WO2015173422A1 - Verfahren und vorrichtung zur residualfreien erzeugung eines upmix aus einem downmix - Google Patents
Verfahren und vorrichtung zur residualfreien erzeugung eines upmix aus einem downmix Download PDFInfo
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- G—PHYSICS
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- G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
- G10L19/008—Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
- G10L19/02—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using spectral analysis, e.g. transform vocoders or subband vocoders
- G10L19/022—Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring
Definitions
- the invention relates to a method and a device for the residual-free generation of an upmix from a downmix.
- window function Fourier transformation multiplied by a window function.
- Different windows have different properties. On the one hand, there are windows that have a very high frequency resolution, but only a very poor amplitude resolution, as is the case for the rectangular window, for example.
- window functions like the flat-top window which has a very bad frequency resolution, but has a very good amplitude resolution. In general, however, will be Used window functions, on the one hand have an acceptable frequency and on the other hand an acceptable amplitude resolution, such as the Hamming window. In audio processing, very often the Hamming window is used, which is necessary for both good frequency and good amplitude resolution.
- each window function generates an error in the signal transformed back in time, the residual already mentioned.
- the channel number of an audio or video multichannel signal is reduced by means of a downmix.
- the linear combination of channels for the downmix is performed in the Fourier space, for example to correct the comb filter by phase-shifted signal components in the signals to be summed (WO11057922).
- Hamming window functions are usually used which have the problems described above. Thus, additional information is lost in the downmix that can not be recovered in the upmix. On the other hand, you could avoid this problem if you created the downmix only in the period. However, this does not allow to precisely solve other problems such as the above-described comb filter.
- the use of different window functions for different channels makes it possible to transfer some channels with a high frequency resolution and other channels with a high amplitude information. As a result of the summation of the channels, different information is maintained. This is particularly, but not exclusively, advantageous for channels with similar, in particular harmonic, signal components.
- the flat-top window has proven to be particularly favorable for the second window function. However, other combinations of window functions are possible. The reversal of this principle of operation is also possible: the flat-top window is thus used for the first window function, and for the second window function another window function, for example a Hamming window, which offers an acceptable amplitude and frequency resolution.)
- the object is achieved by an upmixing or coding device with a correlation comparison device, which receives by correlation comparison a correlated signal, a first individual signal and a second individual signal from the two channels of the downmix.
- a correlation comparison device which receives by correlation comparison a correlated signal, a first individual signal and a second individual signal from the two channels of the downmix.
- the correlation comparison separates the common signal components and the individual signal components. Thereafter, by skilfully summing and subtracting the signals of the downmix with the common and individual signal components, the high frequency resolution information and the high amplitude resolution information are divided, and the poorly resolved information is removed by skillful subtraction.
- phase jumps can be completely corrected by skillful multiplication in the Fourier space of these isolated correlated components and by skillful multiplication as well as addition or subtraction over the period.
- FIG. 1 shows an embodiment of a downmixing device in the frequency domain
- FIG. Figure 2 shows a first embodiment of an upmix or coding device
- FIG. 3 shows a second embodiment of an upmixing or coding device
- FIG. 4 shows a downmix device according to the prior art
- FIG. 5 shows an embodiment of the correlation comparison
- FIG. 6 shows an embodiment for an eight-channel upmix signal
- Fig. 7 shows an embodiment for an upmix or coding device for a downmix signal with four channels and an upmix signal with eight channels;
- Fig. 8 shows an embodiment of an upmix or coding device for a downmix signal with four channels and an upmix signal with eight channels;
- Fig. 9 shows an embodiment for an upmix or coding device for a downmix signal with four channels and an upmix signal with eight channels;
- FIG. 10 shows an exemplary embodiment for calculating the level / loudness of the channels of the
- Upmix signal / multichannel signal to adapt the Level / Loudness of the channels of the upmix signal to the level / loudness of the channels of the multichannel signal
- FIG. 11 shows an exemplary embodiment for calculating the level / loudness of the channels of the
- FIG. 12 shows an embodiment of an upmixing or coding device according to FIG. 2 with correction of the spectral discolorations and audible phase jumps.
- FIG. 13 shows a first embodiment of an upmixing or coding device according to FIG. 3 with correction of the spectral discolorations and audible phase jumps.
- FIG. 14 shows a second embodiment of an upmixing or coding device according to FIG. 3 with correction of the spectral discolorations and audible phase jumps.
- Fig. 15 shows a first embodiment of an upmixing or coding device for a downmix signal with four channels and an upmix signal with eight channels with correction of the spectral discolorations and audible phase jumps.
- FIG. 16 shows a second embodiment of an upmix or coding device for a downmix signal with four channels and an upmix signal with eight channels with correction of the spectral discolorations and audible phase jumps.
- FIG. 17 shows an embodiment for an element 170.1, 170.2, 170.3 and 170.4 of FIG. 15.
- FIG. 18 shows an embodiment for an element 180.1, 180.2, 180.3 and 180.1 of FIG. 16.
- Fig. 1 shows an embodiment of a downmixing device 10.
- the downmix device has a
- the Fourier transform device 11 has one for each channel L 0 (t), Ro (t) and C 0 (t)
- Each Fourier unit 11. L, 11. R, 11. C is designed to divide the input signal into preferably equal-length signal windows.
- the window length has 2 n , for example 512, 1024, 2048, 4096, which is particularly well suited for Fourier transformation.
- the signal windows overlap in time. In an alternative embodiment, the signal windows are not overlapping in time.
- Each signal window is in the Fourier unit with a window function multiplied, which has the same length as the signal window.
- a first window function is used in the Fourier unit 11.L and 11.R, while in the Fourier unit 11.C a second window function is used.
- a Hamming window is used for the first window function.
- other window functions could be used for the first window function that provide acceptable amplitude and frequency resolution, eg a Hann window.
- a flat top window is used for the second window function.
- other window functions could be used which have a high amplitude resolution but a low frequency resolution.
- a flat-top window or another window function can be used, which has a high amplitude resolution but a low frequency resolution
- a Hamming window or another window function that provides acceptable amplitude and frequency resolution.
- the invention works particularly well with the described window functions, however, one could also use other different window functions that have different frequency-amplitude resolutions.
- the Fourier units 11. L, 11. R and 11. C respectively output the respective Fourier-transformed channel L 0 (k), Ro (k) and C 0 (k).
- the center channel C 0 (k), each multiplied by 0.5 (-6dB), is added to the side channels L 0 (k) and Ro (k).
- the invention is not limited to this factor. Even a direct sum or any other linear combination would be possible.
- the amplifier 14 is located somewhere between the signal input and the summer in the downmixer 12 in the center channel C 0 (t) or Fourier-transformed center channel C 0 (k) arranged.
- An adaptive method with time-variable amplifier 14 is also possible, for example in order to temporally optimize the frequency resolution for the Fourier-transformed center channel C 0 (k).
- the downmixer 12 has a first downmixer 12 L and a second downmixer 12 R.
- the first downmixer 12 L mixes the Fourier-transformed first side channel L 0 (k) with the multiplied by 0.5 Fourier-transformed center channel C 0 (k) and outputs the Fourier-transformed first channel L D (k) of the downmix signal.
- the second downmixer 12. R mixes the Fourier-transformed second side channel R 0 (k) with the 0.5 multiplied Fourier-transformed center channel C 0 (k) and outputs the Fourier-transformed second channel Stud (k) of the downmix signal.
- the first downmixer 12 L mixes the Fourier-transformed first side channel L 0 (k) with the multiplied by 0.5 Fourier-transformed center channel C 0 (k) and outputs the Fourier-transformed first channel L D (k) of the downmix signal.
