KR100295801B1 - Method for determining driving state converting time of time lapse video cassette player - Google Patents

Abstract

PURPOSE: A driving state converting time determining method for a time lapse VCR is provided to carry out reading of data simultaneously with recording without any loading stabilization standby time or a driving normalization of a head drum when reading digital video data stored in a field memory, thereby minimizing the size of a memory which temporarily stores video data while recording. CONSTITUTION: A driving state converting time determining method for a time lapse VCR includes the steps of checking a time lapse setting mode input by a user(S11), computing a time required for maximum storing(S13), computing an amount of stored video data or a time thereof while storing video data(S15), checking whether it is a time equal to a loading stabilization standby time(S17), converting a head drum from a driving-stopping state to a loading state if a time remains by the loading stabilization time(S19) or to a rotation driving state instead of the loading state.

Description

How to determine when to switch driving status of time-lapse video player

The present invention relates to a method of determining a time for switching a driving state of a time-lapse video recorder (Time Lapse VCR) for determining a time point for resuming recording after pausing a recording. More specifically, the present invention relates to a loading state from an unloading state to a loading state. Considering the time required to stabilize after switching, or the time required to accelerate to the normal rotational speed after the head drum is stopped, the video data that is selectively compressed during the recording standby time is stored before the maximum storage capacity of the memory is stored. By switching to the loading state or the rotational driving state of the head drum, it is possible to coincide with the timing of reading the image data of the stored memory and the timing of loading stabilization or when the rotational speed of the drum becomes the normal speed, that is, when the actual recording operation starts. The present invention relates to a method for determining a driving state switching time of a time-lapse video recording / reproducing player.

The Time Lapse Video Recorder is installed in major areas such as banks and museums, and is not used to record video frames sent from an external photographing device in real time, but instead of moving and stopping recording tapes. By recording one frame at a predetermined interval, it is used for long-term surveillance observation to prevent theft. As shown in FIG. 1, an analog image signal transmitted from an external photographing device such as CCTV is converted into digital image data. An A / D converter 100; A buffer memory 201 for temporarily storing the digitally converted image data; A field memory 202 which sequentially stores the image data stored in the buffer memory 201 and reads out temporarily when the maximum storage capacity is reached; A D / A converter (300) for converting and outputting digital video data read from the field memory (202) into an analog video signal; A recording unit 400 for recording the analog converted video signal on a recording tape; And a control unit 500 for controlling reading / writing of the memory 201 and 202 so that image signals transmitted from an external photographing apparatus are selectively stored at predetermined time intervals and continuously read according to a user's selection through the input unit 600. It is configured to include,

The recording unit 400 mechanically includes a loading post 1 as shown in FIGS. 1, 2, and 3 in addition to a signal processing unit that performs signal processing for recording an image signal. A loading motor 401 which moves to move the tape to a recording and recording position; A drum motor 402 for rotating the head drum 3 at which the head 2 for recording / reproducing the video signal on the recording tape moved to the recording position is rotated at high speed; And a capstan motor 403 for rotating the capstan shaft 4 so that the recording tape runs at a constant speed at a constant speed.

In the time-lapse video recording / reproducing apparatus configured as described above, the video signal transmitted from the external photographing apparatus is digitally imaged by the A / D converter 100 only one frame at a predetermined time interval according to the input setting time. When the sampled data is temporarily stored in the buffer memory 201 and the sampled image data is temporarily stored in the limited space of the buffer memory 201, the image data is moved and stored in the field memory 202.

By the above process, the image data finally stored in the field memory 202 becomes a video signal corresponding to a short time in which a long real-time video signal is selectively compressed in units of frames.

On the other hand, when the time when the image data is stored in the field memory 202, that is, the recording standby time when the recording is paused is more than a predetermined reference value, the state of the recording unit 400 is unloaded from the loading state (see FIG. 2). The rotational driving of the head drum 3 was paused regardless of whether it was switched to the state (see FIG. 3) or the loading state was switched.

Subsequently, when the image data having the maximum capacity that can be stored in the field memory 202 is stored, the controller 500 continuously outputs the image data stored in the field memory 202 at one time to the D / A converter 300. The analog video signal is converted into an analog video signal, and the state of the recording unit 400 is changed from an unloading state to a loading state again, or the head drum 3 is rotated again. Will be recorded.

While recording is in progress, the input and selectively sampled image data is buffered and stored in the buffer memory 201. When recording is completed, the image data previously stored in the buffer memory 201 and sampled and stored thereafter are recorded. Image data (the presence or absence of this image data depends on the size of the buffer memory 201) is moved to the field memory 202.

