JP2005303887A - Signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer a signal processor which standardizes a broadcasting signal of the PAL system, and creates a digital component signal not to set up flickers when reproducing. <P>SOLUTION: A recording and reproducing device 1 is composed of a tuner 2, a video decoder 3, an audio/digital converter 4, a video capture 5, an MPEG encoder 6, an output controller 7, an input controller 8, an MPEG decoder 9, a video encoder 10, and an audio D-A converter 11. A perpendicular color-difference signal eliminating filter 16 of the video capture 5 performs the conversion processing of the color-difference signal (Cb, Cr) from a 4:2:2 format to a 4:2:0 format for video data which are subjected to size adjustment by a horizontal filter 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a signal processing apparatus that samples a PAL broadcast signal and converts it into a digital component signal.

  When a TV signal is compressed in MPEG (Moving Picture Experts Group) 2 format and recorded digitally on a disk medium such as a DVD (Digital Versatile Disk), the analog video signal must first be sampled and converted to a digital component signal. .

  ITU-RBT.601 (ITU-R: International Telecommunication Union Telecommunication Standardization Sector, BT.601: Recommendation 601) samples luminance signals (Y) and color difference signals (Cb, Cr) that make up digital component signals. The frequencies are determined to be 13.5 MHz and 6.75 MHz, respectively, and the ratio is 4: 2: 2.

  On the other hand, in the DVD-Video standard, MP @ ML (Main Profile at Main Level) is adopted as the MPEG stream, and the ratio of the sampling frequency of the luminance signal to the color difference signal is 4: 2: 0 (for example, Patent Document 1). In practice, the 4: 2: 0 format and the 4: 0: 2 format are repeated. However, for convenience, the format is expressed as 4: 2: 0.

  Therefore, in a digital video recorder that digitally records and reproduces a television broadcast in MPEG2 format, the ratio of the luminance signal of the signal input to the MPEG encoder and the sampling frequency of the color difference signal is changed from 4: 2: 2 to 4: It is necessary to convert to 2: 0 (for example, Patent Document 2).

  In the process of converting the sampling frequency ratio from 4: 2: 2 to 4: 2: 0, a color difference signal existing spatially at a 4: 2: 0 position is generated using a filter. In the 4: 2: 2 format, the luminance signal and the color difference signal are arranged at spatial positions as shown in FIG. In FIG. 3, the “x” mark indicates the spatial position in one frame of the luminance signal, and the “◯” mark indicates the spatial position in one frame of the color difference signal. In MPEG, the luminance signal and chrominance signal information is usually represented by 8-bit data, but in the 4: 2: 2 format, 8-bit luminance signal information is assigned to each pixel. Information of one color difference signal is assigned for each.

  On the other hand, in the 4: 2: 0 format, 8-bit luminance signal information is assigned to each pixel, and 8-bit color difference signal (Cb, Cr) information is assigned to every four pixels. Luminance signals and color difference signals are arranged at spatial positions as shown.

  When this is expressed in the time axis direction, the Top field and the Bottom field are arranged at spatial positions as shown in FIG. 5 (4: 2: 2 format) and FIG. 6 (4: 2: 0 format), respectively. Will be.

The conversion of the color difference signal from the 4: 2: 2 format to the 4: 2: 0 format is performed by multiplying the information of each color difference signal by a filter coefficient considering the sampling position. For example, the color difference signal of the C′3 line in the Top field in the 4: 2: 0 format shown in FIG. 6 is obtained by using the color difference signal information of the C3 line, the C5 line, and the C7 line in the 4: 2: 2 format. ,
[Equation 1]
C'3 = (16 × C3 + 192 × C5 + 48 × C7) / 256
It is converted by the formula. Similarly, the color difference signal for the C'2 line in the Bottom field also uses the information of the color difference signals for the C2, C4 and C6 lines in the 4: 2: 2 format.
[Equation 2]
C'2 = (48 × C2 + 192 × C4 + 16 × C6) / 256
It is converted by the formula. These filter coefficients are not limited to the above values, but are preset values.

  By the way, in a PAL (Phase Alternation by Line) broadcast signal (hereinafter referred to as a PAL signal), the phase of a color subcarrier (color subcarrier) is inverted every television horizontal line in the field.

