JP2002354417A - Image reproducing equipment and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide image reproducing equipment which can take in a capture image effectively. SOLUTION: The image reproducing equipment is provided with a first writing means (13, 14) which extract compressed image data necessary to decode one image from a compressed dynamic image signal and writes the data in a first buffer, a second writing means (13, 15) which write decoded image data corresponding to the compressed image data in a second buffer, a third writing means (23) which writes image data having smaller size in a storage device out of the compressed image data and the decoded image data corresponding to an image capture command, and a reproducing means (22) which reproduces the image data written in the storage device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reproducing apparatus having a capture function and an image reproducing method.

[0002]

2. Description of the Related Art Generally, MPEG2 is known as an encoding system for compressing and storing moving images. In recent years, this MPEG
Research and development of an image reproducing apparatus that reproduces a medium on which compressed image data compressed in accordance with No. 2 is recorded are being advanced.
Some image reproducing apparatuses have a capture function. The capture function means that an image of a target screen can be fetched into a memory during reproduction of a moving image, and only the fetched image (capture image) can be read out and reproduced later.

[0003]

However, when capturing a captured image into a memory, if the captured image is a decoded image, there is a problem that the data amount is large and it takes time to capture the captured image. Further, if the decoded image is compressed and taken in as a captured image, a new image compression circuit is required, which causes a problem in cost.

It is an object of the present invention to provide an image reproducing apparatus and an image reproducing method capable of efficiently capturing a captured image in view of the circumstances described above.

[0005]

In order to solve the above-mentioned problems and achieve the object, an image reproducing apparatus and an image reproducing method according to the present invention are configured as follows.

(1) An image reproducing apparatus according to the present invention comprises: first writing means for extracting compressed image data necessary for decoding one image from a compressed moving image signal and writing the extracted compressed image data in a first buffer; Second writing means for writing decoded image data corresponding to data to a second buffer, a size of the compressed image data written to the first buffer, and a size of the decoded image data written to the second buffer And a third write unit that writes small-size image data of the compressed image data and the decoded image data to a memory based on a comparison result by the comparison unit in response to an image capture command. Means for reproducing image data written in the memory.

(2) In the image reproducing method according to the present invention, a first step of extracting compressed image data necessary for decoding one image from a compressed moving image signal and writing the compressed image data in a first buffer; A second step of writing the decoded image data corresponding to the second buffer to the second buffer; and determining the size of the compressed image data written to the first buffer and the size of the decoded image data written to the second buffer. A third step of comparing and, in response to the image capture command, writing of small-size image data of the compressed image data and the decoded image data to a memory based on the comparison result of the third step;
And a fifth step of reproducing the image data written in the memory.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

It is assumed that the compressed image data reproduced by the image reproducing apparatus of the present invention conforms to the MPEG2 video standard.

FIG. 6 is a diagram showing a data structure of the MPEG2 video standard.

As shown in FIG. 6, an SH (Sequence header), a GOP
(Group Of Picture) and SE (Sequence End Code) are arranged. This GOP includes GH (Group Of Pic)
and a plurality of PICs (Picture Data). This PIC includes PH (Picture Heade)
r), and a plurality of MBs (Macro Brock).

FIG. 7 is a diagram showing a prediction method according to the MPEG2 video standard.

Due to the difference in the prediction method, I-picture, P-picture
-Picture and B-picture. An I-picture is an image that is a prediction starting point without performing prediction on an intra-coded image. The P-picture performs prediction using a temporally past I-picture or P-picture as a reference image. The B-picture performs prediction using a temporally past or future I-picture or P-picture as a reference image.

FIG. 1 is a block diagram showing a schematic configuration of an image reproducing apparatus according to a first embodiment of the present invention. Also,
FIGS. 9 and 10 are flowcharts showing the processing of the control circuit 23 in the image reproducing apparatus according to the first embodiment.

As shown in FIG. 1, this image reproducing apparatus comprises:
Switch (SW1) 11, input buffer 12, decoding circuit 13, grammar interpreter 14, arithmetic circuit 15, capture buffer 16, frame buffer 17, switch (SW 1)
3) 18, memory interface (IF) 19, memory 20, switch (SW2) 21, video output circuit 22,
The control circuit 23 is provided.

The control circuit 23 performs necessary initial settings for the decoding circuit 13, the memory interface 19, the video output circuit 22, the switches 11, 18 and 21 when the image reproducing apparatus is started. When the initialization is completed, the external data transfer device is requested for the compressed image data.

