CN106034239B - Method and apparatus for encoding composite video signal - Google Patents
Method and apparatus for encoding composite video signal Download PDFInfo
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Abstract
The invention relates to the field of video image processing, and discloses a method and a device for coding a composite video signal. The invention comprises the following steps: preprocessing a luminance signal to be encoded and a chrominance signal to be encoded, the preprocessing including: performing luminance comb filtering on a luminance signal to be coded and/or performing chrominance comb filtering on a chrominance signal to be coded; a composite video signal is generated from the preprocessed luminance and chrominance signals. In the invention, the luminance signal to be coded and/or the chrominance signal to be coded are/is comb-filtered at the coding end before the composite video signal is generated, so that the bright-color crosstalk caused by the crosstalk of the luminance signal into the chrominance spectrum or the crosstalk of the chrominance signal into the luminance spectrum can be automatically and efficiently removed from the source.
Description
Technical Field
The present invention relates to the field of video image processing, and more particularly, to a method and apparatus for encoding a composite video signal.
Background
Composite Video Broadcast Signal (CVBS for short)，That is, the video signal after separating the accompanying sound from the full Television signal is a video standard widely used for signal coding, transmission and storage, the common coding modes of the composite video signal are NTSC (National Television standard) and PAL (Phase Alternating Line), and the composite video signal is the color after being modulated by the chrominance subcarrier during codingAnd the degree and the brightness are added.
Since the luminance frequency spectrum in the composite video signal has a large blank area near even harmonics, the frequency spectrum of the chrominance signal is shifted to the blank area of the luminance signal frequency spectrum by a modulation method, and the frequency spectrum of the color difference signal is staggered with the frequency spectrum of the luminance signal, which is called frequency spectrum interspersion.
According to the definition of the international standard for composite video signals: NTSC adds chrominance spectrum signals in a region of +/-1.3 MHz near a luminance spectrum of 3.58MHz by using a spectrum spacing method, wherein the total frequency band is 4.2 MHz; the PAL adds the chrominance spectrum signal using a spectral interpolation method in the region of ± 1.3MHz around the luminance spectrum 4.43MHz, for a total band of 6 MHz.
If the high frequency information in the vertical direction of the luminance signal is rich, the high frequency components of the chrominance signal are spectrally clustered into regions allocated to the chrominance spectrum in an interlaced manner, and the high frequency components of the chrominance signal are also spectrally clustered into the interlaced luminance spectrum, and this mutual influence is called bright-color crosstalk. For this reason, it is difficult for the decoding end to completely and cleanly separate the luminance and chrominance signals, and there are crosstalk components.
At present, most of the methods for reducing the influence of the bright-color crosstalk are better bright-color separation methods used in decoding, and the traditional method has no key points for finding problems: the composite video signal has the problem of luminance and chrominance spectrum cross-talk at the encoding end, and because the luminance signal and the chrominance signal in the CVBS signal exist at certain frequency bands simultaneously, the luminance signal and the chrominance signal cannot be completely separated at the decoding end, and the phenomenon of luminance and chrominance crosstalk is still obvious.
Disclosure of Invention
The present invention is directed to a method and apparatus for encoding a composite video signal, which fundamentally removes crosstalk of bright colors caused by crosstalk of a luminance signal into a chrominance spectrum or crosstalk of a chrominance signal into a luminance spectrum.
To solve the above technical problem, an embodiment of the present invention discloses a method for encoding a composite video signal, including the following steps:
preprocessing a luminance signal to be encoded and a chrominance signal to be encoded, the preprocessing including: performing luminance comb filtering on a luminance signal to be coded and/or performing chrominance comb filtering on a chrominance signal to be coded;
a composite video signal is generated from the preprocessed luminance and chrominance signals.
The embodiment of the invention also discloses a device for coding the composite video signal, which comprises the following units:
a pre-processing unit for pre-processing a luminance signal to be encoded and a chrominance signal to be encoded, the pre-processing unit comprising: a luminance comb filtering subunit, configured to perform luminance comb filtering on the luminance signal to be encoded, and/or a chrominance comb filtering subunit, configured to perform chrominance comb filtering on the chrominance signal to be encoded;
a composite video signal generating unit for generating a composite video signal from the preprocessed luminance signal and chrominance signal.
