Video processing apparatus

Abstract

According to one embodiment, a video processing apparatus includes a video data output device which outputs a data packet signal obtained by packetizing a data enable signal and a synchronization packet signal obtained by packetizing a synchronization signal, a transmission device which transmits the data packet signal and the synchronization packet signal, the data packet signal being delayed by a first delay amount and the synchronization packet signal being delayed by a second delay amount, and a timing controller which generates the data enable signal and the synchronization signal so as to set a pulse of the synchronization signal within a blanking period of the data enable signal based on the data packet signal and the synchronization packet signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2014-197358, filed Sep. 26, 2014, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a video processing apparatus.

BACKGROUND

In general, a video data output device directly transmits a packet signal based on video data to a display device. An I/F format conversion device or a video data processing device is sometimes arranged between the video data output device and the display device. In any case, a signal is transmitted to the display device at a stable timing complying with constraints of the display device.

Various packet signals are transmitted not only from a video data output device to a display device but also from other devices (hardware) different from the video data output device to other devices different from the display device. In this case, packet signals are transmitted via a common transmission device. The transmission device arbitrates between packet signals to determine from which device transmission is performed to which device.

At this time, packet signals are delayed by the transmission device by inconstant delay amounts (different delay amounts). For this reason, the packet signals based on video data from the video output device are transmitted to the display device upon being delayed by different delay amounts. There is therefore a possibility that video data may become a signal which does not meet the constraints of the display device (which is not accepted by the display device).

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a block diagram showing a video processing apparatus according to the first embodiment;

FIG. 2 is a timing chart showing output signals from a video data output device and regeneration signals by a timing controller according to the first embodiment;

FIG. 3 is a block diagram showing a timing controller according to the first embodiment;

FIG. 4 shows timing charts showing the details of regeneration signals by the timing controller according to the first embodiment;

FIG. 5 is a flowchart showing the operation of the timing controller according to the first embodiment;

FIG. 6 is a block diagram showing a modification of the video processing apparatus according to the first embodiment;

FIG. 7 is a block diagram showing a timing controller according to the second embodiment;

FIG. 8 is a timing chart showing output signals from a video data output device and regeneration signals by a timing controller according to the second embodiment; and

FIG. 9 is a timing chart showing output signals from a video data output device and output signals from a transmission device according to a comparative example.

DETAILED DESCRIPTION

In general, when a video data output device transmits a packet signal, video data and a synchronization signal are reproduced based on the packet signal. At this time, in order to meet the constraints of a display device, each pulse of the synchronization signal needs to be set in a corresponding blanking period of the video data. Blanking period is a period except for effective region of video data signal and L-level period of data enable signal.

As indicated by a comparative example in FIG. 9, packet signals (synchronization packet signal S and video data packet signals D) from the video data output device are sometimes delayed by a transmission device by different delay amounts. In this case, a data enable signal DE and a synchronization signal Hsync are reproduced from the packet signals delayed by different delay amounts. Since these packet signals have different delay amounts, the data enable signal DE and the synchronization signal Hsync are generated at timings different from those of the original signals.

More specifically, the timing of a pulse Hp (L level) of the synchronization signal Hsync shifts from the timing of a blanking period Hblank (L level) of the data enable signal DE. As a result, the pulse Hp of the synchronization signal Hsync is located in an effective period (H level) of the data enable signal DE. This causes a mismatch in the relationship between the synchronization signal Hsync and the data enable signal DE. These signals therefore do not meet the constraints of the display device.

This embodiment is to solve the above problem by controlling the timing of the pulse Hp of the synchronization signal Hsync and the width of the blanking period Hblank of the data enable signal DE.

In general, according to one embodiment, a video processing apparatus includes a video data output device which outputs a data packet signal obtained by packetizing a data enable signal and a synchronization packet signal obtained by packetizing a synchronization signal, a transmission device which transmits the data packet signal and the synchronization packet signal, the data packet signal being delayed by a first delay amount and the synchronization packet signal being delayed by a second delay amount different from the first delay amount, and a timing controller which generates the data enable signal and the synchronization signal so as to set a pulse of the synchronization signal within a blanking period of the data enable signal based on the data packet signal and the synchronization packet signal.

