIGS. 16 to 25 later.
[0112]In an apparatus for decoding an audio signal according to another embodiment of the present invention, the ambient information signal modifying unit 1130 applies a filter, which is an example of the surround effect information, to an ambient information signal is then able to modify a stereo signal outputted by the signal output unit 1150 to be similar to a signal (L0, R0) of a general 5.1-channel output signal listened to by a listener.
[0113]FIG. 12 is a diagram for a general 5.1-channel configuration and a path of a signal introduced into a listener. As shown in FIG. 12, GX_Y indicates a transfer function for transferring a signal to a ear Y from a speaker X. For instance, GL_R indicates a transfer function for a sound of a channel L to enter a right ear of a listener and GC_R indicates a transfer function for a sound of a channel C to enter a right ear of a listener. And, the GX_Y is named a head-related transfer function (hereinafter called `HRTF`).
[0114]The signals (L0, R0) entering the listener's ears can be represented as Formula 23 with reference to FIG. 12.
L0=L*GL--L+C*GC--L+R*GR--L+LS*GLS--L+R.- sub.S*GRS--L
R0=L*GL--R+C*GC--R+R*GR--R+LS*GLS--R+R.- sub.S*GRS--R [Formula 23]
[0115]By referring to this, a stereo signal (L',R') outputted from the audio signal decoding apparatus of the present invention can be represented as Formula 24.
[0116]The L' and R' indicate output signals of channels, respectively. D(L) and D(R) indicate source component signals of channel L and R input signals, respectively. A(L) and A(R)® indicate ambient component signals. G_L and G_R indicate filters applied to ambient sound components of the channels, respectively.
[0117]Thus, the ambient component signal modifying unit 1130 is able to modify the ambient component signal to have a prescribed ambient effect using a filter applied to the corresponding ambient component signal. The filter can be included in a bitstream indicating the audio signal inputted to the audio signal receiving unit 1110. The filter can be stored in the ambient component signal modifying unit 1130 of the audio signal decoding apparatus of the present invention. The filter can be inputted via an input device (not shown in the drawing) by a listener. The G_X can be a fixed value or a variable value that varies according to a listener's request. The G_X can provide an effect that the ambient component signal is reproduced at a random virtual position instead of a position of the conventional output unit L or R. Therefore, the G_X can use the HRTF or can be configured by considering cross-talk of the HRTF, by which examples of the present invention are non-limited.
[0118]FIG. 13 is a diagram for an output of a stereo signal including a ambient component signal modified using the filter of Formula 24.
[0119]Referring to FIG. 13, in case that an audio signal decoded according to one embodiment of the present invention is outputted by two output units 1310 and 1320, a listener is able to hear source component signals from the output units 1310 and 1320 disposed in front of the listener. On the contrary, the listener senses filter-applied ambient component signals as if they are outputted from positions of virtual output units 1330 and 1340, respectively. As the effect of using lateral/rear output units for the ambient component signals additionally is obtained to enhance the stereo effect, the listener is able to enjoy the stereo sound effectively using the stereo signal and device.
[0120]An audio signal decoding apparatus according to another embodiment of the present invention is able to give a stereo effect to an audio signal by modifying an extracted source component. And, a corresponding audio signal decoding apparatus is explained with reference to FIG. 14 and FIG. 15 as follows.
[0121]FIG. 14 is a schematic block diagram of an audio signal decoding apparatus 1400 having a source component modifying unit according to another embodiment of the present invention.
[0122]First of all, the audio signal decoding apparatus 1400 mainly includes a ambient component signal extracting unit 1420, a ambient component signal modifying unit 1430, a source component signal extracting unit 1440, a source component signal modifying unit 1450 and a signal output unit 1460. Since the ambient component signal extracting unit 1420, the ambient component signal modifying unit 1430, the source component signal extracting unit 1440 and the signal output unit 1460 play the same functions and roles of the elements having the same names of the former audio signal decoding apparatus 1100 shown in FIG. 11, their details will be omitted in the following description.
[0123]The source component signal modifying unit 1420 receives a source component signal extracted by the source component signal extracting unit 1440 and is then able to modify the source component signal to enhance a stereo effect. The source component signal modifying unit 1420 is able to use a filter capable of giving a surround effect or an extension effect to the source component signal, by which examples of the present invention are non-limited.