First, the decoding operation during normal reproduction will be described. The compressed image data input from the switch 11 is taken into the input buffer 12 and at least one image of the compressed image data is accumulated, and then decoded in a subsequent stage in synchronization with a video signal (frame synchronization signal or field synchronization signal). It is read into the circuit 13. The decoding circuit 13 includes a grammar interpreting unit 14 and an arithmetic circuit 15. The grammar interpreting unit 14 interprets the grammar (syntax) of the compressed image data, extracts the header part of each layer and the motion vector information, and fetches them into its own register. The rest of the payload is
The image data is variable-length encoded image data and sent to the arithmetic circuit 15. The arithmetic circuit 15 includes a variable-length code decoding unit, an inverse scan unit, an inverse DCT unit, an inverse quantization unit, a motion compensation unit, and the like. The control circuit 23 reads the header information and the motion vector information from the register of the grammatical interpretation unit 14 and controls the arithmetic circuit 15. The arithmetic circuit 15 writes the decoded image into the frame buffer 17. Frame buffer 1
The decoded image written in 7 is used as a reference image. Further, the frame buffer 17 is also used as a delay buffer for display. The decoded image read from the frame buffer 17 is sent to the video output circuit 22 via the switch 21. The video output circuit 22 performs necessary processing on the received decoded image, and outputs the analog image to the monitor device.

Next, the capture operation will be described.

The grammar interpreter 14 extracts compressed image data necessary for decoding the picture currently being decoded from the compressed image data during normal reproduction, and writes the extracted compressed image data in the capture buffer 16. FIG. 8 shows the relationship between the picture currently being decoded, the compressed image data that must be present in the capture buffer 16, and the image data to be captured as a captured image when a capture command is issued. This will be described later with an example.

The grammar interpreting unit 14 also controls the input buffer 1
Data size of one image read from 2 | Penc |
Is written to its own register. The decoding circuit 13
Each time decoding of a picture ends, a decoding end interrupt is generated to the control circuit 23. When the control circuit 23 receives the decoding end interrupt, the grammar interpreting unit 14 | Pen
read the value of c |
Σ | Penc | is calculated by adding to the data amount existing in Note that Σ | Penc | also includes the data amount of the header of the layer above the picture layer (the layer where the PIC exists) shown in FIG.

When the control circuit 23 receives the capture interrupt, the decoding size | P of the picture currently being decoded
dec | is calculated. The size of the decoded image is horizontal_size_v included in the SH (Sequence Header) shown in FIG.
alue flag, vertical_size_value flag, and FIG.
Is calculated from the chroma_format in the sequence_extension which is an extension of the sequence layer (the layer where the SH exists) shown in FIG.

The control circuit 23 determines that "Σ | Penc | <| P
dec | ”, the switch 18 is switched to the capture buffer 16 side to store the compressed image data in the memory IF.
The data is written into the memory 20 via the memory 19. Conversely, “Σ | Pe
If nc |> | Pdec | ", the switch 18 is switched to the frame buffer 17 side, and the decoded image data is written to the memory 20 via the memory IF 19. Thus, the image is captured. The control circuit 23 stores in the memory 20 whether the captured image is compressed image data or decoded image data.
Thereby, when reproducing the image captured in the memory 20, decoding processing is performed as necessary.

For example, for CASE2 shown in FIG.
This will be described with reference to FIG. The subscript in FIG. 5 is PH (Pi
The header indicates a temporal_reference flag in the GOP, which indicates the display order in the GOP. It is assumed that when the control circuit 23 receives a capture command from the outside, it decodes a B-picture B16 that precedes an I-picture in a GOP in display order. now,
Assuming that the closed_gop flag of GH (Group Of Picture Header) is “0”, in order to decode B16,
The last P-picture P14 of the immediately preceding GOP is needed. In order to decode P14, all I and P-pictures in the GOP including P14 are required. After all, to decode B16, I2, P5, P
8, P11, P14, I17, and B16 are required, and this data is a candidate to be taken into the memory at the time of capture. The control circuit 23 calculates I2, P5, P
8, P11, P14, I17, and B16 compressed image data (including PH) in the size of SH (Sequence header)
And the value obtained by adding the size of GH (Group Of Picture Header) and the decoded image size of B16. If the former size is smaller than the latter, the compressed image data is written to the memory 20 as a captured image. Conversely, if the size of the latter is smaller than the former, the decoded image data is written to the memory 20 as a captured image. Also, cl
When the osed_gop flag is "1", only I17 is required to decode B16. Therefore, at the time of capture, I17 and P16 are candidates to be written to the memory. The subsequent processing is the same as when the closed_gop flag is “0”.

When the captured image written in the memory 20 is displayed, if the captured image is a compressed image, the control circuit 23 controls the memory IF 19 to send the captured image to the switch 11 and perform the decoding process. To do. If the captured image is a decoded image, the captured image is sent to the switch 21 side.

Referring to the flowcharts shown in FIGS. 9 and 10, various processes in the image reproducing apparatus shown in FIG. 1 will be described.

