EP1024679B1 - Method for decoding distorted radio signals in multichannel audio signals - Google Patents
Method for decoding distorted radio signals in multichannel audio signals Download PDFInfo
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- EP1024679B1 EP1024679B1 EP19990124194 EP99124194A EP1024679B1 EP 1024679 B1 EP1024679 B1 EP 1024679B1 EP 19990124194 EP19990124194 EP 19990124194 EP 99124194 A EP99124194 A EP 99124194A EP 1024679 B1 EP1024679 B1 EP 1024679B1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04S—STEREOPHONIC SYSTEMS
- H04S3/00—Systems employing more than two channels, e.g. quadraphonic
- H04S3/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04S—STEREOPHONIC SYSTEMS
- H04S2420/00—Techniques used stereophonic systems covered by H04S but not provided for in its groups
- H04S2420/07—Synergistic effects of band splitting and sub-band processing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04S—STEREOPHONIC SYSTEMS
- H04S5/00—Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation
Definitions
- the invention relates to a method for decoding multi-channel audio broadcasts, in particular two-channel stereo audio broadcasts, with a respective useful signal per channel, wherein for each of the useful signals transmitted frequency spectrum of a signal source by different temporal occurrence and different levels in the different channels a spatial Impression or a location information for the corresponding signal source is generated, according to the preamble of claim 1.
- Radio receivers for multi-channel audio signals are intended to reproduce the low-frequency (audio) original signal as realistically as possible at a wide variety of signal levels, with level fluctuations of the high-frequency carrier signal and in the event of radio interference.
- This also includes the spatial arrangement of the various reproduced sound sources.
- This spatial arrangement is also referred to below as location information.
- a respective useful signal per channel is provided for this purpose, wherein for each of the useful signals transmitted frequency spectrum of a signal source by different temporal occurrence and different levels in the different channels, a spatial impression or a location information is generated for the corresponding signal source.
- the audio quality of one deteriorates Multi-channel signal, eg at low user signal levels and at fading or multipath reception.
- the channel separation is reduced as a remedy in conventional receivers, up to single-channel (mono) operation. This gives the listener the impression that all signal sources previously distributed in the room are brought together at one point. Such a change of the original signal has hitherto been accepted as the least disturbing measure in difficult reception situations.
- the strategy described above is particularly promising if the single-channel signal obtained has a lower susceptibility to the above-mentioned disturbing influences due to the modulation method used. This is the case in particular in the case of widespread frequency-modulated VHF broadcasting (multplex signal after the pilot tone method). In this case, the mono information is transmitted in the low-frequency, system-less affected portions of the desired signal.
- the mono signal is split into several frequency ranges. These areas are distributed differently and / or with different delay to different audio signal paths (+ Hall or other known measures for creating an artificial surround sound effect).
- the more complex this processing the more and narrower frequency segments can be distinguished. More extensive splits ultimately lead to continuous functions for attenuation-over-frequency and delay-over-frequency, each with its own function for each signal path. For discrete frequency ranges the width of which can be chosen differently, adapted to the stereo sensitivity of the human ear at different frequencies (eg no channel separation in bass, narrow segments at about 1 kHz, large segments at high frequencies).
- EP 0714222 describes a mobile radio receiver which has a pseudo-stereo circuit which, in the presence of a mono signal, processes this into a pseudo-stereo signal. This is particularly advantageous if a stereo receive signal is amplified to increase the quality of reception as a mono-siganal and yet an upscale sound experience is to be achieved. In this way, when the reception quality drops, the switchover to mono operation with subsequent processing to the pseudo-stereo signal is made early on
- Conventional stereo decoders are relatively simple and therefore inexpensive.
- the well-known simple stereo decoders thus have only the choice of completely or partially rejecting the location information in the case of noisy stereo signals.
- This task is accomplished by a method of o.g. Art having the features characterized in claim 1 and by a recipient of the o.g. Art solved with the features characterized in claim 12.
- the location information is extracted from the useful signals and with this current location information from one of the useful signals all mono-signal-containing signals, an artificial spatial sound is generated by distributing different frequency bands to the channel number of the multi-channel audio transmission corresponding channels, each with a different time delay and / or different attenuation of the levels in the different channels.
- spectral distributions of the useful signals of the different channels and / or transit time differences or time differences of respectively two or more different spectral components in the respective useful signal of different channels are compared with one another. From the comparison, parameters for signal attenuation and / or signal delay are determined for each channel for at least two or more different spectral components and the corresponding spectral components are delayed from a single channel signal containing the useful signals of all channels according to the determined parameters and / or attenuated on the channel number Distributed channels such multichannel audio broadcast that a listener for the corresponding spectral components a spatial sound impression is generated, which essentially corresponds to a spatial sound impression of the directly reproduced audio signals of the channels.
- the spectral range is divided into a plurality of predetermined spectral components, wherein frequencies of a spectral component are taken into account differently in the determination of the parameters.
- the disturbing impression of a spatially jumping signal source is reliably avoided in that the predetermined spectral components partially overlap in frequency and the frequencies of a spectral component in the overlapping region are weighted less to an adjacent spectral component.
- the distribution of the spectral components is dynamically changed as a function of the analysis of the useful signals.
- a weighting function In order to prevent short-term events in the useful signal from unduly influencing a surround sound, certain parameters are added over time by means of a weighting function.
- a weighting function a message is transmitted over predetermined periods of time or a summary of a predetermined time period, with a stronger consideration of more recent specific parameters.
- a good prognosis for a future spatial location of a signal source is obtained by interpolating from adjacent spectral components for those spectral components in which a determination of the parameters is not possible, previously using certain parameters optionally weighted, using predetermined parameters or parameter functions, and / or random parameters are used.
- a receiver of the abovementioned type is characterized by an analysis subassembly which distributes spectral distributions of the useful signals of the different channels and / or propagation time differences or transit time differences of two or more different spectral components in the respective useful signal of the different channels compares parameters for signal attenuation and / or signal delay thus determined from the comparison for each channel for at least two or more different spectral components, and a surround module which delays the respective spectral components from a single channel signal containing the useful signals of all channels according to the determined parameters; or attenuated on the channel number of the multi-channel audio broadcast corresponding channels distributed such that a listener receives a spatial sound impression for the corresponding spectral components, which essentially corresponds to a spatial sound impression of the directly reproduced audio signals of the channels.
- the analysis module has for each channel a filter module which divides the respective useful signal or parts of the useful signal into a plurality, in particular four spectral components.
- the analysis module has a level detector for each spectral component to be evaluated and a number of level comparators corresponding to the number of these spectral components, wherein each level comparator compares the levels of an associated spectral component in several, possibly all channels.
- Each level comparator is followed by a signal converter stage, which determines the parameter for signal attenuation and / or the parameter for signal delay from the result of the comparison in the level comparator for each channel of the artificial spatial sound.
- the surround sound assembly has a filter assembly which divides a mono signal containing the useful signals of all channels into a plurality of, in particular five, spectral components, wherein for at least one spectral component a number of attenuator modules and / or delay stages corresponding to the number of channels to be processed is provided, attenuator modules and / or delay stages generate a delayed and / or damped output signal according to the parameters provided for that channel and spectral component by the analyzer assembly. For each channel of the artificial spatial sound, each adder combines the spectral partial signals thus obtained.
- a time offset between the currently analyzing segment of the multi-channel useful signal and the segment of the mono signal manipulated with this data has the advantage that spatial information which clearly emerges only in the course of the signal segment can also have an effect on the design of the spatial sound at the beginning of this signal segment.
- useful signals of different channels of the multichannel audio signal are analyzed with regard to their spectral distribution.
- location information data for describing the original signal determined according to the invention.
- While disturbed Receive times is switched to an artificial surround sound or ambient, which is based on the currently determined from the disturbed Merkanal signal location information, ie the spectral components of the mono signal distributed to the different channels, so that the impression arises that the spectral components would continue their origin at the place determined for this purpose.
- the system switches back to multi-channel operation.
- surround parameters can be identical to the location information.
- the location information and / or surround parameter summarize data at individual frequencies or the signal components in frequency ranges together. The acquisition of the location information takes place at certain times or for certain time intervals.
- the determination of the location information of the multi-channel signal and / or the surround parameters for the design of the surround sound are realized, for example, as continuous functions of the level as a function of the frequency.
- a continuous function of the level as a function of the frequency prevents the impression of a rapid change of location of a signal source when the frequency of the source exceeds a range limit.
- the frequencies of a jointly processed area are optionally included in the calculations with different weightings (frequency-dependent evaluation function).
- the weighting can be chosen differently for the location information than for the surround parameters. Parts of the spectrum are examined or processed, which are firmly demarcated or partially overlap. At this for digital signal processing more suitable division into frequency ranges adjacent frequencies are detected with less weight, so that the disturbing impression of a jumping signal source is reliably avoided here.
- the time difference of the spectral components (transit time differences) in the various channels is taken over into the location information according to the methods described above.
- the time difference between the channels provides a more reliable indication of the location of the signal generation and is therefore better suited as output information for simulating the artificial surround sound.
- a weighting function can prevent short-term events in the payload signal from unduly influencing the surround sound
- the required location information or surround parameters are interpolated from adjacent frequency ranges, previously determined values continue to be used (weighted if necessary), predefined values or functions used (eg, these gaps) Mono treated, so evenly distributed to all channels) and / or (possibly partially) replaced by random parameters.
- the division into frequency ranges (for example range limits), the evaluation functions and / or threshold functions are, for example, designed to be variable, in particular they are changed dynamically on the basis of the analysis of the useful signal.
- This method makes it possible to process individual spectral focuses of the desired signal as a whole, it prevents the splitting and spatial separation of such areas.