- the second downmixer 12. R mixes the Fourier-transformed second side channel R 0 (k) with the
- the first downmixer performs the function
- R D (k) R 0 (k) + 0.5 * C 0 (k)
- a phase correction is additionally performed in the first downmixer 12.L and the second downmixer 12.R, which avoids or reduces a comb filter.
- the amplitude of the complex number L D (k) or R D (k) is adjusted so that applies
- R D (k) 2 R 0 (k) 2 + 0.5 2 * C 0 (k) 2
- the inverse Fourier transformation device 13 has for each channel L D (k) and R u (k) each an inverse Fourier transform unit 13. L, 13. R, which is in each case suitable, an inverse Fourier transform (IFT) of the input signal L D (k) or R ü (k) and output (or process) the channels L D (t) or R u (t) of the downmix signal.
- IFT inverse Fourier transform
- This is preferably an Inverse Discrete Fourier Transform (IDFT), in particular an Inverse Fast Fourier Transform (IFFT).
- Each signal window of L D (k) and R u (k) is multiplied in the inverse Fourier units 13. L and 13. R with the Fourier-transformed first window function (NB in the above-described reversal of the principle of operation: with the second window function) already in the Fourier units 11. L and 11. R (NB in the above-described reversal of the principle of action: in the Fourier unit 11. C).
- FIG. 2 shows a first embodiment of the upmixing or coding device 20.
- the upmixing or coding device 20 has a Fourier transformation device 21, a correlation comparison device 22, a Correction device 29 and a fourth
- the Fourier transform device 21 comprises a first and a second Fourier transform unit 21. L and 21. R.
- the Fourier transformation device 21 is designed to transform a first channel L D (t) and a second channel R u (t) of a downmix signal into Fourier space.
- the channels L D (t) and R u (t) are also subdivided into signal windows and then the respective signal windows are transformed into Fourier space.
- each signal window is multiplied by a window function.
- the first (NB in the above-described reversal of the principle of effect: second) window function from the Fourier transformation device 11 is used as a window function.
- the Fourier transform device 21 outputs the
- the channels L D (k) and R u (k) of the downmix signal are supplied to the correlation comparison device 22.
- the correlation comparison device 22 is embodied, the correlated signal components of the channels L D (k) and R u (k) of the downmix signal, the signal components specific to only the first channel L D (k) and the signal components specific to only the second channel R ü (k) to extract.
- the correlation comparison device 22 is formed from the correlated signal components, the correlated signal C K (k), from the first channel L D (k) specific signal components, the first individual signal L K (k) and from the second channel R D (k ) specific signal components to form the second individual signal R K W ZU.
- a method for determining the correlated and specific signal components of channels L D (k) and R u (k) will be described later with FIG. 5. However, any other method for determining the correlated and specific proportions is possible.
- the correction device 29 has a first one
- Signal processing device 24 a third signal processing device 25.
- the first signal processing device 23 receives the first channel L D (k) of the downmix signal, the correlated signal
- Signal processing device 23 is configured to form the following formed first signal S L (k):
- the second signal processing device 24 receives the second channel R ü (k) of the downmix signal, the correlated signal C K (k) and the second individual signal RKW.
- the third signal processing device 25 receives the first channel L D (k) and the second channel R ü (k) of the downmix signal, the correlated signal C K (k), the first individual signal L K (k) and the second individual signal R K (k).
- the third signal processing device 25 is configured to form the following formed third signal S c (k):
- the fourth signal processing device 28 includes the inverse Fourier transform device 26 and the fifth signal processing device 27.
- the inverse Fourier transformation device 26 is embodied, the first signal S L (k), the second signal S R (k), the third signal S c (k), the correlated signal C K (k), the first individual signal L K ( k) and the second individual signal R K W by applying an inverse
- the inverse Fourier transform device 26 comprises a first inverse Fourier transform unit 26 SL, a second inverse Fourier transform unit 26 SR, a third inverse Fourier transform unit 26 SC, a fourth inverse Fourier transform unit 26 LK, a fifth inverse Fourier transform unit 26 RK, a sixth inverse Fourier transform unit 26 CK on.
- the first inverse Fourier transform unit 26 is a first inverse Fourier transform unit 26 SL, a second inverse Fourier transform unit 26 SR, a third inverse Fourier transform unit 26 SC, a fourth inverse Fourier transform unit 26 LK, a fifth inverse Fourier transform unit 26 RK, a sixth inverse Fourier transform unit 26 CK on.
- the first inverse Fourier transform unit 26 is a first inverse Fourier transform unit 26 SL, a second inverse Fourier transform unit 26 SR, a third inverse Fourier transform unit 26 SC, a fourth inverse Fourier transform unit 26 LK, a fifth inverse Fourier transform unit 26 RK,
- SL is designed to Fourier-transform the first signal S L (k) inversely into the first signal S L (t).
- SR is designed to Fourier-transform the second signal S R (k) inversely into the second signal S R (t).
- SC is configured to Fourier-transform the third signal S c (k) inversely into the third signal S c (t).
- LK is designed to Fourier-transform the first individual signal L K (k) inversely into the first individual signal L K (t) during the time period.
- RK is designed the second individual signal Ric (k) inversely transforms into the second individual signal Ric (t) in the period to Fourier ⁇ .
- CK is designed to Fourier transform the correlated signal C K (k) inversely into the correlated signal C K (t) in the time domain.
- the fifth signal processing device 27 receives the following Fourier transformed signals: the first signal S L (t), the second signal S R (t), the third signal S c (t), the correlated signal C K (t), the first one individual signal L K (t) and the second individual signal R K (t).
- the fifth signal processing device 27 processes these signals into three output signals as follows:
- Cu (t) (S c (t) + R K (t) + L K (t)) * 0.3548.
- gain 0.3548 other gains or gains 0.3 or 0.35 can also be used.
- gains for all signals depending on the original level or the loudness of the corresponding channels of the multi-channel signal as will be described in detail later.
- These three output signals are used as three channels of an upmix signal or further processed into three channels of an upmix signal.
- linear arithmetic operations after the correlation comparison can be performed both in the period and in the Fourier space; thus, further equivalent embodiments are possible. They form part of the invention.
- FIG. 3 shows a second embodiment of the upmixing or coding device 40.
- the upmixing or coding device 40 has a Fourier transform device 4 1, a correlation comparison device 4 2, a
- Correlation comparison device 4 2 correspond to the Fourier transform device 2 1 and the
- Correlation comparison device 2 2 of the first embodiment Correlation comparison device 2 2 of the first embodiment.
- the correction device 4 9 has a first
- the first signal processing device 4 3 receives the first channel L D (k) of the downmix signal, the correlated signal
- the first signal processing device 4 3 is configured to form the first signal L 0 (k) formed as follows:
- the second signal processing device 4 4 receives the second channel R u (k) of the downmix signal, the correlated signal C K (k) and the second individual signal RK W.
- the second signal processing device 4 4 is configured to form the second signal Ru (k) formed as follows:
- R u (k) 2 * R k (k) -R D (k) + 2 * C K (k)
- the third signal processing device 4 5 receives the first channel L D (k) and the second channel R u (k) of the downmix signal, the correlated signal C K (k), the first one individual signal L K (k) and the second individual signal R K (k).
- the third signal processing device 45 is configured to form the following formed third signal Cu (k):
- Cu (k) 2 * (L k (k) + R k (k)) -L D (k) -R D (k) + 4 * C K (k).