[0124]FIG. 15 is a schematic partial block diagram of portions of an audio signal decoding apparatus for modifying a source component signal using a filter for giving an extension effect. In the present invention, the extension effect means the effect of increasing distances of source component signals included in a channel signal in a space. And, an output signal including the extension effect applied source component signals can provide a stereo effect as if being listened to a wide space such as an auditorium, a stadium and the like. A source component signal extracting unit 1540, of which function and role are equivalent to those of the former source component signal extracting unit 1140, extracts a source component signal from the inputted audio signal. Meanwhile, the source component signal extending unit 1550 receives the source component signal and then generates a source component signal, of which distance between the source components is extended, by applying a filter of giving an extension effect to the received source component signal.
[0125]Thus, in the audio signal decoding apparatus according to the present invention, an ambient component signal and/or a source component signal is extracted from an audio signal and is then modified. The modified ambient and/or source component signal is mixed and then outputted. Therefore, it is able to increase the stereo effect generated by the ambient or environmental influence in the recording environment. And, it is able to obtain an audio signal having the enhanced stereo effect using the stereo signal and device only as if using a multi-channel.
[0126]Unlike the former embodiment for further enhancing the stereo effect of the stereo signal in a manner of mixing a modified ambient component signal and a modified source component signal together and then outputting the mixed signal via a single output unit, another embodiment of the present invention proposes an audio signal decoding apparatus having an output unit for outputting an ambient component signal separate from an audio signal including a source component signal and/or a channel signal.
[0127]FIG. 16 is a schematic block diagram of an apparatus 1600 for decoding an audio signal according to another embodiment of the present invention.
[0128]Referring to FIG. 16, the audio signal decoding apparatus 1600 have the same functions and roles of the former decoding apparatus 1100 shown in FIG. 11 in part. Hence, details of an audio signal receiving unit 1601, an ambient component signal extracting unit 1620, an ambient component signal modifying unit 1630 and a source component signal extracting unit 1640 are omitted in the following description. And, the audio signal decoding apparatus 1600 can further include a source component signal modifying unit (not shown in the drawing) for enhancing a stereo effect of a source component signal by receiving the source component signal from the source component signal extracting unit 1640 and then applying a filter for giving an extension effect or a surround effect.
[0129]The ambient component signal modified by the ambient component signal modifying unit 1630 is outputted via a first signal output unit 1650 and the source component signal or the audio signal received by the audio signal receiving unit 1610 is outputted via a second signal output unit 1660. And, both of the source component signal and the audio signal can be outputted via the second signal output unit 1660. Moreover, the audio signal received by the audio signal receiving unit 1610 can include flag information indicating whether at least one of the source component signal and the audio signal is outputted by the signal output unit 1650. In the following description, the second signal output unit 1660 is non-limited to the function of outputting the source component signal but is understood as outputting the source component signal and the audio signal or the audio signal. And, the audio signal of the present invention includes a plurality of channel signals including the source component signal and the ambient component signal.
[0130]Each of the first signal output unit 1650 and the second signal output unit 1660 is configured with a single unit or can be configured with at least two units. For instance, in case that an output system of an audio signal is a stereo system, the first signal output unit 1650 can include two first signal output units corresponding to left and right channels, respectively. And, the second signal output unit 1660 can include two second signal output units corresponding to left and right channels, respectively.
[0131]Although the present invention relates to a case that the output system of the audio signal includes the stereo system, it can be a multi-channel system configured in a manner that each of the first and second signal output units 1650 and 1660 includes at least three units.
[0132]According to one embodiment of the present invention, the audio signal decoding apparatus further includes a first signal output unit for outputting a modified ambient component signal only as well as a second output unit for outputting an audio signal or a source component signal, thereby enhancing a stereo effect of the audio signal. Moreover, by disposing the first signal output unit and the second signal output unit to differing in output directions from each other, a listener is enabled to listen to the audio signal having the enhanced stereo effect. The first and second signal output units for providing the stereo effect enhanced audio signal are explained with reference to FIGS. 17 to 22 as follows.
[0133]First of all, in an audio signal decoding apparatus such as a TV, an audio system and the like, a signal output unit should be disposed within a limited space as long as a separate output unit separated from the decoding apparatus is used. Generally, a second signal output unit for outputting an audio signal or a source component signal has an output direction toward a listener (hereinafter named `front side`). And, it is effect to deliver a stereo effect if a first signal output unit for outputting an ambient component signal is disposed in rear or lateral side of a listener. Yet, due to the disposition within the limited space, the first signal output unit is disposed around the second signal output unit.
[0134]FIG. 17 is a graph for disposition of first and second signal output units. A second signal output unit 1710 has an x-direction output direction. And, first signal output units 1720a and 1720b have output directions differing from that of the second signal output unit 1710.
