Patent Application
20080192146
The present invention relates to video signal processors for reducing noise components of video signals and performs magnification or reduction on video signals.
Video signal processors including NR (noise reduction) circuits for reducing noise included in video signals are known to date (see, for example, Patent Document 1). Hereinafter, a block diagram of a video signal processor including such an NR circuit will be described as an example with reference to
As illustrated in
The NR buffer 11A4 is formed by a field memory, and video signals corresponding to one screen (one field) are temporarily saved therein. After video signals corresponding to one screen have been stored in the NR buffer 11A4, a scaling section 11A5 acquires video signals corresponding to necessary lines from the NR buffer 11A4 and performs magnification or reduction, which will be hereinafter referred to as scaling, on the video signals in the vertical and horizontal directions based on the acquired video signals, and the resultant signals are temporarily saved in a filter buffer 11A6. A display section 11A7 acquires video signals corresponding to one screen from the filter buffer 11A6 to allow an image to be displayed on the screen of a TV set or other equipment in synchronization with, for example, a TV signal.
Problems that the Invention is to solve
In the conventional technique, however, the NR buffer 11A4 is formed by a field memory for storing video signals corresponding to one screen (i.e., one field=540 lines, for example), and thus the following drawback arises.
Specifically, the NR section 11A3 is generally controlled to execute or suspend noise reduction depending on the amount of noise included in video signals. To implement such control, as illustrated in
However, with this configuration, in a situation where the NR section 11A3 is suspended, video signals are input to the scaling section 11A5 without passing through the NR section 11A3. Accordingly, the scaling by the scaling section 11A5 is performed earlier than that in a situation where the NR section 11A3 operates by a period associated with video signals corresponding to one screen (i.e., one field), that is, by a period associated with one vertical pixel signal (e.g., 1/60 second). As a result, video signals are displayed on a video display screen such as a TV screen earlier by a period associated with one vertical pixel signal, so that normal display is not provided.
As a first solution to eliminate the foregoing drawback, for example, it is conceivable to add hardware in which video signals from the decode buffer 11A2 are temporarily copied so that the copied video signals are input to the scaling section 11A5 in a situation where the NR section 11A3 is suspended. As a second solution, it is conceivable to add hardware for use in providing a display of video signals on a video display screen with a delay corresponding to a period associated with one screen to make the video display normal in a situation where the NR section 11A3 is suspended. However, these solutions have the drawback of necessity of additional hardware.
In addition, the NR buffer 11A3 is a field memory and has large capacity, so that a delay time corresponding to one screen is present before an actual display of an image.
It is therefore an object of the present invention to provide a video signal processor in which the capacity of an NR buffer is limited to a small value and video signals are always displayed normally without the necessity of additional hardware in both situations of operation and suspension of an NR section.
To achieve the foregoing object, according to the present invention, an NR buffer is formed by a plurality of line memories, and noise reduction by an NR section and scaling by a scaling section are performed in parallel in such a manner that video signals subjected to noise reduction by the NR section and corresponding to one line are saved in one of the line memories and video signals saved in other line memories and corresponding to a plurality of lines are used for the processing by the scaling section.
Specifically, a video signal processor according to the present invention includes: a noise reduction section for reducing noise components of video signals; an NR buffer for storing video signals whose noise components have been reduced by the noise reduction section, the NR buffer being formed by a plurality of line memories; a magnification/reduction section for performing magnification or reduction on video signals from the NR buffer in vertical and horizontal directions; and a control section for controlling the noise reduction section and the magnification/reduction section, wherein the control section controls the noise reduction section and the magnification/reduction section such that video signals corresponding to one line out of the video signals subjected to the noise reduction are output from the noise reduction section to one of the line memories of the NR buffer and the other video signals corresponding to a plurality of lines and stored in the line memories of the NR buffer except for the line memory to which the video signals corresponding to one line have been input from the noise reduction section are input from the NR buffer to the magnification/reduction section
In the video signal processor of the present invention, the control section includes: NR line buffer address holding units in each of which an address of an associated one of the line memories of the NR buffer is saved; an input switch for selecting one of the addresses of the line memories saved in the NR line buffer address holding units and indicating the selected address to the noise reduction section; an output switch for selecting one of the addresses of the line memories saved in the NR line buffer address holding units and indicating the selected address to the magnification/reduction section; and a buffer management controlling unit for controlling the input switch such that the address of one of the line memories to which video signals corresponding to one line have been input from the noise reduction section is selected from the NR line buffer address holding units in the NR buffer and for controlling the output switch such that the addresses of the line memories except for the line memory whose address has been selected by the input switch are selected from the NR line buffer address holding units.
