WO2008007285A1

WO2008007285A1 - Power failure recovery of video recordings on optical discs

Info

Publication number: WO2008007285A1
Application number: PCT/IB2007/052524
Authority: WO
Inventors: Srinivas R. Kudavelly
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2006-07-07
Filing date: 2007-06-29
Publication date: 2008-01-17
Also published as: TW200818127A

Abstract

A Power Failure recovery method is described such that if a recording process is abruptly interrupted e.g. due to power failure, after the power has been restore, a proper title according to desired application format is created corresponding to the recorded material up to a few seconds before power failure. A method of recording video information onto an optical disc of the rewritable type, a recordable area of the optical disc comprising a video zone for recording said video information and corresponding management information, the video information and the corresponding management information being arranged according to a recording format, the method comprising steps of: recording the video information in the video zone; recording recovery information onto the optical disc; generating and recording the corresponding management information; deleting the recovery information if the preceding recording steps were executed successfully, wherein said recovery information comprises recording information enabling generating said management information.

Description

Power failure recovery of video recordings on optical discs

FIELD OF THE INVENTION

The present invention relates to a method of recording video information onto an optical disc of the rewritable type. The present invention also relates to a method of recovering audio/video information recorded onto an optical disc in case of an error such as a power failure affecting a device for a recording and/or reproducing from said optical disc.

This invention also relates to a device for recording an optical disc implementing such recording and recovery methods. The invention is particularly relevant for optical disc recording device.

BACKGROUND OF THE INVENTION

When recording audio video information on magnetic tape such as videocassettes, power failure is not a problem, as said information has been recorded correctly and could be played back up to the moment of failure immediately.

However, when recording onto optical discs, a complex data management system is generated and recorded on disc, comprising management information, such as title menus, said management information enabling playback and trick play. During recording, the video information is encoded in a format such as MPEG 2 and stored onto the optical disc according to a predefined recording format. Once the recording is stopped, for example when the user decides to stop recording, then the recording devices generates/updates and records said management information on discs Consequently a file system is updated and/or created according to a desired format. Without the management information associated to the recorded video information being present on the disc, the video information cannot be accessed and/or played back, even though the video information as such has been recorded onto the optical disc. Playback is not possible before said management information has been recorded on disc, said management information being usually gathered in a memory and recorded onto the optical disc after the recording is finished. Therefore, in case of an abrupt interruption of the recording process, such as a power failure, the management information will be not available, so that the recorded information cannot be played back anymore. US patent application no 2006/0013085 discloses a method of recording blocks of information onto an optical disc carrier that comprises recovery information being either a recovery header in a private data stream such as a MPEG-2 private stream or a Logical Volume Integrity Descriptor, said recovery information including a recording start address. Therefore, after a power failure has taken place, a suitably adapted recoding device identifies the recording start address and starts reading out and parsing the recorded blocks of information to identify the end of the improperly ended recording. Once such an end is identified, the recording device proceeds to parsing the recorded data for generating and updating the navigation data and the file system in order to include the new recording. The recovery method of US patent application no 2006/001308 carries the disadvantage that parsing the recorded blocks of information to identify the end of the improperly ended recording and parsing the recorded data for generating and updating the navigation data and the file system in order to include the new recording is a time consuming process. Consequently, the user experiences the recovery process negatively, as (s)he is unable to use the recording device during the period of recovery.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a solution to the above problem of reducing the time necessary for recovery after a power failure. The object of the invention is reached by a method of recording video information onto an optical disc of the rewritable type according to claim 1. When the recovery information that is recorded onto the optical disc comprises recording information enabling generating said management information, parsing the recorded information for recovering the recorded video information is not necessary anymore. It is noted that, in method of recording video information onto an optical disc of the rewritable type according to claim 1, the possibility to perform a recovery is tied to the optical disc on which the video information has been recorded and not to the nonvolatile memory of the recording device. When the recovery information is tied to the nonvolatile memory of the recording device, the recovery process needs to be initiated before the optical disc is ejected; otherwise the recorded video information is lost. When the recovery information is present on the disc, the recovery process can be initiated at any moment.

