Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
  • G11B15/18—Driving; Starting; Stopping; Arrangements for control or regulation thereof
  • G11B15/26—Driving record carriers by members acting directly or indirectly thereon
  • G11B15/34—Driving record carriers by members acting directly or indirectly thereon through non-slip drive means, e.g. sprocket
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
  • G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
  • G11B27/022—Electronic editing of analogue information signals, e.g. audio or video signals
  • G11B27/024—Electronic editing of analogue information signals, e.g. audio or video signals on tapes
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
  • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
  • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
  • G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
  • G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
  • G11B27/32—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on separate auxiliary tracks of the same or an auxiliary record carrier
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B2220/00—Record carriers by type
  • G11B2220/90—Tape-like record carriers

Definitions

• This invention relates to a method of synchro ⁇ nizing audio and video information. More specifically, the present invention relates to a process for producing a video tape of the type used in television broadcasting wherein motion picture techniques for synchronizing sound and video may be employed without sacrificing the advan ⁇ tages of modern video editing procedures.
• Background of the Invention In the early days of television, most programs were live or optically recorded (kinescoped) on conven ⁇ tional motion picture film. When a program was first recorded on motion picture film, conventional motion picture techniques for editing and synchronizing the sound and visual tracks could be used.
• SMPTE time code which comprises an 80-bit code of which 40 bits are used to identify the recording time (in hours, minutes and seconds) for each frame and the number of the frame on the tape.
• the use of this SMPTE time code has enabled sophisticated computer controlled techniques for editing video signals and, currently, the editing of video tape is more efficient than the editing of motion picture film wherein various film effects must be spliced together to provide a finished product.
• the principal object of the invention is to provide a simplified and inexpensive method of synchro ⁇ nizing audio and recorded video signals.
• a more specific object of the invention is to enable the use of conventional film synchronizing tech ⁇ niques for post production sound mixing of video tapes.
• a master edited video tape is prepared containing a video signal and a recorded time code identifying each frame.
• the video signal is then transferred to a first sprocketed magnetic film which may operate at a standard motion picture speed.
• a plur ⁇ ality of audio tracks are produced in synchronism with the video information recorded on the work print.
• the recorded audio tracks are mixed to form a master finished audio track which is recorded on a second sprocketed magnetic film together with the time code of the original master edited video tape.
• the audio and video signals may then be combined by using the recorded time codes on the finished audio film and the master edited video tape to drive them in synchronism as the audio is transferred to the video tape.
• Figure 2 is a block diagram showing the means for synchronizing the master edited video tape and the master finished audio film
• Figure 3 is a diagrammatic illustration showing the layout of a video tape machine modified to record on and reproduce from a sprocketed magnetic film.
• a master edited video tape it is necessary to first produce (or have produced) a master edited video tape. Conventionally, this may be accomplished by the us of a number of cameras recording a given scene from different angles. At the same time, an audio track containing the dialogue of the scene involved is recorded in conventional fashion on the tape. The director then edits the recorded video, most advantageously by computer ized editing equipment, to produce a master edited video tape. Typically, the video is recorded by quadraplex scanning techniques on two-inch magnetic tape or by helical scanning techniques on one inch magnetic tape about .5 mils thick.
• the audio track is incomplete because it contains no musi or special sound effects. Accordingly, as a part .of the editing process, it is necessary to build a finished audi track which contains the necessary dialogue, music and sound effects. Obviously, the audio track, including all of the separate parts which make up that track, must be accurately synchronized with the video.
• the contents of the master edited video tape (video, SMPTE time code, and audio) are transferred to and recorded on a sprocket driven magnetic film which thereafter serves as a work print.
• the magnetic film has the width of conventional movie film and is driven at the corresponding conventiona speed. For example, in the case of 16 mm film, the film will be driven at a speed of 36 feet per minute (24 frame per second). In the case of 35 mm film, the film moves a 90 feet per minute.
• the selection of film speed does not constitute a feature of the invention but
• OMPI /fr _ WIPO the foregoing are preferred for purposes of convenience.
• the video signals are re ⁇ corded on a portion of the film which is one-half inch wide.
• the audio track will be recorded just inside the sprocket holes and the conventional SMPTE time code will be recorded outside of the sprocket holes.
• the control track containing the vertical sync pulses which synchro ⁇ nizes the speed of the scanning mechanism will be recorded on the edge of the film opposite the sprocket holes.
• a separate tape or film of the audio is made at the same time so that a high quality dialogue track will be available for subsequent mixing and/or synchronizing.
• Standard magnetic tape for video recording purposes is about .5 mils thick. This tape cannot con ⁇ veniently be handled manually because it is so thin. Accordingly, in the preferred embodiment of the invention, the thickness of the magnetic films is in the order of 3 mils which enables the film to be conveniently handled.
• the 3 mil .sprocketed magnetic film was a 16 mm film, driven at a speed of 36 feet per minute.
• the video recorder/reproducer was a Panasonic helical scan device modified by replacement of the drive mechanism with a standard sprocket wheel move- ment. Because of the variation in speed, it was necessary also to vary the speed of rotation of the scanning unit so that the scanning unit would lay down successive fields as the tape was moved by the sprocket drive mechanism.
• the work print created as described above is next used to "build" the audio tracks containing the dialogue, sound effects, and music.
• Each track is recorded on a separate film and, ideally, the tracks are maintained separate until the final mixing since this, as is well-known, increases the flexibility of the overall system.