In the video signal processor of the present invention, the number of the NR line buffer address holding units is equal to the number of the line memories included in the NR buffer, each of the NR line buffer address holding units holds an address value of an associated one of the line memories of the NR buffer, and the buffer management controlling unit controls the input switch so that the input switch sequentially selects the NR line buffer address holding units in such a manner that video signals output from the noise reduction section and corresponding to one line are cyclically held in the line memories of the NR buffer line by line.
In the video signal processor of the present invention, the noise reduction section reduces noise components of video signals corresponding to one line in synchronization with a horizontal sync signal, and in synchronization with the horizontal sync signal, the magnification/reduction section performs magnification or reduction on the video signals corresponding to one line in vertical and horizontal directions with a horizontal sync signal following the horizontal sync signal used for the reduction of the noise components of the video signals corresponding to one line by the noise reduction section.
The video signal processor of the present invention further includes: an initialization setting section for indicating an initial value for reducing the noise components of the video signals to the noise reduction section and for indicating an initial value for performing magnification or reduction on the video signal in the vertical and horizontal directions to the magnification/reduction section.
In the video signal processor of the present invention, the initialization setting section includes: a noise-reduction initialization setting processing circuit for indicating a noise reduction parameter for reducing the noise component to the noise reduction section; and a magnification/reduction initialization setting processing circuit for indicating, to the magnification/reduction section, a filter parameter for magnification on video signals with a specified magnification factor.
In the video signal processor of the present invention, the magnification/reduction initialization setting processing circuit starts indication after indication by the noise-reduction initialization setting processing circuit has been completed, and, with a vertical sync signal one period before a start of noise reduction performed by the noise reduction section on video signals corresponding to a given line in synchronization with a vertical sync signal or 1/60 second before the start, the magnification/reduction initialization setting processing circuit also starts indication of an initial value for magnification or reduction on video signals using video signals corresponding to a plurality of lines including the given line.
In the video signal processor of the present invention, the noise-reduction initialization setting processing circuit starts indication after indication by the magnification/reduction initialization setting processing circuit has been completed, and with a vertical sync signal one period before a start of noise reduction performed by the noise reduction section on video signals corresponding to a given line in synchronization with a vertical sync signal or 1/60 second before the start, the noise-reduction initialization setting processing circuit starts indication of an initial value for reducing noise components of video signals corresponding to the given line.
The video signal processor of the present invention further includes a display section for outputting video signals subjected to magnification or reduction by the magnification/reduction section in synchronization with the video signals, the display section being provided at a stage subsequent to the magnification/reduction section.
In the video signal processor of the present invention, the display section outputs, to a video display device, video signals corresponding to one line with a given horizontal sync signal also used for magnification or reduction performed on the video signals corresponding to the line by the magnification/reduction section.
In the video signal processor of present invention, the noise reduction section suspends reduction of a noise component for 1/60 second or a period which is N or more times longer than 1/60 second (where N is an integer of two or more).
In the video signal processor of the present invention, the noise reduction section performs no reduction of noise components of video signals to be subjected to magnification or reduction by the magnification/reduction section and corresponding to the lines.
The video signal processor of the present invention further includes a decode buffer for holding video signals obtained by decoding a coded video bit stream or uncompressed digital video signals, and the noise reduction section reduces noise components of the video signals obtained by decoding the video bit stream or the uncompressed digital video signals held in the decode buffer.
As described above, in the video signal processor according to the present invention, video signals subjected to noise reduction by a noise reduction section and corresponding to one line are stored in a line memory in an NR buffer and video signals already stored in a plurality of line memories in the NR buffer and corresponding to a plurality of lines are input to a magnification/reduction section for magnification/reduction on the video signals. Accordingly, the noise reduction section and the magnification/reduction section operate in parallel with each other, and noise reduction and magnification/reduction by these sections are performed in the same cycle of a vertical sync signal for video signals. This makes the processing in the magnification/reduction section performed at the same timing as that in a case where the noise reduction section continues to operate, even when operation of the noise reduction section stops. As a result, it is possible to prevent an image from being displayed on a video display device such as a TV set at a timing earlier by a period corresponding to one vertical sync signal (i.e., one cycle, e.g., 1/60 second). Therefore, an image is normally displayed on the video display device without the necessity of additional hardware.
