Method and circuit for data transmission

Abstract

The sampling rate of the optical and electrical signals provided by a DVD player according to standard IEC 61937 are converted in a first transcoder to the sampling rate of a multimedia network. The signals generated by the first transcoder with the sampling rate of the multimedia network are transmitted through a multimedia network line to a second transcoder, which based on the parameters contained in the signals received generates the signal originally generated by the DVD player and transmits it according to standard IEC 61937 to a DVD decoder. The technique is specifically suited for use in a motor vehicle and is distinguished by low technical complexity since without the transcoding by the two transcoders the encoded data stream at the output of the DVD player would have to be first decoded and then transmitted in multichannel mode as linear PCM data through a multimedia network line, for example, a MOST line. This approach, however, requires three to four times the bandwidth. In addition, the PCM data would have to be re-encoded for copyright reasons.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to the field of signal transmission and decoding systems, and in particular to apparatus and method for transmitting data from a DVD player to a DVD decoder.

[0002] DVD players provide a digital output from which electrical or optical signals may be picked up. An audio decoder such as a Dolby Digital, DTS, MPEG, or MLP decoder may be connected to the output of a DVD player. Unencoded pulse code modulation (PCM) stereo audio data based on the IEC 60958 standard, or encoded multichannel audio data based on the IEC 61937 standard, is sent to the decoder from the digital output of a DVD player. In addition to the audio data, parameter settings (e.g., headers) for the decoder such as for example the sampling rate of the original data source may also be contained in the transmitted data stream. The data stream to be transmitted is biphase-coded and coupled to the sampling rate. The decoder (i.e., the data sink) is thus able to synchronize itself and reconstruct the original sampling rate of the data source, which for a DVD player, for example, is 48 KHz.

[0003] A Media Oriented System Transport or Media Oriented Synchronous Transfer (MOST) is a multimedia network developed for use in a motor vehicle. A fundamental feature of a MOST network is the fact that the applications layer is separate from the network layer. MOST networks also work on the basis of biphase-coded data. Data are typically transmitted at a sampling rate of 44.1 KHz.

[0004] Additional information on MOST networks is disclosed in the publication entitled “No Standard without Digitalization”, Automobil-Entwicklung, May 2000, pages 88-90, and in the publication entitled “Media Oriented System Transport (MOST), Standard for Multimedia Networking in Motor Vehicles” VDI Berichte, no. 1415, 1998, pages 819-834.

[0005] A problem is that data from a data source such as a DVD player, has a first sample rate f1, that is not compatible with a multimedia transmission medium that employs a second sample rate f2, and across which data is transmitted from the data source to a data sink, such as a DVD decoder.

[0006] Therefore, there is a need for a technique for transmitting data from a data source such as a DVD player to a data sink such as a DVD decoder, via a multimedia network line, such as a MOST network, at a frequency that differs from that of the data from the data source.

SUMMARY OF THE INVENTION

[0007] Briefly, according to an aspect of the invention, a signal transmission and decoding system includes a data source that transmits first encoded data over a first transmission medium. A first transcoder receives the first encoded data via the first transmission medium, and transcodes the first encoded data to provide transcoded encoded data that is transmitted over a second transmission medium. A second transcoder that receives the transcoded encoded data via the second transmission medium, and transcodes the transcoded encoded data to provide second encoded data that is transmitted over a third transmission medium. A data sink that receives the second encoded data via the third transmission medium, and decodes the second encoded data to provide decoded data.

[0008] In a preferred embodiment, the data source includes a DVD player, the data sink includes a DVD decoder, and the second transmission medium comprises a MOST bus.

[0009] According to another aspect of the invention, a method of transmitting data from a DVD player to a DVD decoder includes transmitting encoded data from the DVD player over a first transmission medium, and receiving the encoded data and transcoding the received encoded data to provide transcoded encoded data. The transcoded encoded data is transmitted over a second transmission medium, and then received and transcoded to provide received encoded DVD data. The received encoded DVD data is then transmitted over a third transmission medium to the DVD decoder.