Compared with the prior art, the implementation mode of the invention has the main differences and the effects that:
before generating the composite video signal, the invention carries out comb filtering on the luminance signal to be coded and/or the chrominance signal to be coded at the coding end, and can automatically and efficiently remove the bright-color crosstalk caused by the crosstalk of the luminance signal into the chrominance spectrum or the crosstalk of the chrominance signal into the luminance spectrum from the source.
Furthermore, whether comb filtering is performed or not is controlled by combining the luminance boundary information, the chrominance boundary information and the preset boundary threshold value, crosstalk of the luminance signal and the chrominance signal cannot be generated, comb filtering is not used, and the workload of filtering processing can be effectively reduced.
Furthermore, in the step of performing luminance comb filtering on the luminance signal to be coded, the luminance signal is subjected to band-pass filtering first, and then the bandpass signal is subjected to luminance comb filtering, so that the bandpass filtering avoids affecting signals beyond bandpass frequency.
Drawings
Fig. 1 is a flowchart illustrating a method for encoding a composite video signal according to a first embodiment of the present invention;
FIG. 2 is a flowchart illustrating a method for encoding a composite video signal according to a second embodiment of the present invention;
FIG. 3 is a flow chart of a preferred embodiment of the third embodiment of the present invention;
FIG. 4 is a schematic structural diagram of an apparatus for encoding a composite video signal according to a fourth embodiment of the present invention;
fig. 5 is a schematic block diagram of a structure of a composite video signal encoding end of a module for adding bright-color crosstalk cancellation according to a preferred embodiment of the sixth embodiment of the present invention;
fig. 6 is a schematic structural diagram of a bright-color crosstalk elimination module according to a preferred example of the sixth embodiment of the present invention.
Detailed Description
In the following description, numerous technical details are set forth in order to provide a better understanding of the present application. However, it will be understood by those skilled in the art that the technical solutions claimed in the present application can be implemented without these technical details and with various changes and modifications based on the following embodiments.
Interpretation of terms:
if the high-frequency information in the vertical direction of the luminance signal is rich, the high-frequency information is clustered on the frequency spectrum and allocated to the area of the chrominance frequency spectrum in an interlaced mode, and the high-frequency component of the chrominance signal is clustered on the frequency spectrum and allocated to the interlaced luminance frequency spectrum, and the mutual influence is called as the luminance and color crosstalk.
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
A first embodiment of the present invention relates to a method for encoding a composite video signal, and fig. 1 is a flowchart illustrating the method for encoding the composite video signal.
Specifically, as shown in fig. 1, the method for encoding a composite video signal includes the steps of:
It can be understood that the preprocessing in step 101 includes three cases, that is, only performing luminance comb filtering on the luminance signal to be encoded, or only performing chrominance comb filtering on the chrominance signal to be encoded, or simultaneously performing luminance comb filtering on the luminance signal to be encoded and performing chrominance comb filtering on the chrominance signal to be encoded.
Accordingly, when the composite video signal is generated according to the preprocessed luminance signal and chrominance signal in step 102, the luminance signal and chrominance signal may be all comb-filtered signals or some comb-filtered signals.
In the embodiment, before generating the composite video signal, the encoding end performs comb filtering on the luminance signal to be encoded and/or the chrominance signal to be encoded, so that the bright-color crosstalk caused by the luminance signal string to the chrominance spectrum or the chrominance signal string to the luminance spectrum can be automatically and efficiently removed from the source.
A second embodiment of the present invention relates to a method for encoding a composite video signal, and fig. 2 is a flowchart illustrating the method for encoding the composite video signal.
The second embodiment is improved on the basis of the first embodiment, and the main improvement lies in that: whether comb filtering is carried out or not is controlled by combining the brightness boundary information, the chrominance boundary information and the preset boundary threshold value, crosstalk of the brightness signal and the chrominance signal is avoided, comb filtering is not used, and the workload of filtering processing can be effectively reduced. Specifically, the method comprises the following steps:
in step 101, the following substeps are included:
In this embodiment, the luminance boundary information and the chrominance boundary information may be extracted using a boundary detection filter, and the boundary detection filter commonly used includes Canny operator, Sobel operator, Laplacian operator, and the like.
It should be noted that the sequence between step 202 and step 203 is not limited, and they may be executed sequentially or in parallel. It may be performed all together, or only step 202 or only step 203 may be performed.
Furthermore, it is understood that in other embodiments of the present invention, the above step of determining the boundary threshold is not necessary, and all luminance signals and chrominance signals may be comb-filtered.
