摘要:
In playback of a video record (e.g., in video disc form) employing a FM carrier recording format, a defect compensation system is provided which substitutes delayed video signals for current video signals when a defect is encountered. The current video signals are obtained from the output of the player's pickup-responsive FM detector (illustratively of the zero-crossing detector type) via appropriate frequency responsive circuitry comprising a low pass filter (encompassing the recorded video signal bandwidth: e.g., 0-3 MHz.). To detect the occurrence of a defect, the FM detector output is also supplied to additional frequency responsive circuitry having a wideband response which desirably extends from DC to an upper frequency limit (e.g., 0-6 MHz.) well above the highest frequency of the video signal subject to recording. The wideband circuit output is supplied to pair of voltage level comparators, one supplying an output pulse of a given polarity whenever the wideband circuit output voltage level exceeds a level representative of the FM detector output for the maximum frequency of the FM carrier deviation range employed in recording, and the other supplying an output pulse of the given polarity whenever the wideband circuit output voltage level falls below a level representative of the FM detector output for the deviation range's minimum frequency. The comparator outputs are added together to form a defect indication signal. Switching between current and delayed video signals is controlled in response to the defect indication signal. Operation in the delayed signal mode is maintained for a short period after defect indication pulse termination (to allow video circuitry stabilization following the defect transient) by rendering a retriggerable one-shot responsive to the defect indication signal, and combining the output of the one-shot with the defect indication signal to form the switching control signal.
摘要:
In a video disc player, apparatus for generating phase error signals between a reference signal recorded on a video disc record and an external reference are utilized to correct both velocity errors in the recorded signal information and phase errors in the recorded reference signal.
摘要:
A digital video tape recorder ("VTR") that selects data useful for generating images during trick playback operation and records the data in trick play tape segments arranged on a tape to form fast scan tracks and multi-speed playback tracks. Each fast scan track comprises trick play tape segments located on a diagonal, relative to the length of the tape, of the same angle as the angle at which the heads of a VTR are expected to pass over the tape during trick play operation at a specific speed and direction of operation. Each multi-speed playback track comprises a plurality of trick play tape segments arranged parallel to the length of the tape. Data which is used for at least one mode of trick play operation is recorded in each trick play tape segment. Each fast scan track and multi-speed track crosses multiple normal play tracks. During playback at a wide variety of speeds and directions, the heads pass over enough trick play segments of the multi-speed playback track to generate recognizable images during trick play operation. Data is recorded in each trick play segment in a manner that optimizes the amount of data that can be routinely recovered during trick playback operation despite tracking errors.
摘要:
Methods of operating a digital video recording and playback device to identify trick play data, e.g., data that is intended for use during trick play modes of video playback device operation such as fast forward and reverse, by recording headers containing specific trick play information along with the trick play data are described. In one embodiment, the recording of headers which identify data as data intended for use during trick play as opposed to normal play operation is described. In addition to identifying data recorded data as normal play or trick play data headers associated with recorded data may identify the speed and direction of video tape recorder operation during which the specific data associated with the header is intended to be displayed at. When a data block includes data packets, a header may be used to identify various ones of the data packets as being for use during one mode of trick play operation, e.g., a first fast forward speed of operation, and other packets in the same data block as being for use during a second mode of trick play operation.
摘要:
A novel pickup stylus includes a tapering dielectric support element which has a tip defined by a prow and a relatively flat surface remote from the prow. The dielectric support element has an arrowhead-shaped cross-section in the region of its tip with the apex of the arrowhead-shape cross-section located on the prow and its base defined by the rear surface. The entire rear surface of the dielectric support element is covered with conductive material to form a narrow electrode in the region of its tip. To form a narrowed-electrode stylus, a tapering dielectric support element, having a prow and an electrode surface remote from the prow, is introduced in a trapezoidal abrasive groove while relative motion is established therebetween. The electrode face of the support element is gradually tilted toward the abrasive groove until it subtends a shallow angle therewith to form a portion having an arrowhead-shape cross-section in the region of its tip. The support element is lapped later to form a bottom surface defining a stylus shoe.
摘要:
A device for transmitting digital packetized video and audio data is disclosed. The transmitter includes a video encoder, a prioritizer, and a packetizer. The video encoder receives video signals and encodes the video signals into a digital video data stream including codewords. The video encoder also generates motion vectors and fully intra-coded video frames for use by a video tape recorder during trick play operation. The prioritizer is coupled to the video encoder. The prioritizer receives the digital video data stream and prioritizes the video data according to a preselected prioritization scheme optimized for identifying data useful to video tape recorder trick play operation. The preselected prioritization scheme assigns the video codewords in the video data stream to a priority level according to the utility of each video codeword for video tape recorder recording and playback operation and outputs both the video codewords and a priority level signal. The video codewords and the priority level signal are supplied to a transport packetizer which packetizes the video codewords and associates a header with each packet. The headers contain information identifying the assigned priority level of the codewords in each packet. This makes it possible for a video tape recorder receiving the video packets to determine the utility of the codewords in a given packet from the priority level information in the packet headers.
摘要:
A pickup arm has an intermediate portion interconnecting a first end portion and a second end portion. An end of the first end portion is secured to a supporting structure of a disc record player. During playback the first and second end portions are substantially parallel to the turntable surface of the player, and the intermediate portion positions the second end portion near the turntable surface. A signal pickup holder carrying a signal pickup is pivoted to an end of the second end porton remote from the pickup arm supported end in a manner that normally aligns the axes of the holder and the second end portion. During playback the intermediate portion positions the second end portion remote end, carrying the signal pickup holder pivot, as near to a disc record disposed on the turntable surface as practicable, in order to reduce the angle included between (a) the disc record surface, and (b) a line joining the signal pickup tip and the signal pickup holder pivot, thereby reducing deleterious, forward and backward displacement of the signal pickup along the disc record spiral groove as a result of up and down motion of the signal pickup in the spiral groove.