Concepts for auralization using early reflection patterns
The present application concerns early reflection processing concepts for auralization. Embodiments relate to apparatuses and methods for sound rendering considering early reflections and to apparatuses and methods for determining an early reflection pattern.
1 . An apparatus for determining an early reflection pattern for sound rendition, configured to
receive at least one room acoustical parameter which is representative of an acoustical characteristic of an acoustic environment; and
determine an early reflection pattern
which is indicative of a constellation of early reflection positions,
by parameterizing one or more spiral functions centered at a listener position, and placing the early reflection positions using the one or more spiral functions.
2 . The apparatus of claim 1 , wherein the early reflection pattern is for being positioned at the listener position in a manner so that the early reflection positions are located around the listener position and at angular directions from the listener position which are invariant with respect to changes in listener head orientation.
3 . The apparatus of claim 1 , wherein the at least one room acoustical parameter comprises one or more of
room dimensions,
room volume, and
predelay time to a late reverberation.
4 . The apparatus of claim 1 , wherein the at least one room acoustical parameter comprises merely one parameter selected out of
room dimensions,
room volume, and
predelay time to a late reverberation.
5 . The apparatus of claim 1 , wherein the one or more spiral functions comprise a first spiral function and a second spiral function wherein the apparatus is configured to place a first set of early reflection positions using the first spiral function and a second set of early reflection positions using the second spiral function so that each of the first set of early reflection positions is associated with a corresponding early reflection position of the second set of early reflection positions and is positioned on an opposite side of a line perpendicularly crossing a connecting line between the respective early reflection position of the first set of early reflection positions and the corresponding early reflection position of the second set of early reflection positions.
6 . The apparatus of claim 5 , wherein, for each of first set of early reflection positions, the corresponding early reflection position of the second set of early reflection positions is angularly offset relative to the connecting line into an angular direction which is common for all early reflection positions of the first set of early reflection positions.
7 . The apparatus of claim 1 , wherein the one or more spiral functions comprise a first spiral function and a second spiral function wherein the apparatus is configured to place a first set of early reflection positions using the first spiral function and a second set of early reflection positions using the second spiral function so that the first set of early reflection positions is determined in polar coordinates as (r1; β1) and the second set of early reflection positions is determined in polar coordinates as (r2; β2) with
β1
=
n
·
π
3
,
β
2
=
π
8
+
n
·
π
3
,
n
=
[
1
:
nER
/
2
]
base
=
1.85
r
1
=
distfactor
*
base
2
*
β
1
/
π
r
2
=
-
distfactor
*
base
2
*
β
2
/
π
n=[1:nER/2]
wherein nER is a number of early reflection positions and distfactor is a constant.
8 . The apparatus of claim 7 , configured to determine the distfactor based on the at least one room acoustical parameter.
9 . The apparatus of claim 7 , configured to determine the distfactor such that the distfactor is the larger the larger the predelay time to the late reverberation is.
10 . The apparatus of claim 7 , configured to determine the nER based on the at least one room acoustical parameter.
11 . The apparatus of claim 1 , configured to read the at least one room acoustical parameter, from a bitstream comprising a representation of an audio signal to be rendered using the early reflection pattern.
12 . The apparatus of claim 1 , configured to determine a number of early reflection positions so that
the number is larger the larger room dimensions are, or
the number is larger the larger a room volume is, or
the number is larger the larger a predelay time to a late reverberation is.
13 . The apparatus of claim 1 , configured to parametrize the one or more spiral functions and determine a number of early reflection positions so that a distance of a maximally distanced position among the early reflection positions to the listener position is larger
the larger room dimensions are, or
the larger a room volume is, or
the larger a predelay time to a late reverberation is with the distance being smaller than the predelay time.
14 . The apparatus of claim 1 , configured to
support a first determination of the early reflection pattern and a second determination of the early reflection pattern, wherein the first determination is different from the second determination and involves the parameterizing the one or more spiral functions centered at the listener position, and the placement of the early reflection positions using the one or more spiral functions, and
select the first determination in case of the acoustic environment being an indoor environment or in case of a pattern type index in a bitstream comprising a representation of an audio signal to be rendered assuming a predetermined state.
15 . The apparatus of claim 1 , configured to determine the early reflection positions so that the early reflection positions lie in a horizontal plane along with the listener position.
16 . The apparatus of claim 1 , configured to determine the early reflection positions with adjusting an azimuthal rotation of the constellation according to a pattern azimuth parameter in a bitstream comprising a representation of an audio signal to be rendered.
