JP2002315003A - Image-encoding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-encoding device where an arbitrary point is designated, when an image is encoded, and encoding is performed so that a screen image of the point can be regenerated quickly. SOLUTION: A GOP structure is so determined by a GOP structure determining means 22, that a frame which is inputted at present is set as the top of a GOP by a frame designating signal 21. By using a determined picture type 23 for encoding, an input screen image signal is encoded with a video encoder 14. An encoded screen image stream 15 and an encoded sound stream 19 are multiplexed with a video audio multiplexing device 20 and then recorded. Thereby the frame of the designated arbitrary point is made the top of the GOP, and a screen image of the point can be regenerated quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to moving picture coding, and more particularly to a picture coding apparatus employing a coding method which can easily take out a video specified at the time of coding at the time of reproduction. .

[0002]

2. Description of the Related Art Conventionally, in the coding of a moving image, the following three types of image coding methods are used in combination for high efficiency coding and convenience of decoding and reproduction. The first is an intra-frame encoding method, and a frame (screen) encoded by this method is called an I picture. In this encoding method, one image is independently encoded without using the correlation with the motion between images. Therefore, independent frame decoding becomes possible.

[0003] The second is a unidirectional predictive coding system, and a frame coded by this system is called a P picture. In this coding method, an inter-frame motion compensation prediction is performed from a previously coded image to perform coding.
Let it be a reference image for picture encoding. If the similarity between the referenced image and the referenced image is high, the coding efficiency is improved.

[0004] The third is a bidirectional predictive coding system, and a frame coded by this system is called a B picture. In this coding method, inter-frame motion compensation prediction is performed from two temporally preceding or succeeding I-pictures or P-pictures that have been encoded in the past, and the encoding is performed. This image itself is different from a reference image of another image. No. Like the P picture, when the similarity between the image to be referred and the image to be referred to is high, the coding efficiency is improved.

[0005] A GOP (Group of Pictures) is composed of a plurality of pictures coded by the above three types of coding schemes. A GOP is a group of continuous images as viewed on encoded data, and is a unit considering random access. For this reason, the head of the GOP needs to be an I picture as viewed on encoded data. Further, the last of the GOP in the display order needs to be an I picture or a P picture.

When an I-picture without a reference picture is reproduced, a reproduced picture can be created using only the code of the frame. It is necessary to decode it together with the code of the frame. Therefore, when decoding an arbitrary image in a program, such as cueing, if the frame is an I picture, it can be easily reproduced. It is desirable to change the GOP break so that

Conventionally, as this type of image coding apparatus,
For example, as described in Japanese Patent Application Laid-Open No. 8-65678, encoding is performed in accordance with the arrangement order of frames determined according to the quantization step width ratio assigned to each frame and the correlation coefficient value between frames. In some cases, a GOP break is determined.

Further, as described in Japanese Patent Laid-Open Publication No. 8-98185, a scene change is detected from the information amount of an input image, and a picture type and a GOP length are determined from the result, thereby separating the GOP. There are things to decide. Further, as described in Japanese Patent Application Laid-Open Publication No. 2000-261809, there is a method in which a boundary of a GOP is obtained from a change amount between two images, and a GOP boundary is determined based on the boundary.

[0009]

However, in the image coding apparatus of the first conventional example, it is necessary to obtain a correlation coefficient between frames before coding, and the real-time coding is lacking. Thus, there is a problem that an image memory for storing input image data corresponding to at least one GOP is required. Further, in the image encoding apparatus of the second conventional example, there is a problem that in encoding a scene without a scene change, encoding is performed so that GOP breaks appear at regular intervals.

The third conventional image coding apparatus has a problem that a simple motion search needs to be performed before coding, and a processing apparatus that performs high-speed calculation is required. Further, in any of the above-described conventional image coding apparatuses, there is a problem that a GOP cannot be delimited by an externally designated frame.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and designates an arbitrary point when encoding an image so that the image at that point can be quickly reproduced. It is an object of the present invention to provide an image coding apparatus for converting images.

[0012]

According to the present invention, there is provided an image coding apparatus for performing image coding on a continuously input image signal by an image coding method utilizing motion compensation prediction between images. Has a configuration in which there is provided a GOP structure determining means for determining a GOP structure such that a frame currently input by input of a frame designation signal is at the head of the GOP. With this configuration, an arbitrary point can be specified separately from the features and scene changes of the input image,
By setting the frame at the designated point as the head of the GOP, the video at that point can be quickly reproduced.

The image encoding apparatus according to the present invention is characterized in that
GOP structure analysis means for, when a frame designating signal is input, determining a picture type of a frame preceding the frame designated by the frame designating signal and determining whether to change the picture type. Means. With this configuration, it is possible to determine whether the frame before the designated frame can be set as the last frame of the GOP.

