Abstract:
The invention relates to an apparatus for playing back information digitally stored on an optical record carrier, comprising 
     a control circuit by means of which the display and/or reproduction of information, particularly video and/or audio information is selectable and/or controllable, 
     a parameter memory for storing navigation parameters during playback of a record carrier, wherein 
     the apparatus comprises a first non-volatile memory ( 9 ) which is controllable by means of the control circuit ( 6 ), 
     the first non-volatile memory ( 9 ) is provided for storing navigation parameters, 
     the navigation parameters are stored together with record carrier identification information allowing assignment of the navigation parameters to the relevant record carrier ( 3 ), and 
     at the start of a playback process of a record carrier, the navigation parameters assigned to said record carrier ( 3 ) are readable from the first non-volatile memory ( 9 ) and writable into the parameter memory ( 6   a ).

Description:
FIELD OF THE INVENTION 
     The invention relates to an apparatus for playing back information digitally stored on an optical record carrier, comprising 
     a control circuit by means of which the display and/or reproduction of information, particularly video and/or audio information, is selectable and/or controllable, 
     a parameter memory for storing navigation parameters during playback of a record carrier. 
     BACKGROUND OF THE INVENTION 
     An apparatus of this type is known from, for example, WO 98/09290. This known apparatus is provided for playing back digital video record carriers. To control the display of the audio and/or video program, the known apparatus has navigation commands and navigation parameters. Generally, those parameters are understood to be navigation parameters whose information is stored by the playback apparatus during the playback process. The navigation parameters comprise, for example, parameters to which a predetermined function is assigned and also parameters which can be freely used by the provider and are, for example, usable for modifying the behavior of the playback apparatus or for storing the user-performed operations, decisions and/or wishes. Navigation commands and navigation parameters are the basis for providers of record carriers for creating different title structures. The providers can use the navigation commands and navigation parameters for adjusting or changing the status of the playback apparatus, for example, for implementing a parental control system which denies children access to predeterminable video programs. 
     For example, logic AND and OR combinations, comparative operators such as EQUAL/UNEQUAL or register commands are available as navigation commands. 
     The provider can define simple and complex branch structures in a title by means of the navigation commands and the navigation parameters. 
     The navigation parameters of record carriers based on the DVD standard are set to zero at the start and the end of a playback process of a record carrier. 
     SUMMARY OF THE INVENTION 
     It is art object of the invention to provide an apparatus of the type described in the opening paragraph, rendering playback of navigation parameters assigned to a record carrier usable for playback at a later stage. 
     According to the invention, this object is achieved in that the apparatus comprises a first non-volatile memory which is controllable by means of the control circuit, in that the first non-volatile memory is provided for storing navigation parameters, in that the navigation parameters are stored together with record carrier identification information allowing assignment of the navigation parameters to a record carrier, in that, at the start of a playback process of a record carrier, the navigation parameters assigned to said record carrier are readable from the first non-volatile memory and writable into the parameter memory. 
     The navigation parameters assigned to a playback process can thus be stored in the first non-volatile memory and made available for playback at a later stage. During storage in the first non-volatile memory, the navigation parameters are provided during storage with record carrier identification information, for example, a record carrier identification number. This record carrier identification number is stored at a predeterminable location on the record carrier. At the start of a playback process, the control circuit checks whether the relevant record carrier is provided with record carrier identification information. If the relevant record carrier is provided with record carrier identification information, the control circuit checks whether navigation parameters corresponding to this record carrier identification information are stored in the first non-volatile memory. If this is the case, the navigation parameters are read from the first non-volatile memory and written into the parameter memory. Alternatively, an access path to these navigation parameters can be formed. If no navigation parameters relating to record carrier identification information have been stored in the first non-volatile memory, the written record carrier identification information is preferably written by the control circuit into the first non-volatile memory, or a relevant access path is formed. Both a RAM memory and a register memory may be used as a parameter memory. 
