Patent Application
20080212422
The present invention relates in general to a method for writing information on a multiple-layer optical storage disc, and to a device for executing the method.
As is commonly known, an optical storage disc comprises at least one track, either in the form of a continuous spiral or in the form of multiple concentric circles, of storage space where information may be stored in the form of a data pattern. Optical discs are very successful, and several different types have been developed. One such type is DVD (Digital Versatile Disc), and the present invention relates particularly to DVD discs. However, the gist of the present invention is also applicable to other types of discs; therefore, the following description is not to be understood as limiting the scope of the present invention to DVD discs only.
Optical discs may be read-only type, containing information which can only be read by a user. The optical storage disc may also be a writeable type, where information may be stored by a user. Such discs may be a write-once type, indicated as writable (R), but there are also storage discs where information can be written many times, indicated as rewritable (RW). In the case of DVD, a distinction is made between two formats, i.e. the “minus”-format (DVD-R, DVD-RW) and the “plus”-format (DVD+R, DVD+RW).
For writing information in the storage space of the optical storage disc, a storage track is scanned by an optical write beam, typically a laser beam, of which the intensity is modulated to cause material changes which can later be read out by scanning the storage track by an optical read beam. Since the technology of optical discs in general, and the way in which information can be stored in an optical disc, is commonly known, it is not necessary here to describe this technology in more detail. However, it is noted that a storage track defines a range of storage locations having unique addresses.
Typically, an optical storage system comprises an optical disc as a record medium, and further comprises a disc drive apparatus and a host apparatus. The disc drive apparatus is a device, comprising optical means for actually writing data, capable of accessing all storage blocks where it is physically possible to store information. The unique addresses of all these physical storage locations are indicated as physical addresses. The host apparatus, which may be a PC running a suitable program, or an application of a consumer apparatus such as a video recorder, is a device which communicates with the disc drive, and sends commands to the disc drive instructing the disc drive to write certain data to a certain storage location. In contrast to the disc drive apparatus, the host apparatus only has access to a part of the physical storage space, this part being indicated as logical storage space, and the storage blocks in the logical storage space also have logical storage addresses. Although the logical storage space does not need to be a physically contiguous storage space, the storage blocks in the logical storage space have consecutive logical addresses, which are usually not identical to the physical addresses.
Conventionally, an optical disc has only one storage layer containing a storage track. More recently, optical discs have been developed having two or even more storage layers, each storage layer containing a storage track in the shape of a spiral or multiple concentric circles. In such case, the logical storage space extends over multiple storage layers, hence the range of logical addresses extends contiguously over multiple storage layers. The transition from the last block of one storage layer to the first block of the next storage layer is such that the logical address is incremented only by 1.
The present invention relates particularly to optical discs having two storage layers. However, the gist of the present invention is also applicable to discs having three or more layers; therefore, the following description is not to be understood as limiting the scope of the present invention to double-layered discs only.
It is noted that the present invention relates to optical discs where at least two storage layers are approached by a laser beam from the same side. The disc has a main surface which is directed towards the laser; this main surface will be indicated as entrance surface. For access to a specific storage layer, the laser beam enters the disc at the entrance surface, and travels the depth of the disc until it reaches the specific storage layer. Selection of a specific storage layer involves focussing the laser beam at the corresponding depth. In the following, the storage layer which is located closest to the entrance surface will be indicated as first storage layer, and the corresponding logical space will be indicated as L0; the next storage layer will be indicated as second storage layer, and the corresponding logical space will be indicated as L1. Thus, in the case of a dual layer disc, the entire logical space of the disc will be L0+L1.
In the case of a dual layer disc, the first layer L0 extends from an inner radius to an outer radius. In other words, logical address zero corresponds to a certain physical address (30000) relatively close to the centre of the disc, while increasing logical addresses correspond to increasing track radius, such that the highest logical address corresponds to a radius relatively close to the perimeter of the disc.