Embodiments will be described below with reference to the accompanying drawing. Note that the same reference numerals throughout the drawing denote the same parts, and a repetitive description will be made as needed.

First Embodiment

A video processing apparatus according to the first embodiment will be described with reference to FIGS. 1, 2, 3, 4, 5, and 6. In the first embodiment, a timing controller (T-CON) 300 controls the timing of a pulse Hp of a synchronization signal Hsync and the width of a blanking period Hblank of a data enable signal DE. This makes it possible for the timing controller 300 to set the pulse Hp of the synchronization signal Hsync within the blanking period Hblank of the data enable signal DE. It is therefore possible to generate the synchronization signal Hsync and the data enable signal DE which meet the constraints of a display device 400. The first embodiment will be described in detail below.

Arrangement of First Embodiment

FIG. 1 is a block diagram showing the video processing apparatus according to the first embodiment. FIG. 2 is a timing chart showing output signals from a video data output device and regeneration signals by a timing controller according to the first embodiment.

The following description will exemplify a horizontal synchronization signal as a synchronization signal. However, a vertical synchronization signal may be the synchronization signal. In addition, the following description will exemplify a horizontal blanking period as a blanking period. However, a vertical blanking period may be the blanking period.

As shown in FIG. 1, the video processing apparatus includes a video data output device 100, a transmission device 200, the timing controller 300, the display device 400, first to third devices 600a to 600c, and fourth to sixth devices 700a to 700c.

The video data output device 100 is, for example, an application processor. The video data output device 100 outputs packet signals obtained by packetizing the video data enable signal DE (to be simply referred to as the data enable signal DE hereinafter) and the synchronization signal Hsync. The timings of packet signals may or may not be constant.

As shown in FIG. 2, a packet signal is constituted by a synchronization packet signal S and a data packet signal D. The synchronization packet signal S is a signal obtained by packetizing the pulse Hp of the synchronization signal Hsync. The data packet signal D is a signal obtained by packetizing an effective period (H-level period) of the data enable signal DE.

Note that a conversion device (not shown) may be arranged on the subsequent stage of the video data output device 100. This conversion device may packetize the data enable signal DE and the synchronization signal Hsync.

As shown in FIG. 1, the transmission device 200 outputs packet signals from the video data output device 100 to the timing controller 300 while delaying the signals by inconstant delay amounts (different delay amounts).

In addition, the transmission device 200 may arbitrate between various types of packet signals from a plurality of transmission sources (first to third devices 600a to 600c). For example, the transmission device 200 may select a packet signal from a plurality of transmission sources (first to third devices 600a to 600c) and determine one of a plurality of transmission destinations (fourth to sixth devices 700a to 700c) to which the signal is to be transmitted. At this time, various packet signals are output while being delayed by the transmission device 200 by different delay amounts.

The timing controller 300 receives the packet signals delayed by different delay amounts from the transmission device 200, and converts the format of the signals into a format which allows the display device 400 to receive the signals. More specifically, the timing controller 300 generates (regenerates) and outputs the data enable signal DE and synchronization signal Hsync based on the packet signals delayed by the different delay amounts.

As shown in FIG. 2, with regard to the data enable signal DE and the synchronization signal Hsync generated by the timing controller 300, the pulse Hp of the synchronization signal Hsync is set within the blanking period Hblank of the data enable signal DE. The details of the timing controller 300 will be described later.

As shown in FIG. 1, the display device 400 is, for example, an LCD (Liquid Crystal Display). The display device 400 displays a video based on the data enable signal DE and the synchronization signal Hsync generated by the timing controller 300. The display device 400 has a constraint concerning a blanking period for an input signal. That is, in the display device 400, the pulse Hp of the synchronization signal Hsync needs to fall within the blanking period Hblank of the data enable signal DE to display a video.

FIG. 3 is a block diagram showing a timing controller according to the first embodiment.