In addition, the NR buffer is formed by a plurality of line memories in which a line memory associated with one line is added to line memories associated with a plurality of lines necessary for magnification/reduction on video signals by the magnification/reduction section. Accordingly, unlike a conventional processor, it is unnecessary to form an NR buffer by a field memory, and thus size reduction is achieved.
In particular, according to the present invention, initialization setting processes for the noise reduction section and the magnification/reduction section are performed with a vertical sync signal one period before a vertical sync signal with which noise reduction and magnification/reduction on video signals are performed, so that operation frequencies of the noise reduction section and the magnification/reduction section are capable of being reduced, and the circuit configurations of the noise reduction section and the magnification/reduction section are allowed to be omitted in part.
Further, according to the present invention, when the magnification/reduction section performs magnification/reduction on video signal based on a horizontal sync signal, video signals subjected to magnification/reduction and corresponding to one line are output to a video display device such as a TV set in synchronization with the horizontal sync signal based on which the magnification/reduction on the video signals corresponding to one line is performed. Accordingly, unlike a conventional processor, a field memory for storing video signal subjected to magnification/reduction is unnecessary.
As described above, in the video signal processor according to the present invention, an NR buffer is formed by a plurality of line memories. This ensures normal display on a video display device such as a TV set at any time, irrespective of suspension and continuation of operation of the noise reduction section. In addition, it is unnecessary to form the NR buffer by a field memory, so that size reduction of the NR buffer is achieved.
In particular, according to the present invention, initialization setting processes for the noise reduction section and the magnification/reduction section can be performed with margins, and operation frequencies of the noise reduction section and the magnification/reduction section are reduced. Accordingly, the circuit configurations of the noise reduction section and the magnification/reduction section are simplified.
In addition, according to the present invention, the magnification/reduction section performs magnification/reduction on video signals corresponding to one line based on a horizontal sync signal and the video signals subjected to the magnification/reduction and corresponding to one line are output to a video display device such as a TV set in the same cycle of a horizontal sync signal based on which the magnification/reduction is performed. Accordingly, unlike a conventional processor, a field memory for storing video signals subjected to magnification/reduction is unnecessary.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The illustrated video signal processor of this embodiment is a system for decoding a video bit stream compressed in, for example, the MPEG format and reducing noise components of the decoded video signals and also for performing scaling on the video signals.
The video signal processor of this embodiment includes: a video decoder 101; a decode buffer 102; an NR section (noise reduction section) 103; an NR buffer 104; a scaling section 105; a filter buffer 106; a display section 107; and a control section 108.
The video decoder 101 decodes a video bit stream and saves the decoded video signals in the decode buffer 102. The decode buffer 102 is a buffer in which signals decoded by the video decoder 101 are temporarily saved. The temporarily saved video signals are output to the NR section 103 in synchronization with a vertical sync signal (not shown).
The NR section 103 acquires video signals SIG103 saved in the decode buffer 102, receives a horizontal sync signal to reduce noise components of the received video signals line by line in synchronization with the horizontal sync signal, and outputs video signals SIG104 subjected to the noise reduction to the NR buffer 104. To specify a memory address to which the NR section 103 outputs the video signals SIG104 in the NR buffer 104, the NR section 103 acquires a memory address SIG109 from the control section 108 and outputs, to the memory address, the video signals subjected to the reduction of noise components so as to save the signals (which will be specifically described later). As already described above, instead of video signals obtained by decoding a video bit stream, the NR section 103 may, of course, receive uncompressed digital video signals from an analog TV set, a DVD player or a network, for example, to reduce noise components of the received video signals or digital video signals.
The NR buffer 104 is a buffer in which video signals whose noise components have been reduced by the NR section 103 are temporarily saved, and this temporarily saved video signals are then output to the scaling section 105. Specifically, in synchronization with a horizontal sync signal, video data corresponding to one line processed by the NR section 103 are saved in the NR buffer 104 and the data corresponding to one line processed in synchronization with the preceding horizontal sync signal is output to the scaling section 105.