For the second layer L1, there are two possibilities. In one possibility, the logical addresses are numbered in the same way as L0, i.e. increasing from the inner track radius to the outer track radius; this arrangement is indicated as Parallel Track Path (PTP). In another possibility, indicated as Opposite Track Path (OTP), the logical addresses are numbered from the outer track radius to the inner track radius.
When a disc is written according to the PTP arrangement, the laser beam scans L0 in a direction from centre to perimeter. After a jump to L1, writing continues at the innermost track of L1, in the same direction from centre to perimeter. In such case, the storage capacity of L1 is independent from the location of the last block of the first track. In an OTP case, however, after a jump from L0 to L1, writing continues at the location of the jump, in the opposite direction from perimeter to centre; in such case, the size of the available logical space in L1 is clearly dependent on the location of the last block of the first track.
The present invention relates specifically to a disc of OTP type, i.e. a disc having at least one pair of successive storage layers with mutually opposite track direction. However, the gist of the present invention is also applicable to a disc of PTP type.
A typical problem occurs in case the information being written is video information which is copied from a source medium, for instance a hard-disk or an optical disk, such that the total amount of video data is larger than the capacity of the first storage space. A specific problem occurs when the source medium is a DVD+RW disc having a first storage space L0 smaller than the standard size; this situation can occur because in the case of writing information to a DVD+RW disc it is possible to set the size of first storage space L0 to a value smaller than standard.
During writing, the host organizes DVD Video data in cells, and a transition from one layer to the next is only allowed at a cell boundary; this is related to the fact that, on reading video data from disc, it is desirable to have seamless continuation of video image display. On the other hand, the disc drive continues writing in L0 until a predefined logical end address is reached; after having written information at the end address, the disc drive jumps to L1 and continues writing at the next logical address in L1 (at the inner radius in a PTP case, or at the radius of the end address of L0 in an OTP case). Usually, this transition from L0 to L1 does not correspond to a video cell boundary. As a result, on playing the recording, display is not seamless: display may show a delay, a freeze-image, or a “hick-up”, or the disc drive may even crash.
The disc drive, receiving the video data from the host, has no means for generating cell boundaries when approaching the end of L0 (in fact, the disc drive does normally not even “know” that it is writing video information). On the other hand, the host device is not capable of instructing the disc drive to use a specific physical address, and is not capable of instructing the disc drive to make a transition to L1 before having reached the end of L0 (a transition to L1 can only be made at the end of L0).
It may be that the video data from the source medium is already organized in cells; in that case, it is highly likely that the cell boundaries of the source video data are not aligned with the end of the first storage space L0. It may also be that the video data from the source medium is not organized in cells at all.
An important objective of the present invention is to overcome the above difficulties.
More specifically, an objective of the present invention is to assure that the last logical address of a storage layer does not fall inside a video cell.
A particular objective of the present invention is to support seamless image reproduction on reading.
Another particular objective of the present invention is to improve trickplay.
In the above, objectives of the present invention have been explained in the context of video cell boundaries in the case of writing video data. However, it may be desirable for other reasons to organize data in cells, and to have a transition from L0 to L1 correspond to a data cell boundary.
According to an important aspect of the present invention, a host is capable of comparing the amount of video data from the source medium with the storage capacity of the target disc. If the video amount is larger than the (remaining) space in the first logical space L0 but smaller than the total of first logical space L0 and second logical space L1 combined, the host stops writing the video data after having completed a video cell at some distance from the end of the first logical space L0. Then, the remaining space until the end of the first logical space L0 is filled with dummy data, and the host make a transition to the second logical space L1. Depending on design considerations, the host starts writing in the first available storage location of the second logical space L1, or the host may start writing in the second logical space L1 at a location aligned with the end of the last video cell in the first logical space L0, or the host may start writing in the second logical space L1 at a location chosen such that the end boundary of the last cell in the second logical space L1 is aligned with the first cell in the first logical space L0.
