AU722467B2 - Digital video recorder - Google Patents

Description

S F Ref: 321660D1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

a a a...I .t a a a a *u Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Sony Corporation 7-35, Kitashinagawa 6-chome Shinagawa-ku Tokyo

JAPAN

Masaki Oguro Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Digital Video Recorder The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845 Digital Video Recorder 1 BACKGROUND OF THE INVENTION S2 This invention relates to digital video signal 3 recording in a standard play (SP) mode or in a long play (LP) 4 mode, with the digital video signals being recorded with a higher compression ratio in the LP mode than in the SP mode so that a 6 lesser number of tracks may be used to record a frame in the LP 7 mode than in the SP mode. More particularly, this invention is concerned with the recording of subcode data in respective tracks 9 for both the SP and LP modes.

Digital video tape recorders capable of recording 11 digital video signals on a magnetic tape in a cassette, known as D-VCR's, utilize data compression techniques for reducing the -1:e3 amount of data that must be recorded to permit accurate k4 reproduction and display of a video picture. Typically, data compression relies upon discrete cosine transformation (DCT) and variable length encoding. A video frame, after being digitized 7 and compressed, is recorded in a number of tracks, with each 18 track exhibiting the general format shown in Fig. 1. This format 19 includes an ITI area located at the leading portion of each track, followed by an audio area, a video area and a subcode area 21 in this order. The ITI area is used as a timing block to assure 22 the proper positioning of the tape and locating of individual 23 tracks during, for example, an after-recording operation which is 24 used to edit the tape. The audio and video areas contain digital audio and digital video data which, typically, are compressed.

c\340 0

.APP

PATENT

450100-3400 1 Subcode data is recorded in the subcode area and contains 2 information which is useful for quickly locating particular video 3 pictures, frames and tracks during a high speed search. For 4 example, time codes, track numbers, and the like are included in the subcode data that is recorded in the subcode area.

6 Typically, one frame of a video picture that is represented as a 7 video signal in the NTSC standard (also referred to herein as the 8 525/60 standard) is recorded in ten successive tracks and a video 9 picture represented by the PAL standard (also referred to as the 10 625/50 standard) is recorded in twelve successive tracks.

11 Fig. 2A is a schematic representation of the subcode :'12 data recorded in the subcode area in each track (whether recorded 13 in the NTSC or PAL standard); and it is seen that the subcode 14 data is comprised of twelve sync blocks SBO-SB11. A single sync block is schematically illustrated in Fig. 2B and is seen to 1 6 include twelve bytes. The structure of a sync block is the same 7 for each of sync blocks SBO-SB11; but the data content of the 18 respective sync blocks varies, as will be described.

19 The twelve bytes of a sync block include two bytes which form a synchronizing pattern SYNC followed by two bytes of 21 identifying data IDO and ID1. A parity byte IDP follows the ID 22 byte ID1 and is used to correct errors that may be present in the 23 identifying bytes. Five bytes of data are recorded after the 24 parity byte IDP, these five bytes being recorded in a data structure known as a pack which is described further below. Two C\3400.APP -2-

PATENT

450100-3400 1 parity bytes follow the data pack, thereby constituting the 2 twelve byte sync block. Those familiar with digital video 3 recorders will appreciate that the sync block included in the 4 subcode data is shorter it includes a smaller number of bytes) than the sync blocks which are included in the audio and 6 video areas.

7 The identifying bytes IDO and ID1 that are included in :8 the subcode data recorded in a given track are not the same for 9 all of the sync blocks included in that subcode data. For 0 example, Fig. 2C schematically illustrates the identifying bytes 11 IDO and ID1 for sync blocks SBO and SB6; and Fig. 2D illustrates 12 the identifying bytes IDO and ID1 for the sync blocks SB1-SB5 and :13 SB7-SB11. In the example illustrated, the identifying bytes of 14 sync blocks SBO and SB6 differ from the identifying bytes of the ee remaining sync blocks. Byte IDO in all of the sync blocks 16 includes a flag F/R which is used in a high speed search to 1-7 detect the first track in a frame of digital video signals. This 18 F/R flag also is helpful in detecting an address not only for 19 that track but for other tracks; and for convenience, this flag is referred to herein as an address-detecting flag. However, 21 this term is not intended to be used as a limitation or as a 22 strict definition for this F/R flag but, rather, is used simply 23 to identify this flag.

24 As seen in Fig. 2C, the IDO byte in sync block SBO (and also in sync block SB6) includes a 3-bit application identifier C\3400.APP -3-

PATENT

450100-3400 1 AP3 followed by a digital representation of an absolute track 2 number. The absolute track number is represented by eight bits, 3 four of which are included in the IDO byte and the remaining four 4 are included in the ID1 byte. The last four bits of the ID1 byte for sync block SBO (and also for sync block SB6) represent a sync 6 number.

7 The data of the IDO byte in sync blocks SB1-SB5 and 8 SB7-SB11 differ from the data of the IDO byte for sync blocks SBO and SB6 in that, as shown in Fig. 2D, the application identifying bits AP3 found in sync blocks SBO and SB6 are replaced by three 11 bits which represent an index identifier, a skip identifier and a 2 photopicture identifier. The index identifier is used during an *1*3 index search; the skip identifier is used to indicate when a particular frame is to be skipped during a search and playback mode, and the photopicture identifier is used to identify a frame 16 which represents a still picture. The remaining bits of the IDO ly byte and of the ID1 byte in sync blocks SB1-SB5 and SB7-SB11 18 represent the same data as the corresponding bits in the IDO and 19 ID1 bytes in sync blocks SBO and SB6.

Some of the sync blocks included in the subcode data 21 are designated as "main area" sync blocks and the remaining sync 22 blocks in the subcode data are designated as "optional area" sync 23 blocks. For example, sync blocks SB3, SB4, SB5, SB9, SB10 and 24 SB11 are main area sync blocks; whereas sync blocks SBO, SB1, SB2, SB6, SB7 and SB8 are optional area sync blocks. This C\3400.APP -4-

PATENT

450100-3400 1 different designation is used in conjunction with the five bytes 2 of data that are present in each sync block, as shown in Fig. 2B, 3 and as referred to hereinabove as the data pack.

4 When data is recorded in accordance with the NTSC (or 525/60) standard, a video frame is recorded in ten tracks, with 6 the type of subcode data recorded in the data packs of the first 7 five tracks (or first half of the frame) being different from the 8 type of subcode data that is recorded in the data packs of the 9 second five tracks (or second half) of the video frame. Fig. 3 is a table which represents the type of subcode data that is ll recorded in the main area of the subcode data in the first half .12 of the video frame and in the second half of the video frame. It is seen that in the first half of the video frame, the data pack 14 recorded in sync blocks SB3, SB5, SB9 and SB11 of each subcode area represents TTC (or title time code) data, and this pack 16 simply is referred to as the TTC pack. In sync blocks SB4 and 17 SB10 of the first half of the video frame, the data pack may be a 18 TTC pack or, if the digital video signal is recorded for business 19 use (as opposed to personal use), the data pack may be a title binary group (TBG) pack. Typically, for personal use, that is, 21 for the usual consumer use, TBG packs are not recorded. As yet 22 another alternative, the data packs recorded in sync blocks SB4 23 and SB10 in the first half of a video frame may represent no 24 useful information, and such data packs are referred to as "no info" (NOI) packs.