- the useful signal analysis in quiet passages can detect smaller signal amplitudes.
- the timing can better match the characteristics of the current noise situation, e.g. Frequency of fading burglaries are adjusted.
- the artificial surround sound is optionally retained temporarily or permanently. In these periods of time overlapping and / or alternately the determination of the location information and surround parameters and the generation of the room sound carried out. It eliminates the change from multi-channel operation to surround sound and back, or their number is reduced. It creates a harmonious spatial and sound impression.
- a complete multi-channel audio signal contains information about the location of the signal generation or about a spatial arrangement of different signal sources with respect to a recording microphone and thus with respect to the listener at each time or smallest time interval and for each individual frequency.
- the human ear is unable to fully evaluate this wealth of information. Fast changes from one channel to another usually do not occur and would otherwise not be detected by the ear at full speed.
- the multichannel audio signal loses information, for example as a result of noise due to a weakening signal, enough residual information remains for a long time in order to provide an acceptable spatial impression for the ear.
- the invention uses this residual information to artificially restore a surround sound.
- information is still obtained from the disturbed signal during a disturbance in order to design the "artificial" surround sound effect in accordance with the currently transmitted location information.
- the mono signal reaches the loudspeakers, which is subject to an artificial surround sound.
- the information for designing the artificial surround sound effect is obtained from the still available, albeit qualitatively poor, multichannel audio signal.
- the remainders of the spatial information that can be determined by this method are not sufficient to design an artificial spatial sound.
- the detection of the spatial information is temporarily interrupted and worked on with the last determined values or a transition to mono mode.
- a reception quality of a multi-channel audio transmission is normalized to one on the horizontal axis 10.
- the reception quality is optimal whereas towards the origin of the coordinate system the reception quality decreases more and more, until at "0" there is no reception.
- On the respective vertical axis 12 is a channel separation ( Fig. 1 ), a time resolution ( Fig. 2 ), a frequency resolution ( Fig. 3 ) and a quality of the reproduction of the current location information or the surround sound in each case normalized to one.
- the dashed line 14 shows the respective characteristics of a conventional decoder with crossfade from stereo to mono when signal interference occur (mono stereo blend).
- the crossed, solid line 16 shows the respective characteristic when using the location information before the occurrence of a fault and no further evaluation of the location information in the useful signal during the fault.
- the solid line 18 shows the respective characteristic in extracting the location information from the disturbed signal, according to the invention.
- the location information or the location information may be distorted in three parameters, namely the channel separation, the time resolution and the frequency resolution.
- the channel separation ( Fig. 1 ) corresponds to the spatial separation of the signal sources.
- the time resolution ( Fig. 2 ) is reflected, for example, in the maximum speed at which a signal source changes location.
- the frequency resolution ( Fig. 3 ) indicates the extent to which frequency-related signal sources can be localized at different locations.
- the quality of reproduction of location information ( Fig. 4 ) is simply the product of the three parameters. In this presentation, it is initially disregarded that human hearing evaluates the parameters very differently, and this in turn varies with the frequency, the level and other parameters of the signal.
- FIGS. 1 to 4 show for each decoding method basic relationships for the three parameters ( Fig. 1 to 3 ) and the overall quality of the reproduction ( Fig. 4 ) depending on the quality of the received signal plotted on the horizontal axis 10 in the manner previously described.
- This quality can be plotted as a signal to noise ratio, with other types of sturgeon, such as fading or multipath reception, a different scaling could be useful.
- Conventional stereo decoders are relatively simple and therefore inexpensive.
- the mono-stereo-blend technique used so far for stereo receivers is based solely on channel separation control (line 14). In case of disturbances will be right early on one-channel operation blended, the remaining location information is no longer played.
- the method according to the invention uses all the information that is still available (line 18).
- a suitable mix of time and frequency averaging is based on the resolution of the human ear and the processing power of the signal processing modules.
- the temporal resolution will initially, due to the inertia of hearing, cause barely audible quality losses.
- the summary in frequency bands requires recognizable falsifications of the location information in simple systems (arrow 20, fine resolution requires large computing power).
- fine resolution requires large computing power.
- the channel separation is not withdrawn until the residual information available in the signal is no longer sufficient for an acceptable audio quality.
- the method is particularly suitable for decoding weak but largely stable signals, ie below the "mono" level of conventional decoders. This area of the gain in location information is shown by arrow 22.
- FIG. 5 shows a section of a block diagram of an FM stereo broadcast receiver as a preferred embodiment of a receiver according to the invention.
- An antenna 1010 receives radio frequency signals from broadcast stations and forwards them to a selection and demodulation board 1020.
- this module 1020 the signal of a radio station is detected and the modulation content extracted.
- An output signal 1021 of this module 1020 is the sum signal of both stereo channels L + R (left plus right).
- Another output signal 1022 includes the difference signal of the two channels LR.
- a third output 1023 indicates the extent to which the signal reception is subject to interference, whether due to insufficient or rapidly fluctuating signal strength, multipath reception or other events.
- the sum signal 1021 is applied to an assembly 1100 for generating an artificial surround sound.
- Both the sum signal 1021 and the difference signal 1022 are supplied to a stereo decoder 1030, which generates therefrom two output signals 1031 with the right channel R and 1032 with the left channel L. These two signals arrive at an analysis module 1300 for determining the room parameters.
- the assembly 1300 is also connected to the signal 1023.
- the determined space parameters for signal attenuation and signal delay are forwarded to the surround module 1100 via a plurality of lines 1301 and 1302. There they serve as a surround sound parameter for a realistic simulation of the spatial sound.
- FIG. 6 shows an embodiment of the surround sound assembly 1100.
- the mono signal (L + R) 1021 is decomposed in a filter assembly 1110 into five partial spectral signals 1111 to 1115, the highest frequency components being output via signal 1111, the lowest frequency via signal 1115.
- the signal 1111 passes to a first attenuator assembly 1121, then passes through a first delay stage 1131 and passes to a first summing junction or adder 1141.
- a second path carries the signal 1111 via a second attenuator assembly 1122 and a second delay stage 1132 to a second summing junction and adder 1142, respectively.
- the signals 1112, 1113, and 1114 are each routed through two paths through the attenuators 1123 through 1128 and delay stages 1133 through 1138 to the summing points and adders 1141, 1142, respectively.
- Output lines 1143 and 1144 of the two summing junctions 1141, 1142 form the outputs of the block 1100, thus leading to the signals 1101 and 1102.
- the signal attenuation in the attenuators 1121 to 1128 and the sweep time of the delay stages 1131 to 1138 are controlled via signal buses 1129 and 1139, each consisting of eight lines, one line per unit to be controlled. Since humans are unable to recognize the place of origin of low or low frequency sounds, is This frequency range signal separation is not required.
- the signal 1115 is therefore passed directly to the two summing points or adders 1141 and 1142, respectively.
- FIG. 13 shows an embodiment of the analysis board 1300.
- Signals 1031 and 1032 from the stereo decoder 1030 for the right and left audio channels are decomposed into four filter boards 1310 and 1320 into four partial spectral signals 1311 to 1314 and 1321 to 1324, the lowest being from human hearing non-localizable frequencies are not taken into account.
- the amplitude of the signal line 1311 with the highest frequency components of the right channel is determined with a level detector 1331.
- a resultant signal 1351 is applied to a level comparator 1371. Here, it is compared with the corresponding level of the left channel, which has also reached the stage 1371 via signal 1321 and a detector 1341 and line 1361.
- a signal conversion stage 1381 generates from the result of the comparison four control signals 1401 to 1404 for driving the attenuators 1123 to 1128 and delay stages 1133 to 1138 in the surround module 1100. Corresponding signals and processing stages are provided for the signals of the other three spectral components.
- filters 1310/1320 are not used for individual frequency ranges as an alternative, but one determines a function of the level over the frequency per channel, from this a list of a parameter set with characteristic frequencies and associated level values. The frequencies in between can be obtained, for example, by interpolation.
- an analog multi-stage filter for example, operational amplifiers, controlled so that it transforms the supplied mono signal according to these functions / parameters.
- the frequency spectrum is divided into different parts, which according to the in Fig. 8 Weighting functions are weighted as shown. As is immediately apparent Fig. 8 results, some areas overlap. furthermore, in some areas frequencies in the peripheral areas are weighted less heavily than frequencies in the middle of such areas.
- the levels in the frequency subsegments are measured over a longer period of time and these progressions are stored, for example, in a ring buffer and fed to a correlation stage.
- This stage determines by different temporal shifts and subsequent comparison of the channels for which time shift a pronounced match is detectable. This time difference is used as information about the origin of the signal.
- the above-described simple level comparison can continue to take place, wherein a subsequent stage decides which of the two localization strategies results in this case better information (credible, pronounced, constant or other criterion) and further processed.
- gewonennen location information is en provided in the assembly in 1371 and corresponding modules low pass.
- the frequency ranges generated in stages 1310 and 1320 are alternatively split into much finer frequency sub-spectra. All partial spectra with low signal levels are discarded, the remaining parts are added back to signals that correspond to those after the first frequency distribution (eg 1311).
- the digitally calculated low-pass function for this measurement is stopped in the DSP.
- the various measurements are written to a shift register. Each new measurement generates a clock signal and shifts the oldest one out of the register during transmission. A weighted addition of all register components gives the surround parameter.
- the clock to the shift register is interrupted. Alternatively, first all frequency ranges are calculated with sufficient information and then the gaps in other frequency ranges are linearly interpolated from the neighboring ranges.
- the levels in the frequency subsegments are measured over an extended period of time in an alternative embodiment and these waveforms stored in a ring buffer.
- a signal rise or fall is calculated from this recording of the level profile, which is further incorporated into the surround parameters for the duration of the disturbance.