These and other aspects, features and advantages of the present invention will be further explained by the following description with reference to the drawings, in which same reference numerals indicate same or similar parts, and in which:
A host/drive communication link between host device 20 and disc drive 10 is indicated at 5. Likewise, a drive/disc communication link between disc drive 10 and disc 2 is indicated at 6. The drive/disc communication link 6 represents the physical (optical) read/write operation as well as the physical addressing of the disc 2. The host/drive communication link 5 represents a data transfer path as well as a command transfer path.
It is noted that disc drives are known, and that the present invention can be implemented using an existing disc drive; therefore, it is not necessary here to describe the design and operation of the disc drive 10 in great detail.
The optical disc 2 has a storage space 3, which has the form of two or more continuous spiral-shaped tracks or tracks in the form of multiple concentric circles, where information can be stored in the form of a data pattern. Since this technology is commonly known to persons skilled in the art, this technology will not be explained in further detail.
The several tracks of the storage space 3 are located in different storage layers of the optical disc 2.
It is noted that in
The storage locations in the storage layers 40 and 41 have logical addresses; these logical addresses define a logical space. The logical space of the first storage layer 40 is indicated L0, while the logical space of the second storage layer 41 is indicated L1.
In the first logical space L0, logical address 0 is located closer to the centre of the disc 2, and logical end address N is located closer to the perimeter of the disc 2. In the second logical space L1, in the case of an OTP disc, the first logical address N+1 is located closer to the perimeter of the disc 2, substantially aligned with logical end address N of L0, and the logical end address M is located closer to the centre of the disc 2. When information is recorded, the disc drive starts at logical address 0, following the first logical space L0 from the centre to the perimeter, as indicated by arrow 51. After writing in the end address N, a transition is made to the second logical space L1, as indicated by arrow 52, and then the second logical space L1 is followed from the perimeter to the centre, as indicated by arrow 53.
The host 20 receives the video from a video storage medium 21 (
In the following, individual cells are distinguished by adding an index between square brackets. Likewise, individual cell boundaries are distinguished by adding an index between square brackets. The index x of a cell boundary 34[x] corresponds to the index of the cell 35[x] immediately before that cell boundary 34[x]. Further, each cell 35[x] has a length L[x]. Normally, the cells will have equal lengths, but this is not essential; by way of illustrative example, the following will assume that all lengths are equal to a standard length Ls. As will be known to persons skilled in the art, each cell 35[x] contains information (in NAVPACKS) indicating the length L[x] of that cell as well as a pointer to the logical address A[x] of the end of that cell; this information is schematically indicated in
Assume that a data storage system not implemented in accordance to the present invention is to store the video sequence 30. The host device 20 transfers the video sequence 30 to the disc drive 10 over host/drive communication link 5, and the disc drive 10 writes the video sequence 30 to disc 2 over drive/disc communication link 6, wherein the start of the video sequence 30 is written at a block in L0 having a certain logical address which may be determined by the host device 20, or which may be the first available block after a previous recording. As writing continues, the logical addresses increase.
In the following, the invention will be explained for the exemplary case that the contents of a dual-layer DVD+RW disc, which will be indicated as source disc 2S, is to be copied to a dual-layer DVD-RW disc, which will be indicated as target disc 2T.
It is further assumed that the source disc 2S contains a video recording 63 that is distributed over both source storage spaces but does not fill the entire capacity of the source disc 2S. When the recording was made, the first source storage space 61 was filled up to a certain logical end address M (M<Ns), and then a transition was made to the second source storage space 62, where writing continued, in opposite direction, from logical address M+1 onwards, till recording end logical address M+X. For sake of convenience, it is assumed that the recording 63 has started at logical address 0. The data is organized in cells 35, as illustrated in
Thus, the source data 63 comprises a first source data portion 67 having a first logical end address M, and a second source data portion 68 having a second logical start address M+1 and a second logical end address M+X. The physical location of the first logical end address M is substantially aligned with the physical location of the second logical start address M+1.
