Record carrier with watermark
AssigneeKoninklijke Philips Electronics N.V.
InventorsGertjan Yntema, Antonius Jacobus Johannes Werner, Engelbertus Petrus Gerardus Maria Kramer
Life of this patent
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Abstract
The invention relates to a record carrier (1) comprising a pattern of substantially parallel tracks (2) for storing data in the form of marks, in which the data is encoded by means of a channel code. The record carrier further includes a watermark (3) which is provided by controlling the parameter of the channel code so as to introduce a predetermined run length distribution in the marks on the record carrier. Brightness differences are caused by introducing this run length distribution. The invention also relates to a device for reading a record carrier, a method of providing a watermark on the record carrier, and a device for providing a watermark on a record carrier.
Claims13
A record carrier (1) comprising a pattern of substantially parallel tracks (2) for storing data in the form of marks, in which the data is encoded by means of a channel code and the record carrier includes a watermark (3), characterized in that a parameter of the channel code is controlled so as to introduce a predetermined run length distribution in the marks on the record carrier, so that the watermark is detectable on the record carrier.
A device for reading a record carrier (1), the device comprising a system (27, 42) for detecting marks via a light spot (28) on the record carrier, and tracking means (29, 30) for controlling the position of the light spot, characterized in that the device comprises detection means (34) for determining a property of the run length distribution of the marks on the record carrier for detecting a watermark (3).
A method of providing a watermark (3) on a record carrier (1), the method comprising the steps of:
- receiving uncoded data,
- receiving information about the watermark which is to be provided in the encoded data,
- encoding the uncoded data to encoded data by means of a channel code, in which a parameter of the channel code is controlled under the influence of the information about the watermark for introducing a predetermined run length distribution in the marks on the record carrier, so that the watermark is detectable on the record carrier,
- storing the encoded data on the record carrier.
A device for providing a watermark on a record carrier, the device comprising receiving means for receiving uncoded data, the receiving means being further adapted to receive information about the watermark which is to be provided in the encoded data, the device further comprising encoding means for encoding the uncoded data to encoded data by means of a channel code, in which a parameter of the channel code is controlled under the influence of the information about the watermark for introducing a predetermined run length distribution in the marks on the record carrier, so that a watermark is detectable on the record carrier, the device further comprising means for storing the encoded data on the record carrier.
Dependencies are inferred from the claim text.