C\3400.APP

PATENT

450100-3400 1 In those tracks which constitute the second half of the 2 video frame, TTC packs are recorded in sync blocks SB3 and SB9.

3 The data packs included in sync blocks SB4 and SB10 may represent 4 the date (year-month-day) on which the video signal is recorded, known as the VRD pack or they may represent the data on which the 6 audio data is recorded, known as the ARD pack. The user may 7 select whether the VRD or the ARD pack is recorded. If neither 8 pack is included in these sync blocks, the data pack therein is 9 referred to as the NOI pack.

10 In sync blocks SB5 and SB11 of the subcode data 11 recorded in those tracks which constitute the second half of the video frame, a data pack is recorded representing the time (hour- 13 minute-second) at which the video signal is recorded, and this is known as the VRT pack. Alternatively, the data pack may represent the time at which the audio signal is recorded, and .*16 this data pack then is known as the ART pack. If time data is not included in sync blocks SB5 and SB11, the data pack therein 18 is represented as the NOI pack.

19 The subcode data recorded in the optional areas, namely sync blocks SBO, SB1, SB2, SB6, SB7 and SB8, may be user- 21 designated; and in proposals that have been made heretofore for 22 D-VCR's, it has been recommended that if there is no user 23 designation for the recording of subcode data in the optional 24 areas, such optional areas should record the same subcode data as are recorded in the main areas of that track.

C\3400.APP -6-

PATENT

450100-3400 1 The foregoing description of Fig. 3 has assumed the 2 recording of NTSC (525/60) data in ten tracks. The same subcode 3 data configuration may be used for the recording of PAL (625/50) 4 video data in twelve tracks. Of course, in the PAL (625/50) standard, each half of a video frame consists of six tracks.

6 Thus, in both the NTSC (525/60) and PAL (625/50) standards, the 7 subcode data which is recorded in the first half of the video frame is of a different type than the subcode data which is 9 recorded in the second half of the video frame, as is evident 1 0 from the subcode data recorded in sync blocks SB4, SB5, SB10 and 11 SB11 in each half.

2 A data pack which constitutes the TTC, TBG, VRD, ARD, 13 VRT, ART or NOI pack exhibits the data structure shown in Fig. 4.

1 4 Byte PCO is referred to as the header, which identifies the data pack (for example, the header identifies the data pack as the 16 TTC, TBG, VRD, ART, VRT, ART or NOI pack) and bytes PC1-PC4 constitute the appropriate data, such as date, time, etc. It is 18 appreciated that each sync block, such as shown in Fig. 2B, 19 contains only one data pack.

The subcode data shown in Figs. 2A-2D and 3 are 21 recorded with the compressed digital video signal in the standard 22 play (SP) mode. It has been proposed that digital video signals 23 may be data-compressed with a higher degree of compression for 24 recording in a long play (LP) mode, such that the ten tracks of data that are used to represent one NTSC frame may be reduced to C\3400.APP -7-

PATENT

450100-3400 1 five tracks of data (similarly, the twelve tracks of data that 2 are used to represent a PAL frame may be reduced to six tracks of 3 data). By reducing by one-half the number of tracks needed to 4 record a frame of digital video data, twice the amount of data may be recorded; and as a result, the recording time for a given 6 length of tape may be doubled. That is, twice the amount of data 7 or twice the duration of a video program may be recorded in the 8 LP mode than may be recorded in the SP mode.

When data is recorded in the SP mode, ten tracks in the **I,t0 NTSC system and twelve tracks in the PAL system constitute one 11 unit. The recording of subcode data is based upon this unit; and as is shown in Fig. 3, the type of subcode data that is recorded 13 in the first half of this unit differs from the type of subcode .14 data that is recorded in the second half of this unit.

Nevertheless, high speed searching as well as the compilation of 16 title, time, date, duration, etc., all of which are useful for searching or for display to a user, are based upon the 18 (or 12-track) unit. Conveniently, this 10-track (or 12-track) 19 unit constitutes a single frame unit and searching, as well as compilation, thus may be based upon a single frame unit.

21 However, when video data is recorded in the LP mode, the 22 (or 12-track) unit now represents two frames; and searching as 23 well as compilation now is dependent upon a 2-frame unit. If the 24 subcode data recording mechanism and algorithms which are used to record the subcode data during the SP mode (as represented in C\3400.APP -8-

PATENT

450100-3400 1 Fig. 3) also are used to record the subcode data in the LP mode, 2 it is appreciated that the type of subcode data that is recorded 3 with one LP frame (such as an odd frame) differs from the type of 4 subcode data that is recorded with the following (or even) LP frame. This is because, when using the same subcode data 6 mechanism or algorithm, the type of subcode data that is recorded in the first five (or six) tracks differs from the type of 8 subcode data that is recorded in the second five (or six) tracks.

'9 As a result, whereas video data that is recorded in the SP mode can be edited on a frame-by-frame basis, that is, on the basis of 11 a single frame unit, video data that is recorded in the LP mode .2 can be edited only on a 2-frame unit basis. This is particularly 13 troublesome when a common video tape has one video program "4 recorded thereon in the SP mode and another video program recorded in the LP mode.

.16 Another difficulty that arises when the video data may 17 be recorded in the SP or LP mode relates to the state of the F/R 18 flag. In the SP mode, the F/R flag exhibits a during those 19 tracks which constitute the first half of the video frame and a in those tracks which constitute the second half of the video 21 frame. Figs. 5A and 5B illustrate the F/R flag for the NTSC 22 standard. It is seen, therefore, that the F/R flag changes over 23 from to at the first track in each frame and changes over 24 from a to a at the sixth track of the 10-track frame.

Since the change-over of the F/R flag as well as its state can be C\3400.APP

_Q

PATENT

450100-3400 1 used to locate a particular track, the F/R flag is referred to 2 herein as an address-detecting flag and is used during a high 3 speed search to position the tape at the beginning of a frame.

4 If the same subcode recording mechanism or algorithm is used during the LP mode, the F/R flag changes over between "0" 6 and every five tracks which, for the NTSC system, means that 7 the F/R flag changes its state at the beginning of each frame, as 8 shown in Figs. 6A-6B. However, if the beginning of a frame is •oo i 9 detected by sensing the change-over of the F/R flag from to g Si'1 this technique will permit the beginning of only every other 11 frame, such as the beginning of every odd frame, to be sensed because the F/R flag changes over from to at the 13 beginning of every even frame. Thus, by sensing to "1" 14 transitions, the beginning of the even frames will not be detected.

As a result of this discrepancy, it is necessary, 17 during a search operation, to provide some indication of whether 18 the video signal on the digital video tape had been recorded in 19 the SP or LP mode. Depending upon the mode used for recording, different searching techniques are used to locate a desired video 21 picture or to identify the beginning of a video frame.