- the highest peaks in the frequency spectrum are determined. These are used as center frequencies of the spectral split filters 1110.
- the signal 1023 at the input of the module 1040 is alternatively switched through only in the switching direction of stereo to surround sound immediately.
- the flashback from surround sound to stereo on a Passed low pass so that this creates a delay and thus for a limited time even at times of good reception still the artificial surround sound remains activated.
- a delay element may be added, e.g. in the form of a digital FIFO memory.
- the signal sequence currently arriving at the antenna 1010 in the analysis module 1300 the results of the analysis act on a signal segment which has already been received earlier, in accordance with the offset by the time delay.
- a location information which has been clearly worked out during the analysis can thus act on the entire signal sequence from the beginning.
- the two inputs of the fader unit 1040, which carry the signals 1031 and 1031 are to be equipped with delay stages with the same time response.
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Description
Die Erfindung betrifft ein Verfahren zum Dekodieren von Mehrkanal-Audiosendungen, insbesondere von Zweikanal-Stereo-Audiosendungen, mit einem jeweiligen Nutzsignal pro Kanal, wobei für jedes von den Nutzsignalen übertragene Frequenzspektrum einer Signalquelle durch unterschiedliches zeitliches Auftreten und unterschiedliche Pegel in den unterschiedlichen Kanälen ein räumlicher Eindruck bzw. eine Ortsinformation für die entsprechende Signalquelle erzeugt wird, gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a method for decoding multi-channel audio broadcasts, in particular two-channel stereo audio broadcasts, with a respective useful signal per channel, wherein for each of the useful signals transmitted frequency spectrum of a signal source by different temporal occurrence and different levels in the different channels a spatial Impression or a location information for the corresponding signal source is generated, according to the preamble of
Funkempfänger für mehrkanalige Audiosignale, z.B. Stereosendungen, sollen bei unterschiedlichsten Signalpegeln, bei Pegelschwankungen des hochfrequenten Trägersignals und bei Funkstörungen das niederfrequente (Audio-) Ursprungssignal möglichst wirklichkeitsgetreu wiedergeben. Darunter versteht sich auch die räumliche Anordnung der verschiedenen wiedergegebenen Tonquellen. Diese räumliche Anordnung wird nachfolgend auch als Ortsinformation bezeichnet. Bei einer Mehrkanal-Audiosendung, insbesondere Zweikanal-Stereo-Audiosendung, ist dazu einen jeweiliges Nutzsignal pro Kanal vorgesehen, wobei für jedes von den Nutzsignalen übertragene Frequenzspektrum einer Signalquelle durch unterschiedliches zeitliches Auftreten und unterschiedliche Pegel in den unterschiedlichen Kanälen ein räumlicher Eindruck bzw. eine Ortsinformation für die entsprechende Signalquelle erzeugt wird. Bei einigen Empfangssituationen verschlechtert sich die Audioqualität eines Mehrkanalsignals, z.B. bei niedrigen Nutzsignalpegeln und bei Schwund bzw. Mehrwegeempfang. Um in diesen Situationen eine akzeptable Klangqualität weiterhin bereitstellen zu können, wird zur Abhilfe in herkömmlichen Empfängern die Kanaltrennung reduziert, bis hin zum Einkanal-(Mono-)Betrieb. Dies erweckt beim Hörer den Eindruck, alle zuvor im Raum verteilten Signalquellen werden an einem Punkt zusammengerückt. Eine solche Veränderung des ursprünglichen Signals wird bisher als am wenigsten störende Maßnahme bei schwierigen Empfangssituationen akzeptiert.Radio receivers for multi-channel audio signals, such as stereo broadcasts, are intended to reproduce the low-frequency (audio) original signal as realistically as possible at a wide variety of signal levels, with level fluctuations of the high-frequency carrier signal and in the event of radio interference. This also includes the spatial arrangement of the various reproduced sound sources. This spatial arrangement is also referred to below as location information. In a multi-channel audio transmission, in particular two-channel stereo audio transmission, a respective useful signal per channel is provided for this purpose, wherein for each of the useful signals transmitted frequency spectrum of a signal source by different temporal occurrence and different levels in the different channels, a spatial impression or a location information is generated for the corresponding signal source. In some reception situations, the audio quality of one deteriorates Multi-channel signal, eg at low user signal levels and at fading or multipath reception. In order to be able to continue providing acceptable sound quality in these situations, the channel separation is reduced as a remedy in conventional receivers, up to single-channel (mono) operation. This gives the listener the impression that all signal sources previously distributed in the room are brought together at one point. Such a change of the original signal has hitherto been accepted as the least disturbing measure in difficult reception situations.
Die oben beschriebene Strategie ist besonders dann erfolgversprechend, wenn das gewonnene Einkanalsignal aufgrund des verwendeten Modulationsverfahrens eine geringere Anfälligkeit gegenüber den genannten Störeinflüssen aufweist. Dies ist insbesondere beim weit verbreiteten frequenzmodulierten UKW-Rundfunk (Multplexsignal nach dem Pilottonverfahren) der Fall. Hierbei wird die Monoinformation in den niederfrequenten, systembedingt weniger beeinträchtigten Anteilen des Nutzsignals übertragen.The strategy described above is particularly promising if the single-channel signal obtained has a lower susceptibility to the above-mentioned disturbing influences due to the modulation method used. This is the case in particular in the case of widespread frequency-modulated VHF broadcasting (multplex signal after the pilot tone method). In this case, the mono information is transmitted in the low-frequency, system-less affected portions of the desired signal.
Weiterhin sind Verfahren bekannt, um ein Monosignal so zu bearbeiten, dass der Eindruck einer räumlichen Verteilung der Signalquellen entsteht. Dazu wird das Monosignal in mehrere Frequenzbereiche zerlegt. Diese Bereiche werden unterschiedlich stark und/oder mit unterschiedlicher Verzögerung auf verschiedene Audio-Signalpfade verteilt (+ Hall oder andere bekannte Maßnahmen zur Erzeugung eines künstlichen Raumklang-Effekts). Je aufwendiger diese Bearbeitung erfolgt, desto mehr und engere Frequenzsegmente können unterschieden werden. Immer weitergehende Aufspaltungen führen dabei letztlich zu kontinuierlichen Funktionen für Dämpfung-über-Frequenz und Verzögerung-über-Frequenz, jeweils eine eigene Funktion für jeden Signalpfad. Bei diskreten Frequenzbereichen kann deren Breite unterschiedlich groß gewählt werden, angepasst an die Stereoempfindlichkeit des menschlichen Ohrs bei verschiedenen Frequenzen (z.B. keine Kanaltrennung bei Bässen, enge Segmente bei ca. 1kHz, große Segmente bei hohen Frequenzen).Furthermore, methods are known for processing a mono signal in such a way that the impression of a spatial distribution of the signal sources arises. For this purpose, the mono signal is split into several frequency ranges. These areas are distributed differently and / or with different delay to different audio signal paths (+ Hall or other known measures for creating an artificial surround sound effect). The more complex this processing, the more and narrower frequency segments can be distinguished. More extensive splits ultimately lead to continuous functions for attenuation-over-frequency and delay-over-frequency, each with its own function for each signal path. For discrete frequency ranges the width of which can be chosen differently, adapted to the stereo sensitivity of the human ear at different frequencies (eg no channel separation in bass, narrow segments at about 1 kHz, large segments at high frequencies).
Herkömmliche Stereodekoder sind verhältnismäßig einfach und damit preiswert aufgebaut. Das bisher bei Stereoempfängern mit derartigen Stereodekodern verwendete Verfahren mit Mono-Stereo-Blend basiert, wie zuvor bereits erläutert, einzig auf der Steuerung der Kanaltrennung . Bei auftretenden Störungen wird sehr früh auf Einkanalbetrieb umgeblendet, wodurch eine ggf. noch vorhandene Ortsinformation nicht mehr wiedergegeben wird. Die bekannten einfachen Stereodekoder haben bei verrauschten Stereosignalen somit nur die Wahl, die Ortsinformation ganz oder teilweise zu verwerfen.Conventional stereo decoders are relatively simple and therefore inexpensive. The previously used in stereo receivers with such stereo decoder method with mono-stereo-blend based, as previously explained, solely on the control of the channel separation. In case of disturbances is very early on one-channel operation blended, whereby any possibly still existing location information is no longer displayed. The well-known simple stereo decoders thus have only the choice of completely or partially rejecting the location information in the case of noisy stereo signals.
Es ist Aufgabe der vorliegenden Erfindung, ein verbessertes Verfahren und einen verbesserten Empfänger der obengenannten Art zur Verfügung zu stellen, welches die obengenannten Nachteile deutlich reduziert.It is an object of the present invention to provide an improved method and an improved receiver of the type mentioned above, which significantly reduces the above-mentioned disadvantages.
Diese Aufgabe wird durch ein Verfahren der o.g. Art mit den in Anspruch 1 gekennzeichneten Merkmalen und durch einen Empfänger der o.g. Art mit den in Anspruch 12 gekennzeichneten Merkmalen gelöst.This task is accomplished by a method of o.g. Art having the features characterized in
Dazu ist es erfindungsgemäß vorgesehen, dass während des Empfangs der Mehrkanal-Audiosendung in Zeitabschnitten, in denen der Empfang derart gestört ist, dass eine direkte Mehrkanalwiedergabe nicht mehr möglich ist, die Ortsinformation aus den Nutzsignalen extrahiert wird und mit dieser aktuellen Ortsinformation aus einem die Nutzsignale aller Kanäle enthaltenden Monosignal ein künstlicher Raumklang durch Verteilen verschiedener Frequenzbänder auf die der Kanalzahl der Mehrkanal-Audiosendung entsprechende Kanäle mit jeweils unterschiedlicher zeitlicher Verzögerung und/oder unterschiedlicher Dämpfung der Pegel in den verschiedenen Kanälen erzeugt wird.For this purpose, it is provided according to the invention that during the reception of the multichannel audio program in time segments in which the reception is so disturbed that a direct multi-channel reproduction is no longer possible, the location information is extracted from the useful signals and with this current location information from one of the useful signals all mono-signal-containing signals, an artificial spatial sound is generated by distributing different frequency bands to the channel number of the multi-channel audio transmission corresponding channels, each with a different time delay and / or different attenuation of the levels in the different channels.