In an advantageous embodiment, wherein the video information is normally recorded as a sequence of cells, the method is characterized by the recovery information further comprising information with respect to the recorded cells comprising at least cell start address information. The cell address information provides important information for generating the management information, that, if not available as recovery information, can only be obtained by reading and parsing the complete recorded video information.

Preferably, the predetermined area wherein the recovery information is recorded corresponds to a specified disc area for recording temporary information or for recording optional information for improving functionality, such as the Video Recorder Manager User Data. When recording an optical disc, a known problem when recording any information not directly mandated by a recording format is that the resulting optical disc may become unsuitable for playback and/or recording for other devices that do not recognize such additional information. Recoding the recovery information within a specified disc area for recording temporary information or for recording optional information for improving functionality, such as the Video Recorder Manager User Data has the advantage that other recording devices expect that said recovery information may be present and the recovery information may not be accessible to them. Therefore legacy devices, that is devices not enabled to perform recovery of video information according to the invention, would be able to use the disc by ignoring the recovery information, so that the recorded optical disc remains compatible with the used recording format.

Preferably the management information corresponds to a Video Title Set Information (VTSI) as disclosed in WO 01/01415. Such format of the management information enables playback compatibility on standalone DVD players. The invention also related to a method of recovering video information recorded onto an optical disc of the rewritable type according to claim 5.

The invention also relates to a recording device for recording video information onto an optical disc of the rewritable type, enabled to either record and /or recover video information according to a suitable method according to the invention. The invention also relates to a computer software program that when executed on suitable processor enables a recording device to either record and/or recover video information according to according to a suitable method according to the invention.

These and other aspects of the invention are apparent from and will be explained with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will be further explained upon reference to the following drawings, in which:

Fig. 1 illustrates schematically an optical disc of the rewritable type; Fig. 2 shows schematically an optical drive wherein the invention is practiced;

Fig. 3 illustrates schematically the data information structure on an optical disc of the rewritable type suitable for recording video information;

Fig. 4 illustrates schematically the structure of a DVD-video zone on an optical disc of the rewritable type;

Fig. 5a illustrates by means of a flow diagram a method of recording video information onto an optical disc according to an embodiment the invention, while Fig. 5b illustrates a method of recovering recorded video information from an optical disc according to an embodiment of the invention; Fig. 6 illustrates schematically a DVD-video zone and the Video Title Set

(VTS) structure at the moment a power failure takes place during recording while recording the video information according to an embodiment of the invention.

Fig. 7 illustrates schematically a DVD-video zone the Video Title Set (VTS) structure after the recorded information has been recovered by means of a recovery method according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 illustrates schematically an optical disc 11 having a track 12 and a central hole 10. The track 12, being the position of the series of (to be) recorded marks representing information, is arranged in accordance with a single spiral pattern constituting substantially parallel tracks on an information layer. The optical disc may comprise one or more information layers of a recordable type. Known examples of rewritable optical discs are CD-RW, or DVD+/-RW, DVD-RAM or BD-RE. For example, further details about the physical structure and addressing information for DVD+RW or DVD-RW optical discs can be found in references ECMA-337 and ECMA-338, respectively. The information is represented on the information layer by recording optically detectable marks along the track, for instance crystalline or amorphous marks in phase change material. The track 12 on the optical disc is indicated by a pre-embossed track structure provided during manufacture of the blank optical disc. The track structure is constituted, for example, by a pregroove, which enables a read/write head to follow the track during scanning.

The track structure of recordable disc comprises variation of a physical parameter, known in the art as a wobble, usually in the form of periodical radial displacements of the groove from an average centerline. The periodic wobble is further modulated so that further information is stored, such as physical addresses indicating the location of units of information. Said information may further include specific synchronizing marks for locating the start of such information blocks. The position information is encoded in groups comprising a predetermined number of modulated wobbles.

Fig. 2 illustrates schematically a recording device for writing information on the optical disc 11 as illustrated with reference to Fig. 1.

