Data storage medium with improved multi-session recording format

A data storage medium, and an apparatus and method for formatting the same. The medium is preferably characterized as a hybrid or recordable optical disc, and includes a pre-recorded storage area and a recordable storage area. The pre-recorded storage area stores file system data which identifies at least one file to be stored to the recordable storage area during a subsequent recording session, with the file system data having been stored to the pre-recorded storage area during a previous recording session. The file system data further preferably identifies at least one file stored to the pre-recorded storage area during the previous recording session. The pre-recorded and subsequently stored files are preferably disposed within the same logical track on the medium. The pre-recorded file system data includes entries for the subsequently added file(s), and eliminates the need for multiple copies of the file system on the medium.

FIELD OF THE INVENTION

The present invention relates generally to the field of data storage media and more particularly, but without limitation, to a storage medium, such as an optical disc, with an improved multi-session recording format.

BACKGROUND

Data storage media are used to store and retrieve large amounts of digitally encoded data in a fast and efficient manner. Such media have been commercially provided in a number of different forms, such as magnetic, optical and solid-state (e.g., flash memory, etc.).

Of particular interest are optical discs, which store data in a form that can be optically transduced in a readback system. Due to their portability, high data storage capabilities, and relative resistance to damage during handling, optical discs largely remain the worldwide medium of choice to provide and distribute video, audio, software (business, games, etc.), and other types of content.

Optical discs can be provided in a variety of formats, such as compact disc (CD), digital versatile disc (DVD), high density DVD, Blu-Ray, hybrid, mini-disc, etc. Optical discs can also be pre-recorded or recordable by the end user (once or many times), which further enhances the versatility of the media across a number of different markets.

The relative ease with which the content of a particular optical disc can be replicated, however, also constitutes one of the larger issues facing the industry; namely, the protection of intellectual property rights in the content stored on the disc. Along these lines, a number of efforts have been taken to copy protect discs so that unauthorized copying of the contents is prevented, or at least reduced.

Some content providers have desired the ability to append additional information to an optical disc (or other medium) after manufacturing, for copy protection or other purposes. Such information might include a unique serial number, a customer ID, updated files for the pre-recorded data on the disc, etc.

To this end, hybrid optical discs have been proposed with both pre-recorded and recordable portions. The “base” content is stored to the pre-recorded portion during disc manufacturing, and the “new” content is recorded to the recordable portion(s) of the disc at a later time.

Hybrid optical discs often utilize well-known multi-session recording techniques (see e.g., ISO 9660/13490, etc.) to control the writing of data over multiple sessions. For example, the base content is written during a first session, and new data are added to the disc during subsequent recording sessions using a recorder or similar equipment. Such multi-session techniques are also typically used on “regular” (non-hybrid) recordable discs when multiple recording sessions are made.

While a variety of multi-session techniques have been proposed, one commonly employed approach involves recording each session as a new track on the disc. Each new track generally includes an updated copy of the disc file system used to identify the file structure of the disc. Depending on the format, readback systems are generally instructed to find the last (and hence, most up to date) copy of the file system on the disc, and ignore the other, older copies.

Accordingly, with the continued worldwide commercial interest in providing content on optical discs and other types of storage media, there remains a continued need for improvements in the manner in which the content is arranged and identified on the medium. It is to these and other improvements that the present invention is generally directed.

SUMMARY OF THE INVENTION

The present invention is generally directed to a data storage medium, and a method and apparatus for formatting the same. The medium is preferably characterized as an optical disc.

In accordance with preferred embodiments, the medium comprises a pre-recorded storage area and a recordable storage area. The pre-recorded storage area stores file system data which identifies at least one file to be stored to the recordable storage area during a subsequent recording session. The file system data are stored to the pre-recorded storage area during a previous recording session. In this way, the file system generally operates to identify file(s) that will be added to the medium at a later date, but don't yet exist on the medium (or at all).