As shown in
The scaling section 105 acquires video signals SIG105 corresponding to a plurality of lines and saved in the NR buffer 104, receives a horizontal sync signal to perform, in synchronization with this horizontal sync signal, scaling on video signals in the vertical and horizontal directions based on the acquired video signals, and outputs the processed video signals SIG106 to the filter buffer 106. To specify a line corresponding to video signals SIG105 which are to be input from the NR buffer 104, the scaling section 105 acquires a memory address SIG110 of the NR buffer 104 from the control section 108 to take in video signals saved in the acquired memory address.
The filter buffer 106 is a buffer in which video signals subjected to scaling by the scaling section 105 in the vertical and horizontal directions are temporarily saved, and the temporarily saved video signals are output to the display section 107. Specifically, in the filter buffer 106, video signals corresponding to one screen and processed by the scaling section 105 are saved, and with the next vertical sync signal, the saved video signals corresponding to one screen are sequentially output to the display section 107 in synchronization with a horizontal sync signal.
With the next vertical sync signal, the display section 107 acquires the video signals temporarily saved in the filter buffer 106 line by line in synchronization with a horizontal sync signal and outputs the acquired signals to a video display device such as a TV set.
The control section 108 receives a horizontal sync signal and, based on this horizontal sync signal, indicates, to the NR section 103, an NR buffer line address SIG109 for use in indicating one of the line memories 104a through 104e in which video signals corresponding to one line and subjected to reduction of noise components in the NR section 103 are saved. The control section 108 also indicates, to the scaling section 105, an NR buffer line address SIG 110, which is used for indicating a line corresponding to video signals which are to be taken in the scaling section 105 out the five lines and saved in the NR buffer 104. Hereinafter, an inner configuration of the control section 108 will be described with reference to
As illustrated in
The NR line buffer address holding unit 1202 holds a start address of the first line memory 104a in the NR buffer 104. The NR line buffer address holding unit 2203 holds a start address of the second line memory 104b in the NR buffer 104. In the same manner, the NR line buffer address holding unit 3204 holds a start address of the third line memory 104c in the NR buffer 104. The NR line buffer address holding unit 4205 holds a start address of the fourth line memory 104d. The NR line buffer address holding unit 5206 holds a start address of the fifth line memory 104e.
In the configuration of the control section 108 illustrated in
In addition, in the control section 108 illustrated in
In response to an indication signal SIG222 from the buffer management controlling unit 208, the output switch 207 selects four start addresses according to the indication signal SIG222 from start addresses SIG207 through SIG211 respectively held in the five NR line buffer address holding units 1202 through 206, and indicates and outputs the selected start addresses to the scaling section 105 as indication signals SIG212 through SIG215.
In addition, upon the input of video signals from the decode buffer 102 to the NR section 103, the buffer management controlling unit 208 outputs the indication signal SIG221 to the input switch 201 and also outputs the indication signal SIG222 to the output switch 207. The indication signal SIG221 to the input switch 201 indicates one of the five line memories 104a through 104e in which video signals corresponding to one line and subjected to noise reduction by the NR section 103 are to be saved in the NR buffer 104. The indication signal SIG222 to the output switch 207 indicates selection of the addresses of the other four line memories, i.e., the line memories other than the line memory in the address indicated by the indication signal SIG221 to the input switch 201. Accordingly, the indication signal SIG221 to the input switch 201 and the indication signal SIG222 to the output switch 207 do not indicate the same address for selection.
The buffer management controlling unit 208 in the control section 108 performs control such that the five line memories 104a through 104e in the NR buffer 104 and the five NR line buffer address holding units 202 through 206 in the control section 108 are managed as ring buffers. Specifically, the buffer management controlling unit 208 performs control such that at every output of video signals corresponding to one line from the NR section 103, the five line memories 104a through 104e in the NR buffer 104 sequentially hold the video signals corresponding to one line so that the video signals corresponding to one line are cyclically held among the five line memories. Accordingly, the buffer management controlling unit 208 controls the input switch 201 such that the five NR line buffer address holding units 202 through 206 are sequentially selected. Hereinafter, this control will be specifically described.