The portion of the first source storage space 61 beyond physical address M (from physical address M+1 to physical address Ns) has remained empty; this storage space portion, which will be indicated as first remainder storage portion 64, involves Ns-M addresses. The same applies to the portion of the second storage space 62 which lies between the beginning of the second storage space 62 and the beginning of the recording 63 (i.e. from physical address Ns+1 to logical address M+1), which portion will be indicated as second remainder storage portion 65. The second remainder storage portion 65 contains physical addresses N+1 up to and including Ns+(Ns−M), and logical address M+1 corresponds to physical address Ns+(Ns−M)+1. Finally, there is a third remainder storage portion 66 beyond logical address M+X (containing the physical addresses Ns+(Ns−M)+X+1 up to and including 2Ns+1.
At first sight, the logical thing to do is to make a direct copy from the source disc 2S to the target disc 2T. However, this would mean that the target disc 2T would also have empty remainder storage portions, which is not possible for a DVD-RW disc. The invention proposes several solutions, as will be explained in the following.
It is noted that the recording in practice may start at a physical address differing from zero, and some defective storage locations may be encountered, but the consequential renumbering of the target data addresses will be clear to a person skilled in the art and will not be specified here for sake of convenience.
It is further noted that, when writing the video data into the target disc 2T, the cell structure of the video data of the recording 63 in the source disc 2S is maintained. Thus, individual cells are indicated by the same reference numeral 35.
It is noted that the dummy data in the first remainder portion 74 can be any data, for instance zero data.
It is further noted that it is not actually necessary to write dummy data in all addresses of the first remainder portion 74. It is sufficient if the dummy data is written in the first sector of the first remainder portion 74, and that the NAVPACK of this first sector contains the length (Nt−M) of the first remainder portion 74, contains the end address (Nt) of the first remainder portion 74, and contains a code indicating that this video cell only contains dummy data (dummy code).
Now that the host 20 has entirely written the first target storage space 71, a transition can be made to the second target storage space 72, and the second source data portion 68 of the source disc 2S can be copied. The present invention provides three different variations, which will be explained with reference to
In a first variation, illustrated in
The physical end address Nt+A of the second remainder portion 75 is chosen such that the physical size (radial dimension measured on the target disc 2T) of the second remainder portion 75 substantially corresponds to the physical size of the first remainder portion 74. To this end, A is substantially equal to Nt−M.
It is noted that, with respect to the dummy data in the second dummy data portion 75, the same applies as what has been said above with respect to the dummy data in the first remainder portion 74.
It is further noted that the dummy data in first remainder portion 74 may be written as one video cell. Also, the dummy data in the second remainder portion 75 may be written as one video cell. However, it is also possible that these two remainder portions 74 and 75 are written as one combined video cell, because it is not necessary that the cell boundary of the dummy data corresponds to the outer perimeter of the logical storage space.
After having defined the second remainder portion 75, the host 20 continues with reading the data of the second source data portion 68 of the source disc 2S, and sends this data to the disc drive 10, which will write this data into the second target storage space 72, starting at the first address available after the second remainder portion 75, i.e. starting at physical address Nt+A+1. This phase of the recording process according to the present invention is also illustrated in
As will be known to persons skilled in this art, each video cell contains information pointing towards the logical end address of that specific video cell. It is noted that in the target disc 2T, in view of the fact that the remainder portions 74 and 75 are not empty, the logical addresses correspond to the physical addresses. Thus, before sending the video cells of the second source data portion 68 of the source disc 2S to the disc drive 10, the host 20 updates the information in the NAVPACKS; specifically, indications pointing to addresses i are replaced by indications to addresses i+2(Nt−M).
When the recording procedure has been completed, the target disc 2T comprises a copy recording 73 having the same configuration as the source recording 63 of the source disc 2S, in the sense that the end of cell 35P in the first target storage space 71 is aligned with the beginning of cell 35Q in the second target storage space 72. When the copy recording 73 is played, the transition from cell 35P to the next cell 35Q involves a transition from first target storage space 71 to second target storage space 72 without the need for a radial jump, so seamless playback can be assured. A difference between the target disc 2T and the source disc 2S is to be seen in the value of the logical addresses, as mentioned above. Further, in stead of an empty first remainder storage portion 64 and empty second remainder storage portion 65, the target disc 2T has first and second dummy data storage portions 74 and 75 in the first and second target storage spaces 71 and 72, respectively.