The recording device is provided with recording means for scanning the track on the optical disc, the recording means comprising a drive unit 16 for rotating the optical disc 11, a head 18, a positioning unit 21 for coarsely positioning the head 18 in the radial direction on the track, and a control unit 17. The head 18 comprises an optical system of a known type for generating a radiation beam 20 guided through optical elements for focusing said radiation beam 20 to a radiation spot 19 on the track 12 of the optical disc 11. The radiation beam 20 is generated by a radiation source, e.g. a laser diode. The head further comprises (not shown) a focusing actuator for moving the focus of the radiation beam 20 along the optical axis of said beam and a tracking actuator for fine positioning of the radiation spot 19 in a radial direction on the center of the track. The tracking actuator may comprise coils for radially moving an optical element or may alternatively be arranged for changing the angle of a reflecting element.

For reading information, the radiation reflected by the information layer is detected by a detector of a usual type, e.g. a four-quadrant diode, in the head 18 for generating a read signal and further detector signals, such as a tracking error and a focusing error signal for controlling said tracking and focusing actuators.

For recording information the radiation beam 20 is controlled to create optically detectable marks in the recording layer. For this purpose, the recording device comprises write processing means for processing input information to generate a write signal to drive the head 18, which write processing means comprise an input unit 23; and data processing means comprising a formatter 24 and a modulator 25.

The control unit 17 controls the recording and retrieving of information onto and from the optical disc 11 , and may be arranged for receiving commands from a user or from a host computer. To this end, the control unit 17 may comprise control circuitry, for example a microprocessor, a program memory and control gates, for performing the procedures described hereinafter with reference to Fig. 3. The control unit 17 may also be implemented as a state machine in logic circuits. The control unit 17 is connected via control lines 22, e.g. a system bus, to said input unit 23, formatter 24 and modulator 25, to the drive unit 16, and to the positioning unit 21. The input unit 23 receives and pre-processes the user information. For example, when processing audio-video information, the input unit 23, may comprise compression means for compressing input signals such as analog audio and/or video, or digital uncompressed audio/video. Suitable compression means are described for audio in WO 98/16014-A1 (PHN 16452), and for video in the MPEG2 standard (ISO-IEC 13818). The input signal may alternatively be already encoded. The output of the input unit 23 is passed to the formatter 24 for adding control data and formatting the data according to a recording format, e.g. by adding error correction codes (ECC) and/or interleaving. For computer applications units of information may be interfaced to the formatter 24 directly. The formatted data from the output of the formatter 24 is passed to the modulation unit 25, which comprises for example a channel coder, for generating a modulated signal, which drives the head 22. Further the modulation unit 25 comprises synchronizing means for including synchronizing patterns in the modulated signal. The formatted units presented to the input of the modulation unit 25 comprise address information and are written to corresponding addressable locations on the optical disc under the control of control unit 17. The control unit 17 is arranged for recording and retrieving position data indicative of the position of the recorded information volumes.

During the recording operation, marks representing the information are formed on the optical disc. The marks may be in any optically readable form, e.g. in the form of areas with a reflection coefficient different from their surroundings, obtained when recording in materials such as dye, alloy or phase change material, or in the form of areas with a direction of magnetization different from their surroundings, obtained when recording in magneto- optical material. Writing and reading of information for recording on optical disks and usable formatting, error correcting and channel coding rules are well-known in the art, e.g. from the CD system (IEC 908).

For reading, the read signal is processed by a read processing unit comprising a demodulator 26, a de-formatter 27 and output unit 28 for outputting the information. The functioning of the demodulator 26, the de-formatter 27 and the output unit 28 are controlled by the controller 17. Hence, retrieving means for reading information include the drive unit 16, the head 18, the positioning unit 21 and the read processing unit.

The optical disc 11 is intended for carrying user information according to a standardized format, to be playable on standardized playback devices. The recording format includes the way information is recorded, encoded and logically mapped onto the recording space provided by the track 12 and it will be described, by way of example, with reference to Fig 3. The recordable space is usually subdivided into a lead-in area (LI) 31, a data zone (DZ) for recording the information and a lead-out area (LO) 32. The lead-in area (LI) 31 usually comprises basic disc management information and information how to physically access the data zone (DZ). For example, said basic disc management information corresponds to the table of contents in CD systems or the formatting disc control blocks (FDCB) in DVD systems.