[0135]Referring to FIG. 17, the first signal output unit 1720a outputting a ambient component signal can be disposed to have an output direction not in parallel with that of the second signal output unit 1710 and may not exit on a plane where the second signal output unit 1710 is located. Moreover, referring to FIG. 17, the first signal output unit 1720b is located on the same place of the x-y plane where the second signal output unit 1710 is located and can have an output direction not in parallel with that of the second signal output unit 1710.
[0136]The second signal output unit 1710 is responsible for a reproduction of an audio signal or a source component signal and the first signal output unit 1720a or 1720b having the output direction not in parallel with that of the second signal output unit 1710 is responsible for a reproduction of an ambient component signal. Therefore, compared to the case of reproducing the stereo signal using the second signal output unit 1710 only, this case can provide a listener with the audio signal having the enhanced stereo effect.
[0137]FIG. 18 and FIG. 19 schematically show an audio signal decoding apparatus, in which a first signal output unit for outputting an ambient component signal is disposed to have an output direction different from that of a second signal output unit for outputting an audio signal or a source component signal, and a method of reproducing an audio signal using the same. In FIG. 18 and FIG. 19, a channel signal is an example of an audio signal inputted to an audio signal receiving unit of the present invention, includes an ambient component signal and a source component signal, and indicates a signal outputted on each channel.
[0138]Referring to FIG. 18, first signal output units 1850a and 1850b have output directions toward lateral rear sides with reference to output directions of second signal output units 1860a and 1860b, respectively. Ambient component signals are inputted to the first signal output units 1850a and 1850b from a ambient component signal modifying unit 1830, respectively. Source component signals from a source component signal extracting unit 1840 or an audio signal from an audio signal receiving unit (not shown in the drawing) is inputted to the second signal output units 1860a and 1860b. The ambient component signal modifying unit 1830 and the source signal component extracting unit 1840 are equivalent to the former ambient component signal modifying unit 1130 and the former source component signal extracting unit 1140 shown in FIG. 11, of which details will be omitted in the following description.
[0139]As the first signal output unit 1850a/1850b has the output direction toward the lateral rear side, an ambient component signal outputted in the lateral rear direction can have an increased effect of being reflected by a wall of a rear or lateral side. Moreover, a path for delivering an ambient component signal to a listener can be provided in more various ways, whereby a stereo effect of the audio signal can be increased due to a natural delay effect and the like.
[0140]Referring to FIG. 19, first signal output units 1950a and 1950b have output directions toward lateral front sides with reference to the output directions of the first signal output units 1850a and 1850b shown in FIG. 18 and output directions of second signal output units 1960a and 1960b, respectively. Ambient component signals are inputted to the first signal output units 1950a and 1950b from a ambient component signal modifying unit 1930, respectively. Source component signals from a source component signal extracting unit 1940 or an audio signal from an audio signal receiving unit (not shown in the drawing) is inputted to the second signal output units 1960a and 1960b. Details of the ambient component signal modifying unit 1930 and the source signal component extracting unit 1940 will be omitted in the following description.
[0141]As the first signal output unit 1950a/1950b has the output direction toward the lateral front side, a ambient component signal outputted in the lateral front direction can have a further increased effect of being reflected by a wall of a lateral side. Moreover, comparing to the former audio signal decoding apparatus shown in FIG. 18, since spaces required for the first signal output units 1950a and 1950b and the second signal output units 1960a and 1960b are narrow, the present invention is more useful for an audio signal decoding apparatus having a narrow space for an output unit.
[0142]In an audio signal decoding apparatus according to the present invention, first and second signal output units for outputting an ambient component signal and a source component signal can consecutively configure a single output unit. FIG. 20 shows a TV including an audio signal decoding apparatus having the first and second signal output units configured in a single output unit. In this disclosure, the TV is taken as an example. Yet, it can be widely applicable to a device including an audio signal decoder.
[0143]Referring to FIG. 20, an output unit 2010 and 2020 includes two units L and R which are disposed in a vertical direction. The output unit 2010 and 202 includes a first signal output unit for outputting a ambient component signal and a second signal output unit for outputting an audio signal or a source component signal. And, an enlarged internal diagram for the output unit 2101 located to the left of the screen part is shown in a bottom part of FIG. 20. The left output unit 2010 includes a first signal output unit 2011 and a second signal output unit 2012. And, it is able to dispose the first and second signal output units 2011 and 2012 to differ from each other in output direction. For instance, the output direction of the second signal output unit 2012 is disposed toward a front side, while the output direction of the first signal output unit 2011 is disposed toward a lateral rear side or a lateral front side.