In addition, after all the luminance signals and the chrominance signals are comb-filtered, whether the comb-filtered luminance signals and chrominance signals or the originally input luminance signals and chrominance signals which are not comb-filtered are adopted when the composite video signal is generated can be determined according to the extracted luminance boundary information and chrominance boundary information, the preset luminance boundary threshold value and the preset chrominance boundary threshold value.
The embodiment combines the brightness boundary information, the chrominance boundary information and the preset boundary threshold value to control whether comb filtering is carried out or not, the crosstalk condition of the brightness signal and the chrominance signal can not be generated, comb filtering is not used, and the workload of filtering processing can be effectively reduced.
A third embodiment of the present invention relates to a method for encoding a composite video signal, which is an improvement of the first embodiment, and is mainly characterized in that:
first, in the first embodiment, the step of "comb filtering luminance of a luminance signal to be encoded" includes the following substeps:
performing band-pass filtering on a luminance signal to be coded to obtain frequency band information of 1.3MHz of the left and right sides by taking a chrominance subcarrier frequency as a center frequency;
and comb filtering the frequency band information of 1.3MHz frequency bands which are obtained after the band-pass filtering and take the chrominance subcarrier frequency as the center frequency.
In the above-mentioned step of performing luminance comb filtering on the luminance signal to be encoded, the luminance signal is first subjected to band-pass filtering, the obtained band-pass luminance signal (i.e., band information of 1.3MHz around the chrominance subcarrier frequency as the center frequency) is a portion that is likely to generate crosstalk with the chrominance signal, and the luminance comb filtering is performed on the portion, while the remaining portion (e.g., low-pass portion) is not subjected to luminance comb filtering, so that the band-pass filtering avoids affecting signals other than the band-pass frequency.
In the first embodiment, the step of "performing chroma comb filtering on a chroma signal to be encoded" includes the following sub-steps:
comb filtering is carried out on chrominance signals needing to be coded in a frequency band of plus or minus 1.3 MHz.
According to the comb filtering principle, the time domain calculation method of comb filtering in various systems comprises the following steps: comb filtering is carried out in a frequency domain, and for the PAL system, only three lines of information of a time domain local line, a second line before the local line and a second line after the local line are added; for the NTSC system, three lines of information, i.e., the local line, the previous line and the next line in the time domain, are added. Note that here the position of the row is the arrangement on the field, and the position of the row needs to be multiplied by 2 for the frame.
The information of the frequency band of the luminance signal of + -1.3 MHz near the chrominance subcarrier is comb-filtered, and only the relevant three rows of the time domain need to be added.
Comb filtering is carried out on the frequency band of +/-1.3 MHz of the chrominance signal, and for the PAL system, only three lines of information of a time domain local line, a second line before the local line and a second line after the local line are added; for the NTSC system, three lines of information, i.e., the local line, the previous line and the next line in the time domain, are added.
Secondly, preferably, in the step of preprocessing in step 101, the following sub-steps are further included:
extracting a luminance residual signal from a luminance signal to be encoded, wherein the luminance residual signal refers to a luminance signal which is not in a range of 1.3MHz respectively left and right of a chrominance subcarrier frequency as a central frequency;
the luminance residual signal and the comb-filtered luminance signal are added as a pre-processed luminance signal.
Furthermore, it is understood that the luminance residual signal may be obtained by subtracting the band-pass filtered luminance signal from the luminance signal to be encoded (i.e., the luminance input signal) and by using a luminance band-stop filter.
Finally, in step 102, it is preferable to include the following sub-steps:
according to the international standard for the generation of composite video signals, the field sync and field blanking signals are added to the preprocessed luminance and chrominance signals, and the phase of the chrominance sync signal of each line is determined.
As a preferred example of the present embodiment, a flowchart of a specific implementation example is shown in fig. 3.
And step 301, inputting a signal. Splitting input data into a luminance input signal and a chrominance input signal, the subsequent steps require separate processing for luminance and chrominance.
And step 303, brightness comb filtering. The line is marked as the k line, and the PAL uses the outputs of the luminance band-pass filtering units of the k-2, k and k +2 lines for averaging, and can also set three line weights for addition. NTSC uses the outputs of luminance band-pass filtering units in the k-1, k +1 th lines to multiply the corresponding weights of each line for addition.