For example, with the Mth horizontal sync signal (where M is an arbitrary integer), when the NR line buffer address holding unit 1202 in the Nth line is specified for the NR section 103, the (N−4)th line is specified for the NR line buffer address holding unit 2203, the (N−3)th line is specified for the NR line buffer address holding unit 3204, the (N−2)th line is specified for the NR line buffer address holding unit 4205, and the (N−1)th line is specified for the NR line buffer address holding unit 5206, in the scaling section 105.
Next, with the (M+1)th horizontal sync signal, when the NR line buffer address holding unit 2203 in the (N+1)th line is specified for the NR section 103, the (N−3)th line is specified for the NR line buffer address holding unit 3204, the (N−2)th line is specified for the NR line buffer address holding unit 4205, the (N−1)th line is specified for the NR line buffer address holding unit 5206, and the Nth line is specified for the NR line buffer address holding unit 1202, in the scaling section 105.
Then, with the next (M+2)th horizontal sync signal, when the NR line buffer address holding unit 3204 in the (N+2)th line is specified for the NR section 103, the (N−2)th line is specified for the NR line buffer address holding unit 4205, the (N−1)th line is specified for the NR line buffer address holding unit 5206, the Nth line is specified for the NR line buffer address holding unit 1202, and the (N+1)th line is specified for the NR line buffer address holding unit 2203, in the scaling section 105. In this manner, the NR line buffer address holding units 202 through 206 are managed as ring buffers.
Now, an example of operation of a main portion of the video signal processor illustrated in
In the timing chart shown in
As shown in
Next, in synchronization with a vertical active period of a vertical sync signal two periods after the period in which the decoding of the Nth video bit stream starts, the NR section 103 reduces noise components in first field 312 and second field 314 and outputs video signals subjected to the noise reduction. In synchronization with a vertical active period of the vertical sync signal also used by the NR section 103, the scaling section 105 sequentially performs scaling on first field 322 and second field 324, which are Nth video signals whose noise components have been reduced, in the vertical and horizontal directions and outputs the processed video signals.
Now, the noise reduction by the NR section 103 and the scaling by the scaling section 105 within one vertical sync signal will be specifically described with reference to
When noise reduction and scaling are performed on video signals corresponding to one field with every one vertical sync signal in this manner, as shown in
An NR initialization setting process 311 for the processing on the first field by the NR section 103 starts in synchronization with a vertical blanking period of a vertical sync signal two periods after the period in which the decoding of the Nth video bit stream starts. After this NR initialization setting process, an NR process 312 starts. For the processing on the second field, an NR initialization setting process 313 starts in synchronization with a vertical blanking period of a vertical sync signal three periods after the period in which the decoding of the Nth video bit stream starts. After this NR initialization setting process, an NR process 314 starts.
A scaling initialization setting process 321 for the processing on the first field by the scaling section 105 starts in synchronization with the vertical blanking period of the vertical sync signal also used for initializing the noise reduction 312 performed on the Nth first field by the NR section 103. After this scaling initialization setting process, a scaling process 322 starts. A scaling initialization setting process 323 for the processing performed on the second field by the scaling section 105 starts in synchronization with the vertical blanking period of the vertical sync signal also used for initializing the noise reduction process 314 performed on the Nth second field by the NR section 103. After this scaling initialization setting process, a scaling process 324 starts.
In this case, if noise reduction on N+1 1st Field 316, N+1 2nd Field 318 and subsequent fields, for example, are unnecessary and thus the NR section 103 is suspended (this suspension state of noise reduction on these Fields 316 and 318 is represented by broken lines in
In addition, in this embodiment, the control section 108 controls the NR section 103 and the scaling section 105 so that noise reduction on video signals corresponding to one line in the NR section 103 and saving of these video signals in the NR buffer 104 are performed in parallel with scaling on video signals by the scaling section 105 without a collision. Accordingly, the NR buffer 104 is allowed to be formed only by five line memories 104a through 104e. As a result, the configuration of the NR buffer is made simple and the scale thereof is reduced, as compared to a conventional case where an NR buffer is formed by a field memory.
Operation of the sections included in the video signal processor of this embodiment may be implemented by operating a central processing unit (CPU) using software.