For example, if the phase of the color difference signal in each line in a certain frame is represented by “+” and “−”, the phase of the color subcarrier for each color difference signal in the 4: 2: 2 format of FIG.
Top field: + C1, -C3, + C5, -C7, + C9, ...
Bottom field: + C2, -C4, + C6, -C8, + C10, ...
Can be expressed as

But in the next frame,
Top field: -C1, + C3, -C5, + C7, -C9, ...
Bottom field: + C2, -C4, + C6, -C8, + C10, ...
As compared with the previous frame, the phase of the color subcarrier with respect to the color difference signal of the Top field is reversed. This is because the number of horizontal scanning lines of the PAL signal is an odd number of 625, and one line shift occurs between frames, and the order is inverted alternately.

When the color difference signal in each frame is converted into the 4: 2: 0 format in consideration of the phase of the color subcarrier, in the first frame, in the Top field and Bottom field,
[Equation 3]
Top field
C'3 ₁ = (−16 × C3 + 192 × C5−48 × C7) / 256
C'5 ₁ = (−16 × C7 + 192 × C9−48 × C11) / 256
:
[Equation 4]
Bottom field
C'2 ₁ = (48 x C2-192 x C4 + 16 x C6) / 256
C'4 ₁ = (48 x C6-192 x C8 + 16 x C10) / 256
:
In the next frame, in the Top field and Bottom field,
[Equation 5]
Top field
C'3 ₂ = (16 × C3−192 × C5 + 48 × C7) / 256
C'5 ₂ = (16 × C7−192 × C9 + 48 × C11) / 256
:
[Equation 6]
Bottom field
C'2 ₂ = (48 x C2-192 x C4 + 16 x C6) / 256
C'4 ₂ = (48 x C6-192 x C8 + 16 x C10) / 256
:
It becomes.

In particular, if the value of each color difference signal is the same, in the first frame, in the Top field and Bottom field,
[Equation 7]
Top field
C'3 ₁ = C'5 ₁ = (−16 × C + 192 × C−48 × C) / 256 = + C / 2
[Equation 8]
Bottom field
C'2 ₁ = C'4 ₁ = (48 × C−192 × C + 16 × C) / 256 = −C / 2
In the next frame, in the Top field and Bottom field,
[Equation 9]
Top field
C'3 ₂ = C'5 ₂ = (16 × C−192 × C + 48 × C) / 256 = −C / 2
[Equation 10]
Bottom field
C'2 ₂ = C'4 ₂ = (48 × C−192 × C + 16 × C) / 256 = −C / 2
It becomes.

The phase of each color difference signal after conversion at 4: 2: 0 in FIG.
Top field: + C / 2, -C / 2, + C / 2, -C / 2, + C / 2, ...
Bottom field: -C / 2, -C / 2, -C / 2, -C / 2, -C / 2, ...
Thus, the phase of the Top field is inverted every frame. Since the phase of the Bottom field is always constant, when this signal having the same value of each color difference signal is viewed on a television, light and dark are repeated for each frame, resulting in flicker.

In normal television broadcasting, even if the phase is reversed for each frame in this way, viewing is hardly affected, but in a special situation signal pattern in which the values of each color difference signal are exactly the same, flicker is present. Prominently appear.
Japanese Patent No. 3296758 JP 2001-359118 A

  The present invention has been made in view of the above circumstances, and provides a signal processing apparatus that samples a PAL broadcast signal and generates a digital component signal so that flicker does not occur during reproduction.

  To achieve the above object, the signal processing apparatus according to claim 1 is a PAL video signal in which each frame is composed of an odd field and an even field, and the odd field is a plurality of odd numbers in one frame. The color subcarrier phase is 180 degrees different from line to line, and the phase of the color subcarrier in the same line is 180 degrees different from frame to frame, and the even field is a plurality of even lines in one frame. And the phase of the color subcarrier is 180 degrees different for each line, and the ratio of the sampling frequency of the luminance signal Y, the color difference signal Cb, and the color difference signal Cr is 4: 2. : In the signal processing apparatus for generating the digital component signal which is 2, the front of each of the odd lines for each field The chrominance signal is multiplied by a predetermined filter coefficient and added to generate the chrominance signal of the digital component signal having a sampling frequency ratio of 4: 2: 0, and the plurality of chrominance signals for each field. A chrominance signal for generating the chrominance signal of the digital component signal having a sampling frequency ratio of 4: 2: 0 by multiplying the chrominance signal of each even line by a predetermined filter coefficient. The predetermined filter coefficient is set so that the color difference signal disappears as a result of addition when the values of the color difference signals are all equal.

  According to the present invention, when the value of each color difference signal is the same, the color difference signal disappears, so that flicker does not occur and a visually good result can be obtained.

