JP3625717B2 - Video recording / playback device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video recording and reproducing equipment.
[0002]
[Prior art]
Digital VTRs having a function of continuously or intermittently recording image data captured by a surveillance camera on a video tape and a function of reproducing image data recorded on a video tape have already been developed.
[0003]
In such a digital VTR as well as an analog VTR, it is convenient if the playback speed can be controlled. With an analog VTR, the playback speed can be controlled by changing the running speed of the tape, but with a digital VTR, it is difficult to change the running speed of the tape.
[0004]
[Problems to be solved by the invention]
This invention aims to provide a video recording and reproducing equipment that can adjust the playback speed.
[0005]
[Means for Solving the Problems]
A first video recording / reproducing apparatus according to the present invention comprises means for intermittently recording image data captured by a surveillance camera on a recording medium, a memory for temporarily storing image data taken out from the recording medium during reproduction, A means for reading image data stored in the memory one field at a time without thinning out, and when reading image data from the memory one field at a time, the reading time interval between adjacent fields is controlled according to the set reproduction speed. And a means for generating and outputting a reproduced video signal based on the read image data each time image data for one field is read from the memory .
[0006]
A second video recording / reproducing apparatus according to the present invention comprises means for intermittently recording image data captured by a surveillance camera on a recording medium, a memory for temporarily storing image data taken out from the recording medium during reproduction, A means for reading out image data stored in the memory one frame at a time without thinning out , and when reading out image data from the memory one frame at a time, the reading time interval between adjacent frames is controlled in accordance with the set reproduction speed. And a means for generating and outputting a reproduced video signal based on the read image data each time image data for one frame is read from the memory .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments in the case where the present invention is applied to a digital VTR that records and reproduces video captured by a surveillance camera will be described below with reference to the drawings.
[0009]
FIG. 1 shows the configuration of a digital VTR. In FIG. 1, the audio signal processing circuit is omitted.
[0010]
The digital VTR includes a video signal processing circuit 1, a servo system (drum servo system and capstan servo system) 2, a system control circuit 3, a mechanism system 4, an operation panel 5, and the like.
[0011]
The video signal processing circuit 1 is obtained from a decoder (A / D converter) 11, a first FPGA (field programmable gate array) 12, a field memory 13, a JPEG image compression / decompression circuit 14, and an image compression / decompression circuit 14. A memory 15 for storing the encoded data, a formatter 16, a signal recording / reproducing unit 17, a second FPGA 18, an encoder (D / A converter) 19, and a microcomputer (hereinafter referred to as a microcomputer) 20 are provided.
[0012]
The signal recording / reproducing unit 17 includes a recording amplifier, a reproducing amplifier, and a video head. The image compression / decompression circuit 14, the memory 15, and the formatter 16 are controlled by the second FPGA 18. The first FPGA 12 and the second FPGA 18 are controlled by the microcomputer 20.
[0013]
The operation during recording will be described. Although the case where the recording unit is one field unit will be described here, the present invention can also be applied to the case where the recording unit is one frame unit. At the time of recording, the analog video signal sent from the surveillance camera (video camera) is converted into digital image data by the decoder 11. The image data obtained by the decoder 11 is sent to the first FPGA 12.
[0014]
The first FPGA 12 stores the input image data in the field memory 13 in a predetermined cycle of a predetermined number of fields (hereinafter referred to as an image capture cycle). The image capture period is input via the operation panel 5 and set in the microcomputer 20 via the system control circuit 3. The image data stored in the field memory 13 is sent to the image compression / expansion circuit 14 and is compressed by the image compression / expansion circuit 14 to be converted into encoded data. The encoded data obtained by the image compression / decompression circuit 14 is written in the memory 15.
[0015]
Each time the amount of encoded data written in the memory 15 is equivalent to one block unit (a predetermined amount of data for a plurality of fields), the encoded data is read from the memory 15 and sent to the formatter 17. The formatter 16 converts the data into data having a data structure that can be recorded on the video tape.
[0016]
Data obtained by the formatter 16 is recorded on a video tape (recording medium) 21 via a recording amplifier and a video head in the signal recording / reproducing unit 17.
[0017]