Dies hat den Vorteil, dass, obwohl ein Mehrkanaldekoder nach dem Stand der Technik keine Mehrkanaldekodierung mit akzeptabler Qualität mehr vornehmen kann, die in den gestörten Nutzsignalen nach wie vor vorhandene Ortsinformation extrahiert wird und eine Wiedergabe mit einem entsprechenden "künstlichen" Raumklang erfolgt, wobei dieser "künstlich" erzeugte Raumklang im Wesentlichen dem originalen Raumklang entspricht.This has the advantage that although a multi-channel decoder according to the prior art can no longer make multi-channel decoding of acceptable quality, the location information still present in the disturbed useful signals will be extracted and playback will take place with a corresponding "artificial" surround sound "artificially" generated surround sound essentially corresponds to the original surround sound.
Vorzugsweise Weitergestaltungen des Verfahrens sind in den Ansprüchen 2 bis 11 beschrieben.Preferably further developments of the method are described in claims 2 to 11.
In einer bevorzugten Ausführungsform werden spektrale Verteilungen der Nutzsignale der verschiedenen Kanäle und/oder Laufzeitunterschiede bzw. Zeitdifferenzen von jeweils zwei oder mehr verschiedenen Spektralanteilen im jeweiligen Nutzsignal verschiedener Kanäle miteinander verglichen. Aus dem Vergleich werden für jeden Kanal für wenigstens zwei oder mehr verschiedene Spektralanteile Parameter für eine Signaldämpfung und/oder eine Signalverzögerung derart bestimmt und die entsprechenden Spektralanteile aus einem die Nutzsignale aller Kanäle enthaltenden Einkanalsignal gemäß den bestimmten Parameter verzögert und/oder gedämpft auf der Kanalzahl der Mehrkanal-Audiosendung entsprechende Kanäle derart verteilt, dass für einen Zuhörer für die entsprechenden Spektralanteile ein räumlicher Klangeindruck erzeugt wird, welcher im Wesentlichen einem räumlichen Klangeindruck der direkt wiedergegebenen Audiosignale der Kanäle entspricht. Dies hat den Vorteil, dass während einer Empfangsstörung nicht auf Einkanalbetrieb geschaltet werden muss und somit nicht der Eindruck entsteht, die Signalquellen würden in der Raummitte zusammenfallen. Die Verfälschung durch den signalabhängig geformten künstlichen Raumklang erscheint dem Hörer weniger störend, als eine Verfälschung durch Monobetrieb. Kurze Störungen werden vom Hörer gar nicht mehr wahrgenommen. Man kann mit kürzeren Zeitkonstanten bzw. -verzögerungen zum Mehrkanalbetrieb zurückkehren, da ein Pulsiereffekt (bei periodischen Störungen scheint die Signalquelle schnell zwischen verschiedenen Orten zu springen) nicht oder in deutlich geringerem Maß auftritt.In a preferred embodiment, spectral distributions of the useful signals of the different channels and / or transit time differences or time differences of respectively two or more different spectral components in the respective useful signal of different channels are compared with one another. From the comparison, parameters for signal attenuation and / or signal delay are determined for each channel for at least two or more different spectral components and the corresponding spectral components are delayed from a single channel signal containing the useful signals of all channels according to the determined parameters and / or attenuated on the channel number Distributed channels such multichannel audio broadcast that a listener for the corresponding spectral components a spatial sound impression is generated, which essentially corresponds to a spatial sound impression of the directly reproduced audio signals of the channels. This has the advantage that during a reception failure must not be switched to single-channel operation and thus does not give the impression that the signal sources would coincide in the center of the room. The falsification by the signal-dependent shaped artificial spatial sound appears less disturbing to the listener than a falsification by mono operation. Short disturbances are no longer perceived by the listener. One can return to multi-channel operation with shorter time constants or delays because a pulsating effect (in case of periodic disturbances the signal source seems to jump quickly between different locations) does not occur or to a much lesser degree.
Ein unerwünschter Eindruck eines schnellen Ortswechsels einer im Audiosignal wiedergegebenen Signalquelle, wenn die Frequenzen dieser Signalquelle eine Bereichsgrenze zwischen benachbarten Spektralanteilen überschreiten, ist dadurch vermieden, dass die Parameter zur Dämpfung und/oder Verzögerung als stetige Funktion des Pegels/Laufzeitunterschiedes in Abhängigkeit von der Frequenz bestimmt werden.An undesirable impression of a rapid change of location of a signal source reproduced in the audio signal when the frequencies of this signal source exceed a range boundary between adjacent spectral components is avoided by determining the parameters for attenuation and / or delay as a continuous function of the level / delay difference as a function of the frequency become.
Für eine digitale Signalverarbeitung ist es besonders geeignet, wenn der Spektralbereich in mehrere vorbestimmte Spektralanteile aufgeteilt wird, wobei Frequenzen eines Spektralanteiles bei der Bestimmung der Parameter unterschiedlich gewichtet berücksichtigt werden. Hierbei wird der störende Eindruck einer räumlich springenden Signalquelle zuverlässig dadurch vermieden, dass sich die vorbestimmten Spektralanteile in der Frequenz teilweise überlappen und die Frequenzen eines Spektralanteiles im Überlappungsbereich zu einem benachbarten Spektralanteil geringer gewichtet werden. Zweckmäßigerweise wird die Aufteilung der Spektralanteile in Abhängigkeit von der Analyse der Nutzsignale dynamisch verändert.For digital signal processing, it is particularly suitable if the spectral range is divided into a plurality of predetermined spectral components, wherein frequencies of a spectral component are taken into account differently in the determination of the parameters. In this case, the disturbing impression of a spatially jumping signal source is reliably avoided in that the predetermined spectral components partially overlap in frequency and the frequencies of a spectral component in the overlapping region are weighted less to an adjacent spectral component. Expediently, the distribution of the spectral components is dynamically changed as a function of the analysis of the useful signals.
Um zu verhindern, dass kurzzeitige Ereignisse im Nutzsignal einen Raumklang unangemessen stark beeinflussen, werden einmal bestimmte Parameter über die Zeit mittels einer Gewichtungsfunktion ergänzt. Hierbei erfolgt beispielsweise als Gewichtungsfunktion eine Mitteilung über vorbestimmte Zeiträume oder eine Zusammenfassung eines vorbestimmten Zeitraumes unter stärkerer Berücksichtigung jüngerer bestimmter Parameter.In order to prevent short-term events in the useful signal from unduly influencing a surround sound, certain parameters are added over time by means of a weighting function. In this case, for example, as a weighting function, a message is transmitted over predetermined periods of time or a summary of a predetermined time period, with a stronger consideration of more recent specific parameters.
Um Rauschanteile im Nutzsignal von der Gestaltung eines künstlichen Raumklanges fern zu halten, werden bei der Bestimmung der Parameter nur solche Spektralanteile berücksichtigt, die einen vorbestimmten Pegel-Schwellwert oder eine frequenzabhängige Schwellwertfunktion überschreiten. Die innerhalb eines Spektralanteiles bzw. Frequenzbereiches vorhandenen Signalkomponenten beeinträchtigen dadurch eine Ortsbestimmung durch den Vergleich der Nutzsignale verschiedener Kanäle des dominanten Signals nicht mehr.In order to keep away noise components in the useful signal from the design of an artificial spatial sound, only those spectral components which exceed a predetermined level threshold value or a frequency-dependent threshold value function are taken into account in the determination of the parameters. The signal components present within a spectral component or frequency range no longer impair localization by comparing the useful signals of different channels of the dominant signal.
Eine gute Prognose über einen zukünftigen räumlichen Ort einer Signalquelle wird dadurch erzielt, dass für solche Spektralanteile, in denen eine Bestimmung der Parameter nicht möglich ist, diese aus benachbarten Spektralanteilen interpoliert, zuvor bestimmte Parameter ggf. gewichtet weiter verwendet, vorbestimmte Parameter oder Parameterfunktionen verwendet und/oder Zufallsparameter verwendet werden.A good prognosis for a future spatial location of a signal source is obtained by interpolating from adjacent spectral components for those spectral components in which a determination of the parameters is not possible, previously using certain parameters optionally weighted, using predetermined parameters or parameter functions, and / or random parameters are used.
