Video signal processing method for digital video decoder

• US 20050024539A1
• Filed: 08/27/2004
• Published: 02/03/2005
• Est. Priority Date: 06/07/2001
• Status: Active Grant

• Current Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Original Assignee: Yasuhiko Okamoto
• Inventors: Okamoto, Yasuhiko
• Granted Patent: US 7,256,838 B2
• Time in Patent Office: Days
• US Class Current: 348/607
• CPC Class Codes: H04N 5/14 Picture signal circuitry for video frequency region cameras or camera modules comprising electronic image sensors, or control thereof H04N23/00
• CPC Class Codes: H04N 5/46 for receiving on more than one standard at will deflecting circuits of multi-standard receivers H04N3/27

Abstract

A video signal processing apparatus which is provided for a digital video decoder and can automatically and properly adjust a fluctuation of the number of sampling data of digital composite video signals includes: an adjusting circuit which performs a partial adding/deleting process to the video signals so as to correct the fluctuation in number of sampling data constructing the digital composite video signals supplied to the decoder; and a discriminating circuit which compares the number of sampling data of each video signal and the preset reference number of sampling data and outputs an operation signal for the adding/deleting process to the adjusting circuit when a difference between them as a comparison result lies within a predetermined adjusting range.

Claims

1-19. -19. (canceled)

20. A video signal processing method which is provided for a digital video decoder for decoding continuous digital composite video signals in order to suppress a fluctuation of the number of sampling data constructing each of said digital composite video signals to be processed by said decoder, said method comprising:

executing a partial adding/deleting process to each of said digital composite video signals in order to correct the fluctuation of said number of sampling data of each of said digital composite video signals;

comparing said number of sampling data of each of said digital composite video signals with a reference number of sampling data of each of said digital composite video signals,

discriminating whether the number of sampling data of said digital composite video signals should be increased or decreased on the basis of a difference obtained as a result of said comparison, and when said difference lies within a predetermined adjusting range, outputs an operation signal for increasing or decreasing said number of sampling data to said adjusting circuit in order to execute said adding/deleting process.

21. The method according to claim 20, comprising counting the number of sampling data with respect to each of a predetermined number of digital composite video signals, accumulating a difference between each of said count values and said reference number of sampling data, and outputting said operation signal when a result of said accumulation lies within said predetermined adjusting range.

22. The method according to claim 21, wherein said predetermined number of digital composite video signals correspond to a scanning field which is specified between said digital composite video signals each having a vertical sync signal and said predetermined adjusting range is given with respect to said accumulation of the differences with regard to a plurality of digital composite video signals in said field.

23. The method according to claim 21, wherein in order to eliminate instability of image processes accompanied by the switching operations between an adjusting mode in which the number of sampling data is increased or decreased and a non-adjusting mode in which the increase or decrease of the number of sampling data is not performed, the method further comprises:

providing a first adjusting range which is used in said adjusting mode and specified by a pair of threshold values; and

providing a second adjusting range which is specified by a pair of threshold values different from said threshold values and used in said non-adjusting mode.

24. The method according to claim 23, wherein said first adjusting range includes said second adjusting range, so that hysteresis characteristics are given to switching characteristics between said modes.

25. The method according to claim 20, wherein each of said digital composite video signals is video information of a scanning line unit including a blanking portion, and said adding/deleting process is an increase/decrease of said blanking portion.

26. The method according to claim 21, further comprising:

storing each of said digital composite video signals in a memory having a data insertion/extraction port for performing said adding/deleting process to said signal; and

managing said memory by FIFO system and performing said adding/deleting process to each of said digital composite video signals when a control unit receives said operation signal.

