JP2011135319A - Video signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent displayed video from being disturbed even when video setting is changed at an arbitrary timing about a video signal processing device for converting a frame rate. <P>SOLUTION: The video signal processing device includes: memory banks (10 and 11); a video writing unit (12) for selectively writing a video frame in the memory banks at a first frame rate; a video reading unit (13) for selectively reading the video frame from the memory banks at a second frame rate; a write control unit (14) for instructing the video writing unit to write the video frame in either of the memory banks; a read control unit (15) for instructing the video reading unit to read the video frame from either of the memory banks; and a timing adjusting unit (20) for instructing the video reading unit to change video setting about reading after the elapse of a predetermined time after the video writing unit changes vide setting about writing to start writing the video frame in the memory banks. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a video signal processing apparatus that converts a frame rate, and more particularly, to a technique for suppressing video disturbance.

  2. Description of the Related Art In recent years, the number of video signal formats input to a video display device has increased dramatically due to high-capacity storage disks such as BLU-RAY DISC (registered trademark) and high-definition video display devices. The video display device supports many formats by converting an input video signal into a displayable format.

  One of the components of the format is a frame rate. This represents “how many frames are present in one second”. The frame rate is generally 60 frames / second. For example, the frame rate used for a movie is 24 frames / second. Therefore, in a BLU-RAY DISC that records a movie, the frame rate of the recorded video is often 24 frames / second. In general, “Hz” is used as a unit of the frame rate. For example, when the frame rate is 24 frames / second, it is expressed as 24 Hz.

  In a video display device, the video frame rate is generally displayed at 60 Hz. When a video having a frame rate of 24 Hz is input to such a video display device, frame rate conversion from 24 Hz to 60 Hz is performed in the video display device. Frame rate conversion is performed using a memory bank that records video frames. The frame rate is converted by writing the video frame to the memory bank at the frame rate of the input video and reading the video frame at the frame rate of the output video.

  When there is only one memory bank, the image displayed by reading the video frame from the memory bank area where writing has not been completed or by writing the video frame to the memory bank area where reading has not been completed. May be disturbed. Such a phenomenon is called “overtaking”.

  When the writing frame rate is 24 Hz and the reading frame rate is 60 Hz, the reading speed is faster than the writing speed. Therefore, even though only the upper half of the video frame is written in the memory bank, the lower half of the video frame may be read. This causes different video frames to be displayed at the top and bottom of the screen. Such a phenomenon is called “abdominal shortage”.

  In order to avoid these phenomena, a video signal processing apparatus using two memory banks has been disclosed (for example, see Patent Document 1). In this video signal processing apparatus, when the frame rate of the input video is smaller than the frame rate of the output video, the input video is alternately written into the two memory banks. If a corresponding portion of the video frame is written in the memory bank from which data is read, reading is started from that memory bank. In this case, even if the reading is started before the writing to the memory bank is completed, the completion of the writing is earlier than the completion of the reading, so that overtaking and hungry are avoided.

JP 2001-111968 A

  As shown in FIG. 10, when the period from when writing to the memory bank is started until a corresponding portion of the video frame is written is T and the time when the period T ends is T1, in the conventional technique, from the memory bank, Is read earlier than T1, the video frame is read from a memory bank different from the current write destination memory bank. Conversely, if the read start time is later than T1, the video frame is read from the current write destination memory bank.

  In the conventional technique, when the video settings are changed by a user's remote control operation or the like at time t, the video settings on the writing side and the reading side of the video frame are simultaneously changed. Therefore, when the video setting changes from setting A to setting B, for example, at time t, the video frame is read with setting B in waveforms c and d from memory bank 0 in which the video frame is written with setting A. Then, the video settings on the writing side and the reading side with respect to the memory bank 0 become inconsistent, so that the displayed video may be disturbed.

  In view of such a point, the present invention relates to a video signal processing device that converts a frame rate, and an object thereof is to prevent disturbance of a display video even when a video setting is changed at an arbitrary timing.

  In order to solve the above problems, the present invention has taken the following solutions. That is, as a video signal processing device for converting the frame rate of a video signal, a video document for selectively writing video frames to the first and second memory banks and the first and second memory banks at the first frame rate. With respect to the video writing means, the video reading means for selectively reading video frames from the first and second memory banks at the second frame rate, and the video writing means. A writing control means for instructing whether to write a video frame; a reading control means for instructing the video reading means from which of the first and second memory banks to read the video frame; and a video writing means Change video settings for writing and start writing video frames to the memory bank. That it is assumed that a timing adjusting means for instructing a change of the video settings.