22 Optimally, the algorithm shown in Fig. 7 is carried out before a 23 searching operation is initiated. As depicted by the flow chart 24 shown in Fig. 7, before a searching operation is initiated, inquiry S101 should be made to determine whether the video data C\3400.AP

PATENT

450100-3400 1 to be searched was recorded in the SP or LP mode. If it is 2 determined that the video data was recorded in the SP mode, 3 inquiry S102 is made to determine when the F/R flags undergoes a 4 positive transition from to When this inquiry is answered in the affirmative, instruction S103 is carried out to 6 indicate that the first track in a frame is in position to be 7 played back. However, if inquiry Sl01 determines that the video 8 data had been recorded in the LP mode, inquiry S104 is made to 9 sense when the F/R flag undergoes either a positive or negative a 0LO transition. When such a transition is sensed, instruction S105 1 is carried out to indicate that the first track in a frame has been reached and is in position to be played back.

13 While the algorithm shown in Fig. 7 appears to be 14 readily implemented, this algorithm is dependent upon inquiry S101 which, in many instances, is far more complicated than would 16 appear. It would seem that if the video data recorded on a video elato 17 cassette is known to have been recorded in the SP or LP mode, it 18 would be a relatively simple matter to implement and respond to 19 inquiry S101. For example, a user may provide a simple indication, such as providing suitable visual indicia on the 21 video cassette, to indicate whether the video data recorded 22 thereon has been recorded in the SP or LP mode. In some 23 instances, however, a single video cassette may include video 24 data that is recorded in one portion thereof in the SP mode and in another portion thereof in the LP mode. The recording of C\3400.APP -11-

PATENT

450100-3400 1 video data in mixed modes does not permit simple visual indicia 2 to identify the mode or modes in which the video data had been 3 recorded. Consequently, it is not a simple matter to determine 4 whether inquiry S102 or inquiry S104 of the algorithm shown in Fig. 7 should be made. As a result, it would be difficult to 6 search the video tape at a high speed, such as 200 times normal S. 7 speed, to position the first track of the proper frame at the 8 appropriate location for playing back that frame. It will be S. 9 appreciated that, depending upon whether inquiry S102 or S104 is implemented, the video tape may be positioned at the beginning of 11 the second half of a SP frame or, alternatively, the video tape may be positioned only at the beginning of odd LP frames, thus 13 making it difficult, if not impossible, to position the tape at 14 the beginning of an even LP frame.

If, for example, it cannot be determined prior to f 16 initiating a high speed search whether the video data had been oo S 17 recorded in the SP or LP mode, a search for a positive to "1" 18 transition in the F/R flag may be satisfactory to position the 19 first track of each frame in the SP mode, but, as shown in Figs.

8A and 8B, this technique will position the first track in only 21 frames F2, F4, F6, etc. for those frames that had been recorded 22 in the LP mode. Alternatively, if a negative transition from "1" 23 to of the F/R flag is sensed, it is seen that the first track 24 in each of frames F3, F5, F7, etc. will be properly positioned for the video data recorded in the LP mode, but track 5 (the C\3400.APP -12- -13first track in the second half of a SP frame) will be positioned to play back the video data recorded in the SP mode. Typically, the sensing of the middle of a frame of video data during a high speed search is undesired and often unnecessary.

OBJECTS OF THE INVENTION Therefore, it is a preferred object of the present invention to provide a digital video recorder which permits frames to be searched and subcode data to be compiled in a single frame unit irrespective of whether the video data was recorded in the SP or LP mode.

Another preferred object of this invention is to provide a digital video recorder lo which permits the high speed searching of a video tape so as to position that tape at the first track of a frame, based upon the F/R flag recorded in each track, irrespective of whether the video data was recorded in the SP or LP mode.

A further preferred object of this invention is to provide a digital video recorder operable to record video data in either the SP or LP mode, and wherein the same subcode 15 recording/detecting mechanism or algorithm may be used irrespective of whether the video data is recorded in the SP or LP mode.

An additional preferred object of this invention is to provide a digital video recorder operable in either the SP or LP mode, which permits the high speed searching of frames in order to position the record medium at the beginning of a video frame as a function of the F/R flag recorded in each track, irrespective of whether the video data had been recorded in the SP or LP mode.

Still another preferred object of this invention is to provide a common subcode recording mechanism or algorithm that can be used in both the SP and LP modes.

Yet a further preferred object of this invention is to provide a common subcode detecting mechanism or algorithm that can be used for searching or compilation of video data irrespective of whether that video data had been recorded in the SP or LP mode.

SUMMARY OF THE INVENTION The invention discloses an apparatus for selectively recording a digital video signal in a first number of tracks on a record medium in a standard play (SP) mode and in a second number of tracks in a long play (LP) mode wherein each frame of the digital video signal is recorded in first and second sets of tracks in said SP mode and in said first set of tracks in said LP mode, and wherein subcode data is recorded in said first [R:\LIBCC]01768.doc:BFD -14and second sets of tracks for locating frames during a high speed search, said apparatus comprising: first and second video data compressing means for compressing said digital video signal for recording in said SP and LP modes, respectively, said second video data compressing means exhibiting a compression ratio greater than the compression ratio of said first video data compressing means; selecting means for selecting said first or said second video data compressing means to supply the compressed digital video signal for recording; and subcode data generating means for generating subcode data of a first type for recording in said first set of tracks and of a second type for recording in said second set of tracks, whereby subcode data of said first and second types are recorded with a frame of compressed digital video signals in said SP mode and subcode data of only ooooo said first type are recorded with a frame of compressed digital video signals in said LP V mode.

According to another aspect of the present invention an apparatus for reproducing a compressed digital video signal that had been recorded with a first compression ratio in a standard play (SP) mode in a first number of tracks on a record medium and that had been recorded with a second compression ratio in a long play (LP) mode in a second number of tracks, said first number being greater than said second number, wherein each frame of the digital video signal is disposed in first and second sets of tracks in said SP mode and in said first set of tracks in said LP mode, and wherein subcode data is recorded in said first and second sets of tracks for locating frames during a high speed search of the record medium, said subcode data in said first set of tracks being of a first type and said subcode data in said second set of tracks being of a second type, said apparatus comprising: first and second video data expanding means for expanding said compressed digital video signal reproduced from said record medium in said SP and LP modes, respectively; selecting means for selecting said first or second video data expanding means to expand the compressed digital video signal reproduced from said record medium; and subcode data detecting means for detecting the subcode data reproduced from said first set of tracks in both the SP and LP modes to carry out said high speed search.

[R:\LIBCC]01768.doc:BFD For example, in the SP mode, NTSC (or 525/60) data are recorded in ten tracks per frame, with the subcode data recorded in the first five tracks being of a different type than the subcode data recorded in the second five tracks. However, when that same video data is recorded in the LP mode, one video frame is recorded in five tracks; and the S subcode data recorded in those tracks is the same as the subcode data recorded in, for example, the second set of five tracks which are included in an SP mode frame.

As a preferred feature of this invention, the subcode data includes an F/R flag recorded in each track, with this F/R flag undergoing a positive (0 to 1) transition at the beginning of a frame and a negative transition at the middle of the frame when o e a a.

