Method and device for accessing sets of data contained in mass memory

Abstract: The invention relates to a method of access to data sets stored in a bulk memory. During an access time to a data set, the method provides for reading introduction data and exploiting these. This way the method overcomes the problem of long access times in a bulk memory. The method may notably be used when data sets are arranged sequentially on a sequential data carrier, which is for example the case for songs recorded on a magnetic tape. A device for implementing the method is also defined.

Description: The present invention relates to a method for accessing sets of data contained in mass memory, and to a device allowing the method to be implemented. The device may be used particularly in magnetic tape players / recorders. Mass memories are widely used to store relatively large quantities of data. A mass memory requires an information medium which may be formed, for example, by an optically or magnetically readable disk, a magnetic tape or even an electronic circuit on semiconductors. Depending on the mode of reading of the mass memory, and depending on the mode of arranging the data in the mass memory, access for reading the data may require more or less access time. The access time is caused, in large part, by the time which a read device takes to get into position to read the data to be read. The access times may reduce the efficacy of a mass memory when numerous data items arranged in this memory are to be accessed in a non-ordered way. This is the case, for example, of mass memory on a magnetic tape medium. The mass memory may contain data grouped together into sets of data, each set of data representing a song, for example. In order to gain access from one song to another song on the same magnetic tape, the songs being separated by a defined length of this magnetic tape, it is first of all necessary to make the entire defined length of magnetic tape move past the read device. The problem to which the present invention proposes to afford a solution is that of eliminating certain drawbacks due to the access times during access to data in mass memory. Document EP 0 731 469 discloses a device for accessing sets of data according to the preamble of claim 3. Aspects of the present invention are defined to the appended claims. Further characteristics and advantages of the present invention will emerge on reading the description given below of examples in accordance with the present invention, this description being given with reference to the attached drawings in which: Figure 1 contains a flow chart of an access method according to the invention; Figure 2 diagrammatically shows an access device according to the invention. It is obvious that the examples described are given in order to explain and illustrate the present invention and do not constitute limitations of the present invention. In Figure 1, access to a set of data is triggered by an access command 1. On completion of the access command 1, introduction data from an introduction memory 2 are read during a read stage 3. The introduction data read are then subjected to processing 4, which consists, for example, in forwarding these data to a reproduction stage 5. The access command 1 also triggers an operation 6 of accessing a set of data contained in mass memory 7. The reading 3 and processing 4 take place at the same time as the access operation 6. The access operation 6 signals the processing stage 4 after an access time. According to one embodiment of the processing stage 4, the forwarding of the introduction data is interrupted, and it is the data of the set of data accessed which are forwarded to the reproduction stage 5. According to another embodiment, the processing stage 4 forwards the whole of the introduction data read before forwarding the set of data. This is advantageous, for example, when the introduction data are an advertising item. The introduction memory 2 may contain introduction data which are specific to the sets of data. In this case, the read stage 3 recognises, in the access command 1, which set has to be accessed, and it is introduction data specific to this set which are read from the introduction memory 2. The specific introduction data may, for example, constitute a subset of the corresponding set of data, and even more precisely, the start of a song when the set is a song. As the time for accessing each song of the mass memory is variable, the processing stage 4 may be implemented in such a way as to forward to the reproduction 5 only a part of the song accessed during the access operation 6 which has not yet been forwarded during the forwarding of the introduction data at the moment when the access operation 6 terminates and when it signals the processing stage 4. Thus the reproduction 5 of a set of data is uninterrupted and starts at the moment when the access command 1 is given. The specific introduction data may also consist of several subsets of sets of data, these subsets being related by a characteristic which is common with the set of data to be accessed. When the sets of data are songs, this common characteristic may, for example, be a type of song or a date when the song was published. Hence, during the time for accessing a song of type A, the processing stage 4 forwards to the reproduction 5 introduction data comprising extracts from songs of the same type A. Figure 2 shows a sequential information medium 8 which may, for example, be a magnetic tape. On the information medium 8, an introduction memory I stores introduction data 9, and a mass memory M stores sets of data arranged sequentially, including a set 10. The introduction data 9 and the set 10 can be read by the read device 11 when the latter is positioned in front of the medium at the appropriate position. A user 12 controls a control device 13 for accessing the set 10. Following user's command, the read device 11 will read the introduction data 9 and the control device 13 stores the introduction data read in a random-access memory 14. The introduction data are then processed from the random-access memory 14 by a data reproduction unit 15 at the same time as the read device 11 accesses the set 10 for reading. The access time required by the read device 11 to pass from reading the introduction data 9 to reading the set 10 varies particularly as a function of the distance D separating the data 9 and the set 10 on the medium 8. The reproduction unit 15 and the random-access memory 14 are processing means for processing the introduction data. In the case in which the medium 8 is a magnetic tape for use in a music player, the reproduction unit 15 may be an audio data amplifier. The reproduction unit 15 may also be used to reproduce the data of the set 10 once they have been read. The control device 13 then transfers the data of the set 10 directly to the reproduction unit 15. The introduction memory I may contain introduction data which are specific to the sets of data contained in the mass memory M. In this case, for example, only the introduction data specific to the set of data to be accessed are copied into the random-access memory 14 then reproduced. In one variant of the access device, all the specific introduction data are copied into the random-access memory 14, and only the data specific to a set to be accessed are reproduced during the access. Hence the introduction memory does not need to be read every time a set of data has to be accessed. The specific introduction data may be subsets of the sets of data. Depending on the nature of the sets of data, the subsets may, for example, represent a musical extract, a film trailer, a software module, etc. In one variant of operation of the device shown in Figure 2, the data read from the set 10 are still transferred into the random-access memory 14 then reproduced from the random-access memory. When the reading of the set 10 takes place more rapidly than the reproduction of the data from the random-access memory, the reproduction is delayed by comparison with the reading. When the set 10 has been read in its entirety, and when the next command from the control device 13 has to be carried out, the reproduction of the set 10 carries on while the command is being executed.