FIG. 4 shows timing charts showing the details of regeneration signals at the timing controller according to the first embodiment. More specifically, (a) in FIG. 4 is a timing chart showing a regeneration signal when the synchronization packet signal S is located between the Min value and the Max value. In FIG. 4, (b) is a timing chart showing a regeneration signal when the synchronization packet signal S is earlier than the Min value. In FIG. 4, (c) is a timing chart showing a regeneration signal when the synchronization packet signal S is later than the Max value. Note that the Min value and the Max value will be described later.

In the first embodiment, as indicated by (b) and (c) in FIG. 4, when the synchronization packet signal S is earlier than the Min value or later than the Max value, the trailing edge timing of the pulse Hp of the synchronization signal Hsync is controlled as needed. The signals indicated by (a), (b), and (c) in FIG. 4 will be described in detail later.

As shown in FIG. 3, the timing controller 300 includes a packet reception circuit 310, a synchronization packet recognition circuit 320, a timing signal generation circuit 330, a counter 340, a comparator 350, a line buffer 360, and a video data processing circuit 370.

The packet reception circuit 310 separates a packet signal from the transmission device 200 into the synchronization signal S and the data packet signal D. The packet reception circuit 310 outputs the synchronization packet signal S to the synchronization packet recognition circuit 320, and the data packet signal D to the line buffer 360.

The synchronization packet recognition circuit 320 recognizes whether the synchronization packet signal S from the packet reception circuit 310 is a horizontal synchronization packet signal or a vertical synchronization packet signal. The synchronization packet recognition circuit 320 outputs the synchronization packet signal S to the timing signal generation circuit 330 and the comparator 350.

The timing signal generation circuit 330 recognizes the timing of the data enable signal DE based on the synchronization packet signal S from the synchronization packet recognition circuit 320. The timing of the data enable signal DE is recognized based on the synchronization packet signal S (first synchronization packet signal S) which is input before the synchronization packet signal S (second synchronization packet signal S) which will be counted is input. The timing signal generation circuit 330 outputs a control signal to the counter 340 based on the timing of the data enable signal DE. This control signal is a signal for notifying the trailing edge timing of the data enable signal DE.

In addition, the timing signal generation circuit 330 controls the timing of the pulse Hp and the width (time) of the blanking period Hblank in accordance with the control signal (trigger) based on a comparison result from the comparator 350.

In this case, as indicated by (a), (b), and (c) in FIG. 4, the blanking period Hblank includes the pulse Hp, a front porch Hfront, and a back porch Hback. The front porch Hfront indicates a period from a trailing edge of the data enable signal DE to a trailing edge of the synchronization signal Hsync. The back porch Hback is a period from a leading edge of the synchronization signal Hsync and a leading edge of the data enable signal DE. Although the back porch Hback is constant, it need not be constant if the data enable signal DE is present.

The timing signal generation circuit 330 controls the timing of the pulse Hp with reference to the Min value or Max value of the blanking period Hblank.

The Min value of the blanking period Hblank indicates the termination time point in the minimum time of a period (front porch Hfront) from a trailing edge of the data enable signal DE and a trailing edge of the synchronization signal Hsync. The Max value of the blanking period Hblank indicates the termination time point in the maximum time of the front porch Hfront.

The Min value and Max value of the blanking period Hblank are set in advance based on the specifications of the display device 400. More specifically, the Min value is set so as not to violate the constraints of the blanking period Hblank of the display device 400. That is, the Min value is set so that the pulse Hp be to fall within the blanking period Hblank with a sufficient margin. In addition, the Min value and the Max value are set so as to suppress variations in the cycle (one horizontal cycle) of the synchronization signal Hsync. The Min value and the Max value are set by a setting register (not shown) in, for example, an application processor (video data output device).

If the input timing of the synchronization packet signal S is earlier than the Min value of the blanking period Hblank, the timing of the pulse Hp is forcibly set at the timing of the Min value. In contrast to this, if the input timing of the synchronization packet signal S is later than the Max value of the blanking period Hblank, the timing of the pulse Hp is forcibly set at the timing of the Max value.

In FIG. 4, (a), (b), and (c) exemplify timing control on the pulse Hp when the Min value and Max value of the front porch Hfront are respectively “5” and “17”.