27. The method according to claim 21, further comprising:

detecting a horizontal sync signal provided for each of said composite video signals and a vertical sync signal provided for each digital signal group consisting of a predetermined number of said composite video signals from said continuous digital composite video signals;

using a counter to count said number of sampling data of each of said digital composite video signals and resetting a count value of the counter to an initial value every detection of said horizontal sync signal by said detecting unit;

storing the count value obtained by said counter in a first register;

sequentially performing the calculation of said difference between said count value held in said register and said reference number of sampling data and performs said accumulation of each of said calculated result;

storing an accumulation value obtained by said arithmetic operating unit in a second register whose accumulation value is reset to an initial value every detection of said vertical sync signal by said detecting unit; and

performing said discrimination by using said accumulation value every reset of said register.

28. The method according to claim 27, wherein said sync signal detecting unit has a horizontal sync signal detecting circuit for detecting said horizontal sync signal and a vertical sync signal detecting circuit for detecting said vertical sync signal, said horizontal sync signal detecting circuit sends a signal for resetting said count value of said counter, and said vertical sync signal detecting circuit sends a signal for resetting said accumulation result in said second register.

29. The method according to claim 27, further comprising calculating the differential number of sampling data, and sequentially accumulating a result of said calculation.

30. The method according to claim 27, further comprising comparing each of said differences in said digital signal group, obtaining a maximum difference among said differences from a maximum value and a minimum value obtained by said comparison, discriminating whether each of said maximum difference and said accumulation results lies within a predetermined adjusting range or not, and discriminating whether the number of sampling data of said digital composite video signals should be increased or decreased by using each of said discriminated results.

31. The method according to claim 30, further comprising obtaining said maximum difference between said maximum value and said minimum value, and obtaining said maximum difference every detection of said vertical sync signal.

32. The method according to claim 31, further comprising:

a first discrimination of whether said accumulation value that is held in said second register lies within a preset adjusting region or not;

a second discrimination of whether the maximum difference lies within another preset adjusting region or not; and

making a decision regarding the increase/decrease of said number of sampling data on the basis of both of said decision results of both of said first and second discriminations.

33. The method according to claim 32, wherein said decision is made on the basis of an AND of both of said decision results.

34. The method according to claim 32, wherein upon operation in said adjusting mode in which the increase/decrease of said number of sampling data is performed, when said first discriminating circuit unit determines that said accumulation value does not exist in said adjusting region and said second discriminating circuit unit determines that said maximum difference value does not exist in said adjusting region, said discriminating unit makes said general decision so as to switch from said adjusting mode to said non-adjusting mode.

35. The method according to claim 32, wherein upon operation in the non-adjusting mode in which the increase/decrease of said number of sampling data is not performed, when it is determined that said accumulation value exists in said adjusting region and that said maximum difference value exists in said adjusting region, said decision is made so as to switch from said non-adjusting mode to said adjusting mode.

36. The method according to claim 32, wherein in order to eliminate instability of image processes accompanied by switching operations between said adjusting mode in which said number of sampling data is increased or decreased and said non-adjusting mode in which the increase or decrease of said number of sampling data is not performed,

the adjusting region for said first discrimination comprises a first adjusting range which is used upon operation in the adjusting mode and specified by a pair of threshold values and a second adjusting range which is specified by a pair of threshold values which are different from said threshold values and used in said non-adjusting mode, and

said adjusting region for said second discrimination comprises a third adjusting range which is used upon operation in the adjusting mode and specified by a pair of threshold values and a fourth adjusting range which is specified by a pair of threshold values which are different from said threshold values in said third adjusting range and used in said non-adjusting mode.

37. The method according to claim 36, wherein said first adjusting range includes said second adjusting range and said third adjusting range includes said fourth adjusting range, so that hysteresis characteristics are given to switching characteristics between both modes in said first and second discriminations.

38. The method according to claim 36, wherein each of said first and second discriminations sets a decision result in each of said modes as a temporary decision result, makes a final decision on the basis of said temporary decision results and history of a plurality of temporary decision results so as to suppress a inversion of each of said decision result, and wherein said decision is made on the basis of both of said final decision results.