And step 304, extracting brightness boundaries. And obtaining the intensity of the boundary information on the brightness by using a boundary detection filter for judging a boundary threshold value.
And step 306, judging a boundary threshold value. The luminance control information and the chrominance control information are determined according to the luminance boundary strength and the chrominance boundary strength.
The specific rule is as follows:
if the brightness boundary strength exceeds the first brightness boundary threshold value, the chroma boundary strength exceeds the first chroma boundary threshold value, the brightness control signal is 1, otherwise, the brightness control signal is 0;
if the luminance boundary strength exceeds the second luminance boundary threshold value, the chrominance boundary strength exceeds the second chrominance boundary threshold value, the chrominance control signal is 1, otherwise, the chrominance control signal is 0.
And 307, carrying out chrominance comb filtering. The line is labeled as line k, and PAL multiplies the chrominance input signals of three lines k-2, k +2 by the corresponding weight of each line and adds them. NTSC uses chroma input signals of three lines k-1, k +1 to be multiplied by corresponding weights of each line for addition.
And step 308, brightness output selection. Whether the luminance output signal is a result of the luminance comb filtering or the original luminance input signal is selected according to the luminance control information.
And step 310, outputting signals. And combining the luminance output signal and the chrominance output signal for other subsequent modules.
The method embodiments of the present invention may be implemented in software, hardware, firmware, etc. Whether the present invention is implemented as software, hardware, or firmware, the instruction code may be stored in any type of computer-accessible memory (e.g., permanent or modifiable, volatile or non-volatile, solid or non-solid, fixed or removable media, etc.). Also, the Memory may be, for example, Programmable Array Logic (PAL), Random Access Memory (RAM), Programmable Read Only Memory (PROM), Read-Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), a magnetic disk, an optical disk, a Digital Versatile Disk (DVD), or the like.
A fourth embodiment of the present invention relates to an encoding apparatus for a composite video signal, and fig. 4 is a schematic configuration diagram of the encoding apparatus for a composite video signal.
Specifically, as shown in fig. 4, the apparatus for encoding a composite video signal includes the following units:
a pre-processing unit for pre-processing a luminance signal to be encoded and a chrominance signal to be encoded, the pre-processing unit comprising: a luminance comb filtering subunit, configured to perform luminance comb filtering on the luminance signal to be encoded, and/or a chrominance comb filtering subunit, configured to perform chrominance comb filtering on the chrominance signal to be encoded;
a composite video signal generating unit for generating a composite video signal from the preprocessed luminance signal and chrominance signal.
Furthermore, it is understood that the pre-processing unit is disposed after the generation of the line signal and before the generation of the field signal, and it is within the scope of the present invention to dispose the pre-processing unit at any position of the encoding end.
In the embodiment, before generating the composite video signal, the encoding end performs comb filtering on the luminance signal to be encoded and/or the chrominance signal to be encoded, so that the bright-color crosstalk caused by the luminance signal string to the chrominance spectrum or the chrominance signal string to the luminance spectrum can be automatically and efficiently removed from the source.
The first embodiment is a method embodiment corresponding to the present embodiment, and the present embodiment can be implemented in cooperation with the first embodiment. The related technical details mentioned in the first embodiment are still valid in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can also be applied to the first embodiment.
A fifth embodiment of the present invention is directed to an encoding device for a composite video signal, which is an improvement of the fourth embodiment, and is mainly characterized in that: whether comb filtering is carried out or not is controlled by combining the brightness boundary information, the chrominance boundary information and the preset boundary threshold value, crosstalk of the brightness signal and the chrominance signal is avoided, comb filtering is not used, and the workload of filtering processing can be effectively reduced. Specifically, the method comprises the following steps:
the pretreatment unit comprises the following subunits:
a boundary information extracting subunit, configured to extract luminance boundary information of a luminance signal to be encoded and chrominance boundary information of a chrominance signal to be encoded;
a luminance comb filtering control subunit, configured to control whether to perform comb filtering on the luminance signal to be encoded according to the extracted luminance boundary information, chrominance boundary information, and a preset first luminance boundary threshold and a preset first chrominance boundary threshold;
and the chrominance comb filtering control subunit is used for controlling whether to carry out comb filtering on the chrominance signal needing to be coded or not according to the extracted chrominance boundary information, the extracted luminance boundary information, a preset second luminance boundary threshold value and a preset second chrominance boundary threshold value.