Ferner ist ein Empfänger der o.g. Art erfindungsgemäß gekennzeichnet durch eine Analysebaugruppe, welche spektrale Verteilungen der Nutzsignale der verschiedenen Kanäle und/oder Laufzeitunterschiede bzw. Laufzeitdifferenzen von jeweils zwei oder mehr verschiedenen Spektralanteilen im jeweiligen Nutzsignal der verschiedenen Kanäle miteinander vergleicht, aus dem Vergleich für jeden Kanal für wenigstens zwei oder mehr verschiedene Spektralanteile Parameter für eine Signaldämpfung und/oder eine Signalverzögerung derart bestimmt, und eine Raumklangbaugruppe , welche die entsprechenden Spektralanteile aus einem die Nutzsignale aller Kanäle enthaltenden Einkanalsignal gemäß den bestimmten Parameter verzögert und/oder gedämpft auf der Kanalzahl der Mehrkanal-Audiosendung entsprechende Kanäle derart verteilt, dass ein Zuhörer für die entsprechenden Spektralanteile einen räumlichen Klangeindruck erhält, welcher im Wesentlichen einem räumlichen Klangeindruck der direkt wiedergegebenen Audiosignale der Kanäle entspricht.Furthermore, a receiver of the abovementioned type is characterized by an analysis subassembly which distributes spectral distributions of the useful signals of the different channels and / or propagation time differences or transit time differences of two or more different spectral components in the respective useful signal of the different channels compares parameters for signal attenuation and / or signal delay thus determined from the comparison for each channel for at least two or more different spectral components, and a surround module which delays the respective spectral components from a single channel signal containing the useful signals of all channels according to the determined parameters; or attenuated on the channel number of the multi-channel audio broadcast corresponding channels distributed such that a listener receives a spatial sound impression for the corresponding spectral components, which essentially corresponds to a spatial sound impression of the directly reproduced audio signals of the channels.
Mit diesem Empfänger werden die bereits zuvor genannten Vorteile des erfindungsgemäßen Verfahrens erzielt.With this receiver, the aforementioned advantages of the method according to the invention are achieved.
Vorzugsweise Weitergestaltungen des Empfängers sind in den Ansprüchen 12 bis 17 beschrieben.Preferred embodiments of the receiver are described in
In einer bevorzugten Ausführungsform weist die Analysebaugruppe für jeden Kanal eine Filterbaugruppe auf, welche das jeweilige Nutzsignal oder Teile des Nutzsignals in mehrere, insbesondere vier Spektralanteile zerlegt. Die Analysebaugruppe weist für jeden auszuwertenden Spektralanteil einen Pegeldetektor sowie eine der Anzahl dieser Spektralanteile entsprechende Anzahl von Pegelvergleichern auf, wobei jeder Pegelvergleicher die Pegel eines zugeordneten Spektralanteils in mehreren, gegebenenfalls allen Kanälen vergleicht. Jedem Pegelvergleicher ist eine Signalumformerstufe nachgeschaltet, welche aus dem Resultat des Vergleichs im Pegelvergleicher für jeden Kanal des künstlichen Raumklanges den Parameter für Signaldämpfung und/oder den Parameter für Signalverzögerung bestimmt. Die Raumklangbaugruppe weist eine Filterbaugruppe auf, welche ein die Nutzsignale aller Kanäle enthaltendes Mono-Signal in mehrere, insbesondere fünf, Spektralanteile zerlegt, wobei für mindestens einen Spektralanteil eine der Anzahl der zu verarbeitenden Kanläle entsprechende Anzahl von Abschwächerbaugruppen und/oder Verzögerungsstufen vorgesehen ist, wobei Abschwächerbaugruppen und/oder Verzögerungsstufen ein gemäß den für diesen Kanal und diesen Spektralanteil von der Analysebaugruppe bereitgestellten Parametern verzögerts und/oder gedämpftes Ausgangssignal erzeugen. Für jeden Kanal des künstlichen Raumklangs vereinigt je ein Addierer die so gewonnen spektralen Teilsignale.In a preferred embodiment, the analysis module has for each channel a filter module which divides the respective useful signal or parts of the useful signal into a plurality, in particular four spectral components. The analysis module has a level detector for each spectral component to be evaluated and a number of level comparators corresponding to the number of these spectral components, wherein each level comparator compares the levels of an associated spectral component in several, possibly all channels. Each level comparator is followed by a signal converter stage, which determines the parameter for signal attenuation and / or the parameter for signal delay from the result of the comparison in the level comparator for each channel of the artificial spatial sound. The surround sound assembly has a filter assembly which divides a mono signal containing the useful signals of all channels into a plurality of, in particular five, spectral components, wherein for at least one spectral component a number of attenuator modules and / or delay stages corresponding to the number of channels to be processed is provided, attenuator modules and / or delay stages generate a delayed and / or damped output signal according to the parameters provided for that channel and spectral component by the analyzer assembly. For each channel of the artificial spatial sound, each adder combines the spectral partial signals thus obtained.
Ein Zeitversatz zwischen dem gerade analysieren Segment des Mehrkanal-Nutzsignals und dem mit diesen Daten manipulierten Segment des Monosignals hat den Vorteil, dass eine erst im Verlauf des Signalsegments deutlich hervortretende Rauminformation auch schon auf die Gestaltung des Raumklangs zu Beginn dieses Signalsegments wirken kann.A time offset between the currently analyzing segment of the multi-channel useful signal and the segment of the mono signal manipulated with this data has the advantage that spatial information which clearly emerges only in the course of the signal segment can also have an effect on the design of the spatial sound at the beginning of this signal segment.
Nachstehend wird die Erfindung anhand der beigefügten Zeichnungen näher erläutert. Diese zeigen in
- Fig. 1
- eine graphische Darstellung der Kanaltrennung in Abhängigkeit von der Empfangsqualität eines empfangenen Signals für verschiedene Dekodierverfahren,
- Fig. 2
- eine graphische Darstellung der Zeitauflösung in Abhängigkeit von der Empfangsqualität eines empfangenen Signals für verschiedene Dekodierverfahren,
- Fig. 3
- eine graphische Darstellung der Frequenzauflösung in Abhängigkeit von der Empfangsqualität eines empfangenen Signals für verschiedene Dekodierverfahren,
- Fig. 4
- eine graphische Darstellung der Reproduktion der aktuellen Ortsinformation bzw. des Raumklangs in Abhängigkeit von der Empfangsqualität eines empfangenen Signals für verschiedene Dekodierverfahren,
- Fig. 5
- ein schematisches Blockschaltbild einer bevorzugten Ausführungsform eines erfindungsgemäßen Empfängers,
- Fig. 6
- ein schematisches Blockschaltbild einer bevorzugten Ausführungsform einer Analysebaugruppe des erfindungsgemäßen Empfängers von
Fig. 1 , - Fig. 7
- ein schematisches Blockschaltbild einer bevorzugten Ausführungsform einer Raumklangbaugruppe des erfindungsgemäβen Empfängers von
Fig. 1 und - Fig. 8
- verschiedene spektrale Gewichtungsfunktonen.
- Fig. 1
- a graphic representation of the channel separation as a function of the reception quality of a received signal for various decoding methods,
- Fig. 2
- a graphical representation of the time resolution as a function of the reception quality of a received signal for various decoding methods,
- Fig. 3
- a graphical representation of the frequency resolution as a function of the reception quality of a received signal for various decoding methods,
- Fig. 4
- a graphical representation of the reproduction of the current location information or the spatial sound as a function of the reception quality of a received signal for various decoding methods,
- Fig. 5
- 1 is a schematic block diagram of a preferred embodiment of a receiver according to the invention,
- Fig. 6
- a schematic block diagram of a preferred embodiment of an analysis assembly of the inventive receiver of
Fig. 1 . - Fig. 7
- a schematic block diagram of a preferred embodiment of a surround sound assembly of the inventive receiver of
Fig. 1 and - Fig. 8
- different spectral weighting functions.
Erfindungsgemäß werden während des Empfangs von Mehrkanalaussendungen Nutzsignale verschiedener Kanäle des Mehrkanal-Audiosignals hinsichtlich ihrer spektralen Verteilung analysiert. Durch Vergleich der Analysen verschiedener Kanäle wird ermittelt, welche Spektralkomponenten an welcher Stelle im Raum ihren Ursprung haben. Diese erfindungsgemäß ermittelten Daten zur Beschreibung des Ursprungssignals werden nachfolgend als "Ortsinformationen" bezeichnet. Während gestörter Empfangszeiten wird auf einen künstlichen Raumklang umgeschaltet bzw. umgeblendet, der anhand der aktuell aus dem gestörten Merkanal-Signal ermittelten Ortsinformationen gestaltet wird, also die Spektralanteile des Monosignals so auf die verschiedenen Kanäle verteilt, so dass der Eindruck entsteht, die Spektralanteile hätten weiterhin ihren Ursprung am hierfür ermittelten Ort. Nach dem Ende der Störung wird auf Mehrkanalbetrieb zurückgeschaltet bzw. -geblendet. Die Kenngrößen, wie z.B. Eckfrequenzen von Teilfrequenzbändern, und Steuersignale zur Gestaltung des künstlichen Raumklanges werden nachfolgend als "Raumklang-Parameter" bezeichnet. Je nach technischer Realisierung können Raumklang-Parameter identisch sein mit den Ortsinformationen. Die Ortsinformationen und/oder Raumklang-Parameter fassen Daten zu Einzelfrequenzen oder die Signalanteile in Frequenzbereichen zusammen. Die Erfassung der Ortsinformationen erfolgt zu bestimmten Zeitpunkten oder für bestimmte Zeitintervalle.According to the invention, during the reception of multichannel broadcasts, useful signals of different channels of the multichannel audio signal are analyzed with regard to their spectral distribution. By comparing the analyzes of different channels, it is determined which spectral components originate at which point in space. These data for describing the original signal determined according to the invention are referred to below as "location information". While disturbed Receive times is switched to an artificial surround sound or ambient, which is based on the currently determined from the disturbed Merkanal signal location information, ie the spectral components of the mono signal distributed to the different channels, so that the impression arises that the spectral components would continue their origin at the place determined for this purpose. After the end of the fault, the system switches back to multi-channel operation. The parameters, such as corner frequencies of sub-frequency bands, and control signals for the design of the artificial surround sound are hereinafter referred to as "surround parameters". Depending on the technical realization, surround parameters can be identical to the location information. The location information and / or surround parameter summarize data at individual frequencies or the signal components in frequency ranges together. The acquisition of the location information takes place at certain times or for certain time intervals.