- the fourth signal processing device 48 has the inverse Fourier transformation device 46.
- the inverse Fourier transformation device 46 is designed to transform the first individual signal L 0 (k), the second individual signal Ru (k) and the correlated signal Cu (k) into the period by applying inverse Fourier transformation.
- the fourth signal processing device 48 may also include a fifth signal processing device that multiplies Cu (k) or Cu (t) by a gain of 0.3548 (or 0.3 or 0.35 or other gain). Also, for all signals, gains may be used in response to the original level or loudness of the corresponding channels of the multi-channel signal, as will be described in detail later. These three output signals are used as three channels of an upmix signal or further processed into three channels of an upmix signal.
- Coding device 40 has the same advantage as the first embodiment that by clever adding and subtracting of the different signals, a higher frequency and amplitude resolution is achieved for the downmix signals generated with the different window functions.
- the second embodiment of the upmix or coding device 40 has the same advantage as the first embodiment, that it is the phase jumps caused by the Fourier transforms and / or the
- Correlation comparison device 42 arise, equally eliminated.
- this embodiment 40 can also be used for downmix signals that were not generated by a downmixing device 10 having different window functions. This could e.g. the downmix device 10, using two identical window functions instead of two different window functions. Alternatively, this embodiment is also suitable for a downmix that was created in the time domain.
- Fig. 4 shows an embodiment of the prior art of a downmixing device in the time domain.
- K 0.5 (-6dB)
- the embodiment is not limited to this factor. Even a direct sum or any other linear combination would be possible.
- a so-called phase alignment can also be performed in which, depending on the frequency, the phase of at least one of the input signals L 0 (t), Ro (t) and C 0 (t) is shifted in the time domain.
- FIG. 5 shows an exemplary embodiment for a correlation comparison of two signals Li 'and R ⁇ ', in which respectively identical signal components x (t) and y (t) are determined for which the short-term cross-correlation [x ⁇ t) y ⁇ t) dt * 1 -
- time-invariant (stationary) signals is a mathematically accurate solution, and in time-variant (non-stationary) signals has a specific residual behavior (where a residual the difference between the original, non-stationary signal section and its Fourier transform represents).
- Li '(k) is based on this maximum, the result of this subtraction as an imaginary part for Li (k), otherwise, if the imaginary part of Ri' (k) underlies this maximum, the result of this subtraction as an imaginary part for R ⁇ (k).
- Ci (fc) ⁇ Ci (m) e N
- the spectral components are preferably calculated only up to the Nyquist frequency, and the remaining spectral components are determined by mirroring the already calculated values at the Nyquist frequency, using only the complex conjugate components instead of the calculated components.
- the imaginary parts must be deleted.
- the embodiments of the upmixing or coding apparatus 20 and 40 only show the mode of operation for the non-residue determination of an upmix signal with three channels from a downmix signal with two channels. However, it is also possible that only one or only two of the three channels Cu (t) or Cu (k), L 0 (t) or L 0 (k) and Ru (t) or Ru (k) are determined (see eg Fig. 7 to 9). Accordingly will / will even one or two of them
- the embodiments of the upmixing or coding device 20 and 40 only show the function for non-residue determination for a multi-channel signal / upmix signal with three channels and a downmix signal with two channels. However, this embodiment can also be used for multi-channel signals / upmix signals with higher channel number.
- 6 shows an exemplary embodiment of a downmix signal with four channels, eg FL D , FR D , BR D and BL D. From this, an upmix signal with the eight channels FL 0 , FCu, FRu, SiRu, BRu, BCu, BL 0 and SiLu is to be determined.
- FIG. 7 shows a possible embodiment of an upmixing or coding device 80 for determining the upmix signal by applying the four upmixing or coding devices 81.1, 81.2, 81.3 and 81.4 to the four adjacent signal pairs FL D -FR D , FR D -BR D , BR D -BL D and BL D -FL D.
- the four upmixing or coding devices 81.1, 81.2, 81.3 and 81.4 may, for example, be designed as shown in FIG. 2 or 3. However, any other embodiment that falls within the scope of the invention is possible.
- the channels FL 0 , BL 0 and SiLu of the upmix signal from the application of the upmixing or coding devices 81. 1 to the signal pair BL D- FL D are determined.
- the channel FCu of the upmix signal is determined from the application of the upmix or coding devices 81.2 to the signal pair FL D -FR D.
- the channels FR 0 and SiRu of the upmix signal are determined from the application of the upmix or coding devices 81.3 to the signal pair FR D -BR D.
- the channels BR 0 and BCu of the upmix signal are determined from the application of the upmixing or coding devices 81.4 to the signal pair BR D -BL D. Since the corner signals or side signals FL 0 , FR 0 , BR 0 and BL 0 each determine from the two adjacent signal pairs leave, the corner signal must always be determined only by one of the two possible signal pairs.
- each upmix or coding device 81.1, 81.2, 81.3 and 81.4 must determine the corresponding center channel FCu, SiRu, BCu, or SiLu, which is determined from the input signal pair.
- the distribution which determines the upmix or coding devices 81.1, 81.2, 81.3 and 81.4, the side signals, is arbitrary. Thus, only two output signals or only the central channel between the signal pair can be calculated here by the upmixing or coding device 20 or 40 if one or both of the side channels of the signal pair is determined by both adjacent signal pairs or by an adjacent signal pair.
- FIG. 8 shows another possible embodiment of an upmixing or coding device 90 for determining the upmix signal by applying the four upmixing or coding devices 91.1, 91.2, 91.3 and 91.4 to the four adjacent signal pairs BL D -FL D , FL D -FR D , FR D -BR D and BR D -BL D.
- the four upmix or coding devices 91.1, 91.2, 91.3 and 91.4 here correspond to the four upmixing or coding devices 81.1, 81.2, 81.3 and 81.4.
- the corrected from the four upmix or encoders 91.1, 91.2, 91.3 and 91.4 issued central channels K FC, BC SiR K K K SiL and by a second factor B to produce the proper relationship to the side channels.
- FCu A * B * FC K ,
- FRU FR K - B * FC K
- SiRu A * B * SiR K ,
- gains can also be predefined for the side channels FL K , FR K , BR K or BL K output by an upmixing or coding device 91.1, 91.2, 91.3 or 91.4 and / or or or after the subtractors 95.1, 95.2, 95.3 and 95.4, or also immediate gains for the central channels FC K , SiR K , BC K and SiL K output from the four upmix or coding devices 91.1, 91.2, 91.3 and 91.4 immediately before the subtractors 95.1, 95.2, 95.3 and 95.4.
- Gains can be omitted in whole or in part or multiples of the specified signals are formed. All of these embodiments should be considered part of the invention.
- the correction of the side channels depends on which side channels were calculated with which channel pairs. It is particularly the correction of the center channels in the upmixing or coding device 20, 40, 81.1 to 81.4 or 91.1 to 91.4 that these signal components of the side channels R D and L D of the downmix signal and the side channels R K and L K of the correlation comparison for the correction of the center channel C K of the correlation comparison.
- the output Cu of the upmixing or coding device 20 or 40, or the outputs FC K , SiR K , BC K and SiL K of the upmixing or coding device 81.1 to 81.4 or 91.1 to 91.4 thus also contain signal components of the corner channels. This has the effect that the center channels have common parts, and it comes by so-called crosstalk, for example, no clean formation of phantom sound sources. Therefore, in another possible embodiment of an upmix or
- Encoding device 100 proposed to free the center channels of the common signal portions with adjacent center channels.
- the four upmixing or coding devices 101.1, 101.2, 101.3 and 101.4 here correspond to the four upmixing or coding devices 91.1, 91.2, 91.3 and 91.4.