The control circuit 23 initializes each unit (S10) and requests a stream (compressed moving image signal) (S11). Along with this, when a stream is input,
The decoding circuit 13 performs a decoding process and writes a header flag to a register. At this time, the decoding circuit 13
Writes compressed image data necessary for decoding one image into the capture buffer 16. Further, the decoded image data corresponding to the compressed image data written in the capture buffer 16 is written in the frame buffer 17. The decoding circuit 13 generates an end interrupt every time decoding of one picture ends. Also, a capture command interrupt may occur as an external instruction.

If an interrupt occurs (S12, YES) and the interrupt is an end of one-picture decoding (S13, YES), reading of the compressed image size | Penc | and calculation of Σ | Penc | S14).

An interrupt occurs (S12, YES), 1
Instead of the picture decoding end interrupt (S13, N
O), if it is not a capture command interruption (S
20, NO), a process corresponding to the interruption is executed (S30).

An interrupt occurs (S12, YES), and if the interrupt is a capture command interrupt (S13, NO) (S20, YES), || Penc |
And | Pdec | are compared (S21). Σ ｜ Penc
Is smaller than | Pdec | (S21, Y
ES), the compressed image is written to the memory as the captured image (S22). Conversely, | Pdec | is Σ | P
enc | (S21, NO), the decoded image is written to the memory as the captured image (S2).
3). Whether the image written as the captured image is a compressed image or a decoded image is stored (S24).
Later, when the captured image is a compressed image during reproduction of the captured image, the captured image is decoded and output.

FIG. 2 is a block diagram showing a schematic configuration of an image reproducing apparatus according to a second embodiment of the present invention.

[0031] As shown in FIG.
A switch (SW1) 11, an input buffer 12, a decoding circuit 13, a grammatical interpretation unit 14, an arithmetic circuit 15, a capture buffer 16, a frame buffer 17, a memory interface (IF) 19, a memory 20, a video output circuit 22,
The control circuit 23 is provided.

The normal reproducing operation of this image reproducing apparatus is shown in FIG.
Is the same as that of the image reproducing apparatus shown in FIG.

The capture operation will be described. The grammar interpretation unit 14 of the decoding circuit 13 extracts only I-pictures from the compressed image data during normal reproduction and writes the extracted I-pictures in the capture buffer 16. When receiving the capture interrupt, the control circuit 23 writes the last written I-picture present in the buffer 16 or the next I-picture to be written to the memory 20 via the memory IF 19. When displaying the captured image written in the memory 20, the control circuit 23 controls the memory IF 19 and sends the captured image to the switch 11. When the I-picture extracted from the compressed image data has a field structure, that is, pict in PH (Picture Header)
ure_coding_type flag is “intra-coded” and pi in picture_coding_extension which is an extension of picture layer
cture_structure flag is “Top field” or “Bottom f
ield ”, capture only this field as a captured image.
Regardless of the flag of "d" or "Bottom field", the same decoded image is output to the even field and the odd field.

With reference to the flowcharts shown in FIGS. 11 and 12, various processes in the image reproducing apparatus shown in FIG. 2 will be described.

The control circuit 23 initializes each unit (S10) and requests a stream (compressed moving image signal) (S11). Along with this, when a stream is input,
The decoding circuit 13 performs a decoding process and writes a header flag to a register. At this time, the decoding circuit 13
Writes the intra-frame encoded image data (I-picture) into the capture buffer 16. The decoding circuit 13
Each time decoding of one picture ends, an end interrupt is generated. Also, a capture command interrupt may occur as an external instruction.

If an interrupt occurs (S12, YES), and the interrupt is not a capture command interrupt (S20, NO), a process corresponding to the interrupt is executed (S30).

When an interrupt occurs (S12, YES) and the interrupt is a capture command interrupt (S20, YES), the intra-frame coded image data written to the capture buffer 16 is written to the memory as a captured image. (S22). When the intra-frame coded image data is coded on a field basis, only the image data forming one of the even and odd fields forming one frame is written to the memory, When the image data written in the memory is reproduced, the image data is output to both the even field and the odd field constituting one frame.

The operation and effect of the present invention described above will be summarized below.

FIG. 3 is a diagram showing an example of an image reproducing device for capturing a decoded image, and FIG. 4 is a diagram showing an example of an image reproducing device for compressing the decoded image again to capture a compressed image. In the case of the image reproducing apparatus shown in FIG. 3, a decoded image having a large data size is taken into the memory as a captured image, so that the taking time is relatively long. Also,
In the case of the image reproducing apparatus shown in FIG. 4, a new image compression circuit 24 is required to compress the decoded image again.

In the image reproducing apparatus of the present invention shown in FIG.
Compressed image data necessary for decoding one image is extracted from the compressed moving image signal and taken as a captured image as it is. For this reason, it is possible to achieve a reduction in the capture time and simplification of the circuit. However, since the size of the compressed image data may be larger than the size of the decoded image data, the size of the compressed image data is compared with the size of the decoded image data, and the smaller data size is captured as the captured image.