[0010] In one embodiment, the signals of standard IEC 61937 supplied by the DVD player are transmitted to a first transcoder that analyzes the data stream received from the DVD player and determines the sampling rate. The first transcoder adjusts the sampling rate to that of the standard used by the multimedia network by changing the length of the pause packets contained in the data stream. If, for example, the sampling rate of the DVD player at 48 KHz is greater than the 44.1 KHz sampling rate required by the standard of the multimedia network, the first transcoder deletes a predetermined number of zeroes in the pause packets. To achieve this, for example, a phase-locked loop is provided in the first transcoder that converts the frequency of the biphase signal provided by the DVD player from 48 KHz to 44.1 KHz. The data stream generated by the first transcoder is transmitted through a multimedia network line to a second transcoder which, based on the parameters contained in the data stream received by the first transcoder, reproduces the data stream generated by the DVD player. In one embodiment, transmission of data from the DVD player to the first transcoder and from the second transcoder to the DVD decoder is performed according to standard IEC 61937.

[0011] In a data stream based on standard IEC 61937, unassigned bits are present which, in one embodiment of the invention are used to provide control commands. The unassigned bits indicate, for example, how many zeroes must be deleted from the data stream or added to the data stream.

[0012] These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

[0013] The FIGURE is a block diagram illustration of a signal transmission and decoding system.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The FIGURE is a block diagram illustration of a signal transmission and decoding system 10. The system 10 includes a data source 12 that provides a signal on a line 14 to a first transcoder 16. The first transcoder 16 provides a signal on a line 18 (e.g., a multimedia network line such as a MOST bus) to a second transcoder 20, which provides a signal on a line 22 to a data sink 24.

[0015] The present invention shall be discussed in the context of an embodiment wherein the data source is a DVD player, and the data sink is a DVD decoder. The DVD decoder 24 may, for example, be a Dolby Digital decoder, a dts decoder, an MPEG decoder, an MLP decoder, or another multichannel audio decoder. However, the invention is of course not limited to systems wherein the data source is a DVD player, and the data sink is a DVD decoder.

[0016] The first transcoder 16 receives the signal on the line 14, and converts the sampling rate of the received signal to the sampling rate compatible with/required by the line 18. Depending on whether the sampling rate of the DVD player 12 is greater than or less than the sampling rate for the transmission of data over the multimedia network 18, the first transcoder 16 removes zeroes from the pause packets or adds zeroes to them. Certain parameters are contained in the data stream that the first transcoder 16 transfers through the multimedia network 18 to the second transcoder 20. Using these parameters and the data received over the multimedia network 18, the second transcoder 20 recreates the signal originally transmitted by the DVD player 12. The second transcoder 20 transmits the recreated signal to the DVD decoder 25 over the line 22, which may be configured and arranged according to standard IEC 61937.

[0017] The signal transmission and decoding system 10 may be located in a motor vehicle. For example, the DVD player 12 may be connected, for example, through a MOST network to the DVD decoder 24. That is, the multimedia network 18 may be configured and arranged for example as a MOST network. In one embodiment, the signal transmission and decoding system 10 may be employed in a motor vehicle, such as an automobile.

[0018] The present invention is distinguished from techniques wherein the encoded data stream is decoded at the data source (e.g., the DVD player), and then transmitted in multichannel mode as linear PCM data through for example a MOST network. However, this technique requires a bus bandwidth that is three to four times greater than the bus bandwidth required by the system of the present invention. In addition, the PCM data would have to be re-encoded once again for copyright reasons since decoded Dolby or dts data may not be transmitted in an open system. Therefore, when compared to known methods and systems, the present invention is distinguished by significantly less technical complexity despite the requirement of two transcoders.

[0019] Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the form and detail thereof, may be made therein, without departing from the spirit and scope of the invention.