- the gains 103.1, 103.2, 103.3 and 103.4 and the gains 104.1, 104.2, 104.3 and 104.4 correspond to the gains 93.1, 93.2, 93.3 and 93.4 and the gains 94.1, 94.2, 94.3 and 94.4.
- the subtractors 105.1, 105.2, 105.3 and 105.4 correspond to the subtractors 95.1, 95.2, 95.3 and 95.4.
- a correlation comparison 102.1, 102.2, 102.3 or 102.4 is now carried out for each adjacent pair of center channels in order to find out the correlated components Ki, K 2 , K 3 or K 4 .
- the corresponding center channels FC K , SiR K , SiL K or BC K are corrected by the corresponding correlated components Ki, K 2 , K 3 or K 4 .
- the correlation devices 102.1, 102.2, 102.3 or 102.4 correspond to the correlation devices 22 or 42, wherein only the correlated proportion is spent.
- the correlation devices 102.1, 102.2, 102.3 or 102.4 can determine the correlated component directly in the frequency domain without further FT and IFT, as described with FIG. 5.
- the center channels are corrected as follows:
- BC ⁇ BC K - K 2 ,
- FC ' FC K - K 4 .
- a first correlated signal Ki of an adjacent pair FC K -SiR K of the center channels is determined directly from the center channels FC K and SiR K output from the upmix or coding devices 101.2 and 101.3.
- the further specific correlated signals K 2 , K 3 and K 4 are preferably obtained by a center channel output by the upmixing or coding devices 101.1, 101.2, 101.3 and 101.4 and by one of the already correlated signals Ki, K 2 , K 3 or K 4 corrected center channels.
- the order and signal pair that is started are irrelevant. However, according to the above considerations, it is advantageous if only the correlated signal from adjacent center channels is calculated.
- the channels of the upmix signal result in this embodiment
- SiLu A * B * (SiL K - K 3 ),
- FCu A * B * (FC K - K 4)
- Fru FR K - B * (FC K - K 4)
- SiRu A * B * (SiR K - Ki),
- BCu A * B * (BC K - K 2 ).
- the resulting channels of an upmix signal e.g. by the upmix or
- Coding device (s) 20, 40, 80, 90 or 100 certain channels, are adapted by Gain or a gain that depends on the level or the loudness of the original multi-channel signal or the sum of its amplitude spectrum / depends.
- Gain or a gain that depends on the level or the loudness of the original multi-channel signal or the sum of its amplitude spectrum / depends.
- methods are described in order to adapt the level / loudness or the sum of the amplitude spectrum of the upmix signal to the original multi-channel signal.
- the following methods can also be applied to other upmix signals or multi-channel signals.
- This original level or the original cloudness or the sum of the original amplitude spectrum for example, mitübertrag with the downmix signal.
- a problem remains, however, that in Fig. 2 and Fig.
- FIG. 12 represents a variant embodiment of FIG. 2:
- the Fourier transform device 21 comprises a first and a second Fourier transform unit 21. L and 21. R.
- the Fourier transformation device 21 is designed to transform a first channel L D (t) and a second channel R u (t) of a downmix signal into Fourier space.
- the channels L D (t) and R u (t) are also subdivided into signal windows and then the respective signal windows are transformed into Fourier space.
- each signal window is multiplied by a window function.
- the first (NB in the above-described reversal of the principle of effect: second) window function from the Fourier transformation device 11 is used as a window function.
- the Fourier transform device 21 outputs the
- the channels L D (t) and R u (t) are newly used to calculate the individual signal components.
- the channels L D (k) and R u (k) of the downmix signal are supplied to the correlation comparison device 22.
- Correlation comparison device 22 is designed to correlate the signal components of the channels L D (k) and R u (k) of the downmix signal, which are specific only to the first channel L D (k) Signal components and the only the second channel R ü (k) specific signal components to extract.
- Correlation comparison device 22 is embodied, from the correlated signal components, the correlated signal C K (k), from the signal components specific to the first channel L D (k), the first individual signal L K (k) and from the second channel R D (k) specific signal components to form the second individual signal R K W ZU.
- the correlated signal C K (k) from the signal components specific to the first channel L D (k), the first individual signal L K (k) and from the second channel R D (k) specific signal components to form the second individual signal R K W ZU.
- the correction device 129 has a signal processing device 25 and a
- Correction device 139 on. It further transfers the correlated signal C K (k) multiplied by a factor C in the Fourier space, the factor C corresponding, for example, to a decrease of -9 dB, the first individual signal L K (k) and the second individual signal R K W It also supplies the correlated signal C K (k), the first individual signal L K (k) and the second individual signal R K W to the correction device 139.
- the signal processing device 25 receives the first channel L D (k) and the second channel R ü (k) of the downmix signal, the correlated signal C K (k), the first individual signal L K (k) and the second individual signal R K W ,
- the third signal processing device 25 is configured to form the following formed third signal S c (k):
- Fourier transformation device 126 passed.
- the correction device 139 determines the correlated component K2 of all output signals of the correlation comparison device 22. For example, a correlation comparison 112.1 is performed for the correlated signal C K (k) and the first individual signal L K (k) to find out the correlated component Ki, and then for Ki and the second individual signal Ric (k) performs a correlation comparison 112.2 to find out the correlated fraction K2. Alternative signal combinations and correlation comparisons to determine K2 are possible. Subsequently, K2 is multiplied by a factor C in the Fourier space, wherein the factor C corresponds, for example, to a reduction of -9 dB. The result C * K 2 (k) is then passed to the inverse Fourier transformation device 126.
- the fourth signal processing device 128 includes the inverse Fourier transform device 126 and the signal processing device 127.
- the inverse Fourier transformation device 126 is formed, the signal S c (k), the correlated signal C * C K (k), the first individual signal L K (k), the second individual signal Ric (k) and the output signal of the correction device C * Transform K 2 (k) into the period by applying an inverse Fourier transform.
- the corresponding signal window is multiplied by a window function.
- the inverse Fourier transformation device 126 has a first inverse Fourier transformation unit 126.
- SC a second inverse Fourier transformation unit 125. CK, a third inverse Fourier transformation unit 126. LK, a fourth inverse Fourier transformation unit 126. RK and a fifth inverse Fourier transformation unit 126. CKK.
- the first inverse Fourier transform unit 126. SC is designed to Fourier-transform the first signal S c (k) inversely into the first signal S c (t).
- the second inverse Fourier transform unit 126. CK is adapted to transform the second individual signal K C (k) inverse in the second individual signal C K (t) over the period to Fourier ⁇ .
- LK is formed, the third individual signal L K (k) inverted in the third individual signal L K (t) over the period to Fourier transform ⁇ .
- the fourth inverse Fourier transform unit 126. RK is formed, the fourth individual signal RKW inversely in the fourth individual signal RK (t) over the period to Fourier transform ⁇ .
- the fifth inverse Fourier transform unit 126. CKK is configured to Fourier-transform the fifth signal C * K2 (k) inversely into the fifth individual signal (C * K 2 (k)) (t) over time.
- the fifth signal processing device 127 receives the following signals in the period: the first signal S c (t), the correlated signal (C * C K (k)) (t), the first individual signal L K (t), the second individual signal RK (t) and the output signal (C * K 2 (k)) (t) of the correction device 139.
- the signal processing device 127 processes the signals just described into three output signals as follows, wherein K describes another factor which ideally equals gain 14 of FIG. 1 or gain 54 of FIG. 4:
- linear arithmetic operations after the correlation comparison can be performed both in the period and in the Fourier space; thus, further equivalent embodiments are possible. They form part of the invention.