The user information recorded in the data zone (DZ) is further arranged according to an application format, for example comprising a predefined structure of files and directories. Further, at logical level, the user data in the data zone is arranged according to a file system comprising file management information, such as ISO 9660 used in CD systems, available as ECMA-119, or UDF used in DVD systems, available as ECMA- 167.

Usually, in case video information is recorded onto the optical disc, this is usually recorded in a separate volume from other data. For example, Fig. 3 further illustrates such an arrangement as used in the case of recording video information and user data onto a DVD+RW disc. The data zone (DZ) is organized as single volume space and may be further divided into a video section and data section. The Video section comprises a video file system 33, a Video Recorder Manager (VRM) scratch area 34, a Video Recorder Manager Information (VRMI) 35 a Video Recorder Manager User Data (VRM UD) 36, a DVD Video Zone (DVD-VZ) 37 and a backup copy of the Video Recorder Manager Information (VRMI-BK) 38. The optional data section succeeds the video section and it comprises a File system area 39 and the data files 40. The hashed areas in Fig. 3 indicate that the previously described elements of the data zone (DZ) need not be recorded contiguously. The VRM scratch area 34 is an area used by recorders to temporally store data. The Video Recorder Manager Information (VRMI) 35 comprises information with respect for identifying the type of recorder that has generated the DVD-Video menus on the disc. The Video Recorder Manager Information (VRMI) 35 further comprises information whether a data section is present on the disc. The Video Recorder Manager User Data (VRM UD) 36 are optional data structures that may be stored in one or more files, which may be recorded to add functionality and to improve performance on some recorders. The video file system 33 comprises a video volume usually comprising at least a VIDEO RM directory and a VIDEO TS directory in the root directory, The VIDEO RM directory usually comprises the following files:

- VIDEO RM. D AT (comprising the VRM scratch information),

- VIDEO RM.IFO (comprising VRMI information) and - VIDEO RM. BUP (comprising VRMI backup information).

The VIDEO RM directory may comprise other VRM user data files. The VIDEO TS directory usually comprises the following files:

- VIDEO TS. IFO (comprising the Video Manager General information (VMGI)), - VIDEO TS. BUP (comprising a backup of VMGI), and

- a sequence of files for each video title set (VTS), the sequence comprising VTS 01 0.IFO (Video Title Set Information (VTSI) for title #1), VTS OI l. VOB (VTSTT VOBS for VTS #1) and VTS 01 0.BUP (comprising a backup of VTSI for title #1)

Fig. 4 illustrates schematically a possible structure of a DVD-Video Zone (DVD-VZ) 37 on an optical disc of the rewritable type. In the order of recording, it usually comprises a Video Manager (VMG), Video Title Set Information (VTSI) for each video title set (VTS), one or several video title sets (VTS) comprising the video information (TITLEl, TITLE2) and backups (VTSI #1_BK, VTSI #2_BK) of the Video Title Set Information (VTSI) for each video title set (VTS). The Video Manager (VMG) comprises Video Manager Information (VMGI), optionally a video object set VMGM VOBS and a backup copy of VMGI. The Video Title Set Information (VTSI) comprises management information for enabling playback and trick play of the video titles. A suitable example of the structure of the Video Title Set Information (VTSI), corresponding to the DVD+RW Video recording format, has been disclosed in WO 01/01415, to be inserted here by reference. It is noted that in general the Video Objects for all Titles on the disc are put into a single VTS Title Video Object Set (VTTS VOBS) irrespective of the VTS they belong to. It is further noted that usually video object corresponding to different video coding modes have separate VTSI files associated. VTSI files for all VTSes are put in front of this VTTS VOBS with increasing VTS number. In a known real time recording method, the video information is encoded in a format such as MPEG 2 and stored onto the optical disc as a sequence of cells forming a recording within a video title set (VTS). While recording, information for building the Video Title Set Information (VTSI) and updating other management structures such as VMG are stored, usually in volatile memory of the recorder. Once the recording is stopped, for example due to the user decided to stop the recording, then the stored information in the volatile memory of the recording device is used for generating Video Title Set Information (VTSI) and the other management structures are updated so that the newly recorded video information can be accessed and played back. Fig. 5a illustrates by means of a flow diagram a method of recording video information onto an optical disc according to an embodiment the invention,

In step 50 (CMD) a command is received by the recording device to begin recording video information. In step 51 (REC NFO), a power failure mechanism is initiated. In an embodiment of the method, this correspond to storing on the optical disc of recovery information that allows recovery of video information in case of an abrupt interruption of the recording process, such as due to a power failure. Further embodiments with respect to the details of what such recovery information is and where it is recorded on disc will be given later. In step 52 (REC) the recording of the video information takes place. This corresponds to creating a new "title" for the recording. During the recording process, the control information is updated continuously to reflect the recorded video information.