• the same apparatus used to record the work print can be used to play back the work print to build the audi tracks although it is anticipated that in practice a second recorder/ reproducer will be used for this purpose since the audio tracks will usually be formed in a separ ⁇ ate editing area.
• a video screen will be provided so that any selected portion of the work print can be replayed enabling reproduction of moving or still images.
• the ability to replay any selected video frame is a common feature on many commercially available video tape reproducers.
• the sprocketed video film will include the SMPT time code indicating the first frame of the program material.
• the editor will mark this first frame on the work print so that he has a visibly recognizable starting point on the magnetic film.
• the audio tracks will then be built in the same fashion as such tracks are built in the production of a motion picture film.
• pulse controlled motors may drive sprocket wheels which engage the sprockets of the individual tracks, with optical encoding disks fixed to the output shafts of the motors generate the pulses used to maintain fixed relationships between each of the tracks and, of course, the video track.
• this fixed relationship to the video information can be maintained even though it is in the form of a magnetically recorded signal because the signal is recorded on a sprocketed magnetic film at the same speed at which sound editing takes place (e.g. conventional motion picture film speed) .
• the sound editor runs the film and splices any desired sound effect, dialogue or musical effect onto any one or more of the sprocketed tracks which have been running in synchronism with the video film from the starting point.
• the editor need not consider television frame measurement and need only concern himself with film footage as is conventionally done in editing motion picture films. This is highly advantageous because of the editor's familiarity with the practice, its relative simplicity, and also because of the direct "hands on” control which is generally preferred, from a creative point of view.
• each of a plurality of sprocket-driven audio playback machines (each containing one or more audio tracks) is locked to the others by an optical encoder or any other suitable synchronizing means (e.g. selsyn controlled motor or crystal controlled interlock).
• the sprocketed video recorder is likewise locked to the audio playback machines, as is a sprocketed audio film recorder on which the mixed sound track is to be recorded.
• the recorded video from the work print * is displayed on a monitor screen during mixing.
• the mixing engineer combines all of the individual audio tracks (with approp ⁇ riate volume control, fades, etc.) into a master finished audio track on the audio film recorder. Since all of these tracks are driven in synchronism from the same starting point, the master finished audio track will have the desired relatioip to the video with appropriate sound effects as selected by the mixing engineer.
• the SMPTE time code is transferred from the work print to a separate track on the sprocketed film which contains the master finished audio track.
• the sprocketed film contains both the master fin ⁇ ished audio track and a SMPTE time code which represents the video frames corresponding to the audio track.
• the final step is to "lay back" the master finished audio track to the master edited video tape.
• the master audio finished film is threaded onto a sprocketed reproducer having outputs which generat an audio output signal together with a regenerated SMPTE time code.
• the audio film is then brought to the startin point on the film (which has been visibly marked on the film) . It is now possible to transfer the master finishe audio track to the non-sprocketed video tape if the tape and film are locked together so that the audio track remains in exact synchronism with the video. In accor- dance with the invention, such synchronism is maintained by a comparison of the SMPTE time codes appearing on both the tape and film.
• FIG. 2 shows diagrammatically how the master finished audio track is synchronized with the master edited video tape.
• the master finished audio, recorded o sprocketed film, is placed on a conventional audio repro ⁇ ducer 10 and the master edited video tape is placed on a video tape machine 12.
• the SMPTE time codes from both th master finished audio track and the master edited video tape are regenerated and fed to a comparator 14, which generates a servo control error signal when the SMPTE tim codes are not the same. This error signal is then used t control the speed of the video tape so that the film and tape are driven in exact synchronism.
• the master finishe audio track may then be recorded on the master edited video tape in place of the existing audio track. Since
• the audio has been synchronized with the SMPTE time code, it will then be exactly synchronized with the recorded video. There is no need to compensate for differences in speed between the audio film and the video tape becuse the SMPTE time code is employed as the synchronizing means.
• a video screen 16 and a loud speaker 18 may be used to monitor the video and audio tracks, respectively, during the final combining step.
• Figure 3 shows in partially schematic form, the physical layout of the various parts of a video film recorder which was used to record a video work print on sprocketed magnetic film.
• a helical video scanning head 20 is mounted conventionally with its axis at an angle so that the tape (or film) is scanned helically.
• the machine includes a video erase head 22, an audio erase head 23, and an audio record/piayback head 24.
• a SMPTE code read/write head 25 is provided to read or write the
• the driving mechanism comprises a standard film drive sprocket 27 cooperating with a sprocket shoe 28.
• the sprocket drive mechanism is shown diagrammatically since it may be (and preferably is) a standard mechanism of the type used to drive movie film.
• the magnetic film is shown at 29 with arrows indicating the direction of movement.
• the film is wrapped around the top of sprocket 27 passing the video erase head 22 and around the helical scanning head 20
• ⁇ ⁇ ⁇ F ⁇ ⁇ ⁇ (from top to bottom) where it passes the heads 23, 24 and 25, then over a pressure idler 26 and back around the sprocket 27 to a take-up spool.
• the idler 26 is moved by a rotary solenoid (not shown) to exert pressure against film 29 in the PLAY mode, whether in forward or reverse directions. This controls the tension applied by the fil to the scanning drum. For high speed operation, the idle is moved to release the tension.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Management Or Editing Of Information On Record Carriers (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22154336

Family Applications (1)

Country Status (3)

Families Citing this family (6)

Family Cites Families (3)

• 1980
  • 1980-05-12 AU AU61283/80A patent/AU6128380A/en not_active Abandoned
  • 1980-05-12 WO PCT/US1980/000547 patent/WO1981003406A1/en unknown
  • 1980-05-12 EP EP19800901435 patent/EP0051584A1/de not_active Withdrawn

Non-Patent Citations (1)

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