The second embodiment is a method embodiment corresponding to the present embodiment, and the present embodiment can be implemented in cooperation with the second embodiment. The related technical details mentioned in the second embodiment are still valid in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can also be applied to the second embodiment.
A sixth embodiment of the present invention is directed to an apparatus for encoding a composite video signal, which is an improvement of the fourth embodiment, and is mainly characterized in that:
first, the luminance comb filtering subunit includes the following subunits:
the band-pass filtering subunit is used for performing band-pass filtering on the luminance signal to be coded to obtain frequency band information of 1.3MHz on the left and right sides by taking the chrominance subcarrier frequency as a central frequency;
and the first comb filtering subunit is used for comb filtering the frequency band information of the left and right 1.3MHz frequency bands which are obtained after the band-pass filtering and take the chrominance subcarrier frequency as the center frequency.
Accordingly, in the chroma comb filtering subunit, the following subunits are included:
and the second comb filtering subunit is used for carrying out comb filtering on the chrominance signal to be coded in the frequency band of plus or minus 1.3 MHz.
Secondly, preferably, in the pretreatment unit, the following sub-units are also included:
a luminance residual extracting sub-unit for extracting a luminance residual signal from the luminance signal to be encoded, the luminance residual signal being a luminance signal not within each of 1.3MHz around a chrominance subcarrier frequency as a center frequency;
an adder subunit for adding the luminance residual signal and the comb-filtered luminance signal as a pre-processed luminance signal.
Furthermore, it is understood that the luminance residual signal may be obtained by subtracting the band-pass filtered luminance signal from the luminance signal to be encoded (i.e., the luminance input signal) and by using a luminance band-stop filter.
Finally, it is preferable that in the composite video signal generation unit, the following sub-units are included:
and a composite video signal generating sub-unit for adding the field sync and the field blanking signals and determining the phase of the chrominance sync signal for each line according to the international standard for generating the composite video signal.
The third embodiment is a method embodiment corresponding to the present embodiment, and the present embodiment can be implemented in cooperation with the third embodiment. The related technical details mentioned in the third embodiment are still valid in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can also be applied to the third embodiment.
As a preferred example of the present embodiment, fig. 5 is a schematic block diagram of a structure of a composite video signal encoding end to which a bright-color crosstalk elimination module is added. As shown in fig. 5, a bright-color crosstalk elimination module is added at the encoding end, and besides the bright-color crosstalk elimination module, the other part is a commonly used encoding block diagram of the composite video signal, where the bright-color crosstalk elimination module is placed after the line signal is generated (i.e. after the line synchronization and line blanking signals are generated in the figure) and before the field signal is generated (i.e. before the field synchronization and field blanking signals are generated in the figure), and it is within the scope of the present invention to place the bright-color crosstalk elimination module at any position of the encoding end.
The structure diagram of the bright-color crosstalk elimination module is shown in fig. 6, and the bright-color crosstalk elimination module includes a 601 luminance band-pass filter unit, a 602 luminance comb filter unit, a 603 luminance residual signal extraction unit, a 604 luminance output selector unit, a 605 luminance boundary extraction unit, a 606 chrominance boundary extraction unit, a 607 boundary threshold value judgment unit, a 608 chrominance comb filter unit, and a 609 chrominance output selector unit. Specifically, the method comprises the following steps:
601 a luminance band pass filter unit for extracting band information of the luminance signal around the chrominance subcarrier at ± 1.3MHz and transmitting the output data to the luminance comb filter unit.
The 602 brightness comb filter unit is used for only adding three lines of information, namely a time domain line, a line before the line and a line after the line, of PAL when comb filtering is carried out on a frequency domain according to a comb filtering principle; for NTSC, three lines of information, i.e., the time domain line, the line preceding the line, and the line following the line, are added. Note that here the position of the row is the arrangement on the field, and the position of the row needs to be multiplied by 2 for the frame. The unit carries out comb filtering on the frequency band information of the brightness signal at +/-1.3 MHz near the chrominance subcarrier, and only needs to add the related three rows of the time domain.
603 luminance residual signal extraction unit, this unit is used to extract the frequency domain whose luminance information is not near the chroma subcarrier + -1.3 MHz, the simplest method is to use the luminance input signal to subtract the information after the luminance band-pass filter unit, and at the same time, protect the mode using the luminance band-stop filter.
604 luminance output selector unit, this unit selects whether the luminance output signal is the result of the luminance comb filtering or the original luminance input signal, according to the luminance control signal output by the boundary threshold judgment unit.