Die Ermittlung der Ortsinformationen des Mehrkanalsignals und/oder die Raumklang-Parameter zur Gestaltung des Raumklangs werden beispielsweise als kontinuierliche Funktionen des Pegels in Abhängigkeit der Frequenz realisiert. Eine kontinuierliche Funktion des Pegels in Abhängigkeit von der Frequenz verhindert den Eindruck eines schnellen Ortswechsels einer Signalquelle, wenn die Frequenz der Quelle eine Bereichsgrenze überschreitet.The determination of the location information of the multi-channel signal and / or the surround parameters for the design of the surround sound are realized, for example, as continuous functions of the level as a function of the frequency. A continuous function of the level as a function of the frequency prevents the impression of a rapid change of location of a signal source when the frequency of the source exceeds a range limit.
Die Frequenzen eines gemeinsam bearbeiteten Bereichs fließen optional mit unterschiedlicher Gewichtung in die Berechnungen ein (frequenzabhängige Bewertungsfunktion). Die Gewichtung kann bei den Ortsinformationen anders gewählt werden, als für die Raumklang-Parameter. Es werden Teile des Spektrums untersucht bzw. bearbeitet, die fest abgegrenzt sind oder sich teilweise überschneiden. Bei dieser für digitale Signalbearbeitung besser geeigneten Aufteilung in Frequenzbereiche werden benachbarte Frequenzen mit geringerer Gewichtung erfasst, so dass auch hier der störende Eindruck einer springenden Signalquelle zuverlässig vermieden wird.The frequencies of a jointly processed area are optionally included in the calculations with different weightings (frequency-dependent evaluation function). The weighting can be chosen differently for the location information than for the surround parameters. Parts of the spectrum are examined or processed, which are firmly demarcated or partially overlap. At this for digital signal processing more suitable division into frequency ranges adjacent frequencies are detected with less weight, so that the disturbing impression of a jumping signal source is reliably avoided here.
Zusätzlich zur bzw. an Stelle der Analyse von Signalpegeln wird die Zeitdifferenz der Spektralanteile (Laufzeitunterschiede) in den verschiedenen Kanälen nach den oben beschriebenen Verfahren in die Ortsinformationen übernommen. Bei verschiedenen Nutzsignalen (z.B. rhythmusbetonter Popmusik) liefert die Zeitdifferenz zwischen den Kanälen eine zuverlässigere Aussage über den Ort der Signalentstehung und eignet sich daher besser als Ausgangsinformation für die Nachbildung des künstlichen Raumklangs.In addition to or instead of the analysis of signal levels, the time difference of the spectral components (transit time differences) in the various channels is taken over into the location information according to the methods described above. For different useful signals (e.g., rhythmically pop music), the time difference between the channels provides a more reliable indication of the location of the signal generation and is therefore better suited as output information for simulating the artificial surround sound.
Einmal erfasste Ortsinformationen werden alternativ nicht durch die nächste Messung ersetzt, sondern über eine Gewichtungsfunktion ergänzt, z.B. über längere Zeiträume gemittelt oder unter stärkerer Berücksichtigung der jüngeren Messungen zusammengefasst. Somit kann die Erfassung der Ortsinformationen auch kontinuierlich erfolgen. Mit einer Gewichtungsfunktion kann man verhindern, dass kurzzeitige Ereignisse im Nutzsignal den Raumklang unangemessen stark beeinflussenOnce acquired location information is alternatively not replaced by the next measurement, but supplemented by a weighting function, e.g. averaged over longer periods of time or summarized with greater consideration of recent measurements. Thus, the detection of the location information can also be done continuously. A weighting function can prevent short-term events in the payload signal from unduly influencing the surround sound
Bei der Ermittlung der Ortsinformationen werden optional nur solche Spektralanteile berücksichtigt, die einen bestimmten Pegel-Schwellwert bzw. eine frequenzabhängige Schwellwertfunktion überschreiten. Rauschanteile im Nutzsignal werden damit von der Gestaltung des künstlichen Raumklangs ferngehalten. Die innerhalb eines Frequenzbereiches vorhandenen kleinen Signalkomponenten beeinträchtigen ferner nicht mehr die Ortsbestimmung des dominanten Signals.When determining the location information, only those spectral components that exceed a certain threshold level or a frequency-dependent threshold value function are optionally considered. Noise components in the useful signal are thus kept away from the design of the artificial surround sound. The present within a frequency range small signal components also no longer affect the localization of the dominant signal.
Für Frequenzbereiche, deren Analyse keine ausreichende Information über den Ort des Signalursprungs liefert, werden die benötigten Ortsinformationen bzw. Raumklang-Parameter aus benachbarten Frequenzbereichen interpoliert, früher ermittelte Werte weiter verwendet (ggf. gewichtet), vordefinierte Werte oder Funktionen genutzt (z.B. diese Lücken als Mono behandelt, also auf alle Kanäle gleich verteilt) und/oder (ggf. teilweise) durch Zufallsparameter ersetzt. Die Weiterverwendung der zuletzt aus brauchbaren Signalanteilen ermittelten Parameter sowie die Interpolation aus benachbarten Frequenzbereichen ermöglichen eine oftmals gute Prognose über den zukünftigen Ort der Signalquelle.For frequency ranges whose analysis does not provide sufficient information about the location of the signal origin, the required location information or surround parameters are interpolated from adjacent frequency ranges, previously determined values continue to be used (weighted if necessary), predefined values or functions used (eg, these gaps) Mono treated, so evenly distributed to all channels) and / or (possibly partially) replaced by random parameters. The further use of the last of usable signal components determined parameters and the interpolation from adjacent frequency ranges allow an often good prognosis on the future location of the signal source.
Die Aufteilung in Frequenzbereiche (z.B. Bereichsgrenzen), die Bewertungsfunktionen und/oder Schwellwertfunktionen sind beispielsweise variabel ausgelegt, insbesondere werden sie anhand der Analyse des Nutzsignals dynamisch verändert. Dieses Verfahren ermöglicht es, individuelle spektrale Schwerpunkte des Nutzsignals als Ganzes zu bearbeiten, es verhindert die Aufspaltung und räumliche Trennung solcher Bereiche. Darüber hinaus kann die Nutzsignalanalyse bei leisen Passagen kleinere Signalamplituden erfassen. Das Zeitverhalten kann besser an die Charakteristik der aktuellen Störsituation, z.B. Frequenz der Fading-Einbrüche angepasst werden. Bei Störungen im Einkanal-Nutzsignal, z.B. Rauschen, kann individuell reagiert werden, z.B. Reduzierung der Signalpegel und/oder der Kanaltrennung im Bereich hoher Frequenzen, damit die Rauschkomponenten nicht in dem gerade für die Höhenwiedergabe genutzten Kanal besonders stark hörbar werden.The division into frequency ranges (for example range limits), the evaluation functions and / or threshold functions are, for example, designed to be variable, in particular they are changed dynamically on the basis of the analysis of the useful signal. This method makes it possible to process individual spectral focuses of the desired signal as a whole, it prevents the splitting and spatial separation of such areas. In addition, the useful signal analysis in quiet passages can detect smaller signal amplitudes. The timing can better match the characteristics of the current noise situation, e.g. Frequency of fading burglaries are adjusted. For disturbances in the single-channel payload, e.g. Noise, can be reacted individually, e.g. Reduction of signal levels and / or channel separation in the high-frequency range, so that the noise components are not particularly strong in the currently used for Höhenwiedergabe channel.
Auch bei guten Empfangssignalen wird optional vorübergehend oder permanent der künstliche Raumklang beibehalten. In diesen Zeiträumen wird zeitlich überlappend und/oder abwechselnd die Ermittlung der Ortsinformationen und Raumklang-Parameter sowie die Erzeugung des Raumklangs durchgeführt. Es entfallen hierbei die Wechsel von Mehrkanalbetrieb zu Raumklang und zurück, bzw. ihre Zahl wird reduziert. Es entsteht ein harmonischer Raum- und Klangeindruck.Even with good reception signals, the artificial surround sound is optionally retained temporarily or permanently. In these periods of time overlapping and / or alternately the determination of the location information and surround parameters and the generation of the room sound carried out. It eliminates the change from multi-channel operation to surround sound and back, or their number is reduced. It creates a harmonious spatial and sound impression.
Allen Varianten ist gemeinsam, dass die Verzerrungskomponenten eines gestörten Signals nicht mehr die Signalamplitude beeinflussen und damit den Störabstand reduzieren, sondern es leidet nur noch die Ortsinformation bei schlechter werdendem Signal. Ein vollständiges Mehrkanal-Audiosignal enthält zu jedem Zeitpunkt bzw. kleinsten Zeitintervall und für jede einzelne Frequenz eine Information über den Ort der Signalentstehung bzw. über eine räumliche Anordnung verschiedener Signalquellen bzgl. eines Aufnahmemikrofons und damit bezüglich des Zuhörers. Das menschliche Ohr ist nicht in der Lage, diese Fülle an Informationen vollständig auszuwerten. Schnelle Wechsel von einem Kanal zu einem anderen kommen üblicherweise nicht vor und würden im übrigen in der vollen Geschwindigkeit vom Ohr nicht erfasst. Wenn nun das Mehrkanal-Audiosignal, beispielsweise durch Rauschanteile bei schwächer werdendem Signal, an Information verliert, so bleibt dennoch für lange Zeit genug Restinformation übrig, um für das Ohr einen akzeptablen Raumeindruck bereitzustellen. Die Erfindung nutzt diese Restinformation um künstlich einen Raumklang wieder herzustellen.All variants have in common that the distortion components of a disturbed signal no longer affect the signal amplitude and thus reduce the signal to noise ratio, but it suffers only the location information in deteriorating signal. A complete multi-channel audio signal contains information about the location of the signal generation or about a spatial arrangement of different signal sources with respect to a recording microphone and thus with respect to the listener at each time or smallest time interval and for each individual frequency. The human ear is unable to fully evaluate this wealth of information. Fast changes from one channel to another usually do not occur and would otherwise not be detected by the ear at full speed. If, however, the multichannel audio signal loses information, for example as a result of noise due to a weakening signal, enough residual information remains for a long time in order to provide an acceptable spatial impression for the ear. The invention uses this residual information to artificially restore a surround sound.