     The apparatus according to the invention has the advantage that, by means of storage of the navigation parameters, an exchange of information between different playback processes is possible. The exchange of information may be realized both between different playback processes of one and the same record carrier. It is also possible to utilize the playback navigation parameters of a first record carrier for playback of a second record carrier. This is particularly advantageous for series of record carriers, for example for a training course comprising several record carriers. 
     The embodiment of the invention as defined in claim  2  has the advantage that, by means of the interface, an exchange of data relating to the navigation parameters with an external input and/or output apparatus is possible. On the one hand, the playback process of the record carrier can thereby be changed and influenced by means of an external input apparatus. On the other hand, the navigation parameters stored in the first non-volatile memory can be externally read and evaluated. It is particularly possible to provide predetermined navigation parameters for playing back a record carrier, i.e. the playback mode of this record carrier and, for example, given playback sequences can be fixed in advance in that, as defined in claim  11 , navigation parameters determining the playback process for the record carrier are stored in advance in the first non-volatile memory. For example, it is possible to place playback apparatuses at different locations in a museum and store different navigation parameters for the same record carrier. This renders it possible that the same record carrier is played back on the different playback apparatuses, i.e. different playback apparatuses play, for example, different chapters, sections or contents on the same record carrier. 
     The advantageous embodiment of the invention as defined in claim  3  has the advantage that the navigation parameters stored in the first non-volatile memory are updated in a predeterminable manner. 
     By means of the advantageous embodiment of the invention as defined in claim  4 , the temporal history of the change of navigation parameters can be recorded during one or more playback processes. This may be used to particular advantage for market research, error search and the like. The second non-volatile memory is advantageously realized, as defined in claim  5 , as a serial, cyclic buffer memory. The navigation parameters are temporally and serially written into the buffer memory. When the buffer memory is full, the oldest navigation parameters are erased so as to make room for new, updated navigation parameters. Such a serial, cyclic buffer memory is a simple and low-cost facility for storing temporal sequences of the navigation parameters. The further embodiment of the invention as defined in claim  6  has the advantage that the temporal sequences of the navigation parameters are externally readable and further processable. 
     The invention as defined in claim  7  is particularly suitable for apparatuses based on the DVD video standard. In accordance with the DVD video standard, 16 general parameters are provided as navigation parameters which have a length of 2 bytes each. These general parameters are available for the providers of record carriers so as to store the operation behavior of the user and to influence or control the behavior of the playback apparatus. The general parameters can be accessed by means of navigation commands. By storing the general parameters in the first non-volatile memory, information about a playback process of a record carrier can be stored. This information may be loaded from the non-volatile memory for playback at a later stage of the same record carrier or for playback at a later stage of another record carrier and used as a basis for the later playback process. 
     As defined in claim  8 , the apparatus according to the invention is particularly suitable for apparatuses based on the High Quality Video Standard (HQ-Video). In accordance with the HQ-Video standard, at least 16 user parameters of 2 bytes each are provided as navigation parameters. According to the invention, these user parameters are stored in the first non-volatile memory and are thus available for playback at a later stage. 
     In accordance with the DVD standard, the general parameters are set to the value of zero at the start and the end of every playback process. 
     In accordance with the HQ-Video CD standard, the user parameters are undefined at the start and the end of every playback process. 
     The non-volatile storage of the navigation parameters thus represents a modification outside the DVD standard and the HQ-Video CD standard. 
     As defined in claim  10 , the provider, i.e. the manufacturer and marketing representative of record carriers, can determine himself by means of the provider-characteristic information whether his record carrier is to be played back in accordance with the standard without non-volatile storage of the navigation parameters or whether the facility in the apparatus for non-volatile storage of the navigation parameters is to be used. 