However, in the related art, the time point at which the state of the recording unit 400 is changed from the unloading state to the loading state and the time point at which the state of the head drum 3 is changed from the pause state to the normal rotation state are digitally converted images. Same as the point in time when data is completely stored up to the maximum storage capacity of the field memory 202, that is, the amount of digital image data stored in the field memory 202 reaches 100% of the maximum storage capacity of the field memory 202. It was time.

Therefore, as shown in FIG. 4, after the recording unit 400 starts to switch to the loading state, the recording tape is pulled out by the driving of the loading motor 401 until the recording is actually stabilized. During the time period of about 4 seconds to move to the position and stabilize, the image data could not be read and recorded from the field memory 202, and the head drum 3 and the head 2 attached thereto were not recorded. Was not able to read and record the image data from the field memory 202 even during the 4 second time required for driving from the pause state to the normal rotational speed again.

As a result, the time for temporarily storing and waiting for the image data to be sampled in the buffer memory 201 becomes longer by the stabilization waiting time than the time required for the actual recording, and finally the image data input during the recording is performed. There was a problem that the size of the buffer memory 201 for buffer storage of additionally has a capacity corresponding to the stabilization wait time.

Therefore, the present invention was created to solve the above problems, and the method for determining the time to switch the driving state of a time-lapse video recording / replaying player that enables optimal memory use by performing the switching of the driving state for recording in advance. The purpose is to provide.

1 is a block diagram showing an embodiment of a general time-lapse video recording player,

2 is a configuration diagram showing a loading state of the recording unit in the rustable state,

3 is a configuration diagram showing an unloading state of a recording unit;

Figure 4 shows the recording principle of a time-lapse video recording player according to the prior art and the present invention, respectively

5 is a flowchart illustrating a control flow in which a loading switching time is determined by an embodiment of a driving state switching time determining method according to the present invention;

6 is a flowchart illustrating a control flow in which a drum driving time is determined by another embodiment of a driving state switching time determining method according to the present invention;

Fig. 7 shows the maximum storage time calculated by the time-lapse time mode and the loading switching time or drum driving state switching time and the amount of digital image data pre-stored in the field memory at that time. Table shown.

※ Explanation of code for main part of drawing

1: loading post 2: head

3: head drum 4: capstan shaft

5: pinch roller 100: A / D converter

201: buffer memory 202: field memory

300: D / A converter 400: recording unit

401: loading motor 402: drum motor

403: capstan motor 500: control unit

600: input unit

According to an aspect of the present invention, a method of determining a driving state switching time of a time-lapse video recording / reproducing apparatus includes: selecting and compressing video data that is selectively compressed while calculating a recordable remaining time of a memory during intermittent recording of a video signal; Writing in the first step; A second step of repeating the first step until the calculated recordable remaining time is equal to or less than a predetermined time; And a third step of switching the deck unit from an unloading state to a loading state when the calculated recordable remaining time is less than or equal to the predetermined time, or stopping the head drum instead of the third step of switching to the loading state. Each of them is characterized by including a third step of rotating driving.

In the method for determining a driving state switching time of a time-lapse video recording / replaying apparatus according to the present invention as described above, when a recording is started by inputting a time-lapse setting mode from a user, recording is performed while recording the set compression ratio and the size of the storage capacity of the memory. The storage time is calculated using the remaining capacity of the memory in which the digital image data to be selectively compressed is stored.

When the remaining storage time calculated as described above becomes smaller than the predetermined time, the deck data is loaded in advance or the head drum is rotated before the storage space of the memory is filled up. After the storage is completed, the stored information can be read and recorded immediately without additional waiting time.

1, 2, and 3 illustrating a configuration of a time-lapse video recording player according to an embodiment of the method for determining a switching time of a driving state of a time-lapse video recording player according to the present invention. And the flow of the control method will be described in detail with reference to FIG.

The control unit 500 checks the time-lapse setting time mode input from the user (S11), and the time required to store the digital image data compressed up to the maximum storage capacity of the field memory 202 based on this (Tw). It is calculated using the following method (S13).

To exemplify the storage time calculation method, first, the recordable capacity of the recording tape used in the time-lapse video recording apparatus is two hours based on the playback time, and the maximum recordable image of the field memory 202 is obtained. Assume that the amount of data is 150 frames, that is, 5 seconds of play time.

Under the above assumption, when recording in real time without an additional time lapse, all video signals transmitted from an external photographing apparatus are converted into digital image data by the A / D converter 100 and then the buffer memory ( Since it is stored one-to-one in the field memory 202 via 201, the storage time is 5 seconds (= 150 frames) equal to the maximum storage capacity of the field memory 202.