Assuming that the recording has not been interrupted and a stop recording command is received (e.g. the user decided to stop the recording), in step 53 (TTL GEN), the recording device updates and/or create the file system as mandated by the corresponding recording format, so that the content can be accessed and played back. It is noted that without the file system update, the recording cannot be accessed even though the video information as such is present onto the disc. After the successful creating of a recording title and the corresponding management structures, the recovery information intended for recovery in case of an abrupt interruption is deleted from the optical disc in step 54 (DEL REC NFO). In an embodiment of the invention, in the case the known DVD+RW Video recording format, which is substantially disclosed in WO 01/01415, is used for recording on the optical disc, a file entitled VIDEO PS. DAT" (PS standing for Power Safe) is created. Such a file is preferably located in the VIDEO RM directory. The information is preferably recorded in the Video Recorder Manager User Data (VRM UD) 36. When recording an optical disc, a known problem when recording additional information not directly mandated by a recording format is that the resulting optical disc may become unsuitable for playback and/or recording for other devices that do not recognize such additional information. Recoding the recovery information within the Video Recorder Manager User Data (VRM UD) 36 has the advantage that other devices expect that additional information to be present in said area, said additional information possible being not accessible/usable. Therefore legacy devices, that is devices not enabled to perform recovery of video information according to the invention, would skip reading the recovery information, that is the recorded optical disc remain compatible with the recording format. With respect to the recovery information, it comprises information regarding the sequence of cells recorded so far and also the start recording address from where recording has been initiated. With such information available on the optical disc, recovery of the recorded information by parsing the recorded stream is possible. Advantageously the recovery information further comprises recording information enabling generating the management information, for example of the Video Title Set Information (VTSI) structures for the new title that is being recorded. Parsing a recorded stream is a time consuming activity and would be experienced negatively by the end user. Consequently, if the required information is already present with the recovery information, such parsing is not necessary anymore. In an embodiment of the invention, in order to update the file system, the device stores "volume data", that is cell, chapter, virtual chapter information, such as start and/or end addresses, as recovery information.

In more details, an example of suitable recovery information is the logical structure shows in table 1 for the file VIDEO P S. D AT.

Table 1 - logical structure of VIDEO PS. DAT VIDEO_PS.DAT

Item Bytes

An example of a logical structure of an array of chapter markers (CHAPMARK_DB[256]) is disclosed in Table 2.

Table 2 - logical structure of CHAPMARK DB

The term VR CHAPTER refers to "virtual chapter" in the context of

DVD+RW Video format standard. Virtual Chapters are similar to Chapter except that virtual chapters do not start on a cell boundary. As a consequence of this, virtual chapters cannot be played on standard DVD players. An example of a logical structure of the array of virtual chapter markers (CHAPMARK_DB[256]) is disclosed in Table 3.

Table 3 - log ical structure of VR CHAPMARK DB

VR CHAPMARK DB

Item Bytes

CHAPMARK TYPE OO Chapter Marker not used

Ol Chapter Marker played back

10 Chapter Marker not played back

An example of a logical structure of an array for storing cell attributes (CELL DB) is disclosed in Table 4.

Table 4 - logical structure of CELL DB

In an embodiment of the invention, the "VIDE0_PS.DAT" may comprise, apart from cell information, start address of the recording, the information regarding recording mode, aspect ratio. Such information also enables playback of the recorded stream.

It is noted that the VIDEO_PS.DAT as illustrated in the embodiment above comprises information with respect to both chapters and virtual chapter, therefore the information stored therein is sufficient for generated and/or updating not only the VTSI information, but also of VRMI information.