Preferably, the file system data further identifies at least one file stored to the pre-recorded storage area during the previous recording session. Both the previously recorded file(s) and the subsequently recorded file(s) are preferably disposed within the same logical track on the medium.

The file system data preferably comprises a placeholder entry for each new file, with the placeholder entry preferably identifying a start address and an end address for said file.

In some embodiments, the medium is characterized as a hybrid optical disc so that the pre-recorded storage area is formed from a sequence of embossed pits and lands, and the recordable storage area is an area with a recordable layer which stores data in response to application of a write beam thereto.

In other embodiments, the medium is characterized as a recordable optical disc with a recordable layer which stores data in response to application of a write beam thereto. In this case, the pre-recorded storage area comprises a first portion of the layer that has been exposed to the write beam to write data to the first portion, and the recordable storage area comprises a second portion of the layer that has not yet been written through exposure to the write beam.

The file to be subsequently stored to the medium can comprise any number, sizes and types of files, including a software patch to complement an executable file stored in the pre-recorded storage area, a unique serial number for the medium, etc. Advantageously, the resulting medium only has one set of file system data even in view of multiple recording sessions.

These and various other features and advantages of the present invention will be apparent from a reading of the following detailed description in conjunction with the appended drawings.

DETAILED DESCRIPTION

As embodied herein, the present invention is generally directed to a data storage medium and associated method and apparatus for storing data thereto. The storage medium is preferably characterized as an optical disc, but other types of storage media are readily contemplated as well.

FIG. 1provides a simplified, functional block diagram of an optical disc readback system100. An optical disc102is rotated by a disc motor104. An optical disc pick-up assembly comprises a data transducing head assembly106supported by a linear actuator assembly108.

It is common for optical discs such as102to have data stored at a constant linear velocity (CLV) so that the disc rotational speed is varied as the head assembly106moves across the radius of the disc102, but such is not limiting.

A readback processor circuit110receives a modulated readback signal from the head assembly106and performs the appropriate signal processing and conditioning to provide an output signal to an output device112.

The nature and character of the output device112will generally depend upon the type of content stored by the optical disc102; for example, if the optical disc stores audio data, the output device112can comprise an automobile or home stereo system; if the optical disc stores computer data (including MP3 audio files), the output device112can comprise a personal computer (PC); if the optical disc stores video data, the output device112can comprise a television display or home theater system, etc.

FIG. 2provides a simplified elevational representation of a single layer, pre-recorded optical disc120playable by the system100ofFIG. 1. For ease of discussion, the disc120has been arranged inFIG. 2in a “top-down” read orientation; that is, the read transducer is considered as being located above and is looking down upon the disc, to be consistent with the representation inFIG. 1.

The disc120generally includes a substrate122formed of polycarbonate having an outermost diameter of nominally 120 millimeters, mm (10−3meters). An embedded recorded layer124comprises a reflective layer of material having a series of pits and lands at different internal elevations, as shown. A protective backing layer126is preferably formed of resin.

The depth of the pits with respect to the lands is established in relation to the wavelength of the light beam emitted by the head106(e.g., nominally one-quarter wavelength). In this way, the pits will have a different reflectivity as compared to that of the lands in the beam as it is reflected back from the disc120, enabling the generation of a readback signal which is used to decode the data stored on the disc.

The disc120is preferably formed by generating a master disc with the desired pit and land sequence, forming a number of stampers from the master disc and then using injection molding or similar techniques to form a population of replica discs from the stampers. Pre-recorded discs such as120are typically formed in high volume replication facilities where large quantities of replicas are concurrently formed.

FIG. 3illustrates a mastering system130used to create the master disc from which the disc120is replicated. The system130is preferably characterized as a laser beam recorder (LBR). A glass master132is provided with a spun-coat layer of photoresist, and is rotated by a motor134.

A control block136with associated timing circuitry138provides top level control of the mastering process. A signal processing block140receives input data from path142, formats the input data into the desired form and generates the requisite control data, error detection and correction codes, etc. The signal processing block140provides this data to an EFM (extended frequency modulation) encoder144which generates an EFM signal representative of the desired pit and land sequence on the glass master132.