As indicated by (a) in FIG. 4, if the count value (“9”) of the synchronization packet signal S is equal to or more the Min value and equal to or less than the Max value, the comparator 350 outputs a trigger at the input timing of the synchronization packet signal S. That is, the timing signal generation circuit 330 sets the pulse Hp of the synchronization signal Hsync at the input timing of the synchronization packet signal S.

As indicated by (b) in FIG. 4, if the count value (“3”) of the synchronization packet signal S is less the Min value, the comparator 350 outputs a trigger at the input timing of the Min value. That is, the timing signal generation circuit 330 sets the pulse Hp of the synchronization signal Hsync at the timing of the Min value.

As indicated by (c) in FIG. 4, if the count value (“19”) of the synchronization packet signal S is more than the Max value, the comparator 350 outputs a trigger at the timing of the Max value. That is, the timing signal generation circuit 330 sets the pulse Hp of the synchronization signal Hsync at the timing of the Max value without waiting for the synchronization packet signal S. In this case, the first synchronization packet signal S after this timing is discarded.

In this manner, the timing signal generation circuit 330 forcibly controls the timing of the pulse Hp with reference to the Min value or Max value of the blanking period Hblank when the synchronization packet signal S exceeds them. Along with the timing of the pulse Hp, the width of the front porch Hfront of the blanking period Hblank is determined. In addition, the width of the pulse Hp and the width of the back porch Hback are constant. Therefore, the width of the blanking period Hblank is determined along with the timing of the pulse Hp. In this manner, the timing signal generation circuit 330 generates the synchronization signal Hsync, with the timing of the pulse Hp being controlled, and the data enable signal DE, with the width of the blanking period Hblank being controlled.

As shown in FIG. 3, the counter 340 starts counting based on a control signal from the timing signal generation circuit 330. More specifically, as indicated by (a) and (b) in FIG. 4, the counter 340 counts with reference to a trailing edge of the data enable signal DE. The counter 340 outputs the count to the comparator 350.

As shown in FIG. 3, the comparator 350 compares the count from the counter 340 with the reception timing of the synchronization packet signal S from the synchronization packet recognition circuit 320. With this operation, the comparator 350 measures a count value at the reception timing of the synchronization packet signal S. This count value indicates the reception timing of the synchronization packet signal S with reference to a trailing edge of the data enable signal DE. The comparator 350 compares the count value at the reception timing of the synchronization packet signal S with the Min value and Max value of the blanking period Hblank (front porch Hfront). The comparator 350 outputs a control signal (trigger) corresponding to the comparison result to the timing signal generation circuit 330.

As shown in FIG. 3, the line buffer 360 temporarily stores the data packet signal D from the packet reception circuit 310 and outputs the packet to the video data processing circuit 370.

The video data processing circuit 370 processes the data packet signal D from the line buffer 360 as video data. The video data processing circuit 370 outputs the video data based on the data enable signal DE whose timing is controlled by the timing signal generation circuit 330.

Operation in First Embodiment

FIG. 5 is a flowchart showing the operation of the timing controller according to the first embodiment.

As shown in FIG. 5, first of all, in step S1, the packet reception circuit 310 receives a packet signal.

In step S2, the timing signal generation circuit 330 recognizes the timing of the data enable signal DE based on the synchronization packet signal S.

In step S3, the counter 340 starts counting based on the timing of the data enable signal DE. More specifically, the counter 340 starts counting from the trailing edge timing of the data enable signal DE.

In step S4, the comparator 350 measures the count value of the reception timing of the synchronization packet signal S. This count value is obtained by comparing the count obtained by the counter 340 with the reception timing of the synchronization packet signal S.

In step S5, the comparator 350 compares the count value at the reception timing of the synchronization packet signal S with the Min value and Max value of the blanking period Hblank (front porch Hfront).

If it is determined in step S5 that the count value is smaller than the Min value, the timing signal generation circuit 330 sets the pulse Hp at the timing of the Min value in step S6. If it is determined in step S5 that the count value is equal to or more than the Min value and equal to or less than the Max value, the timing signal generation circuit 330 sets the pulse Hp at the input timing of the synchronization packet signal S in step S7. In addition, if it is determined in step S5 that the count value is larger than the Max value, the timing signal generation circuit 330 sets the pulse Hp at the timing of the Max value in step S7.