- FIG. 13 simultaneously solves both of these problems and represents a variant embodiment of FIG. 3:
- the Fourier transformation device 41 comprises a first and a second Fourier transformation unit 21. L and 21. R.
- the Fourier transformation device 41 is designed to transform a first channel L D (t) and a second channel R u (t) of a downmix signal into the Fourier space.
- the channels L D (t) and R u (t) are also subdivided into signal windows and then the respective signal windows are transformed into Fourier space.
- each signal window is multiplied by a window function.
- the first (NB in the above-described reversal of the principle of effect: second) window function from the Fourier transformation device 11 is used as a window function.
- the Fourier transform device 41 outputs the
- the channels L D (t) and R u (t) are newly used to calculate the individual signal components.
- the channels L D (k) and R u (k) of the downmix signal are supplied to the correlation comparison device 42.
- Correlation comparison device 42 is designed to determine the correlated signal components of the channels L D (k) and R u (k) of the downmix signal, the signal components specific to only the first channel L D (k) and those specific to only the second channel R ü (k) Extract signal components.
- Correlation comparison device 42 is configured, from the correlated signal components, the correlated signal C K (k), from the signal components specific to the first channel L D (k), the first individual signal L K (k) and from the second channel R D (k) specific signal components form the second individual signal RK WZU.
- a method of determining the correlated and specific signal portions of channels L D (k) and R D (k) see Figure 5. However, any other method for determining the correlated and specific proportions is possible.
- the correction device 149 has a
- the signal processing device 45 receives the first channel L D (k) and the second channel Hin (k) of the downmix signal, the correlated signal C K (k), the first individual signal L K (k) and the second individual signal RK W.
- the third signal processing device 45 is configured to form the following formed third signal S c (k):
- Cu (k) 2 * (L k (k) + R k (k)) -L D (k) -R D (k) + 4 * C K (k).
- the third signal Cu '(k) is multiplied by a factor C in the Fourier space, the factor C, for example, one Lowering by -9dB corresponds to the inverse
- Fourier transformation device 146 passed.
- the correction device 139 determines the correlated component K2 of all output signals of the correlation comparison device 42. For example, a correlation comparison 122.1 is performed for the correlated signal C K (k) and the first individual signal L K (k) to find out the correlated component Ki, and then for Ki and the second individual signal Ric (k) performs a correlation comparison 122.2 to find out the correlated fraction K2. Alternative signal combinations and correlation comparisons to determine K2 are possible.
- K2 is multiplied by a factor C in the Fourier space, wherein the factor C corresponds, for example, to a reduction of -9 dB.
- the result C * K 2 (k) is then transferred to the inverse Fourier transformation device 146.
- the fourth signal processing device 148 includes the inverse Fourier transform device 146 and the fifth signal processing device 147.
- the inverse Fourier transform device 146 is configured to have the first corrected output of the signal processing device 45, C * C'u (k), the second correlated signal C * C K (k) and the third corrected output of the correcting device 139, C * K 2 (k ) to transform into the period by applying an inverse Fourier transform. For each of the three inverse Fourier transforms, the corresponding signal window is multiplied by a window function. Preferably, with the first (NB in the above-described reversal of the principle of action: second) window function.
- the inverse Fourier transform device 146 comprises a first inverse Fourier transform unit 146.
- the first inverse Fourier transform unit 146. CU is configured to Fourier-transform the first signal C * C'u (k) inversely into the first signal (C * Cu '(k)) (t).
- the second inverse Fourier transform unit 146. CK is designed to Fourier-transform the second signal C * C K (k) inversely into the second signal (C * C K (k)) (t) during the time period.
- the CKK is configured to Fourier-transform the third signal C * K2 (k) inversely into the third signal (C * K 2 (k)) (t) during the time period.
- the fifth signal processing device 147 receives the following signals in the time period: the correlated signal (C * Cu '(k)) (t), the correlated signal (C * C K (k)) (t) and the output signal (C * K 2 (k)) (t) of the correction device 139.
- Correlation comparison device 42 for the determination of correlated fractions according to 1439.1 and 1439.2 as
- Embodiment shows the Figure 14, in which the Upmix- or coding 1440 a
- Signal processing device 158 has.
- Correlation comparison device 42 correspond to Fourier transform device 41 and FIG.
- the correction device 159 has a first signal processing device 43, a second signal processing device 44 and a third one
- Signal processing device 45 on. These correspond to the first signal processing device 43, the second signal processing device 44 and the third
- the correction device 159 has a fourth correction device 1439.1 and a fifth
- the correction device 159 multiplies the output signal of the signal processing device 45 by a factor C im Fourier space, where the factor C corresponds, for example, to a decrease of -9 dB, on the one hand gives the result of the inverse Fourier transformer 156, and on the other hand multiplies it by a factor K which ideally equals the gain 14 of FIG. 1 or the gain 54 of FIG. 4 is.
- the result is added to the output signal of the signal processing device 43 and then transferred to the correction device 1439.1.
- the correction device 1439.1 performs a correlation comparison on the input signals to find out the correlated component Ki '. Subsequently, this correlated component Ki 'is multiplied by a factor C in Fourier space, wherein the factor C corresponds, for example, to a reduction of -9 dB. The resulting signal becomes the inverse
- the correction device 1439.2 performs a correlation comparison on the input signals in order to find out the correlated component K 2 '. Subsequently, this correlated component K 2 'is multiplied by a factor C in the Fourier space, wherein the factor C corresponds, for example, to a reduction by -9 dB. The resulting signal is also supplied to the inverse Fourier transform device 156.
- the fourth signal processing device 158 includes the inverse Fourier transform device 156 and the fifth signal processing device 157.
- the inverse Fourier transformation device 156 is formed, the first corrected output signal of the signal processing device 45, C * C'u (k), the second output signal of the correction device 1439.1, C * Ki '(k), and the third output signal of the correction device 1439.2, C * K 2 '(k) to transform into the period by applying an inverse Fourier transform.
- the corresponding signal window is multiplied by a window function.
- the first (NB in the above-described reversal of the principle of action: second) window function Preferably, with the first (NB in the above-described reversal of the principle of action: second) window function.
- the inverse Fourier transformation device 156 has a first inverse Fourier transformation unit 156. CU, a second inverse Fourier transformation unit 156. CK1 and a third inverse Fourier transformation unit 156. CK2.
- the first inverse Fourier transform unit 156. CU is configured to Fourier-transform the first signal C * C'u (k) inversely into the first signal (C * Cu '(k)) (t).
- the second inverse Fourier transform unit 156. CK1 is configured to Fourier-transform the second signal C * Ki '(k) inversely into the second signal (C * Ki' (k)) (t) over time.
- the third inverse Fourier transform unit 156. CK2 is designed to Fourier-transform the third signal C * K 2 '(k) inversely into the third signal (C * K 2 ' (k)) (t) over time.
- the fifth signal processing device 157 receives the following signals in the time period: the correlated signal (C * Cu '(k)) (t), the correlated signal (C * Ki' (k)) (t) and the output signal (C * K 2 '(k)) (t) of the correction device 159.
- Signal processing device 157 processes the signals just described into three output signals as follows, where K describes another factor, ideally equal to gain 14 of FIG. 1 or gain 54 of FIG. 4, and L another factor, where the factor L corresponds to a reduction of -6dB, for example:
- Lu (t) L * ((1-C) * L D (t) -C * (C * Ki '(k)) (t))
- an upmixing or coding device 1500 of FIG. 15 is proposed, which on the one hand the center channels of their common Signal component freed, and on the other hand eliminates these audible phase jumps.
