Abstract: In a method for coding an audio signal to obtain a coded bit stream, discrete-time samples of the audio signal are transformed into the frequency domain to obtain spectral values. The spectral values are coded with a code table having a limited number of code words of different lengths to obtain spectral values coded by code words, the length of a code word assigned to a spectral value being that much shorter the higher the probability of occurrence of the spectral value is. A raster is then specified for the coded bit stream, the raster having equidistant raster points and the distance between the raster points depending on the code table(s) used. In order to obtain error-tolerant Huffman coding, priority code words, which represent particular spectral values which are psychoacoustically more important than other spectral values, are so arranged in the raster that the start of each priority code word coincides with a raster point.

Abstract: Devices and methods for generating encrypted data, for playing encrypted data and for re-signing originally signed encrypted data are based on the encrypted data, apart from the encrypted media information, to include the information required for decrypting the data and additionally a signature of who has generated the encrypted data. Thus the origin of the encrypted data can be traced back. In particular, passing on the encrypted data to a limited extent by the producer of the *encrypted data, for example to friends or acquaintances, is allowed, while only a mass reproduction of the encrypted data is considered as pirate copying. The pirate copier can, however, be found out with the help of the signature, wherein the signature is optionally protected by an embedded watermark signature. Because this is a concept wherein, when being used legally, only encrypted data occur, the unauthorized removal of the encryption is a statutory offence.

Abstract: A time-discrete audio signal is processed to provide a quantization block with quantized spectral values. Furthermore, an integer spectral representation is generated from the time-discrete audio signal using an integer transform algorithm. The quantization block having been generated using a psychoacoustic model is inversely quantized and rounded to then form a difference between the integer spectral values and the inversely quantized rounded spectral values. The quantization block alone provides a lossy psychoacoustically coded/decoded audio signal after the decoding, whereas the quantization block, together with the combination block, provides a lossless or almost lossless coded and again decoded audio signal in the decoding. By generating the differential signal in the frequency domain, a simpler coder/decoder structure results.

Abstract: For characterizing an information signal having an amplitude-time waveform with local extreme values, at first the local extreme values of the information signal are determined, wherein a local extreme value is defined by a time instant and an amplitude. Furthermore, area information of valleys or mountains of the information signal in case of a one-dimensional amplitude of the information signal or volume information in case of a two-dimensional amplitude of the information signal of valleys or mountains is ascertained. A valley or mountain is defined by a temporal section of the information signal, wherein the section of the information signal extends from the time instant of a local extreme value to a temporarily adjacent value of the information signal having the same amplitude as the local extreme value.

Abstract: In a method for generating an identifier for an audio signal including a tone generated by an instrument, a discrete amplitude-time representation of the audio signal is generated at first, wherein the amplitude-time representation, for a plurality of subsequent points in time, comprises a plurality of subsequent amplitude values, wherein a point in time is associated to each amplitude value. Subsequently, an identifier for the audio signal is extracted from the amplitude-time representation. An instrument database is formed from several identifiers for several audio signals including tones of several instruments. By means of a test identifier for an audio signal having been produced by an unknown instrument, the type of the test instrument is determined using the instrument database. A precise instrument identification can be obtained by using the amplitude-time representation of a tone produced by an instrument for identifying a musical instrument.

Abstract: A method for detecting a transient in a discrete-time audio signal is performed completely in the time domain and includes the step of segmenting the discrete-time audio signal so as to generate consecutive segments of the same length with unfiltered discrete-time audio signals xs(T−1). The discrete-time audio signal in a current segment is subsequently filtered. Then either the energy of the filtered discrete-time audio signal in the current segment can be compared with the energy of the filtered discrete-time audio signal in a preceding segment or a current relationship between the energy of the filtered discrete-time audio signal in the current segment and the energy of the unfiltered discrete-time audio signal in the current segment can be formed and this current relationship compared with a preceding corresponding relationship. On the basis of the one and/or the other of these comparisons it is detected whether a transient is present in the discrete-time audio signal.

Abstract: In order to obtain an integer transform, which provides integer output values, the TDAC function of a MDCT is explicitly carried out in the time domain before the forward transform. In overlapping windows, this results in a Givens rotation which may be represented by lifting matrices, wherein time-discrete sampled values of an audio signal may at first be summed up on a pair-wise basis to build a vector so as to be sequentially provided with a lifting matrix. In accordance with the invention, after each multiplication of a vector by a lifting matrix, a rounding step is carried out such that, on the output-side, only integers will result. By transforming the windowed integer sampled value with an integer transform, a spectral representation with integer spectral values may be obtained. The inverse mapping with an inverse rotation matrix and corresponding inverse lifting matrices results in an exact reconstruction.

