Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.

Musictrace Gmbh

Christian Neubauer

Frank Siebenhaar

Ralph Kulessa

Juergen Herre

Wolfgang Spinnler

Thomas Sporer

Karlheinz Brandenburg

Stefan Kraegeloh

Joerg Pickel

Eric Allamanche

Patrick Aichroth

Stefan Krägeloh

Jörg Pickel

Sascha Disch

Jürgen Herre

Ernst Eberlein

Karsten Linzmeier

Albert Heuberger

Rainer Perthold

Heinz Gerh&auml;user

Hartmut Schott

Roland Plankenb&uuml;hler

For monitoring a data transmitter such as a streaming server, which supplies transmitted data in response to a request of a receiver, an examiner examines a data traffic at the input of a receiver or at the output of the receiver, the examiner being configured to ascertain whether the data traffic falls below a minimum threshold. If the minimum threshold is fallen below, a connection activator initiates a new connection between the receiver and the data transmitter. This serves to enable consistent data-transmitter monitoring, even for non-reliable point-to-point connections via the internet.

Apparatus and method for monitoring data transmitter

The present invention relates to a device for detecting a manipulation of an information signal, having an extractor for extracting an information signal component characteristic for the information signal from the information signal, an encrypter for encrypting the information signal component to obtain an encrypted signal, and a comparator for comparing the encrypted signal to a reference signal, wherein the reference signal is an encrypted representation of a non-manipulated reference signal component of a reference information signal to detect the manipulation.

Device and method for detecting a manipulation of an information signal

Techniques for introducing information into a data stream first obtains the spectral values of the short-term spectrum of the audio signal. Separately, information to be introduced are combined with a spread sequence obtaining a spread information signal, whereupon a spectral representation of the spread information is generated, then weighted with an established psychoacoustic maskable noise energy to generate a weighted information signal, wherein energy of the introduced information is substantially equal to or below the psychoacoustic masking threshold. The weighted information signal and the spectral values of the short-term spectrum of the audio signal are then summed and afterwards processed again to obtain a processed data stream including audio information and information to be introduced. Because the information to be introduced are introduced without changing to the time domain, the block rastering underlying the short-term spectrum are not touched, thus introducing a watermark will not lead to tandem encoding effects.

Method and apparatus for introducing information into a data stream and method and apparatus for encoding an audio signal

The present invention relates to a device for detecting a manipulation of an information signal, having an extractor for extracting an information signal component characteristic for the information signal from the information signal, an encryptor for encrypting the information signal component to obtain an encrypted signal, and a comparator for comparing the encrypted signal to a reference signal, wherein the reference signal is an encrypted representation of a non-manipulated reference signal component of a reference information signal to detect the manipulation.

For embedding watermark information into an information signal including audio and/or video information, first of all a synchronization sequence with a plurality of synchronization sequence units and a data sequence with a plurality of data sequence units are provided, wherein between the data sequence and the synchronization sequence a time shift is present and wherein a degree of shifting depends on the watermark information. A combination means generates a combination sequence having a plurality of combination sequence units from the synchronization sequence and the data sequence shifted with regard to the synchronization sequence, wherein the combination sequence units are derived from synchronization sequence units and shifted data sequence units. The combination sequence is combined with the information signal in order to embed the watermark information into the information signal. A watermark extractor receives a synchronization sequence correlation peak for every data sequence correlation peak associated with the same and therefore determines the watermark information on the basis of the time interval between the synchronization sequence correlation peak and the data sequence correlation peak in a secure and robust way. The concept is robust, provides a high data rate and is simultaneously flexible with regard to the weighting of synchronization energy and data energy and with regard to the robustness on the one hand and data rate on the other hand, respectively.

Method and device for embedding watermark information and method and device for extracting embedded watermark information

The apparatus for determining an impulse response in an environment in which a speaker and a microphone are placed works using an audio signal. Means for spectrally coloring a test signal, which preferably is a pseudonoise signal, works using a psychoacoustic masking threshold of the audio signal to obtain a colored test signal, which is embedded in the audio signal to obtain a measuring signal, which can be fed to the speaker. Means for determining the impulse response preferably performs a cross-correlation of a reaction signal received via the microphone from the environment and the test signal or the colored test signal. With this, an impulse response of an environment may also be determined during the presentation of an audio piece to provide an optimal description of environment for a wave-field synthesis.