Claims: Method for accessing a determined set (10) of data among sets of data contained in a mass memory (7) on an information carrier, comprising the steps of : obtaining a command for access (1) to said determined set of data ; after obtaining said command for access, reading introduction data (9) with a read device (11) from an introduction memory (2) distinct from said mass memory but on said information carrier, processing (4) said introduction data read from said introduction memory, realizing a positioning operation of the read device for access to said determined set of data at the same time as the step of processing said introduction data. Method according to Claim 1, characterised in that processing (4) is carried out on introduction data which are specific to the set of data which is the subject of the access operation (6). Device for accessing sets of data contained in mass memory (M) on an information carrier, access to a determined set (10) of data for reading taking place during an access time, comprising : an introduction memory (I) containing introduction data (9), the introduction memory being separate from the mass memory but on the same information carrier, reading means (11) for reading from the introduction memory, command means for obtaining a command for access to said determined set of data and being at least connected to said introduction memory, characterized in that it comprises : processing means (14, 15) for processing the read introduction data, the processing means acting particularly during the time for positioning the reading means to access said determined set of data. Device according to Claim 3, characterised in that it comprises selecting means for selecting the introduction data specific to the set of data before access to this set, the selection means being linked at least to the reading means. Device according to Claim 3 or 4, characterised in that the mass memory is a sequential information medium and that the sets of data are arranged sequentially. Device according to any one of Claims 3 to 5, characterised in that the introduction data comprise subsets of sets of data. Device according to any one of Claims 3 to 6, characterised in that it further comprises: a temporary memory separate from the mass memory, transferring means for transferring at least a part of a set of data from the mass memory into the temporary memory while this set of data is read, further reading means for reading from the temporary memory, reproduction means for reproducing a set of data at a moment later than the reading of this set, these reproduction means being at least linked to the further reading means. Device according to any one of Claims 5 to 7, characterised in that the sequential information medium is a magnetic tape. Device according to any one of Claims 3 to 8, characterised in that the sets of data are audio and/or video sequences.

Inventors: ARTIGALAS MAX, MEUNIER PAUL LOUIS, ARTIGALAS, MAX, MEUNIER, PAUL LOUIS
Applicants: THOMSON MULTIMEDIA SA, THOMSON MULTIMEDIA
Application year: 1998
Main classification: G11B27
IPC codes: G11B27