  An embodiment of a signal processing apparatus of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a recording / reproducing apparatus 1 as a signal processing apparatus in this embodiment includes a tuner 2, a video decoder 3, an audio A / D converter 4, a video capture 5, an MPEG encoder 6, an output controller 7, and an input controller. 8, an MPEG decoder 9, a video encoder 10, and an audio D / A converter 11.

  The tuner 2 has a function of receiving a PAL broadcast signal (hereinafter referred to as a PAL signal), separating the received PAL signal into a video signal and an audio signal and outputting them. The video decoder 3 has a function of converting the video signal output from the tuner 2 into video data that is a digital component signal (luminance signal (Y) and color difference signals (Cb, Cr)), and an audio A / D converter 4. Has a function of converting the audio signal output from the tuner 2 into digital data (audio data).

  The video capture 5 includes a horizontal filter 15 and a vertical color difference signal removal filter 16 and has a function of performing filtering processing on video data output from the video decoder 3.

  Specifically, the horizontal filter 15 has a function of adjusting the video data output from the video decoder 3 to a predetermined image size, and the vertical color difference signal removal filter 16 is adjusted in size by the horizontal filter 15. The video data has a function of converting color difference signals (Cb, Cr) from the 4: 2: 2 format to the 4: 2: 0 format (details will be described later).

  The MPEG encoder 6 has a function of compressing audio data output from the audio A / D converter 4 and video data output from the video capture 5 to generate MPEG2 format video data.

  The output controller 7 includes a recording device 21 that writes video data to the storage medium 12, and has a function of performing recording control when recording the video data generated by the MPEG encoder 6 on the storage medium 12. The input controller 8 And a reading device that reads the video data written in the storage medium 12, and has a function of performing reading control when reading the video data recorded in the storage medium 12.

  The MPEG decoder 9 has a function of separating and expanding video data and audio data from video data output from the input controller 8. The video encoder 10 has a function of generating and outputting a video signal based on the video data output from the MPEG decoder 9, and the audio D / A converter 11 is based on the audio data output from the MPEG decoder 9. Have a function of generating and outputting an audio signal.

  The storage medium 12 is a writable CD-R, CD-RW, DVD-R, DVD-RW, DVD-RAM, DVD + RW, hard disk, or the like.

  When the recording / reproducing apparatus 1 starts recording of the PAL signal, the tuner 2 separates the received PAL signal into a video signal and an audio signal and outputs them. The audio A / D converter 4 converts the audio signal output from the tuner 2 into digital audio data, and the video decoder 3 converts the video signal output from the tuner 2 into digital video data.

  Next, the horizontal filter 15 of the video capture 5 adjusts the video data output from the video decoder 3 to a predetermined image size, and the vertical color difference signal removal filter 16 converts the color difference signal for each field of each frame. Process.

  For example, the vertical chrominance signal removal filter 16 sets the filter coefficient to a value represented by the following formula 11 and sets the top field C3 to C7 (CN to C (N + 4)) in the 4: 2: 2 format. Using the color difference signal information in the line, calculation is performed according to the equation (11), and C′3 (C′N) color difference signal information in the 4: 2: 0 format is generated.

[Equation 11]
Top field
C'3 = (0 × C3 + 128 × C5 + 128 × C7) / 256
(C'N = (0 × CN + 128 × C (N + 2) + 128 × C (N + 4)) / 256: N is an odd line number)
Similarly, the vertical chrominance signal removal filter 16 sets the filter coefficient to a value represented by the following equation 12 and uses the information of the chrominance signal in the C2 to C6 lines of the Bottom field in the 4: 2: 2 format. The calculation is performed according to the equation (12), and information on the color difference signal of C′2 (C′M) in the 4: 2: 0 format is generated.

[Equation 12]
Bottom field
C'2 = (128 × C2 + 128 × C4 + 0 × C6) / 256
(C'M = (128 × CM + 128 × C (M + 2) + 0 × C (M + 4)) / 256: M is an even line number)
At this time, looking at the phase of the color subcarrier of each color difference signal for each frame, the phase of the color subcarrier of the Top field is inverted 180 degrees for each line, so each color difference signal is actually Is generated according to the following equations (13) and (14).