In the image reproducing apparatus of the present invention shown in FIG.
Only intra-frame encoded image data, that is, only I-pictures, are extracted from the compressed moving image signal and captured as captured images. Therefore, the data amount of the captured image to be written to the memory can be extremely small. Control is also easy. Further, when the intra-frame coded image to be captured has a field structure, only one of the even field and the odd field constituting one frame is captured. Pictures having a field structure are usually interlaced pictures. Therefore, when displaying, the same field is output to the even field and the odd field. In other words, there is no need to capture one frame, and the capture time can be reduced by half.

It should be noted that the present invention is not limited to the above-described embodiment, and can be variously modified in the implementation stage without departing from the scope of the invention. In addition, the embodiments may be implemented in appropriate combinations as much as possible, in which case the combined effects are obtained. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of a plurality of disclosed constituent elements. For example, even if some components are deleted from all the components shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effects described in the column of the effect of the invention can be solved. If you get
A configuration from which this configuration requirement is deleted can be extracted as an invention.

[0043]

According to the present invention, it is possible to provide an image reproducing apparatus and an image reproducing method capable of efficiently capturing a captured image.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an image reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of an image reproducing device according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of an image reproducing device that captures a decoded image.

FIG. 4 is a diagram illustrating an example of an image reproducing device that compresses a decoded image again to capture a compressed image.

FIG. 5 is a diagram for explaining CASE2 shown in FIG. 8;

FIG. 6 is a diagram showing a data structure of the MPEG2 video standard.

FIG. 7 is a diagram showing a prediction method according to the MPEG2 video standard.

FIG. 8 is a diagram illustrating a relationship between a picture currently being decoded, compressed image data that must be present in a capture buffer 16, and image data to be captured as a captured image when a capture command is issued.

FIG. 9 is a flowchart showing a reproducing operation in the image reproducing apparatus according to the first embodiment shown in FIG.

FIG. 10 is a flowchart showing a capture operation in the image reproducing apparatus according to the first embodiment shown in FIG.

FIG. 11 is a flowchart showing a reproducing operation in the image reproducing apparatus according to the second embodiment shown in FIG.

FIG. 12 is a flowchart illustrating a capture operation in the image playback device according to the second embodiment illustrated in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Switch (SW1) 12 ... Input buffer 13 ... Decoding circuit 14 ... Grammar interpreter 15 ... Arithmetic circuit 16 ... Capture buffer 17 ... Frame buffer 18 ... Switch (SW3) 19 ... Memory interface (IF) 20 ... Memory 21 ... Switch (SW2) 22 ... Video output circuit 23 ... Control circuit

Claims (6)

[Claims] A first writing unit that extracts compressed image data necessary for decoding one image from a compressed moving image signal and writes the extracted compressed image data to a first buffer; Second writing means for writing to the second buffer; comparison means for comparing the size of the compressed image data written to the first buffer with the size of the decoded image data written to the second buffer; A third writing unit that writes small-size image data of the compressed image data and the decoded image data to a memory based on a comparison result by the comparison unit in response to a capture instruction; An image reproducing apparatus, comprising: reproducing means for reproducing image data. 2. A first writing means for extracting intra-frame encoded image data from a compressed moving image signal and writing the extracted intra-frame encoded image data into a buffer, and a second unit for writing the intra-frame encoded image data into a memory in response to an image capture command. An image reproducing apparatus, comprising: a writing unit; and a reproducing unit that reproduces image data written in the memory. 3. When the intra-frame coded image data is coded in field units, only the image data forming one of the even field and the odd field forming one frame is stored in the memory. 3. The image reproducing apparatus according to claim 2, wherein, when reproducing the image data written in the memory, the image data is output to both the even field and the odd field constituting one frame. 4. A first step of extracting compressed image data necessary for decoding one image from a compressed moving image signal and writing the extracted compressed image data to a first buffer; and decoding decoded image data corresponding to the compressed image data into a second buffer. A second step of writing to the first buffer; a third step of comparing the size of the compressed image data written to the first buffer with the size of the decoded image data written to the second buffer; A fourth step of writing small-size image data of the compressed image data and the decoded image data to a memory based on a comparison result of the third step in response to a capture instruction; And a fifth step of reproducing the image data. 5. A first step of extracting intra-frame encoded image data from a compressed moving image signal and writing the same in a buffer, and a second step of writing the intra-frame encoded image data to a memory in response to an image capture command. And a third step of playing back the image data written in the memory. 6. When the intra-frame coded image data is coded on a field basis, only the image data forming one of the even field and the odd field forming one frame is stored in the memory. 6. The image reproducing method according to claim 5, wherein when reproducing the image data written in the memory, the image data is output to both the even field and the odd field constituting one frame.