Erfindungsgemäß wird auch während einer Störung immer noch Information aus dem gestörten Signal gewonnen, um den "künstlichen" Raumklang-Effekt gemäß der aktuell übertragenen Ortsinformation zu gestalten. Bei kritischen Empfangssituationen gelangt nur das Monosignal zu den Lautsprechern, welches einem künstlichen Raumklang unterworfen ist. Es erfolgt eine Erfassung der auch im gestörten Signal noch vorhandenen Ortsinformationen auch in den Zeiten, in denen das Signal so stark gestört ist, dass es sich nicht mehr zur Mehrkanalwiedergabe eignet, aber wiederum noch nicht so stark gestört ist, als dass auch die Ortsinformation in hohem Maße verzerrt worden wäre. Somit werden die Informationen zur Gestaltung des künstlichen Raumklang-Effekts aus dem weiterhin verfügbaren, wenn auch qualitativ schlechten Mehrkanal-Audiosignal gewonnen.According to the invention, information is still obtained from the disturbed signal during a disturbance in order to design the "artificial" surround sound effect in accordance with the currently transmitted location information. In critical reception situations, only the mono signal reaches the loudspeakers, which is subject to an artificial surround sound. There is a detection of the even in the disturbed signal still available location information even in the times in which the signal is disturbed so much that it is no longer suitable for multi-channel playback, but again not so much disturbed as that the location information would have been greatly distorted. Thus, the information for designing the artificial surround sound effect is obtained from the still available, albeit qualitatively poor, multichannel audio signal.
In Zeiträumen besonders schlechten Empfangs sind die nach diesem Verfahren ermittelbaren Reste der Rauminformation nicht ausreichend,um einen künstlichen Raumklang zu gestalten. In diesen Zeiten wird die Erfassung der Rauminformation vorübergehend unterbrochen und mit den zuletzt ermittelten Werten weitergearbeitet oder eine Umblendung auf Mono-Betrieb durchgeführt.During periods of particularly poor reception, the remainders of the spatial information that can be determined by this method are not sufficient to design an artificial spatial sound. In these times, the detection of the spatial information is temporarily interrupted and worked on with the last determined values or a transition to mono mode.
Zweckmäßigerweise erfolgt bei ausreichender Empfangsqualität eine Mittelung der Messungen über längere Zeiten oder über Frequenzbereiche, um die Rauschanteile im gestörten Signal zu eliminieren. Diesen Zusammenhang zeigen graphisch die
In den
Die Ortsinformation bzw. die Ortsinformation kann in drei Parametern verzerrt sein, nämlich in der Kanaltrennung, der Zeitauflösung und der Frequenzauflösung. Die Kanaltrennung (
Die
Bei Weiterverwendung vorheriger Ortsinformationen vor der Störung (Linie 16) ist bereits bei leicht gestörten Signalen die Zeitauflösung auf null reduziert (
Das erfindungsgemäße Verfahren nutzt so weit wie möglich alle noch vorhandenen Informationen aus (Linie 18). Ein geeigneter Mix aus Zeit- und Frequenzmittelung orientiert sich am Auflösungsvermögen des menschlichen Gehörs und der Rechenleistung der Signalbearbeitungsbaugruppen. In der Regel wird die zeitliche Auflösung zunächst, wegen der Trägheit des Gehörs kaum hörbare Qualitätseinbußen bewirken. Die Zusammenfassung in Frequenzbänder bedingt jedoch bei einfachen Systemen erkennbare Verfälschungen der Ortsinformation (Pfeil 20, feine Auflösung bedarf großer Rechenleistungen). Bei nachlassendem Informationsgehalt muss man eine oder beide Auflösungen weiter reduzieren. Die Kanaltrennung wird erst zurückgenommen, wenn die im Signal verfügbare Restinformation nicht mehr für eine vertretbare Audioqualität ausreicht. Das Verfahren eignet sich besonders zur Dekodierung von schwachen, aber weitgehend stabilen Signalen, d.h. unterhalb des "Mono"-Pegels konventioneller Dekoder. Diesen Bereich des Zugewinns an Ortsinformation zeigt Pfeil 22.As far as possible, the method according to the invention uses all the information that is still available (line 18). A suitable mix of time and frequency averaging is based on the resolution of the human ear and the processing power of the signal processing modules. As a rule, the temporal resolution will initially, due to the inertia of hearing, cause barely audible quality losses. The summary in frequency bands, however, requires recognizable falsifications of the location information in simple systems (
Über zwei Signale 1101 und 1102 gelangen zwei künstlich aus dem Einkanal-Signal 1021 erzeugte Signale Rs (rechts synthetisch) und Ls (links synthetisch) an eine Überblendeinheit 1040. Auch die Signale 1031 und 1032 werden zur Überblendeinheit 1040 geführt. Das Signal 1023 zur Information über Empfangsstörungen wird ebenfalls zur Überblendeinheit 1040 weiter geleitet. In Abhängigkeit dieses Signals 1023 wird bei schlechter werdendem Empfang von den Signalen 1031 und 1032 auf die synthetischen Signale 1101 und 1102 umgeblendet. Zwei Signale 1041 und 1042 führen die Ausgänge der Überblendeinheit 1040 über zwei Verstärker 1051 und 1052 zu zwei Lautsprechern 1061 und 1062. Die Baugruppen 1030, 1100, 1300, 1040 und 1050 sind beispielhaft in einem digitalen Signalprozessor (DSP) 1500 zusammengefasst werden, wobei die beschriebenen Funktionen insbesondere als Software ausgebildet sind.Via two
Zur Analyse der in unterschiedlichen Kanälen übertragenen Signale werden alternativ keine Filter 1310/1320 für einzelne Frequenzbereiche verwendet, sondern man ermittelt je Kanal eine Funktion des Pegels über der Frequenz, daraus eine Auflistung eines Parametersatzes mit Kennfrequenzen und dazugehörigen Pegelwerten. Die Frequenzen dazwischen kann man beispielsweise durch Interpolation erhalten. Für jeden künstlich zu erzeugenden Kanal wird an Stelle der Baugruppe 1100 beispielsweise ein analoges mehrstufiges Filter, beispielsweise aus Operationsverstärkern, derart gesteuert, dass es das zugeleitete Monosignal entsprechend dieser Funktionen/Parameter umformt.For the analysis of the signals transmitted in different channels,
Bei der Filterung und Bestimmung der Parameter für Signaldämpfung und Signalverzögerung wird beispielsweise das Frequenzspektrum in verschiedene Teile aufgeteilt, welche gemäß der in
Alternativ werden die Pegel in den Frequenzteilsegmenten über einen längeren Zeitraum gemessen und diese Verläufe beispielsweise in einem Ringpuffer gespeichert und einer Korrelationsstufe zugeführt. Diese Stufe ermittelt durch verschiedene zeitliche Verschiebungen und anschließenden Vergleich der Kanäle, für welche Zeitverschiebung eine ausgeprägte Übereinstimmung nachweisbar ist. Diese Zeitdifferenz wird als Information über den Ursprungsort des Signals verwendet. Der zuvor beschriebene einfache Pegelvergleich kann dabei weiterhin erfolgen, wobei eine nachfolgende Stufe entscheidet, welche der beiden Lokalisierungsstrategien in diesem Fall eine bessere Information (glaubwürdiger, ausgeprägter, konstanter oder anderes Kriterium) ergibt und weiterverarbeitet wird.Alternatively, the levels in the frequency subsegments are measured over a longer period of time and these progressions are stored, for example, in a ring buffer and fed to a correlation stage. This stage determines by different temporal shifts and subsequent comparison of the channels for which time shift a pronounced match is detectable. This time difference is used as information about the origin of the signal. The above-described simple level comparison can continue to take place, wherein a subsequent stage decides which of the two localization strategies results in this case better information (credible, pronounced, constant or other criterion) and further processed.
In einer bevorzugten Weiterbildung zur Mittelung und Gewichtung der gewonennen Ortsinformation ist in der in Baugruppe 1371 und entsprechenden Baugruppen en Tiefpass vorgesehen.In a preferred embodiment for averaging and weighting the gewonennen location information is en provided in the assembly in 1371 and corresponding modules low pass.
Die in den Stufen 1310 und 1320 erzeugten Frequenzbereiche (z.B. Signal 1311) werden alternativ in viel feinere Frequenzteilspektren aufgespalten. Alle Teilspektren mit geringen Signalpegeln werden verworfen, die restlichen Teile wieder zu Signalen addiert, die denen nach der ersten Frequenzaufteilung (also z.B. 1311) entsprechen.The frequency ranges generated in
Wenn eine Lücke im Orts-Signal auftritt, also für diesen Spektralteil in allen Kanälen vorübergehend kein ausreichender Pegel vorliegt, wird die im DSP digital berechnete Tiefpassfunktion für diese Messung angehalten. Bei einer Realisierung in digitaler Hardware werden beispielsweise die verschiedenen Messungen in ein Schieberegister geschrieben. Jede neue Messung erzeugt ein Taktsignal und schiebt bei der Übertragung die älteste aus dem Register. Eine gewichtete Addition aller Registerkomponenten ergibt den Raumklang-Parameter. Für die Dauer einer Lücke im Orts-Signal wird der Takt zum Schieberegister unterbrochen. Alternativ werden zunächst alle Frequenzbereiche mit ausreichenden Informationen berechnet und danach die Lücken in anderen Frequenzbereichen linear aus den Nachbarbereichen interpoliert.If there is a gap in the location signal, ie if there is not sufficient level in all channels for this spectral part, the digitally calculated low-pass function for this measurement is stopped in the DSP. For example, when implemented in digital hardware, the various measurements are written to a shift register. Each new measurement generates a clock signal and shifts the oldest one out of the register during transmission. A weighted addition of all register components gives the surround parameter. For the duration of a gap in the location signal, the clock to the shift register is interrupted. Alternatively, first all frequency ranges are calculated with sufficient information and then the gaps in other frequency ranges are linearly interpolated from the neighboring ranges.