The EFM signal is used to modulate a write laser146to selectively expose the layer of photoresist. A motor control circuit148controls both the rotational speed of the glass master132and an actuator150used to advance the write laser146across the radius of the glass master.

FIG. 4provides a simplified elevational representation of a portion of a recordable optical disc160. As with the pre-recorded disc120ofFIG. 2, the recordable disc160is also contemplated as being playable by the system100ofFIG. 1.

The disc160generally includes a translucent substrate162, a recording layer164preferably comprising a layer of nominally translucent dye, a reflective layer166preferably comprising a gold alloy or similar metal, and a protective backing layer168.

During a recording operation, a write beam of light selectively impinges the recording layer164to cause a localized change in the reflectivity of the layer, such as shown by stripe170. The stripe170has a different reflectivity as compared to the nonexposed portions of the recording layer. Thus, the exposed and non-exposed portions of the recording layer164, in conjunction with the underlying reflective layer166, cooperate to function as the pits and lands of the disc120ofFIG. 2.

At this point it will be noted that recordable media such as160are becoming increasingly popular as a means for consumers to create their own media that can be played in standard media players. Commercial application providers are also increasingly using recordable media in lieu of standard replicated media to provide applications to the marketplace. The use of prerecorded media eliminates the time required to utilize a mastering and replication process as depicted byFIG. 3.

Thus, for purposes herein, the term “pre-recorded” will be understood to refer to a disc (or other medium) to which data have already been written, either using permanently embossed pits and lands as shown inFIG. 2, or using recordable media as shown inFIG. 4.

The term “recordable” will be understood to refer to a disc (or other medium) to which data have yet to be written, and thus not only includes the write-once media ofFIG. 4, but read-write media that can be written, erased, and rewritten multiple times.

It follows that a recordable disc such as160to which content has been supplied to some, but not all of the available disc recording area can be characterized as having a pre-recorded portion (i.e., that portion to which data have been written) as well as a recordable portion (i.e., that portion to which data have not yet been written).

Moreover, those skilled in the art will recognize that the respective views ofFIGS. 2 and 4can be combined to represent different portions of a single hybrid disc having both pre-recorded embossed portions (FIG. 2) as well as one or more recordable portions (FIG. 4).

The sectional view ofFIG. 4shows the disc160along a particular track.FIG. 5is perpendicular to the view ofFIG. 4and provides a sectional view of the disc160across several physical tracks. The physical tracks are predefined using a wiggle pre-groove, denoted generally at172. The pre-groove preferably comprises a continuous spiral that extends from the inner diameter (ID) to the outer diameter (OD) of the disc.

Instead of being perfectly concentric, the pre-groove172wobbles at a nominal frequency, such as 22.05 kilohertz (kHz) for a CD-R. This nominal carrier frequency provides motor speed control information to a disc writer system. In addition, the wobble is frequency modulated to provide sector address information commonly referred to as ATIP (absolute time in pre-groove).

The ATIP information is arranged in a number of sequential frames and provides information similar to the information provided by the Q channel in a conventional CD, such as elapsed time (in minutes, seconds and frames), starting and ending times for lead-in and lead-out, and error correction bytes.

ATIP information also typically includes disc type and manufacturer information, a recommended power setting during recording, a maximum recording speed, etc. The physical sectors of data subsequently written to the disc nominally align with the ATIP sectors; that is, the ATIP information serves to define where the actual data sectors will be subsequently placed on the disc.

Wiggle pre-grooves are generally mastered using equipment similar to that shown inFIG. 3. Such pre-grooves are also often used in other types of recordable media, such as recordable DVDs (DVD-R, etc.).

FIG. 6provides a functional block diagram for an optical disc writer system180configured to selectively expose the recording layer164of the recordable disc160to write data thereto.