[R:\LIBCC]01768.doc:BFD

PATENT

450100-3400 1 the video data is recorded in the SP mode; whereas when the video 2 data is recorded in the LP mode, the F/R flag undergoes a 3 positive transition at the beginning of the frame and a negative 4 transition in the vicinity of the middle of the frame. For example, if the video data originally is in the NTSC standard, 6 the F/R flag undergoes a positive transition at the beginning of 7 a frame and a negative transition at the fourth track in that 8 frame when the video data is recorded in the LP mode. If the 9 video data had been recorded in the PAL standard, the F/R flag 0 undergoes a positive transition at the beginning of the frame and i a negative transition at the fourth track included in that frame o:*L2 when recorded in the LP mode. (Of course, opposite transitions 013 are contemplated, that is, a negative transition may be present 14 at the beginning of the frame and a positive transition in the F/R flag may be present in the vicinity of the middle of the 6 frame.) 17 As yet another feature of this invention, apparatus are 18 provided for reproducing the digital video signal recorded in the 19 aforementioned manner. Thus, for executing a high speed search, whether the video data had been recorded in the SP or LP mode, 21 subcode data recorded in only one set of tracks for the SP mode 22 are detected; and the same subcode data are detected for those 23 digital video signals that had been recorded in the LP mode.

24 That is, there is no need to provide different criteria for searching the subcode data for the SP and LP modes: the same C\3400.APP -16- -17criterion may be used for both modes because a common type of subcode data recorded in both SP and LP frames is sensed.

As yet another preferred aspect of this invention, in video reproducing apparatus of the aforementioned type, the same transition in the F/R flag a positive transition) is detected in order to position the record medium at the first track of a video frame, irrespective of whether that frame had been recorded in the SP or LP mode. There is no need to provide separate detecting mechanisms or algorithms for positioning the record medium, depending upon whether that medium had been recorded in the SP or LP mode.

BRIEF DESCRIPTION OF THE DRAWINGS 0o Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a schematic representation of one track of digital video data recorded on, for example, a digital video tape; Figs. 2A-2D are schematic representations of the subcode data recorded in the subcode area shown in Fig. 1; Fig. 3 is a chart illustrating the subcode data recorded in the main area of the subcode area of the different tracks which constitute a video frame; Fig. 4 is a schematic representation of a data pack; 9 *9 9 99io°9 [R:\LIBCC]01768.doc:BFD

PATENT

450100-3400 1 Figs. 5A and 5B are schematic representations of the 2 F/R flag recorded in respective tracks of video frames that had 3 been recorded in the SP mode of operation: 4 Figs. 6A and 6B are schematic representations of the F/R flag recorded in respective tracks of video frames that had 6 been recorded in the LP mode of operation; 7 Fig. 7 is a flow chart representing the manner in which 8 the F/R flag is sensed for the purpose of positioning a record 9 medium at the beginning of a frame recorded in the SP or LP mode; Figs. 8A and 8B are schematic representations of a record medium in which digital video data are recorded in both SP :12 and LP modes; .:13 Fig. 9 is a block diagram of a digital video recorder 14 in which the present invention finds ready application; Figs. 10A-10B schematically illustrate the TTC pack .16 recorded by the apparatus shown in Fig. 9; 17 Fig. 11 schematically illustrates a TBC pack recorded 18 by the apparatus shown in Fig. 9; 19 Fig. 12 schematically illustrates the VRD pack recorded by the apparatus shown in Fig. 9; 21 Fig. 13 schematically illustrates the VRT pack recorded 22 by the apparatus shown in Fig. 9; 23 Fig. 14 schematically illustrates the ARD pack recorded 24 by the apparatus shown in Fig. 9; C\3400.APP -18-

PATENT

450100-3400 1 Fig. 15 schematically illustrates the ART pack recorded 2 by the apparatus shown in Fig. 9; 3 Fig. 16 schematically represents the subcode data 4 recorded in the respective tracks of an NTSC frame recorded in the SP mode; 6 Fig. 17 schematically represents the subcode data recorded in the respective tracks of successive frames recorded :8 in the LP mode; 9 Fig. 18 is a flow chart representing the manner in V 0 which the subcode data shown in Fig. 16 or Fig. 17 is recorded; 1 1 Fig. 19 is a block diagram of video data reproducing apparatus in which the present invention finds ready application; 13 Fig. 20 is a flow chart illustrating the manner in 14 which a high speed search is carried out; Fig. 21 schematically represents subcode data that :16 would be recorded in tracks of successive frames of LP video data 17 that otherwise would be recorded by techniques proposed 18 heretofore; 19 Fig. 22 is a flow chart representing one embodiment of the present invention in which the F/R flag is recorded in either 21 the SP or LP mode; 22 Fig. 23 is a flow chart representing the manner in 23 which the beginning of a frame is sensed as a function of the F/R 24 flag, irrespective of whether the video data had been recorded in the SP or LP mode; and C\3400.APP -19-

PATENT

450100-3400 1 Figs. 24A-24B schematically illustrate the F/R flag 2 that is recorded in accordance with the present invention on a 3 video tape containing video data that had been recorded in both 4 the SP and LP modes.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 6 One embodiment of digital video recording apparatus 7 which incorporates the present invention is illustrated in the S8 block diagram of Fig. 9. In this embodiment, video data supplied 9 in digital form at input terminal 1 and audio data supplied at input terminal 2 is recorded by a rotary head 11 on a magnetic 11 tape 20 in either the SP or LP mode. Digital video data supplied to input terminal 1 is coupled by a selector switch 3 either to a 13 video data compressor 5 or a video data compressor 6, these two '"14 compressors being operable in the SP and LP modes, respectively.

A controller 4 determines the condition of selector 3 in response to a user control supplied to the controller by an entry key 12.

17 For example, if a user selects the standard play mode, controller 18 4 conditions selector 3 to couple the digital video signal to SP 19 mode compressor 5. If, however, the user had selected the long play mode, controller 4 conditions selector 3 to couple the 21 digital video data from input terminal 1 to LP mode compressor 6.

22 Another selector 7 couples either SP mode compressor 5 or LP mode 23 compressor 6 to a multiplexer 8, depending upon whether the user 24 had selected the SP or LP mode for recording. As is shown, selector 7 is controlled by controller 4.

C\3400.APP

PATENT

450100-3400 1 Controller 4 also controls an audio processor 9 to 2 process a digital audio signal supplied thereto from audio input 3 terminal 2 in a manner depending upon whether the SP or LP mode 4 had been selected by the user. It will be appreciated that a greater degree of compression is carried out by the audio 6 processor when the LP mode is selected as opposed to when the SP :i7 mode is selected. The compressed audio data produced by the 8 audio processor is coupled to multiplexer 8.

9 Controller 4 also controls the operation of a subcode 1 0 generator 10 to generate either the subcode data schematically 1 illustrated in Fig. 3 for recording in the main area of the subcode area of each track when the SP mode is selected, or to 13 record only one type of subcode data for each frame when the LP 14 mode is selected. The type of data generated by subcode generator 10 during the SP mode and the type of subcode data "7L6 generated thereby during the LP mode are described below.