[0144]Moreover, it is able to divert or shift the output directions of the first and second signal output units 2011 and 2012 based on characteristic information. The characteristic information can be determined according to characteristics of a sound source or an operation mode thereof. The characteristics or operation mode of the sound source can be included in a bitstream indicating an audio signal inputted to an audio signal decoding apparatus or can be stored in the ambient component signal modifying unit 1130 of the audio signal decoding apparatus according to the present invention. Moreover, the characteristics or operation mode of the sound source can be inputted via a listener input device (not shown in the drawing) by a listener.
[0145]For instance, in case that a listener attempts to reproduce a stereo signal having no surround effect only, the listener inputs a preset 2ch mode using a remote controller or the like. If so, the audio signal decoding apparatus receives it and is then able to divert a disposed direction of the first signal output unit 2011 so that the output direction of the first signal output unit 2011 is identical to that of the second signal output unit 2012. This diversion of the disposed direction can be obtained by the mechanical rotation or by a signal processing method.
[0146]According to another embodiment of the present invention, the output unit including the first and second signal output units can have various configurations. FIG. 21 shows an example the output unit. The output unit can include a plurality of units. And, each of a plurality of the units can include a first signal output unit or a second signal output unit. Referring to FIG. 21, an output unit having a cylindrical configuration is easily rotatable, increases a stereo effect by outputting a different signal to each partitioned area, and controls an output direction of each unit according to the characteristic information. The cylindrical configuration of the output unit does not limit examples of the present invention only if each example includes a plurality of units in a rotatable configuration.
[0147]In an audio signal decoding apparatus according to the present invention, a first signal output unit or a second signal output unit can include a plurality of units as well as an output unit. In this case, a plurality of the units can output signals of different frequency bands and an output direction of each of the units can be adjusted according to unit characteristic information. The unit characteristic information can be determined according to characteristics of a sound source. The characteristics of the sound source can be included in a bitstream indicating an audio signal inputted to an audio signal decoding apparatus or can be stored in the ambient component signal modifying unit 1130 of the audio signal decoding apparatus according to the present invention. Moreover, the characteristics of the sound source can be inputted via a listener input device (not shown in the drawing) by a listener.
[0148]According to a further embodiment of the present invention, it is able to enhance a stereo effect of an audio signal in a manner of disposing a first signal output unit for outputting an ambient component signal over the screen part. FIG. 22 shows a TV as an example of an audio signal decoding apparatus having first and second signal output units disposed vertical to each other in a front side where the screen part is located, in which the first signal output unit is disposed over the screen part. Referring to FIG. 22, an output unit includes a first signal output unit 2210 for outputting a ambient component signal and second signal output units 2220 and 2230 for outputting source component signals. And, the second signal output units can be located to the left and right sides of a screen part 2240. The first signal output unit 2210 is located in the same plane of the second signal output units 2220 and 2230 and the screen part 2240 and can be disposed over the screen part 2240 to be vertical to the second signal output units 2220 and 2230.
[0149]Referring to FIG. 22, when the first signal output unit 2210 of the TV is disposed over the screen part 2240 to be vertical to the second signal output units 2220 and 2230, a ambient component signal is outputted from the first signal output unit 2210 and is then reflected using a ceiling. Thus, comparing to the case that the first signal output unit is located in lateral rear or front of the second signal output unit, the case that the first signal output unit 2210 is located at the top further includes the step of reflection due to collision with the ceiling, whereby a stereo effect of an audio signal can be further enhanced. Moreover, the first signal output unit 2210 is not only located over the screen part 2240 to be vertical to the second signal output units 2220 and 2230 but also disposed over the screen part 2240 by configuring various angles.
[0150]In FIG. 22, shown is the case that the first signal output unit 2210 is located over the screen part 2240. The first signal output unit 2210 can be located over the audio decoding apparatus to be vertical to the front side including the screen part and the second signal output unit or can be located over a backside opposing the front side. And, the first signal output unit can be disposed to form a specific angle with a plane using a physical or electrical method.
[0151]According to a further embodiment of the present invention, proposed is a decoding apparatus and method for enhancing a stereo effect of an audio signal in a manner of re-modifying an ambient component signal by considering an environment where an audio signal decoding apparatus is used. This is explained in detail with reference to FIG. 23 as follows.