     These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a block diagram of an apparatus according to the invention for playing back information digitally stored on an optical record carrier, 
     FIG. 2 shows the storage organization for the navigation parameters with a register memory, a first non-volatile address memory and a second non-volatile serial buffer memory, 
     FIG. 3 is a flow chart illustrating the operation of writing a record carrier based on the DVD standard, 
     FIG. 4 is a flow chart illustrating the storage of the general parameters in the first and/or the second non-volatile memory during playback of a DVD record carrier. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an optical record player system  1  with an optical record player  2  which is provided for playing back information digitally stored on an optical record carrier  3 . The optical record carrier  3  is particularly a record carrier based on the DVD standard, or a record carrier based on the HQ-Video CD standard. The information which is digitally stored on the optical record carrier  3  is read by means of an optical read unit  4  and applied to a decoder circuit  5 . The decoder circuit  5  is further provided for error correction. The decoded and error-corrected data are applied to a control circuit  6 . 
     The control circuit  6  is coupled to a RAM memory  7 , a ROM memory  8 , a first non-volatile memory  9  and a second non-volatile memory  10 . The RAM memory  7  and the ROM memory  8  are provided to control and process the data stream which is applied from the decoder circuit  5  to the control circuit  6 . The first non-volatile memory  9  and the second non-volatile memory  10  are provided for non-volatile storage of navigation parameters. The control circuit is further coupled to a servosystem  11  which controls the angle velocity ω of the optical record carrier as well as the position of the optical read unit  4  as regards the tracks in the optical record carrier  3 . This is denoted by the broken-line arrow r. Furthermore, the servosystem  11  controls the focusing of the optical read unit  4 , which is denoted by the broken-line arrow f. The control circuit  6  transmits relevant control signals to the servosystem  11 . 
     The control circuit  6  is also coupled to a decoder circuit  12 . The decoder circuit  12  is provided to decode, for example, the video and audio data coded in accordance with the MPEG2 standard. The decoder circuit  12  supplies the decoded video data to a display  13  and the decoded audio data to a loudspeaker or a loudspeaker system  14 . For a bidirectional data exchange with external components, the optical record carrier  2  has a bidirectional interface  15 . A keyboard  16 , an external data memory  17  such as, for example, a disc drive as well as further external components can be connected to the bidirectional interface  15 . On the one hand, external data which are supplied, for example, via the keyboard  16  may be applied to the optical record carrier  2  via the bidirectional interface  15 . On the other hand, internal data can be applied from the optical record carrier  2  to external components such as, for example, the external data memory  17 . 
     The control circuit  6  has internally a register  6   a  which is capable of provisionally storing information and supplying it with a short access time. 
     FIG. 2 shows, by way of example and in greater detail the register  6   a , the first non-volatile memory  9  and the second non-volatile memory  10  in accordance with FIG.  1 . The memory elements shown in FIG. 2 are dimensioned for apparatuses based on the DVD standard. In accordance with the DVD standard, 16 general parameters are available as navigation parameters, each having a length of 2 bytes. These general parameters are available as standards for the providers of optical record carriers so as to, for example, store the operation behavior of the user and/or influence or control the behavior of each playback apparatus. The register  6   a  has a memory field  6   b  of 32 bytes which is provided for storing the general parameters. The first non-volatile memory  9  has five memory fields  9   a  to  9   e  of 34 bytes each in the example shown. The individual memory fields  9   a  to  9   e  have record carrier identification fields  9   a   1 ,  9   b   1 ,  9   c   1 ,  9   d   1 , and  9   e   1 , of 2 bytes each, as well as navigation parameter fields  9   a   2 ,  9   b   2 ,  9   c   2 ,  9   d   2  and  9   e   2  of 32 bytes each. The navigation parameter fields  9   a   2  to  9   e   2  are provided for storing the general parameters of the DVD standard. The record carrier identification fields  9   a   1  to  9   e   1  are provided for storing a record carrier identification number which provides the possibility of an assignment between the stored general parameters and the relevant record carrier corresponding to these general parameters. The second