[Equation 13]
1st frame
C'3 ₁ = (0 × C3 + 128 × C5−128 × C7) / 256 = 128 (C5−C7) / 256
C'2 ₁ = (128 × C2−128 × C4 + 0 × C6) / 256 = 128 (C2−C4) / 256
:
[Equation 14]
2nd frame
C'3 ₂ = (0 × C3−128 × C5 + 128 × C7) / 256 = 128 (−C5 + C7) / 256
C'2 ₂ = (128 × C2−128 × C4 + 0 × C6) / 256 = 128 (C2−C4) / 256
:
In a special situation where the values of the color difference signals are exactly the same, the results are all “0” and the color difference signals are not canceled out, but flicker does not occur. Since the influence of the absence of the color difference signal is smaller than the occurrence of flicker, the visual result is good.

  As shown in FIG. 2, the spatial position of the color difference signal in the video data obtained by converting the color difference signal information of the Top field and Bottom field for each frame is slightly moved as compared with the conventional one. Doing so does not change enough to affect viewing. In FIG. 2, a color difference signal indicated by a broken line is a spatial position in the conventional conversion method (corresponding to FIG. 6).

  Next, the MPEG encoder 6 compresses the audio data output from the audio A / D converter 4 and the video data output from the video capture 5 to generate MPEG2 format video data, and the output controller 7 The video data generated by the encoder 6 is recorded on the storage medium 12.

  When reproducing the video data thus converted, the input controller 8 reads the video data from the storage medium 12 and supplies the video data to the MPEG decoder 9. The MPEG decoder 9 converts the supplied video data into video data and audio. Separate and decompress data. The video encoder 10 converts the expanded video data into an analog video signal, and the audio D / A converter 11 converts the expanded audio data into an analog audio signal and outputs it.

  Expressions 11 to 14 are examples in the present embodiment, and are not limited thereto.

  In addition, the recording / reproducing apparatus 1 is shown as an embodiment of the present invention, but the present invention is not limited to this, and as shown by the broken line in FIG. May be. In this case, the playback device 22 includes an input controller 8, an MPEG decoder 9, a video encoder 10, and an audio D / A converter 11, and the playback function is the same as the conventional one. On the other hand, the recording device 21 includes a tuner 2, a video decoder 3, an audio A / D converter 4, a video capture 5, an MPEG encoder 6, and an output controller 7, and performs the same processing as the recording / reproducing device 1 described above.

It is a figure which shows the function structure of a recording / reproducing apparatus. It is a figure which shows the spatial position of the luminance signal and color-difference signal in 4: 2: 0 format. It is a figure which shows the spatial position of the luminance signal and color-difference signal in 4: 2: 2 format. It is a figure which shows the spatial position of the luminance signal and color-difference signal in 4: 2: 0 format. It is a figure which shows the spatial position (Yt cross section) of the luminance signal and color difference signal in 4: 2: 2 format. It is a figure which shows the spatial position (Yt cross section) of the luminance signal and color difference signal in 4: 2: 0 format.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Recording / reproducing apparatus, 2 ... Tuner, 3 ... Video decoder, 4 ... Audio A / D converter, 5 ... Video capture, 6 ... MPEG encoder, 7 ... Output controller, 8 ... Input controller, 9 ... MPEG decoder, 10 ... Video encoder, 11 ... Audio D / A converter, 12 ... Storage medium, 15 ... Horizontal filter, 16 ... Vertical color difference signal elimination filter, 21 ... Recording device, 22 ... Playback device

Claims (1)

A PAL video signal in which each frame is composed of an odd field and an even field, the odd field is composed of a plurality of odd lines in one frame, and the phase of the color subcarrier is 180 degrees different for each line; The phase of the color subcarrier on the same line is different by 180 degrees for each frame, the even field is composed of a plurality of even lines of one frame, and the phase of the color subcarrier is different by 180 degrees for each line In a signal processing device that generates a digital component signal in which the ratio of sampling frequencies of the luminance signal Y, the color difference signal Cb, and the color difference signal Cr is 4: 2: 2.
The color difference of the digital component signal in which the ratio of the sampling frequencies is 4: 2: 0 by multiplying the color difference signal of each of the plurality of odd lines by a predetermined filter coefficient for each field. Generate a signal,
The color difference of the digital component signal in which the ratio of the sampling frequencies is 4: 2: 0 by multiplying the color difference signal of each of the plurality of even-numbered lines by a predetermined filter coefficient for each field. A color difference signal generating means for generating a signal;
The signal processing apparatus according to claim 1, wherein the predetermined filter coefficient is set such that the color difference signal disappears as a result of addition when the values of the color difference signals are all equal.

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