- Fig. 15 determines the upmix signal by applying the four upmix or coding devices 170.1, 170.2, 170.3 and 170.4 to the four adjacent signal pairs BL D -FL D , FL D -FR D , FR D -BR D and BR D -BL D.
- the Fourier transform device 161 is designed to transform the first input signal FL D , the second input signal FR D , the third input signal BR D and the fourth input signal BL D into the Fourier space by applying a Fourier transformation. For each of the three Fourier transforms, the corresponding signal window is multiplied by a window function. Preferably, with the first (NB in the above-described reversal of the principle of action: second) window function.
- the Fourier transformation device 161 has a first inverse Fourier transformation unit 161, BL, a second Fourier transformation unit 161, FL, a third Fourier transformation unit 161, FR and a fourth Fourier transformation unit 161, BR.
- BL is designed to Fourier-transform the first input signal BL D (t) into the first signal BL D (k).
- the second Fourier transform unit 161. FL is designed to Fourier-transform the second input signal FL D (t) into the second signal FL D (k).
- FR is configured to Fourier-transform the third input signal FR D (t) into the third signal FR D (k).
- BR is designed to Fourier-transform the fourth input signal BR D (t) into the fourth signal BR D (k).
- the input signal of the upmix or coding device 170.1 is the signal pair BL D (k) -FL D (k).
- the input signal of the upmix or coding device 170.2 is the signal pair FL D (k) -FR D (k).
- the input signal of the upmix or coding device 170.3 is the signal pair FR D (k) -BR D (k).
- the input signal of the upmix or coding device 170.4 is the signal pair BR D (k) -BL D (k).
- the four upmix or coding devices 170.1, 170.2, 170.3 and 170.4 correspond to the upmixing or coding devices 170.1, 170.2, 170.3 and 170.4 shown in FIG. 17, respectively.
- Fig. 17 shows for the first channel L D (k) and the second channel R D (k) of the downmix signal in the Fourier space a
- Correlation comparison device 42 see FIG. 3, and a correction device 49 on.
- the correction device 49 has a signal processing device 45.
- the signal processing device 45 receives the first channel L D (k) and the second channel R ü (k) of the downmix signal, the correlated signal C K (k), the first individual signal L K (k) and the second individual signal RKW.
- the output signal Cu '' (k) of the signal processing device 45 is multiplied by a factor C in the Fourier space, the factor C corresponding to a decrease of -9dB, for example, and gives the respective output signal for the upmixing or coding devices 170.1, 170.2, 170.3 and 170.4.
- the output signal of the upmixing or coding device 170.1 is the signal S S iL (k).
- the output of the upmix or coding device 170.2 is the signal S F c (k).
- the Output signal of the upmix or coding device 170.3 is the signal S S iR (k).
- the output of the upmix or coding device 170.4 is the signal S B c (k).
- the output signals S S iL (k), S F c (k), S S iR (k) and S B c (k) are supplied to the inverse Fourier transform device 166.
- the correlation comparison 102.1 is performed for the signal pair S F c (k) -Ssi R (k) to find out the correlated component Ki.
- a correlation comparison 102.2 is carried out for Ki and S B c (k) in order to find out the correlated fraction K 2 .
- a correlation comparison 102.3 is carried out for K 2 and S S iL (k) in order to find out the correlated fraction K 3 .
- a correlation comparison 102.4 is carried out for K 3 and S F c (k) in order to find out the correlated fraction K 4 .
- Alternative signal combinations and correlation comparisons to determine K 4 are possible.
- K 4 is multiplied by a factor C in Fourier space, where the factor C corresponds, for example, to a reduction of -9 dB.
- C * K 4 (k) is passed to the inverse Fourier transform device 166.
- a correlation comparison 162.1 is performed on the first input signal FL D (k) in the Fourier space and the third input signal BR D (k) in Fourier space in order to find out the correlated component K 5 .
- a correlation comparison 162.2 is performed on the second input signal FR D (k) in the Fourier space and the fourth input signal BL D (k) in Fourier space in order to find out the correlated component Ke.
- a correlation comparison 162.3 is performed on K 5 and Ke in order to find out the correlated fraction K 7 .
- Alternative signal combinations and correlation comparisons to determine K 7 are possible.
- K 7 is multiplied by a factor C in the Fourier space, the factor C, for example, a reduction of -9dB equivalent.
- C * 7 (k) is sent to the inverse
- Fourier transform device 166 passed.
- the inverse Fourier transformation device 166 is formed, the first correlated signal S S iL (k), the second correlated signal S F c (k), the third correlated signal S si R (k), the fourth correlated signal S B c (k) to transform the fifth output of the correlation comparison 102.4, C * K 4 (k), and the sixth output of the correlation comparison 162.3, C * K 7 (k), into the period by applying an inverse Fourier transform.
- the corresponding signal window is multiplied by a window function.
- the inverse Fourier transformation device 166 comprises a first inverse Fourier transformation unit 166.
- SIL a second inverse Fourier transformation unit 166.
- FC a third inverse Fourier transformation formation unit 166, SIR, a fourth inverse Fourier transformation unit 166, BC, a fifth inverse Fourier transformation unit 166, K4 and a sixth inverse Fourier transformation unit 166 K7 on.
- SIL is designed to Fourier-transform the first signal S S iL (k) inversely into the first signal S S iL (t).
- the second inverse Fourier transformation unit 166 is designed to Fourier-transform the first signal S S iL (k) inversely into the first signal S S iL (t).
- FC is configured to Fourier-transform the second signal S F c (t) inversely into the second signal S F c (t) during the time period.
- SIR is designed to Fourier-transform the third signal S S iR (k) inversely into the third signal S S iR (t) during the time period.
- BC is designed to Fourier-transform the fourth signal S B c (k) inversely into the fourth individual signal S ⁇ c (t) in the time domain.
- the fifth inverse Fourier transform unit 166 is configured to Fourier-transform the second signal S F c (t) inversely into the second signal S F c (t) during the time period.
- SIR is designed to Fourier-transform the third signal S S iR (k) inversely into the third signal S S iR (t) during the time period.
- BC
- K4 is designed the fifth signal C * K 4 (k) inversely into the fifth signal (C * K 4 (k)) (t) in the period to Fourier transform.
- K7 is designed to Fourier-transform the sixth signal C * 7 (k) inversely into the sixth signal (C * K 7 (k)) (t) during the time period.
- FC u (t) S FC (t) - C * ((C * K 4 (k)) (t) - (C * K 7 (k)) (t)))
- SiR u (t) SsiR (t) -C * ((C * K 4 (k)) (t) - (C * K 7 (k)) (t)))
- BC u (t) S BC (t) -C * ((C * K 4 (k)) (t) - (C * K 7 (k)) (t)))
- the individual page signals in the period BL u (t), FL u (t), FR U (t) and BR u (t) by means of the gains 163.1, 163.2, 163.3 and 163.4 with a factor K, ideally equal to the gain 14 of FIG. 1 or the gain 54 of FIG.
- the resulting channels of the upmix signal BL u (t), SiL u (t), FL u (t), FC u (t), FR u (t) SiR u (t), BR u (t) and BC u (t) can be adjusted by gains which are different from the level or loudness of the original multichannel signal or loudness. depends on the sum of its amplitude spectrum / depends. In the following, below, procedures are described to match the level / loudness or the sum of the amplitude spectrum of the upmix signal to the original multichannel signal. However, the following methods can also be applied to other upmix signals or multi-channel signals. This original level or the original cloudness or the sum of the original amplitude spectrum, for example, mitresstrag with the downmix signal.