non-volatile memory  10  is constituted by a serial, cyclic buffer memory. In the following example, it has seven memory fields  10   a ,  10   b ,  10   c ,  10   d ,  10   e ,  10   f  and  10   g  comprising 32 bytes each. The second non-volatile memory  10  is provided to store a temporal sequence of the general navigation parameters. In the relevant example, the second non-volatile memory has no record carrier identification fields so as to save memory locations and realize the memory in a possibly simple manner. However, it is also possible to provide a plurality of serial cyclic memories and give them a record carrier identification field so as to be able to store also temporally serial sequences of the general navigation parameters of different record carriers. The memory fields  9   a  to  9   e  of the first non-volatile memory  9  can be addressed individually. The second non-volatile memory  10  has only one common memory address. Navigation parameters to be newly stored are always initially written into the upper memory field  10   a  of the second non-volatile. memory  10 . In the subsequent storage process, the new navigation parameters are stored in the upper memory field  10   a , and the navigation parameters which are already present in the second non-volatile memory  10  are shifted one memory field further down, i.e. the navigation parameters of the memory field  10   a  are shifted into the memory field  10   b , the navigation parameters of the memory field  10   b  are shifted into the memory field  10   c , and so forth. The navigation parameters stored in the lowest memory field  10   g  are erased at a subsequent, new storage process. Thus, the seven last stored general navigation parameters are present in the second non-volatile memory  10 . 
     FIG. 3 shows a flow chart of the process of writing a record carrier based on the DVD standard. This writing process is perforrned whenever a record carrier  3  is inserted into the optical record player  2 . 
     A first block  20  represents the result “record carrier-in”, i.e. an optical record carrier  3  has been inserted into the optical record player  2  in accordance with FIG.  1 . Subsequently, a provider ID is written in a block  21 . The provider ID is characteristic information which is stored in a standard form on a defined location of the DVD record carrier. With reference to the provider ID, it is checked in a subsequent step  22  whether the optical record player  2  is to operate in accordance with the DVD standard or whether, in accordance with the provider ID, a non-standard behavior is desired by the provider. To this end, the four last letters of the provider ID are checked in the block  22 . When these four last letters have a given letter combination, for example, the letter combination GRPM, then the optical record player  2  recognizes that the provider has provided a non-standard playback behavior, i.e. a non-volatile storage of the general navigation parameters. 
     In accordance with the DVD standard, the general navigation parameters are set to zero at the start and the end of every playback process. Therefore, it is not possible in the case of standard behavior of the DVD apparatus to store data relating to a playback process of a CD and to make them available for playback at a later stage. This possibility is provided by the non-standard behavior of the optical record player  2 . When the four last letters of the provider ID are unequal to GRPM, then the optical record player switches to the standard DVD behavior, which is shown in the block  23  in FIG.  3 . When the four last letters of the provider ID are equal to GRPM, then the optical record player recognizes that it is not to operate in accordance with the DVD standard, i.e. the general parameters are not to be set to zero at the start and the end of a playback process. In the block  24 , a record carrier identification number is therefore initially read from the record carrier. This record carrier identification number is stored at a defined location on the record carrier. In a subsequent step  25 , it is checked whether the record carrier identification number is known to the optical record player, i.e. whether already general navigation parameters are already stored under this record carrier identification number in the first non-volatile memory. If this is not the case, the record carrier identification number is written in a step  26  into one of the record carrier identification fields  9   a   1  to  9   e   1  and the assigned memory field is thus initialized for storage of the assigned navigation parameters. To this end, one of the memory fields  9   a  to  9   e , which is not yet occupied, is selected. When all memory fields  9   a  to  9   e  are occupied with information, the memory field having the oldest information is erased and made available for the new record carrier identification number. Simultaneously, the access path is formed for the envisaged memory field. 