Apparatus and method of determining an impulse response and apparatus and method of presenting an audio piece

According to an inventive scheme for introducing a watermark into an information signal, the information signal is at first transferred from a time representation to a spectral/modulation spectral representation). The information signal is then manipulated in the spectral/modulation spectral representation in dependence on the watermark to be introduced to obtain a modified spectral/modulation spectral representation, and subsequently an information signal provided with a watermark is formed based on the modified spectral/modulation spectral representation. An advantage is that, due to the fact that the watermark is embedded and/or derived in the spectral/modulation spectral representation or range, traditional correlation attacks as are used in watermark methods based on a spread-band modulation cannot succeed easily.

Watermark embedding

An apparatus for suppressing feedback in an environment where a microphone and a loudspeaker are located, comprises a means for embedding a test signal into a loudspeaker signal, a microphone signal or a modified microphone signal, preferably by using a psychoacoustic masking threshold by using a pseudo-noise test signal, a means for determining a characteristic of a transmission channel in the environment between the loudspeaker and the microphone by using the embedded test signal and the microphone signal, a filter for filtering the loudspeaker signal to obtain a filtered loudspeaker signal, wherein the filter is adaptable to be adapted with regard to its filter characteristic to the characteristic of the transmission channel by the means for determining, as well as a means for subtracting the filtered loudspeaker signal from the microphone signal to obtain the modified microphone signal, in which the feedback is reduced due to the loudspeaker signal. The feedback suppression concept provides an effective feedback suppression without audio quality loss, by which particularly an artist is not affected in his artistic performance.

Apparatus and method for suppressing feedback

An inventive method for introducing information into a data stream including data about spectral values representing a short-term spectrum of an audio signal first performs a processing of the data stream to obtain the spectral values of the short-term spectrum of the audio signal. Apart from that, the information to be introduced are combined with a spread sequence to obtain a spread information signal, whereupon a spectral representation of the spread information is generated which will then be weighted with an established psychoacoustic maskable noise energy to generate a weighted information signal, wherein the energy of the introduced information is substantially equal to or below the psychoacoustic masking threshold. The weighted information signal and the spectral values of the short-term spectrum of the audio signal will then be summed and afterwards processed again to obtain a processed data stream including both audio information and information to be introduced. By the fact that the information to be introduced are introduced into the data stream without changing to the time domain, the block rastering underlying the short-term spectrum will not be touched, so that introducing a watermark will not lead to tandem encoding effects.

Prior to embedding a watermark in an audio signal, a spectral representation of the audio signal and a spectral representation of the watermark signal are determined. The spectral representation of the watermark signal is then processed on the basis of a psychoacoustic masking threshold of the audio signal. The processed watermark signal is combined with the audio signal to obtain an audio signal bearing a watermark. The spectral representation of the watermark signal is processed iteratively as follows: first a predetermined watermark initial value is selected, then the interference introduced into the spectral representation of the audio signal after a quantization of the spectral representation of the audio signal is determined and then, if the interference introduced by the watermark initial value exceeds the predetermined interference threshold, the watermark initial value is modified progressively until the resulting interference introduced into the spectral representation of the audio signal after quantization is less than or equal to the predetermined interference threshold. The modified watermark initial value at the end of the iteration is used as the processed watermark signal to be combined with the audio signal. As a result it is no longer possible for a watermark to be quantized out. Instead, full control over the energy of the watermark is achieved. A watermark can therefore be embedded in an audio signal to provide either the best possible degree of watermark detectability or the best possible audio quality.

Device and method for embedding a watermark in an audio signal

In a coding method and a coder for introducing a non-audible data signal into an audio signal, the audio signal is first transformed to a spectral range and the masking threshold of the audio signal is determined. A pseudo-noise signal and a data signal are provided and multiplied with each other so a to provide a frequency-spread data signal. The spread data signal is weighted with the masking threshold, and thereafter the audio signal and the weighted data signal are superimposed. In a method and a decoder for decoding a data signal introduced into an audio signal in non-audible manner, the audio signal is first sampled and thereafter the sampled audio signal is filtered in non-recursive manner. The filtered audio signal is subsequently compared to a threshold value so as to retrieve the data signal.

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Nuremberg, Germany

Christian Neubauer