The video signal processor illustrated in
This embodiment is particularly characterized by an NR/scaling initialization setting section (initialization setting section) 403. The NR/scaling initialization setting section 403 indicates an initialization setting signal (noise reduction parameter) SIG404 for reducing noise components to the NR section 404 and also indicates an initialization setting signal (filter parameter) SIG412 for scaling in the vertical and horizontal directions to the scaling section 406.
The initialization switch SIG503 switches between the NR initialization setting processing circuit 501 and the scaling initialization setting processing circuit 502. This initialization switch SIG503 receives decoded video signals saved in the decode buffer 402 illustrated in
Based on the received information, the NR initialization setting processing circuit 501 creates a noise reduction parameter for reducing noise components of video signals necessary for the NR section 404, and indicates this parameter to the NR section 404 as a signal SIG506. Based on the received information, the scaling initialization setting circuit 502 creates a filter parameter for scaling on video signals in the vertical and horizontal directions necessary for the scaling section 406, and indicates this parameter to the scaling section 406 as a signal SIG507.
As shown in
Now, an example of operation of a main portion of the video signal processor of this embodiment will be described based on the timing chart shown in
In
Based on the indicated noise reduction parameter, the NR section 404 reduces noise components of first field 621 and second field 622, in synchronization with the vertical sync signal two periods after the period in which the decoding of the Nth video bit stream starts. Based on the indicated filter parameter, the scaling section 406 performs scaling on first field 631 and second field 632, which are Nth video signals whose noise components have been reduced, in the vertical and horizontal directions, in synchronization with the vertical sync signal also used by the NR section 404.
Then, in synchronization with the next vertical sync signal to the period in which the Nth scaling in the vertical and horizontal directions starts, the display section 408 outputs first field 641 and second field 642, which are video signals subjected to the Nth scaling in the vertical and horizontal directions.
In this embodiment, the NR/scaling initialization setting processing section 403 performs creation and indication of a noise reduction parameter to the NR section 404 and creation and indication of a filter parameter to the scaling section 406 are performed with the vertical sync signal (i.e., in 1/60 second) one period before the actual noise reduction and scaling. Accordingly, as compared a conventional case in which such creation and indication are performed in a short period, i.e., a vertical blanking period of a vertical sync signal, an operation frequency of the NR/scaling initialization setting processing section 403 can be reduced. In addition, processes in the NR section 404 and the scaling section 406 are completed in a period (i.e., 1/60 second) from a vertical sync signal to the next vertical sync signal, so that operation frequencies of the NR section 404 and the scaling section 406 can also be reduced, and the circuit scales thereof are reduced accordingly.
In this embodiment, operation of the NR/scaling initialization setting section 403 may also be implemented by operating a central processing unit (CPU) using software.
In this embodiment, a noise reduction parameter is created first, and a filter parameter is then created. However, conversely, a filter parameter may be created first before a noise reduction parameter is created.
Now, a video signal processor according to a third embodiment of the present invention will be described with reference to
The video signal processor illustrated in
This embodiment is characterized in that the filter buffers 106 and 407 illustrated in
Specifically, in this embodiment, in one vertical sync signal shown in
Accordingly, in synchronization with a line of video signals processed by the scaling section 805 as described above, the display section 806 outputs the video signals corresponding to the line to a video display device such as a TV set. As a result, as shown in the timing chart of
In this manner, at the same timing of scaling performed on video signals line by line by the scaling section 805 in synchronization with a horizontal sync signal, the display section 806 sequentially outputs video signals line by line to a device such as a TV set in synchronization with the horizontal sync signal. This allows video display device such as a TV set to provide normal display.
Accordingly, in this embodiment, it is unnecessary to provide a filter buffer (i.e., a field memory) (e.g., the filter buffer 11A6 described in the conventional example shown in
As described above, according to the present invention, an NR buffer for storing video signals subjected to noise reduction is formed by a plurality of line memories and processing in a noise reduction section and processing in a scaling section are performed in parallel. Accordingly, the present invention is useful for video signal processors for use in noise reduction for, for example, digital TV sets or DVD players and processing on TV output signals.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-300515 | Oct 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2005/015984 | 9/1/2005 | WO | 00 | 2/21/2006 |
