Abstract: A method for encoding a digitized audio signal which includes the step of selecting one of two or more psycho acoustic model provided for generating masking thresholds used in a data reduction process. The selecting criterion is the available data rate for the encoded bit stream. Each one of the two or more psycho acoustic models is adapted to a specific data rate of the encoded bit stream. In a second embodiment, the method includes the step of combining two or more masking thresholds resulting from different psycho acoustic models, thereby leading to a more accurate calculation of a masking threshold for the data reduction process. Further, there are appropriate apparatuses for the encoding of digitized audio signals.

Abstract: A cassette for use with a recording apparatus comprises: a housing for a recording medium, the housing having a first surface and side walls, the recording medium being accessible through one of the side walls; at least a part of a chip card affixed to the housing, forming a second surface of the housing and closing the cassette, the chip card part having a memory formed integrally therewith and externally accessible contacts; and, the contacts of the chip card being positioned on the second surface to be engageable by corresponding contacts in the recording apparatus when the cassette is inserted therein. One of the side walls has an access door for the recording medium and the second surface forms an upper wall of the housing as defined by the access door. The part of the chip card forming the second surface of the housing has a marking position at which light transmissivity can be controlled. The marking position can be rendered non transmissive to light to prevent recording.

Abstract: A method of simultaneously transmitting and decoding an audio signal and an auxiliary signal which is inseparable from the audio signal includes the step of allocating a loudness level to the audio signal which is higher than the level of the auxiliary signal whereby the auxiliary signal is inaudible during playback of the audio signal and does not deteriorate the playback of the audio signal. The audio signal is encoded by dividing it into a number of frequency bands. The auxiliary signal is transmitted in one of the frequency bands at a level much lower than the level of the audio signal.

Abstract: Electrical contact surfaces, especially when connected to a chip, are designed to be purely functional. However, according to the present disclosure, the contact surfaces are designed so that their external shape is that of a visible letter or symbol with a meaningful content. These contact surfaces may, e.g., be placed on cassette casings for recognition. In a stripe or bar code unit consisting of several code components, i.e., bars, individual bars are electrically conductive to facilitate additional coding. The electrically conductive bars or the contact surfaces are preferably connected to the terminals of an integrated circuit.

Abstract: In a broadcast receiver, a dynamic compression of the signal is switched on or off in dependence on whether such a compression has been carried out at the transmitting end. An identification bit is transmitted for identifying this compression at the transmitter end. The object is to create a broadcast receiver which effects automatic switching-on or switching-off of an amplitude compression but manages without a transmitted identification bit. The received audio signal is applied to a signal analysing circuit which determines the scale factors of the signal and generates switching voltages dependent on the scale factors. The present invention has particular applicability for broadcast receivers in a motor vehicle or with subsequent signal recording.

Abstract: In an MPEG multi-channel audio signal processor, a decoder requires a respective decoder matrix for determining different output channels from coded audio data. Some transmitted information indicates basic parameters of the multi-channel system. This information may be used to address a currently required decoder matrix which is stored in a decoder memory. The storage of a large number of such matrices would be required to enable the decoder to decode all possible channel configurations. Instead of addressing a required decoder matrix stored in decoder memory, initially the current encoder matrix is reconstructed in the decoder using the related transmitted information. The required decoder matrix is then computed from the reconstructed encoder matrix using a matrix inversion technique.

Abstract: In a method of transmitting a signal wherein the signal is partitioned into windows comprised of overlapping blocks with each block containing a partial signal. The partial signal in each block is converted into a digital signal and individually coded with a selected window function f(n). The overlapping areas of the window functions are weighted such that the resultant of the overlapping functions in each block equals one. The coded signals are transmitted. The received signals are reconverted into partial analog signals. The window functions are selected in accordance with frequency changes in the original signal.