The operation during playback will be described. At the time of reproduction, the data read from the video tape 21 by the video head in the signal recording / reproducing unit 17 is converted into the original encoded data via the reproducing amplifier and formatter 16 in the signal recording / reproducing unit 17. The encoded data obtained by the formatter 16 is temporarily stored in the memory 15.
[0018]
The second FPGA 18 reads the encoded data stored in the memory 15 for each field. At this time, the second FPGA 18 controls the reading interval between fields according to the set reproduction speed. The reproduction speed is input by the operation panel 5 and set in the microcomputer 20 via the system control circuit 3.
[0019]
The encoded data read from the memory 15 is sent to the image compression / decompression circuit 14 and decompressed. Digital image data obtained by the image compression / decompression circuit 14 is stored in the field memory 13. The image data for one field stored in the field memory 13 is repeatedly read out by the first FPGA 12 and sent to the encoder 19. The encoder 19 converts the sent image data into an analog video signal, and then sends it to a monitor (not shown).
[0020]
FIG. 2 is a time chart for explaining a method for adjusting the reproduction speed.
[0021]
Here, it is assumed that image data is taken into the field memory 13 at intervals of To seconds as shown in FIG. Here, for convenience of explanation, it is assumed that image data is taken into the field memory 13 at intervals of 1 second (60 field periods) during recording.
[0022]
During normal speed reproduction, as shown in FIG. 2B, when reading image data from the memory 15 for each field, the reading interval T between fields is set to 1 second (To seconds). The encoded data for one field read from the memory 15 at intervals of 1 second is decompressed by the image compression / decompression circuit 14 and then stored in the field memory 13. The first FPGA 12 repeatedly reads out the image data stored in the field memory 13 and sends it to the encoder 19. Therefore, the same image is repeatedly displayed every second. The period T at which the video is switched is the same as the image capture period To at the time of recording.
[0023]
At the time of double speed reproduction, as shown in FIG. 2C, when reading image data from the memory 15 for each field, the reading interval T between fields is set to 0.5 seconds (To / 2 seconds). The The encoded data for one field read from the memory 15 at intervals of 0.5 seconds is decompressed by the image compression / decompression circuit 14 and then stored in the field memory 13. The first FPGA 12 repeatedly reads out the image data stored in the field memory 13 and sends it to the encoder 19. Therefore, the same image is repeatedly displayed every 0.5 seconds. The period T when the video is switched is ½ of the image capture period To at the time of recording.
[0024]
At the time of half-speed reproduction, as shown in FIG. 2D, when reading image data from the memory for each field, the reading interval T between fields is set to 2.0 seconds (2 To seconds). . The encoded data for one field read from the memory 15 at intervals of 2.0 seconds is decompressed by the image compression / decompression circuit 14 and then stored in the field memory 13. The first FPGA 12 repeatedly reads out the image data stored in the field memory 13 and sends it to the encoder 19. Therefore, the same image is repeatedly displayed every 2.0 seconds. The period T when the video is switched is twice the image capture period To at the time of recording.
[0025]
【The invention's effect】
According to the present invention, a video recording and reproducing equipment that can adjust the playback speed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a digital VTR.
FIG. 2 is a time chart for explaining a method of adjusting a reproduction speed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Video signal processing circuit 2 Servo system 3 System control circuit 4 Mechanism system 5 Operation panel 11 Decoder 12 1st FPGA
13 Field Memory 14 Image Compression / Expansion Circuit 15 Memory 16 Formatter 17 Signal Recording / Reproducing Unit 18 First FPGA
19 Encoder 20 Microcomputer

Claims (2)

Means for intermittently recording image data captured by the surveillance camera on a recording medium;
Memory that temporarily stores image data retrieved from the recording medium during playback,
Means for reading out image data stored in the memory one field at a time without thinning;
Means for controlling a reading time interval between adjacent fields in accordance with a set reproduction speed when reading image data from the memory one field at a time; and
Means for generating and outputting a reproduction video signal based on the read image data each time image data for one field is read from the memory;
Video recording and reproducing apparatus characterized in that it comprises. Means for intermittently recording image data captured by the surveillance camera on a recording medium;
Memory that temporarily stores image data retrieved from the recording medium during playback,
Means for reading out image data stored in a memory frame by frame without thinning out;
Means for controlling a reading time interval between adjacent frames according to a set reproduction speed when reading image data frame by frame from the memory; and
Means for generating and outputting a reproduced video signal based on the read image data each time image data for one frame is read from the memory;
A video recording / reproducing apparatus comprising:

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