The image encoding apparatus according to the present invention is characterized in that
The OP structure determining means changes the picture type of the previous frame according to the determination of the GOP structure analyzing means, and
It has a configuration in which a GOP structure changing means for cutting P is provided. With this configuration, even if the frame before the designated frame cannot be the last frame of the GOP by the determination of the GOP structure analysis means, it can be made the last frame of the GOP by changing the picture type. Can be cut at an arbitrary frame.

According to the present invention, there is provided an image encoding apparatus for encoding an input image signal in accordance with a notice of an encoding picture type from the GOP structure determining means. And a configuration in which a delay of an input video signal in the video signal buffer is used for image encoding with a change in picture type in the video encoder. With this configuration, even if there is a frame whose picture type has been changed by the GOP structure changing unit, the encoder is notified of the new picture type, and the encoding is performed without providing the encoder with any further special picture type changing unit. It can be performed.

An image coding apparatus according to the present invention is an image coding apparatus for performing image coding on a continuously input image signal by an image coding method using motion compensation prediction between images. The GOP structure is determined so that the currently input frame becomes the head of the GOP by input, the determined encoding picture type is notified, and it is determined whether the picture type of the previous frame needs to be changed. GOP that outputs a notification of a change in picture type for encoding when it is determined that
A structure determining means, and a video encoder for coding an input video signal accompanied by a change in picture type in accordance with a picture type notification for coding and a picture type change notification for coding from the GOP structure determining means. Have. With this configuration, when there is no buffer,
If there is a frame whose picture type has been changed by the GOP structure changing means, it is possible to notify the encoder of a method of changing the picture type of the input frame that has already been input, and perform encoding using the new picture type. be able to.

An image encoding apparatus according to the present invention comprises: an audio encoder for encoding an input audio signal to output an audio stream; and an audio encoder from the audio encoder based on a multiplexing picture type notification from the GOP structure determining means. A video / audio multiplexing device that multiplexes the stream and the video stream from the video encoder. With this configuration, it is possible to specify the correct picture type for the video stream and multiplex it with the audio stream.

The video encoding apparatus according to the present invention has a configuration in which the video / audio multiplexing apparatus outputs the time information given in the multiplexing of the video stream and the audio stream to the first frame of the GOP. . With this configuration, it is possible to specify the position of the specified frame in the multiplexed stream.

The image coding apparatus according to the present invention has a configuration including recording means for recording the time information. With this configuration, the time information can be used as the cueing information at the time of reproduction, and the cueing of the designated frame at the time of recording can be quickly performed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. First, an image coding apparatus according to a first embodiment of the present invention will be described with reference to the block diagram of FIG. In FIG. 1, a video input device 11 such as a video camera outputs a video input video signal 12 to a video signal buffer 13. The video signal buffer 13 stores the video signal for a certain time,
Send to video encoder 14.

On the other hand, the GOP structure determining section 22 determines a GOP structure for encoding a video signal, and furthermore, when a frame currently input to the video input device 11 is specified by the frame specifying signal 21. Means that the frame is G
The GOP structure is determined so as to be at the head of the OP, and the determined encoding picture type notification 23 is input to the video encoder 14 in frame units. Further, the determined multiplexing picture type notification 24 is input to the video / audio multiplexing device 20 in consideration of the encoding delay occurring in the video encoder 14. The video encoder 14 encodes the input video signal 12 using the picture type notified by the coding picture type notification 23, and inputs the input video signal 12 to the video / audio multiplexing apparatus 20 as the video stream 15.

A voice is input using a voice input device 16 such as a microphone, for example, and sent as an input voice signal 17 to an audio encoder. The audio encoder 18 encodes the input audio signal 17 and converts the audio stream 19 into a video / audio multiplexer 20.
Enter

The video / audio multiplexing device 20 multiplexes the input video stream 15 and audio stream 19 using the picture type of the multiplexing picture type notification 24, and forms a multiplexed stream 25 as a recording device 27.
Output to Furthermore, the video / audio multiplexing device 20
Specifies the frame designated at the head of the GOP by the external frame designation signal 21 by the multiplexing picture type notification 24, extracts the time information of the frame, and outputs the time information 26. The recording device 27 receives the multiplexed stream 25 and the time information 26 from the video / audio multiplexing device 20 and records them on a recording medium.

As described above, the image coding apparatus according to the present embodiment uses an external frame designating signal 21
Can be set at the head of the GOP, and by recording the time information 26 of the frame, the designated frame can be quickly searched and displayed when the multiplex stream 25 is reproduced using this. be able to.