The system180includes a control block182that provides top level control for the system. A signal processing block184receives input data from path186, formats the input data into the desired form and generates the requisite control data. The signal processing block184provides the processed data to encoder188which, as before, generates an EFM signal representative of the desired pit and land sequence on the disc160.

The system180further includes a write assembly190comprising a tracking (T) laser assembly192, a write (W) laser assembly194and an actuator196. The tracking laser assembly192emits a light beam with selected focal depth and width to detect the pre-groove172, while the write laser assembly194is modulated by the EFM signal to write the encoded data to the disc. A readback signal from the tracking laser assembly192is provided to an ATIP detect and decode block198.

The block198decodes the timing information from the nominal frequency of the wobble to enable a motor control block200to provide the necessary control signals to a motor202to rotate the disc160at the appropriate velocity, and to enable the control block182to correctly position the write laser assembly194to nominally follow the pre-groove172.

FIG. 7provides a generalized representation of a format204for a selected disc to which data have been written during a single recording session. The format204includes a lead-in zone206, a program area208and a lead-out zone210. The content data stored to the program area208are shown to be arranged in two tracks, although this is for illustration only.

The tracks are identified at212and214, and are separated by pause fields216and218. For clarity, the term “track” as used inFIG. 7does not refer to a physical track (i.e., a single revolution of the disc), but rather to a “logical track;” that is, a self-contained zone in which a cohesive set of data are stored (such as an audio track on an audio CD, etc.), as known in the art.

The lead-in and lead-out zones206,210are configured in accordance with the applicable format to provide signals that allow the readback system100(FIG. 1) to identify the start and end of the disc. Additionally, the lead-in zone206is shown to include a table of contents (TOC)220which identifies, inter alia, the starting and ending addresses for each track, the start address for the lead-out210, etc.

FIG. 8provides a related format224for a recordable or hybrid disc to which data are recorded over multiple recording sessions. For purposes herein, the term “session” will be defined as a full set of operations carried out to successfully place content data on the associated medium. Thus, for example, the mastering and replication process described with respect toFIGS. 2 and 3would be viewed as a single recording session, as would the operation of the system ofFIG. 6by a user to successfully record desired content data to a recordable disc using a personal computer.

It will be noted that in the latter example, if at the conclusion of the writing process the user immediately followed up by a relaunching of the attendant PC application program to begin afresh and add a new set of content data to the disc, such would be viewed as two separate sessions, even if such operations occurred sequentially in time. Thus, the term “session” as used herein is given its ordinary meaning as understood by those skilled in the art.

The format224inFIG. 8has lead-in, program area and lead-out zones226,228and230, as before. A first track (TRACK1)232comprises content data stored during a first recording session, and a second track (TRACK2)234comprises content data that is subsequently added to the disc during a second recording session. Other fields shown inFIG. 8include a pause field (P1)236, a run-out field238, a link field240, and a run-in field242in the program area228, and a TOC244in the lead-in226.

For at least certain types of recordable media such as CD-R and CD-R/W, the writer system (e.g.,180) may not rely upon the TOC244in recording mode. Instead, the system will utilize a recordable memory area (RMA) field246. This field can be located as desired, such as in the lead-in zone226.

As those skilled in the art will recognize, the RMA246stores various information with regard to the content on the disc, such as the start and end locations for each recording session. Thus for example, at the end of session1(i.e., the writing of TRACK1), the RMA246stores one start/end location for session1.

At the end of session2(i.e., the writing of TRACK2), the RMA246is updated to store a second start/end location for the second session, and so on. When the disc is full, or it is determined that no additional data will be written to the disc, the writer180preferably creates the table of contents from the RMA246and writes this to the TOC field244in the lead-in zone226. It will be noted that once the TOC244has been written, the recordable disc can be read by any standard readback system as if the disc were actually a pre-recorded, embossed disc, if the content is of a selected type (e.g., CD audio).