  According to this, even if the video setting on the writing side is changed, the video setting on the reading side for the memory bank to which the video frame was written starts to be written to another memory bank with the video setting on the writing side after the change. Until the predetermined time elapses. That is, the video frame written in the memory bank with the video setting before change is read out with the video setting before change.

  The present invention relates to a video signal processing apparatus that performs frame rate conversion, and can prevent display video from being disturbed even if video settings are changed at an arbitrary timing.

It is a block diagram of the video signal processing apparatus which concerns on one Embodiment of this invention. It is a timing chart of writing and reading to a memory bank. It is a timing chart showing the time zone which should instruct | indicate the change of a video setting, and the time which the memory bank of reading origin determines. It is a timing chart showing the current read time from the memory bank and the predicted time to start reading next. It is a timing chart showing the case where the prediction time which starts reading from a memory bank, and the readable time from the memory bank are near. It is a timing chart showing the case where the estimated time which starts reading from a memory bank, and the time which actually starts reading from the memory bank differ. It is a timing chart showing the case where a video setting is not changed. It is a block diagram of the video signal processing apparatus which concerns on the modification of FIG. It is a block diagram of the video signal processing apparatus which concerns on another modification of FIG. 6 is a timing chart of writing and reading with respect to a memory bank according to a conventional video signal processing apparatus.

  FIG. 1 is a configuration diagram of a video signal processing apparatus according to an embodiment of the present invention. The video signal processing apparatus includes a video writing unit 12, a video reading unit 13, a writing control unit 14, a reading control unit 15, a recording unit 16, and a timing adjustment unit 20. The recording unit 16 includes a memory bank 10 and a memory bank 11. The memory bank 10 and the memory bank 11 may be either physically separated or areas may be separated in the same memory.

  In the memory bank 10 and the memory bank 11, video frames before frame rate conversion (hereinafter referred to as pre-conversion video) are stored. The video writing unit 12 receives the input video signal and selectively writes the pre-conversion video in the memory bank 10 and the memory bank 11 at a frame rate of, for example, 24 Hz. For example, the video writing unit 12 may write the pre-conversion video in the memory bank 10 or the memory bank 11 based on the input synchronization signal. The video reading means 13 selectively reads video frames from the memory bank 10 and the memory bank 11 at a frame rate of 60 Hz, for example. As a result, the converted video whose frame rate has been converted is output as an output video signal.

  When the frame rate before conversion is smaller than the frame rate after conversion based on the input synchronization signal, the writing control unit 14 converts the video writing unit 12 to either the memory bank 10 or the memory bank 11 before conversion. Instructs whether to write video. In addition, when the video settings such as normal, wide, zoom, and the like are changed by the user's remote control operation, the writing control unit 14 writes the pre-conversion video to the memory bank with a size corresponding to the video setting. The writing unit 12 is instructed. That is, the change in the video setting on the writing side is reflected every time when the change of the video setting is instructed by the user, when the memory bank to which the pre-conversion video is written is changed.

  Based on the input synchronization signal and the output synchronization signal, the read control means 15 instructs the video read means 13 from which one of the memory bank 10 and the memory bank 11 the video frame is read so as not to cause a stomach cut. To do. When the video setting is changed, the reading control unit 15 instructs the video reading unit 13 to read the video frame from the memory bank with a size corresponding to the video setting. Also, the read control means 15 measures the timing at which the video reading means 13 can read from the memory bank in which the video writing means 12 is currently writing the pre-conversion video based on the input synchronization signal and the output synchronization signal. Then, the timing adjustment means 20 is notified of the timing. The timing adjusting unit 20 instructs the video reading unit 13 to change the video setting on the reading side at the timing notified from the reading control unit 15.

  FIG. 2 is a timing chart for writing to and reading from the memory bank. When the video setting on the writing side is changed from setting A to setting B, for example, at time t, the video writing means 12 writes the pre-conversion video in the memory bank 11 with setting B. The read control means 15 measures the time T from when the video writing means 12 starts writing to the memory bank 11 at the setting B until the video reading means 13 can read from the memory bank 11, and The timing adjustment means 20 is notified of the time T1 at which reading from the bank 11 is possible. If the time when the video reading unit 13 actually starts reading from the memory bank is before T1, the read control unit 15 instructs the memory bank 10 to the video reading unit 13. On the contrary, if it is after T1, the memory bank 11 is instructed to the video reading means 13.