Fig. 5b illustrates a method of recovering recorded video information from an optical disc according to an embodiment of the invention. In step 55 (DSK CHK) it is checked whether an optical disc comprising recorded video information or suitable for recording video information has been inserted into the recording device. In step 56, the presence of the recovery information, indicating that an interrupted recording is present on the optical disc, is checked. For example, the recovery is initiated based on the presence of the "VIDEO P S. D AT" file in the VIDEO RM directory. In an embodiment of the method, the presence of the "VIDEO_PS.DAT" is checked as part of the disc-recognition of the optical drive. The existence ofVIDEO_PS.DAT" is indication that a "previous" recording has been "abruptly interrupted", for example due to power failure, therefore recovery needs to be initiated for the optical disc. The disc-recognition is initiated for following scenarios:

- user opens the tray and closes the tray with or without of disc inside the tray;

- after power failure occurs the system autonomously triggers the disc-recognition.

In step 57 it is decided whether recovery information has been detected or not. If no recovery information was detected, the optical disc is used according to user instructions in step 58. If recovery information was detected, in step 59 (TTL GEN) the file system is re-created / updated based on the contents inside the "VIDEO_PS.DAT" file and after that the "VIDEO_PS.DAT" will be deleted.

In an embodiment of the invention, the recovery process when recovery information is detected is made conditional on user confirmation to initiate the process. In an alternative embodiment, the recording device may be provided with an "Auto recovery" feature. Such a recording device, when being re-powered after a power failure, automatically recovers the recording without user confirmation and upon successful recovery the recording device enters Standby Mode. With respect to implementation of previously described recording and recovery methods in the recording device as described with reference to Fig. 2, in an embodiment recovery means 29 for generating the recovery information are provided. The control unit 17 is further enabled to receive the recovery information and control the recording means to record said recovery information and, upon successful completion of the recording process, to delete said recovery information. Further recovery control means 29a for using the recovery information present on the optical disc for generating the corresponding management information are provided. The control unit 17 is further enabled to receive the generated management information and control the recording means to recording said management information. In an alternative embodiment, the recovery means 29 and the recovery control means 29a may be integrated into the control unit 17, for example by means of suitable firmware. It is further noted that existing recording devices may be enabled to implementing the recording and recovery methods according to the invention by means of a suitable computer product, such as a firmware update. With respect to implementation in a recording device of the previously described methods, preferably the contents of the VIDEO_PS.DAT file is updated at regular intervals, for example every 5 seconds. The updated information is written based on the trigger from the device that video information that has been buffered has been actually written on the optical disc. By this approach when power failure occurs the device only recovers video information that is actually present on the optical disc. This acts as a synchronization mechanism, such that the recovery process does not create management information for a recording that is neither "short" nor "more" than the actual video information present on the optical disc. If the recovery information was being updated periodically, for example every 5 seconds the recording device is able to create valid title for the interrupted recording up to 5 seconds accuracy to the instance power failure occurred. For example, if the recording has been started at 1 :00:00 pm [h:mm:ss] and power failure occurred at 1 :30:00 pm , then a recording device according to the invention can recover the recording till 1 :29:25 pm. The consequences of a power safe recording method according to the invention can be described with reference to Figs. 6 and 7. Fig. 6 illustrates schematically a DVD-video zone and the Video Title Set (VTS) structure at the moment a power failure takes place during recording while recording the video information according to an embodiment of the invention. Two video titles 62 and the corresponding Video Title Set Information (VTSI) 61 were present on the optical disc prior to initiating the recording process. The recorded video information (REC INF) 63 is present is recorded on optical disc succeeding TITLE 2. Not illustrated in fig 6, the recovery information (VIDEO_PS.DAT) is recorded on the optical disc in the Video Recorder Manager user data. Arrow 64 indicates the end of the recorded video information when the recording was interrupted, e.g. due to a power failure. Fig. 7 illustrates schematically a DVD-video zone the Video Title Set (VTS) structure after the recorded video information (REC INF) has been recovered by means of a recovery method according to an embodiment of the invention. A new title (TITLE 3) 72 has been created and the corresponding management and navigation information 71 has been recorded on the disc. Alternatively, the new title is integrated in an existing Video Title Set (VTS) and the corresponding VTSI information is updated. Preferably, not illustrated in Fig 7, the VRMI information may also be updated based on the recovery information, for example the information relating to virtual chapters. The position of the arrow 64 indicated that the part of the video information recorded after the last update of the recovery information (in the above mentioned example, up to the last 5 seconds) is not part the new title 72.