Effects in First Embodiment

According to the first embodiment described above, the timing controller 300 controls the timing of the pulse Hp of the synchronization signal Hsync and the width of the blanking period Hblank of the data enable signal DE. This enables the timing controller 300 to set the pulse Hp of the synchronization signal Hsync within the blanking period Hblank of the data enable signal DE. Therefore, it is possible to generate the synchronization signal Hsync and the data enable signal DE which meet the constraints of the display device 400.

At this time, controlling the Min value of the blanking period Hblank makes it possible to generate the synchronization signal Hsync and the data enable signal DE which meet the constraints of the display device 400. In addition, controlling also the Max value of the blanking period Hblank makes it possible to suppress variations in the cycle (one horizontal cycle) of the synchronization signal Hsync. This enables the display device 400 to perform stable display.

Modification of First Embodiment

FIG. 6 is a block diagram showing a modification of the video processing apparatus according to the first embodiment. The difference between the modification and the above embodiment will be mainly described.

As shown in FIG. 6, the video processing apparatus includes a display signal output device 500.

The display signal output device 500 converts output signals from the timing controller 300 into signals in various formats, and outputs the signals to the display device 400. The display signal output device 500 converts an input signal into a signal in a format such as the DSI (Display Serial Interface), LVDS (Low Voltage Differential Signaling), or eDP (Embedded Display Port) format. This enables the video processing apparatus to cope with various signal formats.

Second Embodiment

A video processing apparatus according to the second embodiment will be described with reference to FIGS. 7 and 8. According to the second embodiment, a timing controller 300 includes a first line buffer 360_0 and a second line buffer 360_1. The data packet signals D are alternately stored in the first line buffer 360_0 and the second line buffer 360_1 in an arbitrary unit, and are alternately output. This can suppress the exhaustion of reception data at the time of data transfer. The second embodiment will be described in detail below.

Note that only differences between the second embodiment and the first embodiment will be mainly described while a description of parts similar to the first embodiment will be omitted.

Arrangement of Second Embodiment

FIG. 7 is a block diagram showing a timing controller according to the second embodiment. FIG. 8 is a timing chart showing output signals from a video data output device and regeneration signals at the timing controller according to the second embodiment.

As shown in FIG. 7, the timing controller 300 includes the first line buffer 360_0, the second line buffer 360_1, and a line buffer data output circuit 380.

The first line buffer 360_0 and the second line buffer 360_1 temporarily store data packet signals D from the packet reception circuit 310, and output the signals to the line buffer data output circuit 380. The line buffer data output circuit 380 alternately outputs data from the first line buffer 360_0 and the second line buffer 360_1. The data packet signals D are alternately stored in the first line buffer 360_0 and the second line buffer 360_1 in an arbitrary unit, and are alternately output.

As shown in FIG. 8, the first line buffer 360_0 and the second line buffer 360_1 store, for example, data corresponding to about one horizontal cycle and then output the data. In addition, while data 0 stored in the first line buffer 360_0 is output, data 1 is stored in the second line buffer 360_1. While data 0 stored in the second line buffer 360_1 is output, new data 0 is stored in the first line buffer 360_0.

In this case, (A) in FIG. 8 indicates a case in which the count value of a synchronization packet signal S1 is larger than the Max value, and a pulse Hp of a synchronization signal Hsync is set at the timing of the Max value without waiting for the synchronization packet signal S1. That is, the pulse Hp is set at a timing earlier than that of a pulse Hp′ which is the normal timing based on the synchronization packet signal S1. Along with this setting, the timing of the termination of a blanking period Hblank (a leading edge of a data enable signal DE) is earlier than that of the termination of a normal blanking period Hblank′.

According to the second embodiment, thereafter, data 0 in the first line buffer 360_0, which has already been stored, is output at a leading edge timing of the blanking period Hblank. That is, this can suppress the exhaustion of reception data at the time of data transfer.

Although the two line buffers, namely the first line buffer 360_0 and the second line buffer 360_1 have been described above, three or more line buffers may be used.