17 Although not discussed herein, it will be appreciated 18 that compressors 5 and 6 carry out data compression in a manner 19 known to those of ordinary skill in the art, including image decimation, blocking, DCT conversion, variable quantizing, 21 variable length encoding, and so on. If the input video signal 22 admits of the NTSC standard, SP mode compressor 5 cooperates with 23 multiplexer 8 and recording heads 11ii to record the compressed 24 video data in ten tracks per frame. Similarly, LP mode compressor 6 cooperates with the multiplexer and recording heads C\3400.APP -21-

PATENT

450100-3400 1 to record the NTSC video signal in the LP mode in five tracks per 2 frame. If, however, the video signal supplied to input terminal 3 1 is in the PAL standard, SP mode compressor 5 operates to record 4 the compressed video data in twelve tracks per frame in the SP mode; and LP mode compressor 6 operates to record the compressed 6 video data in six tracks per frame in the LP mode.

Multiplexer 8 is operable to record the compressed 8 audio data supplied from audio processor 9, the compressed video *9 data supplied either from SP mode compressor 5 or LP mode '0 compressor 6 and the subcode data supplied from subcode generator 10 in the audio, video and subcode areas shown in Fig. 1. ITI 2 data is supplied to and recorded by multiplexer 8 in the ITI 0 .13 area; but this forms no part of the present invention per se and 14 is not further discussed herein.

The subcode data supplied by subcode generator 0.

16 admits of the data construction shown in Figs. 2A-2D; and the 17 data bytes of Fig. 2B are recorded as data packs having the form 18 shown in Fig. 4. The type of data represented by each data pack 19 may be as follows: Fig. 10A illustrates the title time code (TTC) pack 21 whose header byte PCO (in hexadecimal form) is "13h". The TTC 22 pack is an indication of elapsed time in hours-minutes-seconds.

23 Fig. 10B illustrates the TTC pack similar to that shown in Fig.

24 10A, but in Fig. 10B, bit numbers S1-S6 are assigned particular C\3400.APP -22-

PATENT

450100-3400 1 values of the vertical interval time code or the linear time 2 code, as may be selected by the user.

3 Fig. 11 represents the title binary group (TBG) pack 4 whose header byte PC0 is "14h" in hexadecimal form. As mentioned above, the TBG pack is used primarily for business applications; 6 and is replaced by the TTC pack in the subcode data recorded by 7 consumer use D-VCR's.

.8 Fig. 12 illustrates the video recording date (VRD) pack 9 whose header byte PCO is "62h" in hexadecimal form. The VRD pack 1 .0 represents the date in year, month and day on which the video data is recorded. Bit DS in byte PC1 indicates whether the date 2 is in standard or Daylight Saving Time; and bit TM indicates 13 whether the time at which the video data is recorded differs from 14 Greenwich mean time by an odd or even multiple of a half-hour. For example, video data recorded in India is recorded .16 at a time which differs from Greenwich mean time by an odd 17 multiple of a half-hour. In most of the rest of the world, video 18 data will be recorded at a time which differs from Greenwich mean 19 time by an even multiple of a half-hour.

Fig. 13 illustrates a video recording time (VRT) pack 21 which indicates the time, in hours, minutes and seconds, at which 22 the video data is recorded. Here, the header byte PCO is "63h" 23 in hexadecimal form.

24 Fig. 14 illustrates the audio recording date (ARD) pack whose header byte PCO is "52h" in hexadecimal form. The data C\3400.APP -23-

PATENT

450100-3400 1 recorded in the ARD pack is seen to be substantially the same as 2 the data recorded in the VRD pack.

3 Fig. 15 illustrates the audio recording time (ART) pack 4 whose header byte PCO is "53h" in hexadecimal form. It will be seen that the ART pack is substantially the same as the VRT pack.

6 When subcode data generator 10 operates to generate the subcode data that is recorded in each track of a frame recorded 8 in the SP mode, the first set, or first half, of the tracks .9 contains one type of subcode data and the second set, or second half of the tracks contains a different type of subcode data.

*1 Thus, when the digital video data represents an NTSC signal, such :*12 that one frame of digital video data is recorded in ten tracks, 13 the first set of five tracks contains one type of subcode data 14 and the second set of five tracks contains a different type of subcode data. Similarly, if the digital video data represents a PAL signal, wherein one frame of the PAL signal is recorded in 17 twelve tracks, the first set of six tracks contains subcode data 18 of one type and the second set of six tracks contains subcode 19 data of a different type. As discussed above in conjunction with Fig. 3, the subcode data is recorded in particular sync blocks 21 which constitute the main area of the subcode data. This subcode 22 data recording format for an NTSC (525/60) video signal recorded 23 in the SP mode is schematically illustrated in Fig. 16. Here, 24 the first set of five tracks TO-T4 contains the subcode data recorded in sync blocks SBO-SB11 in each track. TTC packs are C\3400.APP -24-

PATENT

450100-3400 1 recorded in sync blocks SB3, SB5, SB9 and SB11 in each of tracks 2 TO-T4; and sync blocks SB4 and SB10 in these tracks are recorded 3 with the TTC pack or, if the video data is recorded by a business 4 user, with the TBG pack. If the user wishes not to record the TTC or the TBG pack in sync blocks SB4 and SB10 of tracks TO-T4, 6 no info NOI is recorded. In tracks TO-T4 of the NTSC signal :7 recorded in the SP mode, sync blocks SBO-SB2 and SB6-SB8 are the :8 "optional areas" discussed above in conjunction with Fig. 3.

0*0* 9 In the second set of five tracks T5-T9 of the NTSC 0 video signal recorded in the SP mode, the TTC pack is recorded in .:61 1 sync blocks SB3 and SB9; date information represented by the VRD 0 12 or ARD packs is recorded in sync blocks SB4 and SB10 and time 13 information represented by the VRT or ART packs is recorded in 14 sync blocks SB5 and SB11. As mentioned above, the VRD and ARD packs represent the date (year, month and day) at which the video 6 or audio data (as may be selected by the user) are recorded; and 17 the VRT and ART packs represent the time (hours, minutes, 18 seconds) at which the video or audio data (as may be selected by 19 the user) are recorded.

As illustrated in Fig. 16, TTC information is recorded 21 in both the first and second sets of tracks of a frame recorded 22 in the SP mode; whereas date and time information (which are more 23 useful for a high speed search and for data compilation) are 24 recorded only in the second set of data tracks. As an advantageous feature of the present invention, the time code data C\3400.APP

PATENT

450100-3400 1 which is recorded in the second set of tracks in the SP mode are 2 recorded in the single set of tracks which constitute the frame 3 in the LP mode. That is, whereas an SP-recorded frame includes 4 two sets of tracks, an LP-recorded frame contains only a single set of tracks; and the time code data recorded in this single set 6 of tracks in the LP mode is the same type of data that is recorded in the second set of tracks in the SP mode.

8 The subcode data format recorded in the main areas of '9 the subcode area in each track included in a frame of digital video data recorded in the LP mode is illustrated in Fig. 17.

