1. Field of the Invention
This invention relates to video tape recording apparatus and in particular to apparatus for producing a synchronized video tape recording from asynchronously recorded video information.
2. Discussion Relative to the Prior Art
Although apparatus embodying the invention has a wide variety of uses, the description of a particular problem which such apparatus solves is perhaps best illustrative of the present state of the art: A video camera for use in producing a recorded tape that is playable in a consumer video recorder typically cooperates with a shoulder-carried helical-scan recorder for producing a helical-scan video recording of various scenes. In its usual form, the shoulder-carried recorder has a continuously running head-wheel and a tape transport which runs, like a conventional photographic movie camera, at the whim of the camera operator. For example, the operator will record a scene by pressing his tape-advance button; stop the scene recording when desired by releasing the "button"; shoot another scene by pressing the "button"; stop recording that scene by again releasing the "button"; and so on, all the while the head-wheel continuously runs. What ensues, therefore, is a series of recorded scenes which have proper sync therewithin, but which are all asynchronous with respect to each other. When playing such a recording of asynchronously recorded scenes through a consumer recorder operating in its playback mode, the television which cooperates with the recorder may exhibit, in varying degrees, one or more of the following disturbances as the servos of the recorder try to switch from locking on to one recorded scene to locking on to the next recorded scene: picture roll-over; a vertically traveling bar within the television display; picture tear; jitter. Such disturbances are bad in and of themselves, but are especially distressful when the cooperating television has a long time constant in its vertical and horizontal sync circuits. In such cases the disturbances may be quite long-lived.
Although apparatus embodying the invention is primarily adapted to solve the aforementioned problem, such apparatus has inherent versatility and may be employed, for instance, to "splice" scene information from two or more tapes of asynchronized information; which tapes may or may not have the same recording format; and which "spliced" scene information may be recorded in any of a variety of different formats. Scenes recorded on two different tapes which are, for example, playable on a Betamax machine (Sony Corp.) may be "spliced" together and recorded on a tape having either the Betamax or the VHS (Panasonic; Matsushita Corp.) formats. Or, a scene recorded in the Betamax format may be "spliced" to a scene recorded in the VHS format, and the resultant "spliced" scene information may be recorded in either the Betamax or the VHS formats, etc. Such techniques, as well as an improved still-framing technique which is both devoid of the image degradation that commonly occurs when using a consumer recorder in a still-framing mode, and which cannot cause undue tape and head wear while still-framing, will be discussed in detail below. Indeed, a form of still-framing may, by means of the invention, be provided to a video recorder which otherwise does not have such capability.