[0152]Referring to FIG. 23, an apparatus for decoding an audio signal according to the present invention mainly includes an audio signal extracting unit 2310, an ambient component signal extracting unit 2320, an environment information generating unit 2330, an ambient component signal modifying unit 2340, a source component signal extracting unit 2350, a first signal output unit 2360 and a second signal output unit 2370. The audio signal extracting unit 2310, the ambient component signal extracting unit 2320, the source component signal extracting unit 2350, the first signal output unit 2360 and the second signal output unit 2370 have the same functions and roles of the audio signal extracting unit 1110, the ambient component signal extracting unit 1120, the source component signal extracting unit 1140, the first signal output unit 1650 and the second signal output unit 1660 shown in FIG. 11 or FIG. 16. And, their details will be omitted in the following description. The audio signal decoding apparatus further includes a source component signal modifying unit (not shown in the drawing) for modifying an extracted source component signal, whereby a stereo effect of an audio signal can be enhanced.
[0153]The environment information generating unit 2330 transfers various preset modes to a listener input device (not shown in the drawing) and is then able to output preset environment information corresponding to a mode selected by a listener. As an example of the preset mode, there exists a wall-mounted mode or a stand mode in case of TV. The environment information generating unit 2330 outputs the environment information corresponding to the wall-mounted mode or the stand mode to the ambient information signal modifying unit 2340. The environment information corresponding to the wall-mounted mode may be set to a narrower distance between an audio signal decoding apparatus and a reflecting plane rather than the stand mode. Meanwhile, a listener is able to directly input environment information to the environment information generating unit 2330. For instance, a listener is able to input a distance between a backside of the audio signal decoding apparatus and a reflecting plane, a distance between a topside of the apparatus and a ceiling, a distance between a lateral side of the apparatus and a reflecting plane and the like using an input device. And, the environment information generating unit 2330 is then able to generate the environment information.
[0154]Moreover, the environment information can include information on ambient characteristics between the audio signal decoding apparatus and a listening position. For instance, the information on the ambient characteristic can include a distance between the decoding apparatus and the listening position. An optimal listening position for maximizing a stereo effect of an audio signal can be varied by the distance between the audio signal decoding apparatus and the listening position. Hence, the environment information generating unit 2330 receives the distance via the listener input device, generates the environment information and is then able to output the generated environment information to the ambient component signal modifying unit 2340. Moreover, the environment information generating unit 2330 is able to estimate a position of a listener using a separate detecting device (not shown in the drawing). For instance, the environment information generating unit 2330 is able to estimate a distance between the audio signal decoding apparatus and a listener using such a separate sound sensor as a microphone, a remote controller or the like.
[0155]An audio signal decoding apparatus and method according to the present invention can further enhance a stereo effect of an audio signal in a manner of modifying an ambient component signal based on the above-generated environment information.
[0156]According to a further embodiment of the present invention, by outputting an ambient component signal to be more delayed than a source component signal or by giving an extension effect to a source component signal, it is able to enhance a stereo effect of an audio signal. FIG. 24 is a schematic diagram of an audio signal decoding apparatus further including an output delaying unit 2451. Referring to FIG. 24, a first signal output unit 2450 for outputting an ambient component signal includes an output delaying unit 2451 and an output unit 2452 and is able to output an ambient component signal at a time delayed more than a source component signal outputted by a second signal output unit 2460. Hence, an effect of giving a stereo effect can be obtained by maximizing a reverberant effect of an audio signal.
[0157]FIG. 25 is a schematic diagram of an audio signal decoding apparatus further including an extension effect applying unit 2561. Referring to FIG. 25, a second signal output unit 2560 for outputting a source component signal includes an extension effect applying unit 2561 and an output unit 2562. The extension effect applying unit 2561 brings an effect of extending a distance of each source component signal outputted from the second signal output unit 2560, whereby an audio signal can be listened to in a wider space.
[0158]Moreover, an audio signal decoding apparatus according to the present invention includes both an output delaying unit within a first signal output unit and an extension effect applying unit within a second signal output unit, thereby enhancing a stereo effect of an audio signal.
[0159]According to the present invention, the above-described decoding/encoding method can be implemented in a program recorded medium as computer-readable codes. The computer-readable media include all kinds of recording devices in which data readable by a computer system are stored. The computer-readable media include ROM, RAM, CD-ROM, magnetic tapes, floppy discs, optical data storage devices, and the like for example and also include carrier-wave type implementations (e.g., transmission via Internet). And, a bitstream generated by the encoding method is stored in a computer-readable recording medium or can be transmitted via wire/wireless communication network.
[0160]While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.
[0161]Accordingly, the present invention is applicable to encoding and decoding of an audio signal.
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2010-09-23 Method and an apparatus of decoding an audio signal
2012-07-19 method and an apparatus for processing an audio signal
2012-09-20 Method and an apparatus for processing an audio signal
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