605 luminance boundary extraction unit which extracts luminance boundary information using a boundary detection filter and transfers output data to a boundary threshold value judgment unit. Commonly used boundary detection filters include Canny operators, Sobel operators, Laplacian operators, and the like.
606 chrominance boundary extraction unit, which uses boundary detection filter to extract chrominance boundary information and sends the output data to the boundary threshold judgment unit.
607 boundary threshold value judging unit, which generates a luminance control signal and a chrominance control signal according to the intensity of the luminance boundary extraction information and the chrominance boundary extraction information.
If the brightness boundary strength exceeds the first brightness boundary threshold value, the chroma boundary strength exceeds the first chroma boundary threshold value, the brightness control signal is 1, the brightness signal needs to be comb-filtered, otherwise, the brightness control signal is 0, and the brightness signal does not need to be comb-filtered. If the brightness boundary strength exceeds the second brightness boundary threshold value, the chroma boundary strength exceeds the second chroma boundary threshold value, the chroma control signal is 1, the chroma signal needs to be comb-filtered, otherwise, the chroma control signal is 0, and the chroma signal does not need to be comb-filtered.
A 608 chroma comb filter unit, which performs comb filtering on the band of + -1.3 MHz of chroma signals, and only adds three lines of information of a time domain local line, a second line before the local line and a second line after the local line for PAL; for NTSC, three lines of information, i.e., the time domain line, the line preceding the line, and the line following the line, are added.
609 chrominance output selector unit, this unit selects the chrominance output signal to be the result of chrominance comb filtering or the original chrominance input signal according to the chrominance control signal outputted by the boundary threshold value judging unit.
It should be noted that, each unit mentioned in each device embodiment of the present invention is a logical unit, and physically, one logical unit may be one physical unit, or may be a part of one physical unit, or may be implemented by a combination of multiple physical units, and the physical implementation manner of these logical units itself is not the most important, and the combination of the functions implemented by these logical units is the key to solve the technical problem provided by the present invention. Furthermore, the above-mentioned embodiments of the apparatus of the present invention do not introduce elements that are less relevant for solving the technical problems of the present invention in order to highlight the innovative part of the present invention, which does not indicate that there are no other elements in the above-mentioned embodiments of the apparatus.
In summary, the present invention relates to a method and an apparatus for eliminating crosstalk between a luminance signal and a chrominance signal at an encoding end of a composite video signal. Key issues for bright-color crosstalk: the problem of crosstalk of luminance and chrominance spectrums exists at a coding end of a composite video signal, and the method carries out bright-color crosstalk elimination at the coding end.
That is, the present invention provides a method and apparatus for eliminating the bright color crosstalk problem at the encoding end, and proposes to filter the frequency band of the luminance signal in the vicinity of the chrominance subcarrier in the + -1.3 MHz band and the frequency band of the chrominance signal in the + -1.3 MHz band by using a comb filtering method, so as to weaken and eliminate the intensity of the crosstalk of the luminance signal and the chrominance signal to the frequency band divided to the other side signal. And simultaneously, extracting a brightness boundary and a chrominance boundary, judging through a boundary threshold value, not using comb filtering for the frequency band of the brightness signal within +/-1.3 MHz and the frequency band of the chrominance signal within +/-1.3 MHz near the chrominance subcarrier without crosstalk of the brightness signal and the chrominance signal to the frequency band of the opposite signal, and otherwise using comb filtering.
It is to be noted that in the claims and the description of the present patent, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, the use of the verb "comprise a" to define an element does not exclude the presence of another, same element in a process, method, article, or apparatus that comprises the element.