17 . A system for sound rendering, configured to receive first information on the listener position and a sound source position of a sound source; and
render an audio signal of the sound source using a room impulse response whose early reflection portion is determined by the early reflection pattern
which is indicative of the constellation of early reflection positions, and
which is positioned at the listener position in a manner so that the early reflection positions are located around the listener position and at angular directions from the listener position which are invariant with respect to changes in listener head orientation,
the system comprising the apparatus for determining the early reflection pattern according to claim 1 .
18 . The system of claim 17 , further configured to generate a diffuse late reverberation portion of the room impulse response.
19 . The system of claim 17 , further configured to, in rendering the audio signal, generate a set of loudspeaker signals by forming a summation over direct sound contribution loudspeaker signals relating to a direct sound source portion of the room impulse response and early reflection contribution loudspeaker signals relating to the early reflection portion of the room impulse response.
20 . The system of claim 17 , further configured to generate early reflection contribution loudspeaker signals relating to the early reflection portion of the room impulse response by performing a rendition of the audio signal of the sound source from the early reflection positions.
21 . The system of claim 20 , further configured to, in generating the early reflection contribution loudspeaker signals relating to the early reflection portion of the room impulse response by performing the rendition of the audio signal of the sound source from the early reflection positions, render the audio signal of the sound source from each early reflection position in a manner level adjusted according to a distance of the respective early reflection position to the listener position.
22 . The system of claim 21 , further configured to, in rendering the audio signal of the sound source from each early reflection position in a manner level adjusted according to the distance of the respective early reflection position to the listener position,
offset a level at which the audio signal of the sound source is rendered from the respective early reflection position, using a level offset, or amplify the level with a level factor, which offset or factor is common for all early reflection positions, and
set the level offset or level factor according to an amplitude correction factor.
23 . The system of claim 21 , further configured to, in rendering the audio signal of the sound source from each early reflection position in a manner level adjusted according to the distance of the respective early reflection position to the listener position, modify the level adjustment according to the distance of the respective early reflection position to the listener position relative to a level adjustment used by the apparatus for rendering of the audio signal from the sound source positon according to a distance attenuation exponent.
24 . The system of claim 20 , further configured to, in generating the early reflection contribution loudspeaker signals relating to the early reflection portion of the room impulse response by performing the rendition of the audio signal of the sound source from the early reflection positions, render the audio signal of the sound source from each early reflection position in a manner spectrally shaped according to one or more frequency response parameters.
25 . The system of claim 17 , further configured to, in performing the rendition of the audio signal of the sound source from the early reflection positions, use Head Related transfer Functions (HRTFs) specific for a listener head orientation.
26 . A non-transitory computer-readable storage medium including a bitstream configured for being subject to sound rendition according to the system of claim 17 .
27 . A method for determining an early reflection pattern for sound rendition, comprising
receiving at least one room acoustical parameter which is representative of an acoustical characteristic of an acoustic environment; and
determining an early reflection pattern
which is indicative of a constellation of early reflection positions,
by parameterizing one or more spiral functions centered at a listener position, and placing the early reflection positions using the one or more spiral functions.
28 . A method for sound rendering, comprising
receiving first information on the listener position and a sound source position of a sound source; and
rendering an audio signal of the sound source using a room impulse response whose early reflection portion is determined by the early reflection pattern
which is indicative of the constellation of early reflection positions, and
which is positioned at the listener position in a manner so that the early reflection positions are located around the listener position and at angular directions from the listener position which are invariant with respect to changes in listener head orientation,
the method comprising the method for determining the early reflection pattern according to claim 27 .
29 . A non-transitory digital storage medium having stored thereon a computer program for performing a method for sound rendering, comprising receiving first information on the listener position and a sound source position of a sound source; and
rendering an audio signal of the sound source using a room impulse response whose early reflection portion is determined by the early reflection pattern
which is indicative of the constellation of early reflection positions, and
which is positioned at the listener position in a manner so that the early reflection positions are located around the listener position and at angular directions from the listener position which are invariant with respect to changes in listener head orientation,
the method comprising the method for determining the early reflection pattern according to claim 27 ,
when the computer program is run by a computer.
30 . A non-transitory digital storage medium having stored thereon a computer program for performing a method for determining an early reflection pattern for sound rendition, comprising
receiving at least one room acoustical parameter which is representative of an acoustical characteristic of an acoustic environment; and
determining an early reflection pattern
which is indicative of a constellation of early reflection positions,
by parameterizing one or more spiral functions centered at a listener position, and placing the early reflection positions using the one or more spiral functions,
when the computer program is run by a computer.