:'il Here, it is assumed that the video signal is in the NTSC standard 12 and, thus, one frame of the digital video data recorded in the LP 1 3 mode is comprised of five tracks TO-T4. The next frame of the 14 NTSC digital video data recorded in the LP mode also is comprised of five tracks T5-T9. A comparison between Figs. 16 and 17 *a16 indicates that the set of five tracks which constitute the frame 17 of the NTSC digital video data recorded in the LP mode is of the 18 same type of subcode data that is recorded in the second set of 19 tracks five tracks) which contain the second half of the frame of the NTSC digital video signal in the SP mode. That is, 21 sync blocks SB4 and SB10 of tracks TO-T4 and of tracks T5-T9 of 22 the NTSC digital video signal recorded in the LP mode represent 23 date information similar to the date information included in sync 24 blocks SB4 and SB10 of tracks T5-T9 of the NTSC digital video signal recorded in the SP mode. Likewise, sync blocks SB5 and C\3400.APP -26-

PATENT

450100-3400 1 SB11 of tracks TO-T4 and of tracks T5-T9 of the NTSC digital 2 video signal recorded in the LP mode include the same time data 3 as are included in sync blocks SB5 and SB11 of tracks T5-T9 for 4 the NTSC digital video signal recorded in the SP mode. Stated otherwise, whereas each frame of the digital video signal 6 recorded in the SP mode is comprised of first and second sets of 7 tracks, each set including an equal number of tracks five o 8 tracks for the NTSC standard and six tracks for the PAL 9 standard), one frame recorded in the LP mode is comprised of only a single set of tracks (five tracks in the NTSC standard and six .11 tracks in the PAL standard). The subcode data that is recorded 12 in the set of tracks which constitute a frame in the LP mode is the same type of data as the subcode data that is recorded in the 14 second set of tracks the second half) which are included in '.15 the frame of the SP-recorded video data. Although subcode data "16 of first and second types are recorded in the first and second 17 sets of the tracks which constitute an SP frame, only one type of 18 subcode data is recorded in an LP frame.

19 Fig. 18 illustrates a flow chart that characterizes the manner in which subcode generator 10 of Fig. 9 records the 21 subcode data. That is, the flow chart of Fig. 18 represents the 22 manner in which either the subcode data shown in Fig. 16 or the 23 subcode data shown in Fig. 17 is recorded. Initially, inquiry S1 24 is made to determine whether the apparatus shown in Fig. 9 is operable in the SP or LP mode. It is recalled that a user C\3400.APP -27-

PATENT

450100-3400 1 operates entry key 12 to select either the SP mode or the LP mode 2 of operation. If the user had selected the SP mode, instruction 3 S2 is carried out, whereby subcode generator 10 generates the TTC 4 pack for recording in sync blocks SB3, SB5, SB9 and SB11 in the first half of the frame of digital video data in tracks TO- 6 T4) and also generates the TTC or TBG packs (or NOI) in sync 7 blocks SB4 and SB10. During the second half of the video frame, 8 that is, when tracks T5-T9 are recorded, subcode generator 9 generates the TTC pack for recording in sync blocks SB3 and SB9 and then generates either time data (VRT or ART packs) or date *.11 .data (VRD or ARD packs), or NOI, for recording in sync blocks 12 SB5, SB11 and in sync blocks SB4, SB10, as depicted in Fig. 16.

13 If, however, the user had selected the LP mode for 14 recording, instruction S3 is executed, whereby subcode generator 15 10 generates the TTC data pack for recording in sync blocks SB3 and SB9 in each track and then generates time data VRT or ART 17 packs for recording in sync blocks SB5 and SB11 in each track or 18 generates date data VRD or ARD packs for recording in sync blocks 19 SB4 and SB10 in each track. Thus, depending upon whether the user selects the SP or LP mode for recording, the subcode data is 21 recorded in the format shown either in Fig. 16 or in Fig. 17.

22 It is appreciated that, if the LP mode of recording is 23 selected, the TBG pack is not recorded. This is acceptable 24 because the TBG pack typically is reserved for business use recording and not for consumer use. Since the quality of the C\3400.APP -28-

PATENT

450100-3400 1 video picture ultimately reproduced from compressed video data 2 that had been recorded in the LP mode is less than the quality of 3 the video picture that is reproduced from the compressed video 4 data that had been recorded in the SP mode, it is expected that, when the LP mode is used, that is, when consumer use of the D-VCR 6 is implemented, there is no need to record the TBG pack. Thus, the omission of the TBG pack from the subcode data recorded 8 during the LP mode is acceptable; and no problem therefrom is 9 expected.

Fig. 19 is a block diagram of digital video reproducing S::11 apparatus that is compatible with the recording apparatus shown 12 in Fig. 9 and wherein the present invention finds ready application. Here, the digital video signal that had been 14 recorded on magnetic tape 20 in either the SP or LP mode is reproduced by heads 21 and supplied to a demultiplexer 22. The demultiplexer separates the reproduced data into separate audio, 17 video and subcode channels supplied to an audio processor 23, a 18 video selector 24 and a subcode detector 30, respectively. Audio 19 processor 23 operates on the audio data supplied thereto to decompress the audio data, subject the decompressed audio data to 21 interpolation, if necessary, and then supply the recovered audio 22 data to an audio output terminal 26.

23 Subcode data detected by subcode detector 30 is 24 supplied to a controller 29 and provides an indication thereto of whether the data recovered from tape 20 had been recorded in the C\3400.APP -29-

PATENT

450100-3400 1 SP or LP mode. For example, subcode detector 30 may sense the 2 absence from main areas in, for example, tracks TO-T4 of date 3 and/or time data to indicate the presence of digital video data 4 that had been recorded in the SP mode, as seen in Fig. 16. If the subcode detector senses the presence of date and/or time data 6 in the subcode area in each track, subcode detector 30 thus i. 7 provides controller 29 with an indication that the digital video S. 8 data had been recorded in the LP mode, as best appreciated from 9 Fig. 17. Controller 29 supplies a suitable SP/LP control signal to audio processor 23 and to selectors 24 and 27, thereby 11 controlling these circuits in a manner compatible with SP or LP 12 recorded data.

13 Selector 24 couples video data either to an SP mode 14 expander 25 or to an LP mode expander 26, depending upon whether 15 controller 29 sets the state of selector 24 to the SP or LP 16 state, as determined by subcode detector 30. Similarly, selector 17 27 couples either the SP mode expander or the LP mode expander to 18 a video output terminal 28, depending upon whether controller 29 19 is provided with an SP or LP indication from the subcode detector. Thus, depending upon whether the original digital 21 video signal had been compressed and recorded in the SP or LP 22 mode, that video signal, when reproduced from tape 20, is 23 expanded in a compatible manner.

24 Although not shown herein, it will be appreciated that SP mode expander 25 and LP mode expander 26 include variable C\3400.APP

PATENT

450100-3400 1 length decoders, inverse quantizers and inverse DCT circuits 2 known to those of ordinary skill in the art. Thus, the digital 3 video data that had been compressed by compressors 5 and 6 in 4 Fig. 9 now are expanded by matching expander circuits 25 and 26, respectively.

6 The subcode data detected by subcode detector 30 is .7 used during a high speed search to locate desired frames and to 8 position tape 20 such that the beginning of a selected frame is 9 located for reproduction by head 21. The subcode data sensed during a high speed search also is used for compilation of, for 11i example, titles of video programs recorded on tape 20, dates 12 and/or times of recording, duration, etc. Such information may be displayed to the user to simplify his selection of desired 14 frames to be reproduced.