  The timing adjusting unit 20 instructs the video reading unit 13 to change to the setting B at T1. That is, when the memory bank from which the video frame is read is switched from the memory bank 10 in which the pre-conversion video is written in the setting A to the memory bank 11 in which the pre-conversion video is written in the setting B, the video setting for the video reading means 13 is performed. Will be instructed to change. Note that the user may set T1 or may be set in advance by the designer.

  As shown in FIG. 3, the timing adjusting unit 20 changes the video setting to the video reading unit 13 after the video reading unit 13 completes the reading from the memory bank and starts the next reading. Need to be instructed. On the other hand, from which memory bank the video reading means 13 reads the video frame is determined when the reading is actually started. As a result, the timing adjusting unit 20 applies to the video reading unit 13 before the time when the video reading unit 13 starts reading the next video frame, that is, before the next memory bank to be read is determined. It is necessary to instruct to change the video settings.

  Therefore, as shown in FIG. 4, the timing adjustment unit 20 predicts the time when the video reading unit 13 starts reading the video frame from the memory bank next based on the output synchronization signal. Then, the timing adjustment unit 20 calculates the difference between the predicted time and T1. When this difference is larger than the threshold value, the predicted time and the actual read start time substantially coincide. The threshold is, for example, a time that can reflect a change in the video setting for the video reading unit 13, and may be set by the user or previously set by the designer. If the predicted time is later than T1, the timing adjusting unit 20 instructs the video reading unit 13 to change the video setting at T1. As a result, the change of the video setting is reflected when the memory bank that is the reading source of the video reading means 13 is switched. On the contrary, if the predicted time is before T1, the timing adjustment unit 20 does not instruct the video reading unit 13 to change the video setting.

  On the other hand, when the difference between the time predicted by the timing adjustment unit 20 and T1 is smaller than the threshold value, the predicted time may be different from the actual read start time as in the following two cases, for example. Then, there is a possibility that the video settings are inconsistent on the writing side and the reading side with respect to the memory bank to be read next.

  In the first case, the timing adjusting unit 20 instructs the video reading unit 13 to change the video setting because the predicted time is later than T1, but the video reading unit 13 actually starts from T1. This is a case where reading has started before.

  This will be specifically described with reference to FIGS. In the memory read waveforms shown in FIGS. 5 and 6, actual read is indicated by a solid line, and read prediction is indicated by a broken line. That is, the boundary between the solid line and the broken line represents the current time.

  In FIG. 5, the timing adjusting unit 20 predicts the rising edge of the waveform d as the next reading start time, and instructs the video reading unit 13 to set B because the predicted timing is later than T1. However, in FIG. 6, the rising edge of the actual waveform d is before T1, so it can be said that the timing adjustment means 20 should have instructed the video reading means 13 to set A.

  In the second case, contrary to the first case, the timing adjustment unit 20 did not instruct the video reading unit 13 to change the video setting because the predicted time is before T1. Actually, this is a case where the video reading means 13 starts reading after T1. As in these two cases, if video settings are mismatched between the writing side and the reading side for the memory bank to be read next, the display video image may be disturbed.

  In order to prevent these two cases, the timing adjustment unit 20 notifies the read control unit 15 whether or not to change the video setting for the video reading unit 13 when the difference between the predicted time and T1 is smaller than the threshold value. To do. Then, when the notification from the timing adjusting unit 20 indicates that the video setting is to be changed, the read control unit 15 instructs the video reading unit 13 to switch the memory bank serving as the read source.

  This is shown in FIG. Since the difference between the predicted time and T1 is smaller than the threshold value, the timing adjustment unit 20 notifies the reading control unit 15 that the video setting is not changed to the video reading unit 13. Then, the reading control unit 15 instructs the video reading unit 13 not to switch the reading source memory bank, that is, the memory bank 10. As a result, the video settings on the writing side and the reading side for the memory bank 10 are set to A and match. In the waveform d, since the read completion time from the memory bank 10 is later than the write completion time to the memory bank 11, the memory bank 11 can be used as the read source. Here, by intentionally using the memory bank 10 as a reading source, it is possible to prevent inconsistency in the video settings between the writing side and the reading side with respect to the memory bank 10.