Effects in Second Embodiment

In the first embodiment, if the count value of the synchronization packet signal S is larger than the Max value, the pulse Hp of the synchronization signal Hsync is set at the timing of the Max value without waiting for the synchronization packet signal S ((c) in FIG. 4). Along with this setting, the back porch Hback is set as a constant value. That is, the data enable signal DE may rise before the synchronization packet signal S after the pulse Hp and the subsequent data packet signal D are received. This causes a problem in data transfer (exhaustion of reception data) because there is no data which can be received.

In contrast to this, according to the second embodiment, the timing controller 300 includes the first line buffer 360_0 and the second line buffer 360_1. The data packet signals D are alternately stored in the first line buffer 360_0 and the second line buffer 360_1 and are alternately output. More specifically, while data 0 stored in the first line buffer 360_0 is output, data 1 is stored in the second line buffer 360_1. Subsequently, while data 1 stored in the second line buffer 360_1 is output, new data 0 is stored in the first line buffer 360_0. That is, data on the next line is stored in the line buffer in advance. This can suppress exhaustion of reception data at the time of data transfer.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

Claims

1. A video processing apparatus comprising:

a video data output device which outputs a data packet signal obtained by packetizing a data enable signal and a synchronization packet signal obtained by packetizing a synchronization signal;

a transmission device which transmits the data packet signal and the synchronization packet signal, the data packet signal being delayed by a first delay amount and the synchronization packet signal being delayed by a second delay amount different from the first delay amount;

a timing controller which generates the data enable signal and the synchronization signal so as to set a pulse of the synchronization signal within a blanking period of the data enable signal based on the data packet signal and the synchronization packet signal; and

a display device which displays a video based on the data enable signal and the synchronization signal generated by the timing controller.

2. The apparatus of claim 1, wherein the timing controller comprises:

a counter which starts to count based on the data enable signal;

a comparator which compares a count value of an input of the synchronization packet signal obtained by the counter with a count value corresponding to a Min value and a count value corresponding to a Max value in the blanking period; and

a timing signal generation circuit which generates the data enable signal and the synchronization signal so as to set a pulse of the synchronization signal within a blanking period of the data enable signal in accordance with a comparison result obtained by the comparator.

3. The apparatus of claim 2, wherein the timing signal generation circuit sets a pulse of the synchronization signal at a reception timing of the synchronization packet signal when the count value of an input of the synchronization packet signal is not less than the count value corresponding to the Min value and not more than the count value corresponding to the Max value,

sets a pulse of the synchronization signal at a timing of the count value corresponding to the Min value when the count value of the input of the synchronization packet signal is smaller than the count value corresponding to the Min value, and

sets a pulse of the synchronization signal at a timing of the count value corresponding to the Max value when the count value of the input of the synchronization packet signal is larger than the count value corresponding to the Max value.

4. The apparatus of claim 3, wherein when the count value of the input of the synchronization packet signal is larger than the count value corresponding to the Max value, the synchronization packet signal is discarded.

5. The apparatus of claim 2, wherein the counter starts counting with reference to a trailing edge of the data enable signal.

6. The apparatus of claim 1, wherein the synchronization signal comprises a horizontal synchronization signal, and the blanking period comprises a horizontal blanking period.

7. The apparatus of claim 1, wherein the synchronization signal comprises a vertical synchronization signal, and the blanking period comprises a vertical blanking period.

8. The apparatus of claim 1, wherein the timing controller further comprises a first line buffer and a second line buffer configured to alternately store the data packet signals from the video data output device and alternately output the data packet signals.

9. The apparatus of claim 8, wherein while the first line buffer outputs a first data packet signal of the data packet signals, the second line buffer stores a second data packet signal of the data packet signals different from the first data packet signal.

10. The apparatus of claim 1, wherein the video data output device comprises an application processor.

11. The apparatus of claim 1, wherein the transmission device selects and receives a packet signal from any one of a plurality of transmission source devices, selects any one of a plurality of transmission destination devices, and transmits the packet signal.

12. The apparatus of claim 1, further comprising a display signal output device configured to convert formats of the data enable signal and the synchronization signal from the timing controller and output the data enable signal and the synchronization signal to the display device.