Claims

1. A signal transmission and decoding system, comprising:

a data source that transmits first encoded data over a first transmission medium;

a first transcoder that receives said first encoded data via said first transmission medium, and transcodes said first encoded data to provide transcoded encoded data that is transmitted over a second transmission medium;

a second transcoder that receives said transcoded encoded data via said second transmission medium, and transcodes said transcoded encoded data to provide second encoded data that is transmitted over a third transmission medium; and

a data sink that receives said second encoded data via said third transmission medium, and decodes said second encoded data to provide decoded data.

2. The signal transmission and decoding system of claim 1, wherein said data source comprises a DVD player.

3. The signal transmission and decoding system of claim 2, wherein said data sink comprises a DVD decoder.

4. The signal transmission and decoding system of claim 1, wherein said data source comprises means for providing said first encoded data as packetized data that is transmitted over said first transmission medium.

5. The signal transmission and decoding system of claim 1, wherein said packetized data comprises a header field and data field.

6. The signal transmission and decoding system of claim 1, wherein said first transcoder comprises a phase-locked loop that converts the frequency of said first encoded data configured as a biphase signal data, to the frequency of said second transmission medium.

7. The signal transmission and decoding system of claim 6, wherein said first transcoder comprises means for transcoding said first encoded signal that complies with standard IEC 61937, and transcoded encoded signal is configured and arranged to be transmitted over said second transmission medium that is configured as a MOST network.

8. The signal transmission and decoding system of claim 6, wherein unassigned bits according to standard IEC 61937 are configured to provide command control data.

9. The signal transmission and decoding system of claim 8, wherein the unassigned bits are indicative of how many zeroes must be added to or deleted from the pause packets of the data stream.

10. The signal transmission and decoding system of claim 8, wherein said data sink comprises a multichannel decoder.

11. The signal transmission and decoding system of claim 8, wherein said data sink comprises a dts decoder.

12. The signal transmission and decoding system of claim 8, wherein said data sink comprises an MPEG decoder.

13. The signal transmission and decoding system of claim 8, wherein said data sink comprises an MLP decoder.

14. A method of transmitting data from a DVD player to a DVD decoder, comprising:

transmitting encoded data from the DVD player over a first transmission medium;

receiving said encoded data and transcoding said received encoded data to provide transcoded encoded data;

transmitting said transcoded encoded data over a second transmission medium;

receiving said transcoding encoded data and transcoding said received transcoded encoded data to provide received encoded DVD data; and

transmitting said received encoded DVD data over a third transmission medium to the DVD decoder.

15. The method of claim 14, wherein said step of transcoding said received encoded data comprises transcoding said received encoded data comprising sampled data having a sampled frequency f1, to provide said transcoded encoded data having a sampled frequency f2.

16. The method of claim 15, wherein said step of transcoding said received transcoded encoded data comprises transcoding said received transcoded data comprising data having a sampled frequency f2 to provide said received encoded DVD data having a sampled frequency f1

17. The method of claim 16, wherein said second transmission medium is configured and arranged as a MOST bus.

18. The method of claim 14, wherein said step of transcoding said received encoded data comprises determining the sampling rate f1, of the data stream supplied by the DVD player and transcoding said received encoded data to provide said transcoded encoded data having a sampling rate f2 associated with the second transmission medium.

19. The method of claim 18, wherein said step of transcoding said received encoded data comprises changing the number of bits within a pause data field of said received encoded data configured as packetized data.

20. The method of claim 19, wherein said step of changing the number of bits comprises deleting a predetermined number of digital zeroes from the pause data field in order to convert the sampling rate.

21. The method of claim 19, wherein said step of changing the number of bits comprises adding a predetermined number of digital zeroes to the pause data field in order to convert the sampling rate.

22. A motor vehicle signal transmission and decoding system, comprising:

a DVD player that transmits first encoded data over a first transmission medium:

a first transcoder that receives said first encoded data via said first transmission medium, and transcodes said first encoded data to provide transcoded encoded data that is transmitted over a second transmission medium;

a second transcoder that receives said transcoded encoded data via said second transmission medium, and transcodes said transcoded encoded data to provide second encoded data that is transmitted over a third transmission medium; and

a DVD decoder that receives said second encoded data via said third transmission medium, and decodes said second encoded data to provide decoded data.