- FIG. 16 determines the upmix signal by applying the four upmix or coding devices 180.1, 180.2, 180.3 and 180.4 to the four adjacent signal pairs BL D -FL D , FL D -FR D , FR D -BR D and BR D -BL D.
- the Fourier transformation device 161 corresponds to the Fourier transformation device 161 of FIG. 15.
- the input signal of the upmixing or coding device 180.1 is the signal pair BL D (k) -FL D (k).
- the input signal of the upmix or coding device 180.2 is the signal pair FL D (k) -FR D (k).
- the input signal of the upmixing or coding device 180.3 is the signal pair FR D (k) -BR D (k).
- the input signal of the upmix or coding device 180.4 is the signal pair BR D (k) -BL D (k).
- the four upmix or coding devices 180.1, 180.2, 180.3 and 180.4 correspond to the upmixing or coding devices 180.1, 180.2, 180.3 and 180.4 shown in FIG. 18, respectively.
- FIG. 18 shows for the first channel L D (k) and the second channel R ü (k) of the downmix signal in the Fourier space a correlation comparison device 42, see FIG. 3, and FIG.
- the correction device 49 has a signal processing device 43, a
- Signal processing device 44 and a signal processing device 45 are identical to Signal processing device 44 and a signal processing device 45.
- Correlation comparison device 42 is multiplied by a factor C in Fourier space, where the factor C corresponds, for example, to a decrease of -9 dB, and gives the respective first output signal for the upmixing or coding devices 180.1, 180.2, 180.3 and 180.4.
- the first signal processing device 43 receives the first channel L D (k) of the downmix signal, the correlated signal C K (k) and the first individual signal L K (k).
- the first signal processing device 43 is designed to form the respective second output signal 2 * L k (k) -L D (k) + 2 * C K (k) for the upmixing or coding devices 180.1, 180.2, 180.3 and 180.4.
- the second signal processing device 44 receives the second channel R ü (k) of the downmix signal, the correlated signal C K (k) and the second individual signal RKW.
- the second signal processing device 44 is formed, the respective third output signal 2 * R k (k) -R D (k) + 2 * C K (k) for the Upmix or coding devices 180.1, 180.2, 180.3 and 180.4 to form.
- the third signal processing device 45 receives the first channel L D (k) and the second channel R ü (k) of the downmix signal, the correlated signal C K (k), the first individual signal L K (k) and the second individual signal R K (k).
- the third signal processing device 45 is configured to form the following signal Cu "(k):
- the output signal Cu '' (k) of the signal processing device 45 is multiplied by a factor C in the Fourier space, the factor C, for example, a decrease by -9dB corresponds, and gives the respective fourth output signal for the Upmix- or coding 180.1, 180.2, 180.3 and 180.4.
- the first output signal of the upmixing or coding device 180.1 of FIG. 16 is the signal Sil / (k).
- the second output signal of the upmixing or coding device 180.1 is the signal SBL (k).
- the third output signal of the upmixing or coding device 180.1 is the signal S S iL (k).
- the fourth output signal of the upmixing or coding device 180.1 is the signal S F L (k).
- the first output of the upmix or encoder 180.2 is the signal FC (k).
- the second output signal of the upmixing or coding device 180.2 is the signal S F L (k).
- the third output of the upmix or encoder 180.2 is the signal S F c (k).
- the fourth output of the upmix or encoder 180.2 is the signal S F R (k).
- the first output signal of the upmixing or coding device 180.3 is the signal SiR '(k).
- the second output of the upmix or encoder 180.3 is the Signal S FR (k).
- the third output signal of the upmixing or coding device 180.3 is the signal S S iR (k).
- the fourth output signal of the upmix or coding device 180.3 is the signal S BR (k).
- the first output signal of the upmix or coding device 180.4 is the signal BC (k).
- the second output signal of the upmixing or coding device 180.4 is the signal S BR (k).
- the third output of the upmix or coding device 180.4 is the signal S B c (k).
- the fourth output of the upmix or encoder 180.4 is the signal S BL (k).
- the output signals Sil / (k) S siL (k), FC (k), S FC (k), SiR '(k), Ssi R (k), BC (k) and S B c (k) are applied to the inverse Fourier transform device 1606 passed.
- the correlation comparison 1602.1 is performed for the signal pair S F c (k) -FC (k) to find the correlated component Ki. Subsequently, for Ki and S FR (k), a correlation comparison 1602.2 is performed in order to find out the correlated fraction K2. K2 is multiplied by gain 173.2 by a factor C in the Fourier space, where the factor C corresponds, for example, to a decrease of -9 dB, and then to the inverse Fourier transformation device 1606. Alternative signal combinations and correlation comparisons to determine K2 are possible.
- the correlation comparison 1602.3 is performed for the signal pair S BR (k) -S B c (k) to find out the correlated fraction K 3 .
- a correlation comparison 1602.4 is performed in order to find out the correlated fraction K 4 .
- K 4 is given by Gain 173.4 multiplied by the same factor C in the Fourier space, and then passed to the inverse Fourier transform device 1606.
- Alternative signal combinations and correlation comparisons to determine K 4 are possible.
- the correlation comparison 172.1 is performed for the signal pair S S I L (k) -S BL (k) to find out the correlated component K 5 .
- Ke is given by gain 173.1 multiplied by the same factor C in Fourier space, and then given to inverse Fourier transform device 1606.
- Alternative signal combinations and correlation comparisons to determine Ke are possible.
- the correlation comparison is 172.3 is for the signal pair S S iR (k) - conducted S F R (k) to find out the correlated portion K. 7 Subsequently, for K 7 and S BR (k), a correlation comparison 172.4 is performed to find out the correlated fraction Ks. Ks is multiplied by the gain 173.3 multiplied by the same factor C in the Fourier space, and then passed to the inverse Fourier transform device 1606. Alternative signal combinations and correlation comparisons to determine Ks are possible.
- the inverse Fourier transform device 1606 is formed, the first correlated signal Sil /, the second correlated signal C * Ke (k), the third correlated signal SsiL (k), the fourth correlated signal FC '(k), the fifth correlated signal C * K 2 (k), the sixth correlated signal S F c (k), the seventh correlated signal SiR '(k), the eighth correlated signal C * Ks (k), the ninth correlated signal SsiR (k) that correlated tenth Signal BC (k), the eleventh correlated signal C * K 4 (k) and the twelfth correlated signal S B c (k) by applying an inverse Fourier transform in the period to transform.
- the inverse Fourier transform device 1606 comprises a first inverse Fourier transform unit 1606. SiL, a second inverse Fourier transform unit 1606. CK6, a third inverse Fourier transform region unit 1606. SSIL, a fourth inverse Fourier transform unit 1606. FC, a fifth inverse Fourier transform unit 1606. K2, a sixth inverse Fourier transform unit 1606. SFC , an eighth inverse Fourier transform unit 1606. CK8, a ninth inverse Fourier transform unit 1606. SSIR, a tenth inverse Fourier transform unit 1606.
- the first inverse Fourier transform unit 1606. SIL is designed to Fourier-transform the first signal SiL '(k) inversely into the first signal SiL' (t).
- the second inverse Fourier transform unit 1606. CK6 is configured to Fourier-transform the second signal (C * Ke) (k) inversely into the second signal ((C * Ke) (k)) (t) during the time period.
- SSIL is designed to Fourier-transform the third signal S S iL (k) inversely into the third signal S S iL (t) during the time period.