Abstract: An apparatus for scalable encoding a spectrum of a signal including audio and/or video information, with the spectrum comprising binary spectral values, includes a means (102) for generating a first sub-scaling layer and a second sub-scaling layer in addition to a means (106) for forming the encoded signal, with the means (106) for forming being implemented so as to include the first sub-scaling layer and the second sub-scaling layer into the encoded signal that the first and the second sub-scaling layer are separately decodable from each other. In contrast to a full-scaling layer, a sub-scaling layer includes only the bits of a certain order of a part of the binary spectral values in the band, so that, by additionally decoding a sub-scaling layer, a more finely controllable and a more finely scalable precision gain may be achieved.

Abstract: In a method of extracting a signal identifier from a time signal, the temporal occurrence of signal edges in the time signal is detected (12), wherein a signal edge has a specified temporal length. In addition, the temporal interval between two selected detected signal edges is determined (14). From the temporal interval determined, a frequency value is calculated (16), the frequency value being associated with a time of occurrence of the frequency value in the time signal so as to obtain a coordinate tuple from the frequency value and the time of occurrence for this frequency value. A signal identifier is created from a plurality of coordinate tuples (18), each coordinate tuple including a frequency value and a time of occurrence, which is why the signal identifier includes a sequence of signal identifier values reproducing the temporal form of the time signal. The extracted signal identifier is based on signal edges of the time signal and thus reproduces the temporal form of the time signal.

Abstract: A method of coding stereo audio spectral values first carries out grouping of those values in scale factor bands, with which scale factors are associated. Sections are formed next, each comprising at least one scale factor band. The spectral values are coded within at least one section with a code book assigned to the section, out of a plurality of code books each with a code book number assigned to it, the number of the code book used being transmitted as side information to the coded stereo audio spectral values. At least one additional code book number is provided, which does not refer to a code book but shows information relevant to the section to which it is assigned. A method of decoding stereo audio spectral values which are partly coded by the intensity stereo process and which have side information uses the relevant information, showing the additional code book numbers, to cancel the existing coding of the stereo audio spectral values.

Abstract: In a method for signalling a noise substitution when coding an audio signal, the time-domain audio signal is first transformed into the frequency domain to obtain spectral values. The spectral values are subsequently grouped together to form groups of spectral values. On the basis of a detection establishing whether a group of spectral values is a noisy group or not, a codebook is allocated to a non-noisy or tonal group by means of a codebook number for redundancy coding of the same. If a group is noisy, an additional codebook number which does not refer to a codebook is allocated to it in order to signal that this group is noisy and therefore does not have to be redundancy coded. By signalling noise substitution by means of a Huffman codebook number for noisy groups of spectral values, which are e.g.

Abstract: In determining a coding block raster on which a decoded signal is based, a segment of the decoded signal is picked out first, said segment beginning at a certain output sampling value of the decoded signal. Said segment is then converted into a spectral representation, whereupon said spectral representation is then evaluated in relation to a predetermined criterion in order to obtain an evaluation result for the segment. This procedure is repeated for a plurality of different segments beginning at different output sampling values each, in order to obtain a plurality of evaluation results. Finally, the plurality of the evaluation results is searched in order to establish the evaluation result that has an extreme value as compared to the other evaluation results, in such a way that it can be assumed that the segment to which this evaluation result is allocated matches the coding block raster on which the decoded signal is based.

Abstract: In a method for transferring a music signal into a note-based description, a frequency-time representation of the music signal is first generated, with the frequency-time representation comprising coordinate tuples, with a coordinate tuple including a frequency value and a time value, with the time value indicating the time of occurrence of the assigned frequency in the music signal. Thereupon, a fit function will be calculated as a function of the time, the course of which is determined by the coordinate tuples of the frequency-time representation. For time-segmenting the frequency-time representation, at least two adjacent extreme values of the fit function will be determined. On the basis of the determined extreme values, a segmenting will be carried out, with a segment being limited by two adjacent extreme values of the fit function, with the time length of the segments indicating a time length of a note for the segment.