An advantage of the embodiment illustrated in
An advantage of this approach is that the size of the third remainder portion 76 has increased, which is available for possible further recordings. In this case, the target disc 2T does not have the second dummy data portion 75.
According to a further elaboration of the present invention, it is possible to further increase the efficiency in the use of storage space by recording the data from the second source data portion 68, at least partly, into the first target storage space 71, behind the first target data portion 77. Thus, after having written the first target data portion 77, the host 20 continues with reading the data of the second source data portion 68 of the source disc 2S, and sends this data to the disc drive 10, which will write this data in the first target storage space 71, starting at the first address available after the first target data portion 77, i.e. starting at physical address M+1, such that cell 35Q is adjacent to cell 35P. This phase of the recording process according to the present invention is illustrated in
When this phase has been completed, the first target storage space 71 of the target disc 2T contains a second target data portion 81, copy of a first part of the second source data portion 68, extending from physical address M+1 to physical address M+Y. The portion of the first target storage space 71 beyond this address, i.e. from physical address M+Y+1 to physical address Nt, will be indicated as first remainder portion 84.
According to an aspect of the present invention, this first remainder portion 84 of the target disc 2T is defined as a dummy data portion, indicated by the hatching in
Now that the host 20 has entirely written the first target storage space 71, a transition can be made to the second target storage space 72, and the remainder part of the second source data portion 68 of the source disc 2S can be copied. The present invention provides three different variations, which are comparable to the variations explained with reference to
In a first variation, illustrated in
In a second variation, not illustrated, comparable to the variation of
In a third variation, illustrated in
According to a further elaboration of the present invention, it is possible to even further increase the efficiency in the use of storage space by using the entire first target storage space 71.
In the embodiment illustrated in
It is noted that the process of taking data from a video cell and recoding this data to define a new cell is a process known per se to persons skilled in this art, so it is not necessary here to explain this process in great detail. It is noted that, in this embodiment, logical addresses are equal to physical addresses. It is further noted that, in this embodiment, the end address of the first cell part 35R1 is equal to Nt, and that the length of the first cell part 35R1 is smaller than the length of the original cell 35R, so the NAVPACK information in the first cell part 35R1 relating to cell length and cell end address must be adapted. It is further noted that, in this embodiment, the end address of the second cell part 35R2 remains the same but the length of the second cell part 35R2 is smaller than the length of the original cell 35R, so the NAVPACK information in the second cell part 35R2 relating to cell length must be adapted.
As a result of splitting the cell 35R into two new cells, one cell boundary is added at the transition from the first target storage space 71 to the second target storage space 72. If this cell boundary is not added, seamless display can not be assured when the recording 73 is played.
It may, however, be undesirable to increase the total number of cell boundaries.
A combination of the embodiments of
In the embodiments of
When receiving a copy command for recording 63, the host 20 is designed to first copy the first source data portion 67 to the first target storage space Lt0 [steps 101-104]. The host starts reading a video cell from the first source storage space Ls0 of the source disc 2S, starting from logical source address i [step 101], and writes this video cell to the first target storage space Lt0 of the target disc 2T, starting from logical target address i [step 102]. When the host 20 is associated with two disc drives, one source disc drive for reading the source disc and one target disc drive for writing the target disc, the host may send the video data to be written to the target disc drive as soon as it receives the video data from the source disc drive. However, it is also possible that the host receives video data of an entire video cell and stores this video data in a buffer memory, and sends data from this buffer memory to the target disc drive only after having received an entire video cell. It is also possible that the host is associated with one disc drive only, so that this disc drive is first used for reading the entire source disc, after which the source disc is replaced by the target disc and the disc drive is used for writing the target disc; in that case, the host may first store the entire recording 63 on its hard disc and use the information from its hard disc when writing the target disc.
In step 103, the host continues to the next cell. In step 104, the host checks whether this next cell is located in the second source storage space Ls1 of the source disc. If not, then the host jumps back to step 101 and the above process is repeated.