- the fourth inverse Fourier transform unit 1606. is configured to Fourier transform the fourth signal FC (k) inversely into the fourth signal FC (t) in the time domain.
- the fifth inverse Fourier transform unit 1606. K2 is designed to Fourier-transform the fifth signal C * K 2 (k) inversely into the fifth signal (C * K 2 (k)) (t) over time.
- the sixth inverse Fourier transform unit 1606. SFC is designed to Fourier-transform the sixth signal S F c (k) inversely into the sixth signal S F c (t) in the time domain.
- SIR is configured to Fourier-transform the seventh signal SiR '(k) inversely into the seventh signal SiR' (t).
- the eighth inverse Fourier transform unit 1606. CK8 is formed, the second signal (C * Ks) (k) inversely into the eighth signal ((C * Ks) (k)) (t) in the period to Fourier transform.
- the ninth inverse Fourier transform unit 1606. SSIR is configured to Fourier-transform the ninth signal S S iR (k) inversely into the ninth signal S S iR (t) during the time period.
- the tenth inverse Fourier transform unit 1606. BC is configured to Fourier transform the tenth signal BC (k) inversely into the tenth signal BC (t) during the time period.
- K4 is configured to Fourier-transform the eleventh signal C * K 4 (k) inversely into the eleventh signal (C * K 4 (k)) (t) in the time period.
- SBC is configured to Fourier-transform the twelfth signal S B c (k) inversely into the twelfth signal S B c (t) in the time period.
- SiL u (t) C * Sil / (t) + SsiL (t) -C * ((C * K 6 (k)) (t)
- FC u (t) C * FC (t) + S FC (t) -C * ((C * K 2 (k)) (t) S iRu (t) C * SiR '(t) + S siR (t) -C * ((C * K 8 (k)) (t)
- the individual page output signals BL u (t), FL u (t), FR u (t) and BR u (t) in the period by means of the gains 163.1, 163.2, 163.3 and 163.4 with a factor K, ideally equal to the gain 14 of FIG. 1 or the gain 54 of FIG. 4, and the subtractors 167.1, 167.2, 167.3 and 167.4 on the basis of the first input signal in the period BL D (t), based on the second input signal in the period FL D (t) of the third input signal in the period FR D (t) and based on the fourth input signal in the period BR D (t) as follows:
- BR u (t) BR D (t) -K * (SiR u (t) + BC u (t))
- the resulting channels of the upmix signal BL u (t), SiL u (t), FL u (t), FC u (t), FR u (t) SiR u (t), BR u (t) and BC u (t ) can be adjusted by gains, which depend on the level or the loudness of the original multi-channel signal or on the sum of its amplitude spectrum.
- gains depend on the level or the loudness of the original multi-channel signal or on the sum of its amplitude spectrum.
- methods are described in order to adapt the level / loudness or the sum of the amplitude spectrum of the upmix signal to the original multi-channel signal.
- the following methods can also be applied to other upmix signals or multi-channel signals. This original level or the original cloudness or the sum of the original amplitude spectrum, for example, mitübertrag with the downmix signal.
- FIG. 10 shows a method / apparatus for calculating a loudness or the sum of the amplitude spectrum of a multi-channel upmix signal / multi-channel signal according to ITU-R recommendation BS.1770-3.
- a K-filter 61 is applied to each signal window of each channel to be processed.
- the sum of the squares of the data points of the signal window is formed in the unit 62, which corresponds to the power of the channel in the signal window (derived from the power spectrum).
- the sum of the amplitude spectrum of the signal window in the period or in the Fourier space in the unit 62 can be formed for this purpose.
- the power / sum of the amplitude spectrum of each channel is weighted with a corresponding gain 63 before being summed up in 64.
- the units 65 and 66 are further processing of the output of the sum 64. Details can be found in the said recommendation, which is inserted here by reference. If the original loudness or sum of the original amplitude spectrum is calculated based on the multichannel signal, all the channels of the upmix signal can be compared with the sum of the original amplitude spectra (also derived from the original loudness) and the sum of the amplitude spectra (also derived from the loudness) of the upmix signal are corrected.
- the channels of the multi-channel signal / upmix signal are divided into two groups. For example, in side channels and in center channels. Side channels are, for example, FL, FR, BL, BR, TpFL, TpFR, TpBL, TpBR, BtFR, BtFL, FRc, FLc or their subcombinations.
- Central channels are, for example, FC, BC, SiR, SiL, TpFC, TpBC, TpSiR, TpSiL, TpC, BtFC or their subcombinations.
- the side channels in Fig. 11 should be referred to as Sl, S2, etc.
- the center channels in Fig. 11 shall be referred to as Cl, C2, etc.
- For the first group (side channels) a common loudness / a common sum of the amplitude spectra is calculated and for the second group (middle channels) an individual loudness / an individual sum of the amplitude spectrum is calculated for each channel. This is done both for the original multi-channel signal with the side channels SOI, S02, S03, ...
- the periodic distances usually correspond to the length of a signal to be processed, the window length for the calculations may only include the beginning (for example, a look-ahead of about 900ms), a longer section or the entire signal length.
- the upmix signal and the individual loudness Gcui / G C u2, G C u3 / ⁇ or the individual sum the amplitude spectra A C ui, A C u2, A C u3, ⁇ the center channels CU1, CU2, CU3, ... of the upmix signal are calculated in the upmix or coding device in the periodic intervals.
- the corresponding signal segments / signal window of the side channels SU1, SU2, SU3, ... of the Upmixsignals are then / A su multiplied by the factor A.
- the corresponding Signal sections / signal windows of the center channels CU1, CU2, CU3, of the upmix signal are respectively multiplied by the associated individual factor A CO i / A C ui, A C0 2 / A C u2, A C0 3 / A C u3.
- the correction of the level / loudness / amplitude spectra is not limited to the exemplary embodiments illustrated here.
- the claims of this correction (e.g., 46 to 49) may also be applied to other upmix signals and encoding and / or upmixing devices, and is not limited to the upmix signals and coding and / or upmixing devices of the dependent claims.
- the invention is not limited to the described embodiments. Although the invention has been described in the context of audio signals, it is not limited to these. The invention can be applied to all correlated multichannel signals. An example is a downmix of three color channels of a video signal in two color channels and the subsequent restoration by the method described in the embodiments.
- the left channel became the first channel and the right channel the second channel of the downmix signal.
- the first channel of the downmix signal according to the claims may also be the left channel of the downmix signal and the second channel of the downmix signal according to the claims may also be the right channel of the downmix signal. Consequently, the first and the second individual signal and the first and the second signal may also have a side-reversed meaning.
- the apparatus for determining a first, second and / or third channel of the multi-channel signal refers to all of the operations performed after the correlation comparisons 22 and 42 with respect to the embodiments of FIGS. 2, 3, 12, 13, 14, 15 and 16 ,
- this device includes units 28 (48, 128, 148, 158) and 29 (49, 129, 149, 159), the functions of units 28 (48, 128 , 148, 158) and 29 (49, 129, 149, 159) can also be shifted among each other.
- this device includes the units 48 and 49, wherein the functions of the units 48 and 49 can also be shifted among each other.
- the correction device and the
- Signal processing device in the embodiments 15 to 18 are not explicitly drawn.
- the functions necessary for determining the residual signal or correction signal should count as belonging to the correction device.
- the functions necessary for determining the channels of the multi-channel signal should belong to the signal processing device.
- the inverse Fourier transform device in the embodiments may be arranged both in the correction device and in the signal processing device, or both or outside thereof.
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