Data processing: speech signal processing – linguistics – language – Audio signal time compression or expansion
Reexamination Certificate
1998-12-04
2001-05-08
{haeck over (S)}mits, T{overscore (a)}livaldis I. (Department: 2741)
Data processing: speech signal processing, linguistics, language
Audio signal time compression or expansion
C704S200100, C700S094000
Reexamination Certificate
active
06230141
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and an apparatus for the synchronization of a first decoder with a second decoder, in particular of an internal audio decoder of a DVD player with an external audio decoder of a multi-channel amplifier.
BACKGROUND OF THE INVENTION
Audio coding systems, such as Dolby AC-3 and MPEG-2 audio, permit the transmission of high-quality audio signals, including, in particular, the transmission of multi-channel sound. If the possible reproduction configurations are defined by “x,y”, where x is the number of front channels and y is the number of surround channels, then, for example in the case of Dolby AC-3, the following reproduction configurations are possible: 3/2, 3/1, 2/2, 3/0, 2/1, 2/0, 1/0. In addition, a low-frequency channel can also be transmitted.
In order to enable such multi-channel sound reproduction, the transmitted audio data stream must first of all be decoded by a multi-channel audio decoder suitable for this purpose. However, if the device provided for reproduction contains merely a two-channel audio decoder, then multi-channel sound reproduction can be carried out only by using an external multi-channel audio decoder. The audio data are in this case output via a serial digital interface from the reproduction device to the multi-channel decoder. If the audio signals are intended to be output accompanying a video signal, such as, for example, during the playback of a film stored on a DVD, then a synchronization method is necessary in order to achieve lip synchronism between the picture and multi-channel sound reproduction.
SUMMARY OF THE INVENTION
The invention is based on the object of specifying such a method for the synchronization of a first decoder with a second decoder which is distinguished by simple method steps and little hardware outlay resulting therefrom.
The invention is based on the further object of specifying an apparatus for carrying out the method according to the invention.
In principle, the inventive method for the synchronization of a first decoder with a second decoder consists in the fact that
a first value is allocated to a counting variable;
first data are received by the first decoder;
second data, which are identical to the received first data or are produced from the latter after processing, are output by the first decoder to the second decoder, the counting variable being decremented or incremented respectively for the outputting of a predetermined volume of data;
the first decoder begins decoding the first data when the counting variable assumes a second value, which corresponds to the beginning of the decoding of the second data by the second decoder.
In particular, the method can be employed if the first and second data contain multi-channel audio signals which are transmitted in frames which, in turn, can be subdivided into blocks.
In this case, the multi-channel audio signals have preferably been coded according to an MPEG-2 audio algorithm, Dolby AC-3 algorithm or another audio option of the DVD.
The method can be used in a particularly advantageous manner if the first decoder is a two-channel audio decoder and the second decoder is a multi-channel audio decoder.
It is advantageous for the counting variable to be allocated a first value which is produced from system parameters such as the data coding method, the transmission speed or the data rate.
The second decoder advantageously begins decoding when a predetermined fraction of a frame of the multi-channel audio signals has been transmitted or when the said frame has been completely transmitted.
In this case, the counting variable is decremented in a bit-by-bit, byte-by-byte or word-by-word manner.
It is furthermore advantageous if the first data are unpacked after reception by the first decoder and stored in a memory and, for outputting to the second decoder, are read from the memory and formatted.
In particular, the method is advantageous if the first decoder decodes audio signals from the first data, which audio signals are output synchronously with video signals which have been transmitted with the audio signals in a common data stream and have been decoded by a video decoder.
In principle, the inventive apparatus for the synchronization of a first decoder with a second decoder comprises an interface, via which second data can be output from the first decoder to the second decoder, and a counting register which is allocated a first value as a function of the coding method used for the second data and/or of the transmission speed of the interface and/or of the data rate of the interface, the counting register being incremented or decremented when the data are output via the interface, and, when the counting variable reaches a value corresponding to the beginning of the decoding of the data by the second decoder, the first decoder being fed a control signal, which initiates the decoding of first data by the first decoder.
The counting register is advantageously part of the first decoder, the counting register being allocated the first value by a system controller.
It is particularly advantageous if the first decoder contains, in addition to a processor for process control and decoding of the first data, one or more of the following units:
one or more memories for the storage of the first data on their reception and/or for buffer-storage in the event of processing of the first data;
an unpacker unit, which serves to unpack the received data into an elementary stream;
a formatting unit, which carries out formatting for serial outputting via the interface.
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German Search Report.
Böhm Johannes
Schroder Ernst F.
Deutsche Thomson-Brandt GmbH
Herrmann Eric P.
Tripoli Joseph S.
{haeck over (S)}mits T{overscore (a)}livaldis I.
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