Fig. 20 is a flow chart representing the manner in which a high speed search for a desired frame is executed.

17 Initially, the user enters the identity of the frame in question 18 by supplying to, for example, subcode detector 30 (or controller 19 29) the desired time (in hours, minutes and seconds) at which the frame in question was recorded. This inputting of time data is 21 represented by instruction S11 in Fig. 20. Then, a high speed 22 search is carried out whereby subcode data recorded in the 23 respective tracks is played back, as represented by instruction 24 S12. The played back VRT packs are compared to the user-entered input time, as represented by inquiry S13, and the routine simply C\3400.APP -31-

PATENT

450100-3400 1 cycles through instruction S12 and inquiry S13 until the 2 reproduced VRT pack coincides with the user-entered time. When 3 inquiry S13 detects this coincidence, the movement of tape 20 is 4 stopped, as represented by instruction S14, and the high speed search is completed. Then, as represented by instruction S15, a 6 fine search is carried out to move the tape to the first track of 7 the first frame recorded at the user-entered time.

8 The foregoing search may be carried out by comparing 9 the user-entered time to ART packs that are reproduced from the tape. Alternatively, the user may enter a recording date; and .11 inquiry S13 operates to compare the VRD or ARD packs with the 12 user-entered date. Still further, the high speed search 13 represented by the flow chart shown in Fig. 20 may be implemented 14 by comparing user-entered date and time to VRD and VRT packs or to ARD and ART packs that are recovered from the subcode area in each track scanned at high speed during this high speed search.

17 It is appreciated that when the video data is recorded 18 in the SP mode, VRT or VRD (or, alternatively, ARD or ART) packs 19 are recorded in the subcode area included in each frame, even though this data is not recorded in each track. Likewise, when 21 the digital video data is recorded in the LP mode, the VRT or VRD 22 (or, alternatively, the ART or ARD) packs likewise are recorded 23 in each frame. Thus, a high speed search based upon VRT, VRD, 24 ART or ARD packs is carried out on the basis of a single frame unit irrespective of whether the video data was recorded in the C\3400.APP -32-

PATENT

450100-3400 1 SP or LP mode. Consequently, the same high speed searching 2 mechanism or algorithm may be used for both SP and LP 3 reproduction. Heretofore, as discussed above, one type of search 4 mechanism or algorithm must be used when the digital video data had been recorded in the SP mode and another search mechanism or 6 algorithm must be used when the video data had been recorded in 7 the LP mode. Accordingly, by reason of the present invention, 8 the searching mechanism or algorithm may be simplified because 9 separate mechanisms or algorithms need not be provided for the SP and LP modes, respectively.

:"11 Fig. 21 schematically represents a problem that would 12 be present if the prior art technique is used to record both SP and LP subcode data. That is, if the technique used to record 14 subcode data for the SP mode also is used to record data for the LP mode, it is seen that, when the NTSC standard is adopted, the :16 subcode data recorded in the first set of five tracks TO-T4 17 (which constitute a complete LP frame) differs from the subcode 18 data recorded in the second set of tracks T5-T9 (which constitute 19 a next-following complete LP frame). That is, in tracks TO-T4 of Fig. 21, VRD or VRT (or, alternatively, ARD or ART) packs are not 21 recorded and, thus, a search based upon this data, such as 22 represented by the flow chart shown in Fig. 20, will not be 23 capable of positioning those frames constituted by tracks TO-T4.

24 When the prior art technique of recording subcode data in the SP mode is used to record subcode data in the LP mode, a high speed C\3400.APP -33-

PATENT

450100-3400 1 search will sense only every other frame; whereas the present 2 invention permits a high speed search to sense every LP frame.

3 Using the prior art technique, a high speed search is dependent 4 upon a 2-frame unit, whereas the present invention permits a high speed search to be conducted for a single frame unit.

6 While Figs. 16, 17 and 21 illustrate SP and LP 7 recording of NTSC (525/60) video signals, it is appreciated that S8 the present invention is equally applicable to the recording of 9 PAL (625/50) video signals. When PAL signals are recorded in the SP mode, each frame is constituted by twelve tracks; and when 11 recorded in the LP mode, each PAL frame is constituted by six 12 tracks. Nevertheless, the teachings and principles of the :13 instant invention are applicable to such PAL signals.

14 As discussed above, particularly in conjunction with 1 5 Figs. 5A and 5B, when the NTSC video signal is recorded in the SP *(16 mode, the F/R flag included in the IDO byte of each sync block is 17 a for tracks TO-T4 and is a for tracks T5-T9. That is, 18 the F/R flag undergoes a positive transition at the first track 19 in the frame and undergoes a negative transition at the first track in the second set of tracks in that frame. When the NTSC 21 signal is recorded in the LP mode, it is preferred that the F/R 22 flag in each sync block undergo a positive transition at the 23 first track in each frame. However, if the technique that is 24 used to record subcode data in the SP mode also is used to record subcode data in the LP mode, it is seen, from Figs. 6A-6B, that C\3400.APP -34-

PATENT

450100-3400 1 the F/R flag undergoes a positive transition at the first track 2 in alternate frames but undergoes a negative transition at the 3 first track in the remaining frames. However, since a positive 4 transition in the F/R flag typically is used to identify the beginning of a frame, it is preferable to have this flag undergo S6 a positive transition at the beginning of each frame recorded in 7 the LP mode and not simply at the beginning of alternate frames, o 8 as represented by Fig. 6B. This preferred control over the F/R flag in both the SP and LP recording modes is depicted by the flow chart shown in Fig. 22.

This flow chart represents the recording of the digital 12 video signal in the NTSC standard. Initially, inquiry S21 13 determines whether the digital video signal is to be recorded in 14 the SP or LP mode, as selected by the user. If the SP mode is 15 selected, instruction S22 is carried out, wherein the F/R flag is o••o• 16 set at for the first set of five tracks which constitute half 17 the SP frame; and then this flag is changed over to for the 18 second set of five tracks which comprise the remainder of the 19 frame. However, if the user selects the LP mode of recording, instruction S23 is carried out, wherein the F/R flag is set to 21 for the first three tracks which constitute the LP frame; and 22 then the flag is changed over to for the remaining two tracks 23 of the LP frame. Alternatively, if the digital video signal is 24 in the PAL standard, instruction S22 sets the F/R flag to for the first set of six tracks in the SP frame and to for the C\3400.APP

PATENT

450100-3400 1 second set of six tracks for the SP frame. For recording the 2 signal in the LP mode, instruction S23 sets the F/R flag to "1" 3 for the first three tracks of the LP frame and to for the 4 last three tracks of the LP frame.