Next, an image coding apparatus according to a second embodiment of the present invention will be described with reference to the block diagram of FIG. The image coding apparatus according to the second embodiment of the present invention shown in FIG. 2 has a configuration in which the video signal buffer 13 is removed from the image coding apparatus according to the first embodiment shown in FIG. The elements are similar to those shown in FIG. In FIG. 2, an input video signal 12 input from an image input device 11 of the image encoding device according to the present embodiment is directly input to a video encoder 14. Here, when the frame at the head of the GOP is designated by the frame designation signal 21, the frame preceding the designated frame must be changed to a P picture or an I picture in order to be the last frame of the GOP. May not be.

At this time, in the GOP structure determining unit 22,
If it is determined that the picture type needs to be changed, a picture type change notification for encoding 28 is sent to the video encoder 14. When receiving the encoding picture type change notification 28, the video encoder 14 disconnects the GOP by changing the picture type of the immediately preceding frame that is currently input.

As described above, the image coding apparatus according to the present embodiment is suitable for cutting a GOP at an arbitrary frame and searching for a start without providing a special buffer at an input stage of a video signal. Encoding can be performed.

Next, referring to the block diagram of FIG.
The GOP structure determining unit included in the image encoding device according to the first embodiment of the present invention will be described. FIG.
In, the reference GOP structure generation unit 31 generates a reference picture type 32 for each frame as a picture type of a GOP structure that is basic in the system. When a frame specifying signal 21 specifying a frame to be searched is input, the reference GOP structure generating unit 31 initializes the inside thereof, generates the picture type with the specified frame as the head of the GOP, Thereafter, the generation of the picture type is continued for each frame.

The GOP structure analyzer 33 outputs the reference picture type 32 generated and output by the reference GOP structure generator 31.
And stores it in the GOP structure analysis unit 33 for each frame. When the frame designating signal 21 is input, the reference picture type of the GOP frame received so far is determined, and it is determined whether or not the GOP end condition is satisfied by the picture type of the frame before the designated frame. . If the frame specification signal 21 is not specified, or if the frame specification signal 21 is specified but the picture type of the previous frame does not need to be changed, the picture type change request 34 is not notified. When the frame specification signal 21 is specified and the picture type of the previous frame needs to be changed, a picture type change request 34 is notified to the GOP structure changing unit 37.

The picture type storage buffer 35 stores the reference picture type 3 generated by the reference GOP structure generation unit.
2, the same number of frames as the video signal buffer 13 shown in FIG. 1 is stored therein, and the delayed picture type 36 delayed by the picture type
It is sent to the structure changing unit 37.

The GOP structure change unit 37 receives the delayed picture type 36 and the picture type change request 34 generated by the GOP structure analysis unit 33. If the picture type change request 34 is not specified, the delayed picture type 3
6 is output as the encoding picture type notification 23.
However, in this case, the GOP structure changing unit 37 does not output the encoding picture type change notification 28 as shown in FIG. 4, for example. When the picture type change request 34 is specified, the GOP structure change unit 37 changes the delayed picture type 36 to the I-picture or P-picture according to the instruction of the picture type change request 34. Then, the GOP is disconnected, and the encoding picture type notification 23 is output.

The picture type notification for encoding 23 is input to an encoding delay 38, and a delay equivalent to the delay required for encoding in the video encoder 14 and a display order (display order) to an encoding order (coding order). Are output as the multiplexing picture type notification 24 after the frame order is changed.

Thus, in the image encoding apparatus according to the present embodiment, when the frame at the head of the GOP is specified and the picture type of the frame preceding the specified frame is changed accordingly, the changed picture The type can be notified to the video encoder, and error-free encoding can be performed even when a GOP is cut at an arbitrary frame.

Next, referring to the block diagram of FIG.
A GOP structure determining unit included in the image encoding device according to the second embodiment of the present invention will be described. FIG.
Has the same structure as that of FIG. 3 except that the picture type storage buffer 35 is removed from the GOP structure determining unit shown in FIG. The image encoding device shown in FIG. 2 has no buffer at the video input stage, and the input video signal 12 captured by the video input device 11 is directly (without delay) input to the video encoder 14. Therefore, the reference picture type 32 generated by the reference GOP structure generating unit 31 also needs to be input to the video encoder 14 as the encoding picture type notification 23 without delay. 32 is sent to the GOP structure changing unit 37 without passing through the reference picture type storage buffer 35 as shown in FIG.

The frame to be the head of the GOP is designated by the frame designation signal 21, and the GOP structure analysis unit 3
When it is necessary to change the picture type of the frame preceding the frame specified by the frame specifying signal 21 by GOP3, the GOP structure analysis unit 33 sends the picture type change request 3
4 is output.