However, if the recording time using the same recording tape of 2 hours based on the playback time, but the time-lapse setting mode selected by the user is 72 hours, that is, the video screen for 72 hours based on the actual elapsed time, In the case of recording down to 2 hours of video signal based on the playback time, the compression ratio is 36: 1. As shown in FIG. 3, the A / D converter 100 is provided once per 36 frames. After sampling by digital conversion and temporarily stored in the buffer memory 201 and later stored in the field memory 202, the maximum storage time in this case is 150 (maximum storage of the field memory 202) Capacity is 180 seconds (3 minutes) (= 5400 frames of the actual video signal), which is a time corresponding to x36 (compression ratio of the video screen) ÷ 30 (frames per second).

That is, the time Tw required for storing the compressed digital image data up to the maximum capacity of the field memory 202 is as follows.

Tw = (Tm x N) / 30 (1)

Where Tm is the maximum number of frames that can be stored in field memory and N is the compression rate.

After calculating the maximum storage time (or the corresponding frame number = Tm × N) through the above method, the field is based on the time required and the stabilization time of loading state (generally about 4 seconds). The memory 202 continuously calculates the elapsed time (the number of frames to be stored) since the digital image data to be selectively compressed is first stored (S15), and the time point at which the calculated time is Tw-4 (the field memory) When the number of frames stored in 201 is reached at 150-120/36) (S17), the recording unit 400 is switched from the unloaded state to the loaded state (S19).

For example, when the setting mode is 72 hours as described above, four seconds (corresponding to 3.33 frames) before the maximum storage time of 180 seconds (150 frames, the maximum storage frame) is completed, that is, the field memory 202 When 176 seconds have elapsed since the digital image data starts to be stored (when the number of stored frames reaches 146.6 and about 147 frames), the controller 500 checks this and then, as shown in FIG. 3, the field memory 202. ) Will be driven before all of the recording unit 400 is filled.

When the recording unit 400 starts to switch to the loading state, the recording tape is drawn out to the recording position by the driving of the loading motor 401, and the head 2 is driven by the drum motor 402. The speed is stabilized at normal speed. The time point of about 4 seconds elapses for this process is the same time point as 150 seconds after the digital image data being selectively compressed in the field memory 202 starts to be stored. The digital video data stored at the maximum is read out temporarily, and then recording operation is performed immediately without stabilization waiting time.

FIG. 6 is a flow chart illustrating a control flow of a drum driving state switching time determining method according to another embodiment of a driving state switching time determining method according to the present invention. The time required for storing the digital image data up to the maximum capacity of the field memory 202 according to the mode is calculated, and the elapsed time since the digital image data being selectively compressed is first stored is continuously calculated to calculate the calculated time. Check whether or not the time has reached the time of Tw-4 (S31 ~ S37),

When it is confirmed that the calculated time reaches the time Tw-4, unlike the conventional method of switching to the unloading state, the head drum 3 is driven to rotate (S39).

It takes about 4 seconds for the head drum 3 to start to rotate and reach the normal rotational speed. The time elapsed is selected in the field memory 202 as in the embodiment. Since the digital video data to be compressed is the same time as 150 seconds after starting to be stored, the digital video data stored in the field memory 202 is read out at a time, and the recording operation is performed immediately without stabilization waiting time. Will be.

FIG. 7 shows that when the storage capacity of the field memory 202 is 5 seconds and the loading stabilization waiting time and the head drum normal driving time are 4 seconds, respectively, the field of the digital image data according to each time-lapse setting mode. The maximum storage time required in the memory 202, the loading state switching time and the head drum driving state switching time, and the amount of digital image data pre-stored in the field memory at that time are shown as a percentage of the total field memory capacity. .

As described above, when the loading stabilization waiting time or the drum speed normalization waiting time is removed, the video data is read from the field memory 202 and the actual recording time is 5 seconds, so the size of the buffer memory 201 is 10: Assuming a compression ratio of 1, it is sufficient to store 0.5 seconds or 15 frames, but in the conventional case, a frame number of 24 to 27, which is the number of frames corresponding to about 8 to 9 seconds (5 seconds + 3 to 4 seconds), is selected. Use a size that can be stored. That is, under the condition of having the same lowest compression ratio, the same function can be performed with a buffer memory having a smaller size than the conventional one.

Therefore, the loading switching time determination method and the drum driving state switching time determination method of the time-lapse video recording player according to the present invention made by the above process, respectively, loading stabilization at the time of reading the digital image data stored in the field memory; It is a very useful invention that can record immediately without waiting time and drum speed normalization waiting time, so that the size of the buffer memory temporarily storing image data during recording can be minimized.

Claims (2)

During intermittent recording of a video signal, a first step of recording the video data to be selectively compressed into the memory while calculating the recordable remaining time of the memory; A second step of repeating the first step until the calculated recordable remaining time is equal to or less than a predetermined predetermined time; And a third step of rotationally driving the head drum which is stopped when the calculated recordable remaining time is less than or equal to the predetermined time. The method of claim 1, wherein the predetermined time is equal to the time required for reaching the normal rotational speed of the head drum.