Of particular note are the run-out, link and run-in fields238,240and242inFIG. 8. These three fields are commonly employed to account for interleaving and error correction system requirements. For example, to fully recover the last sector of TRACK1, it is generally necessary to additionally read the contents of the run-out field238since the last sector of TRACK1is interleaved over previous and later sectors on the disc. Similarly, the run-in field242is read in order to successfully recover the first sector in TRACK2.

The link field240preferably comprises a dead zone to which no data have been written, and serves to separate the respective sessions since interleaving rules cannot generally be maintained with recordings that stop and start again.

FIG. 9shows a format254that is similar to that ofFIG. 8, and so like reference numerals have been used for similar features in both drawings. The format254is suitable for certain types of ROM discs, such as CD-ROM, which can require a copy of a file system near the beginning of the first track.

As those skilled in the art will recognize, some optical discs (and other types of media) store data in the form of files, which can be defined as logical groupings of sectors, the respective contents of which are combined to form a larger data structure (e.g., a “file”). File system conventions will vary depending upon the operational environment, but generally each entry in the file system will logically identify the start and end address of each file on the disc (or portion thereof).

Accordingly, during the first recording session, a first file system field256was incorporated into the TRACK1field232in order to identify the files stored in that track. During the subsequent recording session, a second file system field258was incorporated into the TRACK2field234, with the contents of the second field258incorporating the contents of the first field256, plus having appended thereto the additional file information for the files in the second track.

While operable, there are a number of undesirable limitations associated with these and other multi-session recording schemes. The overhead in terms of unusable space to accommodate multiple recording sessions can become significant, and can adversely affect the ability to get a selected amount of content onto a single disc.

Under many current schemes, even the addition of a very small recording session, such as the addition of a drive serial number, can require a new track, as well as all of the attendant fields associated therewith (new file system, run-in and run-out fields, etc.).

Moreover, it can be operationally inefficient and time consuming to search for the last track and locate the most up-to-date file system data on a disc when multiple copies are present, since there are few limitations on the numbers and sizes of the respective tracks that can be applied to a disc. When utilized, the RMA field can also present additional overhead costs in terms of both processing requirements and storage space.

Accordingly,FIG. 10provides a novel format300for an optical disc (or other storage medium) with an improved multi-session capability. The exemplary format300includes lead-in, program area and lead-out zones302,304, and306, as before. The program area304is shown to include a track1field308, which stores one or more pre-recorded files that were written to the disc during a previous (e.g., first) recording session310.

The pre-recorded field308includes pre-recorded file system data312, which serves to identify the files stored in the field308, as well as to identify the file(s) to the recorded to the disc during subsequent recording session(s) (314). Thus, when written, the file system data312pre-identifies one or more files that have not yet recorded onto the disc, nor will be during the current recording session.

These subsequently added files are preferably arranged in fields316(new file1),318(new file2) and320(new file3). Of course, this is merely for illustration, in that multiple sets of files could readily be provided in each of these fields as desired. These fields316,318and320are generally separated by gap fields322,324,326and328(G1through G4). A TOC330is also written to the lead-in302during the previous recording session310.

It will be noted that the new files in fields316,318and320are in the first track (TRACK1); while alternatively the new files could be arranged in one or more new tracks, such is unnecessary and indeed, might cause a standard readback system to overlook the data in field312. Thus, multiple copies of the file system are avoided (as well as the need for the RMA zone).

As mentioned above, the pre-recorded file system data312preferably includes entries for each of the pre-recorded files in field308, as well as placeholder entries for the new files. While the particular format for the file system data will vary widely depending on the requirements of a given application, Table 1 sets forth a generalized exemplary format to aid in the present discussion:

The “placeholder” entries are defined during authoring and can be any length depending on the known and/or anticipated needs for the recordable areas.

The file names can also be arbitrarily defined, allowing the use of an additional table or other conversion mechanism during subsequent operation. The file names can alternatively be given standard names (e.g., disc_serial_no.bat; software_patch1.bat; software_patch2.bat; etc.) to readily allow subsequent access by the pre-recorded content, or by other applications. Provision can thus be readily be made for any number and types of additional files to be subsequently added to the disc.