Abstract: A method of coding a time-discrete stereo signal, the stereo signal having a first and a second channel, permits scalable stereo coding. At first, a mono signal is formed from the stereo signal, which is then coded, whereupon the coded mono signal is transmitted to a bit stream. Thereafter, the coded mono singal is decoded again, whereupon stereo information is formed on the basis of the coded/decoded mono signal and the first and second channels, with such stereo information being coded and being also written into the bit stream in order to obtain a bit stream comprising a complete coded monolayer as well as a layer with coded stereo information.

Abstract: In determining a coding block raster on which a decoded signal is based, a segment of the decoded signal is picked out first (11), said segment beginning at a certain output sampling value of the decoded signal. Said segment is then converted into a spectral representation (12), whereupon said spectral representation is then evaluated in relation to a predetermined criterion (13) in order to obtain an evaluation result for the segment. This procedure is repeated for a plurality of different segments beginning at different output sampling values each, in order to obtain a plurality of evaluation results. Finally, the plurality of the evaluation results is searched (14) in order to establish the evaluation result that has an extreme value as compared to the other evaluation results, in such a way that it can be assumed that the segment to which this evaluation result is allocated matches the coding block raster on which the decoded signal is based.

Abstract: The present invention permits a combination of a scalable audio coder with the TNS technique. In a method for coding time signals sampled in a first sampling rate, second time signals are first generated whose sampling rate is smaller than the first sampling rate. The second time signals are then coded according to a first coding algorithm and written into a bit stream. The coded second time signals are, however, decoded again, and, like the first time signals, transformed into the frequency domain. From a spectral representation of the first time signals, TNS prediction coefficients are calculated. The transformed output signal of the coder/decoder with the first coding algorithm, like the spectral representation of the first time signal, undergoes a prediction over the frequency to obtain residual spectral values for both signals, though only the prediction coefficients calculated on the basis of the first time signals are used. These two signals are evaluated against each other.

Abstract: A method for detecting a transient in a discrete-time audio signal is performed completely in the time domain and includes the step of segmenting the discrete-time audio signal so as to generate consecutive segments of the same length with unfiltered discrete-time audio signals xs(T-1). The discrete-time audio signal in a current segment is subsequently filtered. Then either the energy of the filtered discrete-time audio signal in the current segment can be compared with the energy of the filtered discrete-time audio signal in a preceding segment or a current relationship between the energy of the filtered discrete-time audio signal in the current segment and the energy of the unfiltered discrete-time audio signal in the current segment can be formed and this current relationship compared with a preceding corresponding relationship. On the basis of the one and/or the other of these comparisons it is detected whether a transient is present in the discrete-time audio signal.

Abstract: A method for detecting a transient in a discrete-time audio signal is performed completely in the time domain and includes the step of segmenting the discrete-time audio signal as to generate consecutive segments of the same length with unfiltered discrete-time audio signals. The discrete-time audio signal in a current segment is filtered. Either the energy of the filtered discrete-time audio signal in the current segment is compared with the energy of the filtered discrete-time audio signal in a preceding segment or a current relationship between the energy of the filtered discrete-time audio signal in the current segment and the energy of the unfiltered discrete-time audio signal in the current segment is formed and this current relationship compared with a preceding corresponding relationship. Whether a transient is present in the discrete-time audio signal is detected using one and/or the other of these comparisons.

Abstract: A method for coding or decoding an audio signal combines the advantages of TNS processing and noise substitution. A time-discrete audio signal is initially transformed to the frequency domain in order to obtain spectral values of the temporal audio signal. Subsequently, a prediction of the spectral values in relation to frequency is carried out in order to obtain spectral residual values. Within the spectral residual values, areas are detected encompassing spectral residual values with noise properties. The spectral residual values in the noise areas are noise-substituted, whereupon information concerning the noise areas and noise substitution is incorporated into side information pertaining to a coded audio signal. Thus, considerable bit savings in case of transient signals can be achieved.

Abstract: In a method for concealing errors in an audio data stream the occurrence of an error is detected in the audio data stream, audio data prior to the occurrence of the fault being intact audio data. Thereafter a spectral energy of a subgroup of the intact audio data is calculated. After forming a pattern for substitute data on the basis of the spectral energy calculated for the subgroup of the intact audio data, substitute data for erroneous or missing audio data which correspond to the subgroup are created on the basis of the pattern.