While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
Claims (6)
1. A method of encoding a composite video signal, comprising the steps of:
preprocessing a luminance signal to be encoded and a chrominance signal to be encoded before generating a composite video signal, the preprocessing comprising: performing luminance comb filtering on a luminance signal to be coded and/or performing chrominance comb filtering on a chrominance signal to be coded;
generating a composite video signal from the preprocessed luminance and chrominance signals; wherein, in the step of preprocessing the luminance signal to be coded and the chrominance signal to be coded, the following substeps are included:
extracting luminance boundary information of the luminance signal to be coded and chrominance boundary information of the chrominance signal to be coded;
controlling whether to comb-filter the luminance signal to be coded according to the extracted luminance boundary information, chrominance boundary information, a preset first luminance boundary threshold value and a preset first chrominance boundary threshold value; and/or controlling whether to comb-filter the chrominance signal needing to be coded or not according to the extracted chrominance boundary information, the extracted luminance boundary information, a preset second chrominance boundary threshold value and a preset second luminance boundary threshold value; the step of "comb-filtering luminance of the luminance signal to be encoded" includes the following substeps:
performing band-pass filtering on the luminance signal to be coded to obtain frequency band information of 1.3MHz of the left and right sides by taking the chrominance subcarrier frequency as a center frequency;
comb filtering is carried out on the frequency band information of 1.3MHz frequency width on the left and the right of the central frequency of the chrominance subcarrier frequency obtained after the band-pass filtering;
in the step of "performing chroma comb filtering on a chroma signal to be encoded", the following sub-steps are included:
and comb filtering the chrominance signal to be coded in the frequency band of plus or minus 1.3 MHz.
2. A method for coding a composite video signal according to claim 1, wherein said step of preprocessing the luminance signal to be coded and the chrominance signal to be coded further comprises the sub-steps of:
extracting a luminance residual signal in the luminance signal to be coded, wherein the luminance residual signal is a luminance signal which is not in the range of 1.3MHz respectively at the left and the right of the central frequency of the chrominance subcarrier frequency;
adding the luminance residual signal and the comb-filtered luminance signal as the pre-processed luminance signal.
3. A method for encoding a composite video signal according to any one of claims 1 to 2, wherein said step of generating the composite video signal from the preprocessed luminance signal and chrominance signals comprises the sub-steps of:
for the preprocessed luminance signal and chrominance signal, the field sync and field blanking signals are added, and the phase of the chrominance sync signal of each line is determined.
4. An apparatus for encoding a composite video signal, comprising:
a pre-processing unit for pre-processing a luminance signal to be encoded and a chrominance signal to be encoded before generating a composite video signal, the pre-processing unit comprising: a luminance comb filtering subunit, configured to perform luminance comb filtering on the luminance signal to be encoded, and/or a chrominance comb filtering subunit, configured to perform chrominance comb filtering on the chrominance signal to be encoded;
a composite video signal generating unit for generating a composite video signal from the preprocessed luminance signal and chrominance signal; wherein the preprocessing unit comprises the following subunits:
a boundary information extracting subunit, configured to extract luminance boundary information of the luminance signal to be encoded and chrominance boundary information of the chrominance signal to be encoded;
a luminance comb filtering control subunit, configured to control whether to perform comb filtering on the luminance signal to be encoded according to the extracted luminance boundary information, chrominance boundary information, and a preset first luminance boundary threshold and a preset first chrominance boundary threshold;
a chrominance comb filter control subunit, configured to control whether to perform comb filtering on the chrominance signal to be coded according to the extracted chrominance boundary information, luminance boundary information, a preset second luminance boundary threshold value, and a preset second chrominance boundary threshold value; and, the luminance comb filtering subunit includes the following subunits:
the band-pass filtering subunit is used for performing band-pass filtering on the luminance signal to be coded to obtain frequency band information of 1.3MHz on the left and right sides by taking the chrominance subcarrier frequency as a central frequency;
a first comb filtering subunit, configured to comb filter, for frequency band information of each 1.3MHz frequency bandwidth on the left and right sides, which take the chrominance subcarrier frequency as a center frequency, obtained after the band-pass filtering;
in the chroma comb filtering subunit, the following subunits are included:
and the second comb filtering subunit is used for comb filtering the chrominance signal to be coded in the frequency band of plus or minus 1.3 MHz.
5. An apparatus for encoding a composite video signal according to claim 4, further comprising, in the preprocessing unit, the sub-units of:
a luminance residual extracting sub-unit, configured to extract a luminance residual signal from the luminance signal to be encoded, where the luminance residual signal is a luminance signal that is not within each of 1.3MHz around a chrominance subcarrier frequency as a center frequency;
an adder sub-unit for adding the luminance residual signal and the comb-filtered luminance signal as the pre-processed luminance signal.
6. An apparatus for encoding a composite video signal according to any one of claims 4 to 5, wherein said composite video signal generating unit comprises the following sub-units:
a composite video signal generating subunit for adding the field sync and the field blanking signals to the preprocessed luminance signal and chrominance signal, and determining the phase of the chrominance sync signal of each line.
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