With reference toFIG. 11, each of the gap fields322,324,326and328generally comprise a post-file field332, a gap (link) field334, and a pre-file field336, which operate as before with respect toFIGS. 8 and 9. However, it will be noted that the pre-recorded file data312will identify these boundaries beforehand.

If a newly added file is added that is smaller than the size provided for in the file system312, the gap field334can accordingly be made larger to take up the remaining space otherwise dedicated to the new file. An “actual length” indicator can be provisioned in a suitable reference table as needed so that the system100can verify the actual length of the file from the file itself rather than the file system data312.

The file system data312can readily be generated in response to the control block136of the writer system130ofFIG. 3, so that the data are provided on the glass master132and subsequent replicated discs120. Alternatively, the file system data312can be generated in response to the control block182of the writer system180ofFIG. 6so that the data are arranged onto the recordable disc160. It is contemplated that the resulting discs will be readily accessible by a standard readback system, such as100inFIG. 1.

It will now be appreciated that this novel format presents several advantages over the prior art. The format provides for an efficient utilization of hybrid and/or recordable discs, regardless whether only a very small amount, or significant amounts, of additional data are supplied to the disc. With this format, content providers can supply pre-recorded content on embossed or recordable areas and then update the discs with software patches, identification serial numbers or other information, copy protection algorithms, etc. as desired, either prior to or after shipment of the discs (such as during installation, via remote link, etc.).

While the foregoing discussion has generally presented single sided, single layer optical discs, the novel format can readily be extended to multi-sided, multi-layer discs, as well as other formats of media, optical or otherwise.

In view of the foregoing, it will now be understood that preferred embodiments of the present invention are generally directed to a data storage medium (such as120,160,300), and a method and apparatus (such as130,180) for formatting the same. The medium is preferably characterized as an optical disc.

In accordance with preferred embodiments, the medium comprises a pre-recorded storage area (such as308) and a recordable storage area (such as316,318,320). The pre-recorded storage area stores file system data (such as312) which identifies at least one file to be stored to the recordable storage area during a subsequent recording session (such as314), and wherein the file system data are stored to the pre-recorded storage area during a previous recording session (such as310).

Preferably, the file system data further identifies at least one file stored to the pre-recorded storage area during the previous recording session. The at least one file stored to the pre-recorded storage area is characterized as a first file, wherein the at least one file to be stored to the recordable storage area is characterized as a second file, and wherein the first and second files are each stored in a common logical track on the medium (seeFIG. 10).

The file system data preferably comprises a placeholder entry for said at least one file to be recorded to the recordable storage area, said placeholder entry identifying a start address and an end address for said file (see Table 1).

In some embodiments, the medium is characterized as a hybrid optical disc so that the pre-recorded storage area is formed from a sequence of embossed pits and lands (such as at120), and the recordable storage area is an area with a recordable layer which stores data in response to application of a write beam thereto (such as at160). In other embodiments, the medium is characterized as a recordable optical disc with a recordable layer (such as164) which stores data in response to application of a write beam (such as194) thereto, wherein the pre-recorded storage area comprises a first portion of said layer that has been exposed to said write beam, and wherein the recordable storage area comprises a second portion of said layer that has not yet been exposed to said write beam.

The file to be subsequently stored to the medium can comprise a software patch to complement an executable file stored in the pre-recorded storage area, a unique serial number for the medium, etc.

For purposes of the appended claims, the recited means for directing will be understood consistent with the foregoing discussion to correspond to the disclose control blocks136,182ofFIGS. 3 and 6, respectively.

In addition, although embodiments described herein are generally directed to the formatting of optical discs, it will be appreciated that any number of different formats and types of optical discs, as well as any number of other formats and types of data storage media can be readily utilized without departing from the spirit and scope of the claimed invention.