It should be noted that the above-mentioned embodiments are meant to illustrate rather than limit the invention. And that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verbs "comprise" and "include" and their conjugations do not exclude the presence of elements or steps other than those stated in a claim. The article "a" or an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements and by means of a suitable programmed computer. A computer program may be stored/distributed on a suitable medium, such as optical storage or supplied together with hardware parts, but may also be distributed in other forms, such as being distributed via the Internet or wired or wireless telecommunication systems. In a system/device/apparatus claim enumerating several means, several of these means may be embodied by one and the same item of hardware or software. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

CLAIMS:

1. A method of recording video information onto an optical disc of the rewritable type, a recordable area of the optical disc comprising a video zone for recording said video information and corresponding management information, the video information and the corresponding management information being arranged according to a recording format, the method comprising steps of: recording the video information in the video zone; recording recovery information onto the optical disc; generating and recording the corresponding management information; deleting the recovery information if the preceding recording steps were executed successfully, wherein said recovery information comprises recording information enabling generating said management information.

2. A method according to claim 1, the video information being recorded as a sequence of addressable units, such as cells, the method characterized by the recovery information further comprising information with respect to the recorded addressable units comprising at least unit start address information.

3. A method according to claims 1 or 2, characterized by the recovery information being recorded into a predetermined area corresponding to a disc area for recording temporary information or for recording optional information for improving functionality, such as the Video Recorder Manager User Data.

4. A method according to any of the preceding claims, characterized by the management information comprising Video Title Set Information (VTSI).

5. A method of recovering video information recorded onto an optical disc of the rewritable type, a recordable area of the optical disc comprising a video zone for recording said video information and corresponding management information, the video information and the corresponding management information being arranged according to a recording format, the method comprising steps of: reading recovery information recorded on the optical disc according to any of the methods of claims 1-4; - generating management information based on said recovery information; recording said management information so that the video information and the corresponding management information are arranged according to a recording format; deleting said recovery information.

6. A method according to claim 5, characterized by the management information comprising Video Title Set Information.

7. A method according to claim 5, characterized by the recovery information being recorded into a predetermined area corresponding to a disc area for recording temporary information or for recording optional information for improving functionality, such as the Video Recorder Manager User Data.

8. A recording device comprising: recording means for recording information onto an optical disc 11 of the rewritable type, a recordable area of the optical disc comprising a video zone for recording video information and corresponding management information, the video information and the corresponding management information being arranged according to a recording format; recovery means 29 for generating the recovery information, the recovery information comprises recording information enabling generating said management information; control unit 17 for enabling the recording means to record said recovery information on the optical disc, the control unit further enabled to decide if a recording was successful and for further enabling the recording means to delete the recovery information if a recording was successful.

9. A recording device according to claim 8, characterized in that the recording means being enabled to record the recovery information in a predetermined area corresponding to a disc area for recording temporary information or for recording optional information for improving functionality, such as the Video Recorder Manager User Data.

10. A recording device comprising: recording means for recording information onto an optical disc 11 of the rewritable type, the optical disc further comprising at least recorded video information and recovery information, said recovery information comprises recording information enabling generating management information corresponding to the recorded video information; reading means for reading said recovery information; recovery control means 29a for generating said corresponding management information based on said recovery information; control unit 17 for enabling the recording means to record said management information according to a recording format and to delete said recovery information.

11. A recording device according to claim 8, characterized in that the reading means are enabled to reading the recovery information from a predetermined area corresponding to a disc area for recording temporary information or for recording optional information for improving functionality, such as the Video Recorder Manager User Data.

12. A computer software program that when executed on suitable processor enables a recording device to either record video information according to any of claims 1-4 and/or recover video information recorded onto an optical disc according to any of claims 5-

7.