  Note that the timing adjustment unit 20 may notify the reading control unit 15 that the video reading unit 13 is to change the video setting. In this case, the timing adjusting unit 20 instructs the video reading unit 13 to set B, and the reading control unit 15 switches the memory bank to be read from the video reading unit 13, that is, the memory bank 11 Can be indicated.

-Modification 1-
FIG. 8 is a block diagram of a video signal processing apparatus according to a modification of FIG. The write control unit 14 and the read control unit 15 shown in FIG. 1 may be realized by software processing of the CPU 17.

-Modification 2-
FIG. 9 is a block diagram of a video signal processing apparatus according to another modification of FIG. The timing adjustment unit 20 shown in FIG. 8 may be realized by software processing of the CPU 17.

  As described above, according to the present embodiment, regarding the video signal processing apparatus for converting the frame rate, even when the video setting is changed at an arbitrary timing, the video settings on the writing side and the reading side for the memory bank to be read next are performed. Since they match, the displayed video is not disturbed.

  Three or more memory banks may be used. In this case, if the difference between the time predicted by the timing adjusting unit 20 and T1 is smaller than the threshold, the reading control unit 15 indicates that the notification from the timing adjusting unit 20 indicates that the video setting on the reading side is changed. The video reading means 12 may indicate to the video reading means 13 a memory bank other than the memory bank currently writing the pre-conversion video.

  The video signal processing apparatus according to the present invention is useful for various televisions, projectors, and the like because the displayed video is not disturbed even if the video settings are changed during frame rate conversion.

10 memory bank (first memory bank)
11 Memory bank (second memory bank)
12 video writing means 13 video reading means 14 writing control means 15 reading control means 17 CPU
20 Timing adjustment means

Claims (9)

A video signal processing device for converting a frame rate of a video signal,
First and second memory banks;
Video writing means for selectively writing video frames to the first and second memory banks at a first frame rate;
Video reading means for selectively reading video frames from the first and second memory banks at a second frame rate;
Write control means for instructing the video writing means which of the first and second memory banks to write the video frame;
Reading control means for instructing the video reading means from which of the first and second memory banks to read a video frame;
Instructing the video reading means to change the video setting for reading after a predetermined time has elapsed since the video writing means changed the video setting for writing and started writing the video frame to the memory bank. A video signal processing apparatus comprising: a timing adjustment unit configured to perform timing adjustment; The video signal processing apparatus according to claim 1, wherein
The video signal processing apparatus, wherein the writing control means and the reading control means are realized by software processing of a CPU. The video signal processing apparatus according to claim 2, wherein
The video signal processing apparatus, wherein the timing adjustment means is realized by software processing of the CPU. The video signal processing apparatus according to claim 1, wherein
The writing control means instructs the video writing means to write a video frame in the memory bank with a size corresponding to the video setting related to the writing,
The video signal processing apparatus according to claim 1, wherein the read control means instructs the video read means to read a video frame from the memory bank with a size corresponding to the video setting relating to the reading. The video signal processing apparatus according to claim 1, wherein
The video signal processing device, wherein the video writing means writes a video frame to the memory bank in accordance with an input synchronization signal. The video signal processing apparatus according to claim 1, wherein
The video signal processing apparatus, wherein the timing adjusting unit instructs the video reading unit to change video settings related to the reading when a memory bank from which a video frame is read is switched. The video signal processing apparatus according to claim 1, wherein
The timing adjusting unit predicts a timing at which the video reading unit starts to read a video frame next, and determines the timing to the video reading unit according to a time difference between the predicted timing and a timing at which the predetermined time has elapsed. A video signal processing apparatus for instructing to change video settings related to reading. The video signal processing apparatus according to claim 7,
The timing adjustment unit notifies the readout control unit whether to change the video setting related to the readout based on the predicted timing,
The video signal processing apparatus, wherein the read control means instructs the video read means to switch a memory bank from which a video frame is read when the notification indicates that the video setting is to be changed. . The video signal processing apparatus according to claim 8, wherein
The reading control means notifies the timing adjusting means of the timing at which the video reading means can read the video frame from the memory bank in which the video writing means is writing video frames.
The timing adjustment unit calculates a difference between the predicted timing and the notified timing, and when the difference is smaller than a threshold value, whether to change the video setting related to the readout to the readout control unit A video signal processing device that notifies whether or not.

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