     When it is determined in block  25  that the record carrier identification number is known and that general navigation parameters for this record carrier identification number are stored in the first non-volatile memory  9 , then the access path is formed in a step  27  for that memory field of the memory fields  9   a  to  9   e  in which the general navigation parameters assigned to the relevant record carrier identification number are stored. 
     In the subsequent playback process, represented by the block  30 , the general navigation parameters stored at the end of the previous playback process of the record carrier are now available. 
     FIG. 4 shows a flow chart of storing the general parameters in the first non-volatile memory  9  and in the second non-volatile memory  10 , as well as loading the general parameters from the first non-volatile memory  9  during playback of a DVD record carrier, which storage and loading are controlled by means of the control circuit  6 . Initially, the optical record player  2  is in a waiting state  30  as regards the first non-volatile memory  9  and the second non-volatile memory  10 . During this waiting state  30 , a playback process of the optical record carrier  3  takes place, i.e. the control circuit  6  is continuously supplied with information by means of the optical read unit  4  and the decoder circuit  5 . In accordance with the information applied to the control circuit  6 , also the general navigation parameters stored in the memory field  6   b  of the register  6   a  may change. The change of the general navigation parameters is dependent on the way in which the provider of the record carrier makes use of the general navigation parameters. The provider of the record carrier may determine, by corresponding program sequence structures on the record carrier, when and under what conditions the general navigation parameters are to be written from the register  6   a  into the first non-volatile memory  9  and/or the second non-volatile memory  10 . For this purpose, two specific commands are provided, which are recognized by the control circuit  6 . As a first control command, an addition of the value of zero to the memory field  6   b  of the register  6   a  is provided. Such an addition of the value of zero does not change anything in the memory field  6   b  of the register  6   a . The control circuit  6  of course recognizes that such a control command not influencing the register  6   a  was present in the data stream supplied by the record carrier  3 . This result “addition of zero to the memory field  6   b  of the register  6   a ” is denoted by the reference numeral  31  in the FIG. 4 flow chart. When this result  31  occurs, the control circuit  6  stores the general parameters stored in the memory field  6   b  of the register  6   a  in the first non-volatile memory  9  under the relevant record carrier identification number as well as simultaneously in the upper memory field  10   a  of the second serial non-volatile memory  10 . This is shown as block  33  in FIG.  4 . After performing this storage, the optical record player  2  again assumes the waiting state  30 . A further control command relating to the first non-volatile memory  9  is the control command “subtract zero from the general navigation parameters stored in the memory field  6   b ”. This result is denoted by the reference numeral  32  in the FIG. 4 flow chart. The value of the general navigation parameters stored in the memory field  6   b  is neither changed by this “subtract zero” command. However, the control circuit  6  recognizes when such a command is present in the data stream read from the optical record carrier  3 . When this control command is recognized, the control circuit  6  loads the general navigation parameters from the first non-volatile memory  9  into the memory field  6   b  of the register  6   a . Subsequently, the system changes to the waiting state  30  again as regards the storage operations of the first non-volatile memory  9  and the second non-volatile memory  10 . 
     The general navigation parameters stored in the first non-volatile memory  9  and in the second non-volatile memory  10  may be both externally read and externally changed by means of the bidirectional interface  15 . For external reading, an external data processing unit may be used. For external influencing, for example, pagers, a keyboard or a bar code reader are feasible. 
     The system according to the invention thus provides the possibility of storing intermediate results of a playback process of a record carrier in the first non-volatile memory  9  and in the second non-volatile memory  10  and making them available for playback at a later stage. Furthermore, the serial, second non-volatile memory provides the possibility of recording temporal sequences of the change of the general navigation parameters, reading them via the bidirectional interface  15  and then evaluating them by means of external data processing units. 
     Moreover, the bidirectional interface provides the possibility of externally writing information for playback of a record carrier into the first non-volatile memory  9  and thereby externally influence and control playback of the record carrier.