From the foregoing, it may be generalized that, when a 6 digital video signal is recorded in the SP mode, wherein a frame 7 consists of M tracks, the F/R flag changes over from one state to 8 the other at every M/2 tracks. For recording in the LP mode, S9 wherein a frame is recorded in M/2 tracks, if the digital video signal is an NTSC signal, the F/R flag preferably is set to "1" 1 1 for (M/2 1)/2 tracks and is set to for the remaining 12 tracks. Of course, if the digital video signal is in the PAL standard, the F/R flag is set to for the first three tracks 14 of the LP frame and to for the last three tracks of the LP *:15 frame. That is, for the LP mode, the F/R flag undergoes a change 16 in state at the first and N-th tracks of each frame, where 17 (M/2 l)aN(1/2) (M/2 Consequently, whether the 18 digital video signal is recorded in the SP or LP mode, the 19 beginning of a frame, that is, the first track in a frame, can be detected simply by sensing the changeover in the F/R flag from 21 to Hence, a common searching mechanism or algorithm may 22 be used in both the SP and LP modes to sense the beginning of a 23 frame.

24 Fig. 23 is a flow chart which represents the manner in which the beginning of a frame of a digital video signal that had C\3400.APP -36-

PATENT

450100-3400 1 been recorded in either the SP or LP mode is determined. Inquiry 2 S31 is made to sense when the F/R flag undergoes a transition 3 from to When this transition is sensed, instruction S32 4 is executed to indicate that the track which contains this transition is the first track of the frame, irrespective of whether that frame was recorded in the SP or LP mode.

*7 Figs. 24A and 24B schematically illustrate an NTSC 8 digital video signal that is recorded on a magnetic tape in the S:9 SP mode for tracks 0-9 and in the LP mode for tracks 10-30. The state of the F/R flag in each track also is depicted; and Fig.

1 24B illustrates the transition of this flag. It is seen that, 12 consistent with the present invention, the F/R flag undergoes a 1-3 positive transition at the beginning of each frame, whether that 14 frame is recorded in the SP mode (as in tracks 0-9) or in the LP mode (as in tracks 10-14, 15-19, 20-24 and 25-29). In the LP (6 mode, consistent with the flow chart shown in Fig. 22, the F/R 17 flag is set to for the first three tracks of the LP frame and 18 to for the last two tracks of that frame.

19 While the foregoing has described the state of the F/R track as being for the first three tracks and for the 21 last two tracks of an LP frame for an NTSC digital video signal, 22 it will be appreciated that, alternatively, the F/R flag may be a 23 for the first two tracks and a for the last three tracks.

24 The present invention also is applicable to the recording of "standard" and HDTV NTSC and PAL digital video C\3400.APP -37-

PATENT

450100-3400 1 signals in the SP mode. For example, when recording an HDTV NTSC 2 signal (also known as the 1125/60 standard), the HDTV signal is 3 recorded by compressor 6 (Fig. 9) in twenty tracks and the F/R 4 flag undergoes a transition every ten tracks. That is, when recording the 1125/60 HDTV signal, the F/R flag is set to in 6 the first set of ten tracks and to in the second set of ten 7 tracks in the HDTV frame. Similarly, when recording a PAL HDTV 8 signal, also known as the 1250/50 standard, one frame of the HDTV 9 signal is recorded in twenty-four tracks. Hence, the F/R flag is set to in the first twelve tracks of the HDTV frame and to 11 in the second twelve tracks of that frame.

12 While the present invention has been particularly shown *13 and described with reference to preferred embodiments, it will be 14 readily appreciated by those of ordinary skill in the art that various changes may be'made in form and details without departing So"S16 from the spirit and scope of the invention. Some of these 17 changes have been discussed above and others will be apparent 18 from the teachings herein. Therefore, it is intended that the 19 appended claims be interpreted to cover the embodiments specifically disclosed, those alternatives which have been 21 mentioned and all equivalents thereto.

*C\3400.APP -38-

Claims (14)

1. An apparatus for selectively recording a digital video signal in a first number of tracks on a record medium in a standard play (SP) mode and in a second number of tracks in a long play (LP) mode wherein each frame of the digital video signal is recorded in first and second sets of tracks in said SP mode and in said first set of tracks in said LP mode, and wherein subcode data is recorded in said first and second sets of tracks for locating frames during a high speed search, said apparatus comprising: 9 10 first and second video data compressing means for compressing said digital video signal for recording in said SP and LP modes, respectively, said second video data compressing means exhibiting a compression ratio greater than the compression ratio of said first video data compressing means; selecting means for selecting said first or said second video data compressing means to supply the compressed digital video signal for recording; and subcode data generating means for generating subcode data of a first type for recording in said first set of tracks and of a second type for recording in said second set of tracks, whereby subcode data of said first and second types are recorded with a 9 frame of compressed digital video signals in said SP mode and subcode data of only said first type are recorded with a frame of compressed digital video signals in said LP mode.

2. The apparatus of claim 1 wherein a frame of said compressed digital video signal is recorded in M tracks in the SP mode and in M/2 tracks in the LP mode.

3. The apparatus of claim 2 wherein a respective set of tracks consists of M/2 tracks. R:\LIBCC\01768.doc

4. The apparatus of claim 2 wherein said subcode data of said first type is recorded in M/2 tracks and contains both title time code data and recording time data; and wherein said subcode data of said second type is recorded in M/2 tracks and contains title time code data and not recording time data.

The apparatus of claim 3 wherein the digital video signal admits of a 525/60 standard and

6. The apparatus of claim 3 wherein the digital video signal admits of a S 10 625/50 standard and M 12.

7. An apparatus for reproducing a compressed digital video signal that S"had been recorded with a first compression ratio in a standard play (SP) mode in a first S" number of tracks on a record medium and that had been recorded with a second compression ratio in a long play (LP) mode in a second number of tracks, said first number being greater than said second number, wherein each frame of the digital video signal is disposed in first and second sets of tracks in said SP mode and in said first set 5555 of tracks in said LP mode, and wherein subcode data is recorded in said first and second sets of tracks for locating frames during a high speed search of the record medium, said subcode data in said first set of tracks being of a first type and said subcode data in said second set of tracks being of a second type, said apparatus comprising: first and second video data expanding means for expanding said compressed digital video signal reproduced from said record medium in said SP and LP modes, respectively; selecting means for selecting said first or second video data expanding means to expand the compressed digital video signal reproduced from said record medium; and subcode data detecting means for detecting the subcode data reproduced from said first set of tracks in both the SP and LP modes to carry out said high speed search. R:\LIBCC\01768.doc -41-

8. The apparatus of claim 7 wherein a frame of said compressed digital video signal is disposed in M tracks in the SP mode and in M/2 tracks in the LP mode.

9. The apparatus of claim 8 wherein each of said first and second sets of tracks consists of M/2 tracks.

The apparatus of claim 9 wherein the digital video signal admits of a 525/60 standard and M= *oo

11. The apparatus of claim 9 wherein the digital video signal admits of a 625/50 standard and M= 12.

12. The apparatus of claim 8 wherein said subcode data of said first type is recorded in M/2 tracks and contains both title time code data and recording time data; and wherein said subcode data of said second type is recorded in M/2 tracks and contains title time code data and not recording time data.

13. An apparatus for selectively recording a digital video signal, said apparatus being substantially as described herein with reference to Figs. 9 to 24B of the accompanying drawings.

14. An apparatus for reproducing a compressed digital video signal, said apparatus being substantially as described herein with reference to Figs. 9 to 24B of the accompanying drawings. DATED this Tenth Day of May, 1999 Sony Corporation Patent Attorneys for the Applicant SPRUSON FERGUSON R:\LIBCC\01768.doc