Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Patent
1998-01-07
1999-09-14
Nguyen, Huy
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
386 95, 386 81, H04N 5783
Patent
active
059534877
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to the field of image recordation and playback, and in particular concerns user programming of control commands and data referring to recorded image tracks.
Current image recording formats for consumer equipment and the like utilize a high proportion of the available recording media for program content, namely video and audio. There is often little recording capability available for occasional use, such as to record user derived commands and data. One low data rate signal that can be recorded on a tape or similar medium is a timing indication signal. In the VHS tape format, control track pulses are generated at the image picture rate and are recorded together with the program content. On replay, these pulses are utilized to control reproduction so as to maintain the same rate as when recorded.
The control track pulses are recorded along an edge of the tape and mark each frame, whereas the video program content is recorded across the width of the tape. Typically in the NTSC TV standard the control track pulses have a repetition period of about 16.6 milliseconds and a duration or duty cycle of about 50%, that is, alternately 8 milliseconds at one level (e.g., high) and 8 milliseconds at another level (e.g., zero). In PAL operation the repetition period is 20 milliseconds and the pulse duration is about 10 milliseconds.
It has been recognized that such a control track signal does not make good use of the magnetic media. The part of the recorded control track signal that is needed to control timing of playback to match the image picture rate, is only a single edge such as the leading rising edge during each period. The remainder of the control track between the rising edges of successive periods could be varied to encode additional data.
In the early 1980's the Video Index Search Signal (VISS) was introduced and utilized an existing recording track for supplementary data such as a count for referencing particular portions of the program on the tape. The rising edges of the control track signal are used for playback speed control as above. According to the VISS standard, the trailing, non-time critical edge of the control track pulse can be controllably phase shifted, while maintaining the timing of the leading edge for use in controlling playback speed. Data is encoded by varying the phase of the trailing edge of the recorded command track signal between two distinct phases, representing digital true and false or one and zero value data bits.
This phase encoding method is uncomplicated. A logical "1" value can be encoded, for example, by advancing the phase of the trailing edge, thus shortening the positive portion of the control pulse to a duration of about 27.5% of the pulse repetition period. A logical "0" value delays the trailing edge as compared to a nominal 50% duty cycle, for example to produce a pulse of 60% duration. Simple timing and gating circuits can distinguish between pulses having a duty cycle that is longer or shorter than a reference duration (e.g., 50%), to decode the data into a serial digital data stream using this relatively dependable and inexpensive communication channel technique. However, each control track pulse period can encode only one data bit to a one or zero value. The data rate is slow.
Video cassette recorders (VCRs) can employ the VISS method to mark the starting point of a recording or a segment of a recording, as a means to enable cuing for subsequent replay. A standard for such index signals employs a marker sequence consisting of a 63 bit succession in which the first and last bits are logical zeros and all the intermediate bits are logical ones, the zeros and ones being distinguished by the phase difference of the trailing edge of the control pulse.
A similar use of control track encoding is employed by a system known as VHS Address Search Signal or VASS, which also uses phase difference of the trailing edge to encode logical data. The VASS system enables a digital address to be written to the control track during rec
REFERENCES:
patent: 4519003 (1985-05-01), Scholz
patent: 4549231 (1985-10-01), Namiki
patent: 5333091 (1994-07-01), Iggulden et al.
patent: 5748332 (1998-05-01), Lee
*Patent Abstracts of Japan, vol. 017, No. 082, Feb. 18, 1993 and Japanese Pat. 4-283447.
**Patent Abstracts of Japan, vol. 007, No. 266, Nov. 26, 1983 and Japanese Pat. 58-146072.
***Patent Abstracts of Japan, vol. 009, No. 097, Apr. 26, 1985 and Japanese Pat. 59-221851.
****Patent Abstracts of Japan, vol. 017, No. 184, Apr. 9, 1993 and Japanese Pat. 4-337548.
*****Patent Abstracts of Japan, vol. 006, No. 171, Sep. 4, 1982 and Japanese Pat. 57-088542.
Engle Joseph Craig
Herzberg Jesse Edward
Kim Sung Jo
Metcalfe Robert Harold
Platte Hans-Joachim
Davenport Francis A.
Laks Joseph J.
Nguyen Huy
Thomson Consumer Electronics
Tripoli Joseph S.
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