Die Pegel in den Frequenzteilsegmenten werden in einer alternativen Ausführungsform über einen längeren Zeitraum gemessen und diese Verläufe in einem Ringpuffer gespeichert. Zu Beginn einer Störung wird aus dieser Aufzeichnung des Pegelverlaufs ein Signalanstieg bzw. -abfall berechnet, der für die Dauer der Störung weiter in die Raumklang-Parameter eingearbeitet wird.The levels in the frequency subsegments are measured over an extended period of time in an alternative embodiment and these waveforms stored in a ring buffer. At the beginning of a disturbance, a signal rise or fall is calculated from this recording of the level profile, which is further incorporated into the surround parameters for the duration of the disturbance.
In einer Weiterführung der Erfindung werden die höchsten Spitzen im Frequenzspektrum ermittelt. Diese werden als Mittenfrequenzen der Filter 1110 zur Spektralaufteilung verwendet.In a continuation of the invention, the highest peaks in the frequency spectrum are determined. These are used as center frequencies of the spectral split filters 1110.
Das Signal 1023 am Eingang der Baugruppe 1040 wird alternativ nur in der Schaltrichtung von Stereo zum Raumklang sofort durchgeschaltet. Bei der Rückblendung vom Raumklang zum Stereo hingegen über einen Tiefpass geführt, so dass hierbei eine Verzögerung entsteht und somit für begrenzte Dauer auch zu Zeiten guten Empfangs noch der künstliche Raumklang aktiviert bleibt.The
Am das Signal 1021 führenden Eingang der Raumklangbaugruppe 1100 kann ein Verzögerungselement hinzugefügt werden, z.B. in Form eines digitalen FIFO-Speichers. Hierdurch wird zwar die gerade an der Antenne 1010 eintreffende Signalsequenz in der Analysebaugruppe 1300 bearbeitet, die Ergebnisse der Analyse wirken aber auf ein Signalsegment, das bereits früher empfangen wurde, entsprechend dem Versatz durch die Zeitverzögerung. Eine erst im Verlauf der Analyse klar herausgearbeitete Ortsinformation kann so auf die gesamte Signalsequenz von Beginn an wirken. Um den Zeitversatz beim Umblenden vom künstlichen Raumklang auf die Wiedergabe der Originalsignale zu kompensieren, sind auch die beiden Eingänge der Umblendeinheit 1040, die die Signale 1031 und 1031 führen, mit Verzögerungsstufen gleichen Zeitverhaltens auszustatten.At the input of the
Claims (17)
- Method for decoding multichannel audio transmissions, in particular two-channel stereo audio transmissions, having one respective useful signal per channel, wherein a spatial impression or a local information item for the corresponding signal source is generated for each signal-source frequency spectrum which is transmitted by the useful signals, through occurrence at different times and through different levels in the different channels, characterized in that during the reception of the multichannel audio transmission the local information is extracted from the useful signals at least in time periods in which the reception is disrupted in such a way that direct multichannel reproduction is no longer possible, and this current local information is used to generate artificial spatial noise from a monosignal containing the useful signals of all the channels through distribution of various frequency bands over the channels corresponding to the number of channels of the multichannel audio transmission, in each case with different time delays and/or different damping of the levels in the various channels.
- Method according to Claim 1, characterized in that spectral distributions of the useful signals of the various channels and/or differences in propagation times or time differences of, in each case, two or more various spectral components in the respective useful signal of various channels are compared with one another, parameters for signal attenuation and/or for delaying signals are determined for at least two or more different spectral components from the comparison for each channel, and the corresponding spectral components from a single-channel signal which contains all the useful signals of the channels are distributed, having being delayed and/or attenuated in accordance with the specific parameters, over channels corresponding to the number of channels of the multichannel audio transmission, in such a way that a spatial sound impression, which corresponds essentially to a spatial sound impression of the directly reproduced audio signals of the channels, is generated for someone listening to the corresponding spectral components.
- Method according to Claim 1 or 2, characterized in that the parameters for the attenuating and/or delaying processes are determined as a constant function of the level and/or propagation time difference in accordance with the frequency.
- Method according to one of the preceding claims, characterized in that the spectral range is divided into a plurality of predetermined spectral components, wherein various frequencies or frequency ranges of a spectral component are taken into account with different weighting in the determination of the parameters.
- Method according to Claim 4, characterized in that the division of the spectral components is changed dynamically as a function of the analysis of the useful signals.
- Method according to Claim 4 or 5, characterized in that the predetermined spectral components overlap partially in frequency and the frequencies of a spectral component in the region of overlap with an adjacent spectral component are weighted to a lesser degree.
- Method according to one of the preceding claims, characterized in that parameters which have been determined once are supplemented over time by means of a weighting function.
- Method according to Claim 7, characterized in that averaging over predetermined time periods or compilation of a predetermined time period with a high degree of consideration being given to parameters which have been determined relatively recently occurs as a weighting function.
- Method according to one of the preceding claims, characterized in that only spectral components which exceed a predetermined level threshold value or a frequency-dependent threshold value function are taken into account in the determination of the parameters.
- Method according to one of the preceding claims, characterized in that for spectral components in which the parameters cannot be determined, said parameters are interpolated from adjacent spectral components, previously determined parameters are used further, if appropriate, weighted, and predetermined parameters or parameter functions are used and/or random parameters are used.
- Method according to one of the preceding claims, characterized in that a time offset is brought about between the analysed time segment of the multichannel useful signal and the segment of the monosignal which is manipulated with this data by delaying the signal reproduction.
- Receiver (100) for multichannel audio transmissions having a multichannel decoder which outputs a plurality of useful signals from various channels separately,
characterized by an analysis module (1300) which compares spectral distributions of the useful signals of the various channels and/or propagation time differences of, in each case, two or more different spectral components in the respective useful signal of the various channels with one another, determines parameters for signal attenuation and/or signal delay from the comparison for each channel for at least two or more different spectral components, and a spatial noise module (1100) which distributes the corresponding spectral components from a single-channel signal which contains the useful signals of all the channels, delayed and/or attenuated in accordance with the specific parameters, over the channels corresponding to the number of channels of the multichannel audio transmission, in such a way that a person listening to the corresponding spectral components receives a spatial sound impression which corresponds essentially to a spatial sound impression of the directly reproduced audio signals of the channels. - Receiver (100) according to Claim 12, characterized in that said receiver (100) has, for each channel (1031, 1032), a filter module (1310, 1320) which decomposes the respective useful signal into a plurality of spectral components (1311 to 1314, 1321 to 1324), in particular four thereof.
- Receiver (100) according to Claim 13, characterized in that the analysis module (1300) has a level detector (1331, 1341) for each spectral component.
- Receiver (100) according to Claim 13 or 14, characterized in that the analysis module (1300) has a number of level comparators (1371) corresponding to the number of spectral components, wherein a level comparator compares the level of an assigned spectral component in at least two channels.
- Receiver (100) according to Claim 15, characterized in that connected downstream of each level comparator (1371) is a signal shaping stage (1381) which determines the parameter for signal attenuation and/or the parameter for signal delay for each channel from the result of the comparison in the level comparator (1371).
- Receiver (100) according to Claim 15 or 16, characterized in that the spatial sound module (1100) has a filter module (1110) which decomposes a monosignal (1021) containing the useful signals of all the channels into a plurality of spectral components (1111 to 1115), in particular five thereof, wherein a number of attenuator modules (1121 to 1128) and/or delay stages (1131 to 1138) corresponding to the number of the channels is provided for at least one spectral component, wherein attenuator modules (1121 to 1128) and delay stages (1131 to 1138) generate an output signal which is delayed and/or attenuated in accordance with the parameters for signal delay and/or signal attenuation which are determined for this channel and this spectral component, wherein an adder element (1141, 1142) which is connected downstream for each channel adds all the output signals from various spectral components of a channel to one another.
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DE1999100819 DE19900819A1 (en) | 1999-01-12 | 1999-01-12 | Prodder for decoding multi-channel distorted radio signals by extracting spatial information from the data signal and recombining this with mono signal data |
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ATE359687T1 (en) * | 2003-04-17 | 2007-05-15 | Koninkl Philips Electronics Nv | AUDIO SIGNAL GENERATION |
PL1618763T3 (en) * | 2003-04-17 | 2007-07-31 | Koninl Philips Electronics Nv | Audio signal synthesis |
SE0301273D0 (en) * | 2003-04-30 | 2003-04-30 | Coding Technologies Sweden Ab | Advanced processing based on a complex exponential-modulated filter bank and adaptive time signaling methods |
WO2009066960A1 (en) | 2007-11-21 | 2009-05-28 | Lg Electronics Inc. | A method and an apparatus for processing a signal |
US9338552B2 (en) | 2014-05-09 | 2016-05-10 | Trifield Ip, Llc | Coinciding low and high frequency localization panning |
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