If the host finds that the next cell is located in the second source storage space Ls1 of the source disc 2S, the host calculates the size Nt−M of the remaining portion 74 of the first target storage space Lt0, and calculates the size A for the initial dummy portion 75 in the second target storage space Lt1 [step 111]; in this case, this size A is equal to the size Nt−M of the remaining portion 74 of the first target storage space Lt0.
In a next phase, the host defines the remaining portion 74 of the first target storage space Lt0 as a dummy portion, by writing dummy data into this storage space portion 74, i.e. from physical address M+1 to physical address Nt [step 121].
In a next phase, the host defines the initial dummy portion 75 in the second target storage space Lt1 as a dummy portion, by writing dummy data into this storage space portion 75, i.e. from physical address Nt+1 to physical address 2Nt−M [step 122].
In a next phase, the copying process continues. In step 131, the host reads a video cell from the second source storage space Ls1 of the source disc, starting from logical source address i. Before recording this cell, the cell is recoded. In step 132, the host reads the pointer information P indicating the logical end address of the current video cell, and in step 133 the host calculates a new value for this pointer, indicated as target pointer PT, by increasing the source pointer P by NT−M+A. In step 134, the host replaces the source pointer P by the target pointer PT. In step 135, the host writes the current video cell with the replaced target pointer PT to the second target storage space Lt1 of the target disc, starting from logical address i+NT−M+A.
Then, the host proceeds to the next video cell of the source recording 63 [step 136]. If the end of the recording has not yet been reached [step 137], the host returns to step 131 and the above process is repeated.
Similar to method 200 of
Similar to method 300 of
Then, the host continues with the remaining cells from the source recording 63 [steps 531-537]. It is noted that the address pointer information in the cells does not need to be changed, so steps 432-434 are omitted.
With reference to
It is noted that, in order to facilitate these steps, the host may comprise a buffer memory 23 where the previous cell 35N is stored for possible combination with part of the next cell.
With reference to
In the above, it has been assumed that the source data is available on a source medium in the form of a multi-layered optical disc, while part of the source data is located in a first layer and part of the source data is located in a next layer. The present invention can, however, also be implemented in case the source data is available in one contiguous storage space, without being divided over two (or more) storage spaces. An example of such situation is for instance the case where the source data is located on a source medium having a capacity larger than the storage capacity of the DVD-RW disc; an example of such source medium is a hard disc.
Another example of such situation is for instance the case where the source data is located on a single-layer optical disc, while a first portion of the first storage space Lt0 of the target dual-layer disc has already been used for storing data, such that the copying process can not start recording the copy data from the first address in the first target storage space Lt0.
In all of these examples, it may be that the available storage space in the first target storage space Lt0 is not enough for recording the entire copy recording, so a transition has to be made from the first target storage space Lt0 to the second target storage space. In any case, the host has at all times information available regarding the size of the remaining part of the first target storage space Lt0, and regarding the size of the cells to be copied. Thus, in all of these cases, the host can perform the method as described with reference to
It is noted that the above example relates to the transition from the first storage space L0 to the second storage space L1. Similar considerations would play a roll when a disc has three or more storage layers, and a transition is to be made from the second storage space L1 to a third storage space L2, or from the third storage space L2 to a fourth storage space L3, etc.
It should be clear to a person skilled in the art that the present invention is not limited to the exemplary embodiments discussed above, but that several variations and modifications are possible within the protective scope of the invention as defined in the appending claims.
In the above, the present invention has been explained with reference to block diagrams, which illustrate functional blocks of the device according to the present invention. It is to be understood that one or more of these functional blocks may be implemented in hardware, where the function of such functional block is performed by individual hardware components, but it is also possible that one or more of these functional blocks are implemented in software, so that the function of such functional block is performed by one or more program lines of a computer program or a programmable device such as a microprocessor, microcontroller, digital signal processor, etc.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05300472.7 | Jun 2005 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2006/051727 | 5/31/2006 | WO | 00 | 12/7/2007 |