The GOP structure change unit 37 receives the reference picture type 32 and the picture type change request 34.
The frame whose picture type is changed by the picture type change request 34 is the immediately preceding frame. Since the picture type of this frame is output as the coding picture type notification 23, the GOP structure changing unit 3
In FIG. 7, instead of changing the GOP structure, an encoding picture type change notification 28 is transmitted to the video encoder (1 in FIG. 2).
Output to 4). When the video encoder 14 receives the coding picture type change notification 28, the video encoder 14 changes the picture type already notified by the coding picture type notification 23 in accordance with the instruction of the coding picture type change notification 28, and performs coding. Become

The encoding delay 38 receives the encoding picture type notification 23 and the picture type change request 34. The encoding delay 38 is equivalent to the delay required for encoding in the video encoder 14 and the frame order is changed from the display order (display order) to the encoding order (coding order) for the input encoding picture type. ) And then output as a multiplexing picture type notification 24. That is, the encoding delay 38
Is, if the picture type change request 34 is specified,
The picture type of the frame notified before the current encoding picture type notification 23 is changed to be the last of the GOP, stored internally, and output as the multiplexing picture type notification 24.

Thus, in a configuration in which a buffer is not provided at the input stage of the video signal, the encoding for changing the picture type at the encoding stage in the video encoder 14 is performed so that the designated frame becomes the head of the GOP. The video encoder 14 can be notified of a picture type change notification, and can perform error-free encoding even when a GOP is cut at an arbitrary frame. Further, since a video signal buffer for storing an input video signal is not required and a special arithmetic unit is not required, an image encoding device which can be easily realized can be provided.

Next, referring to the flowchart of FIG.
The processing procedure of the GOP structure analysis unit (33 in FIG. 4) included in the image encoding device according to the second embodiment of the present invention shown in FIG. 2 will be described. The process is started in FIG. 5, and in step S10, G
It is determined whether or not a frame to be the head of the OP is specified. If there is no designation of the first frame, step S11
Then, the process does not output the picture type change request 34, and further proceeds to step S12 to store the currently input reference picture type 32 inside the GOP structure analysis unit (33 in FIG. 4) and ends the processing.

If it is determined in step S10 that the first frame of the GOP is specified by the frame specifying signal 21, the process proceeds to step S13. In step S13, the picture type stored as specifying the previous frame is determined. If the picture type is an I picture or a P picture, the process proceeds to step S11. In step S13, if the picture type stored as specifying the previous frame is a B picture, the process proceeds to step S14,
A picture type change request 34 is output and the process proceeds to S12,
The reference picture type 32 is set to the GOP structure analysis unit (3 in FIG. 4).
The processing is terminated after saving in 3). That is, if there is a designation by the frame designation signal 21 and the frame preceding the designated frame is a B picture, the picture type change request 34 is output.

[0041]

The image encoding apparatus according to the present invention is constructed as described above. In particular, an arbitrary frame designated by specifying an external frame designation signal while encoding an input image signal. GOP in real time
By recording the time information of the frame that is the head of the GOP, the head of the head frame can be easily located at the time of reproduction of the multiplexed stream, and the designated frame can be quickly searched and reproduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an image encoding device according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of an image encoding device according to a second embodiment of the present invention;

FIG. 3 is a block diagram of a GOP structure determining unit of the image encoding device according to the first embodiment of the present invention;

FIG. 4 is a block diagram of a GOP structure determination unit of an image encoding device according to a second embodiment of the present invention;

FIG. 5 is a flowchart illustrating a processing procedure of a GOP structure analysis unit of the image encoding device according to the first and second embodiments of the present invention.

[Explanation of symbols]

 Reference Signs List 11 video input device 12 input video signal 13 video signal buffer 14 video encoder 15 video stream 16 audio input device 17 input audio signal 18 audio encoder 19 audio stream 20 video / audio multiplexer 21 frame designation signal 22 GOP structure determination unit 23 code Notification of multiplexing picture type 24 multiplexing picture type notification 25 multiplexed stream 26 time information 27 recording device 28 encoding picture type change notification 31 reference GOP structure generation unit 32 reference picture type 33 GOP structure analysis unit 34 picture type change request 35 Picture type storage buffer 36 Delayed picture type 37 GOP structure changing unit 38 Encoding delay

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C059 KK36 MA05 MA14 PP05 PP06 PP07 RC04 RC32 SS11 TA00 TA18 TA25 TB03 TC47 UA02 UA34

Claims (8)

[Claims] An image coding apparatus for performing image coding on a continuously input image signal by an image coding method using motion compensation prediction between images, wherein a frame currently input by a frame designation signal is input. An image coding apparatus comprising: a GOP structure determining unit that determines a GOP structure so as to be at the head of a GOP. 2. The apparatus according to claim 1, wherein when the frame designating signal is input, the GOP structure determining means determines a picture type of a frame preceding the frame designated by the frame designating signal, and determines whether to change the picture type. 2. The image encoding apparatus according to claim 1, further comprising a GOP structure analysis unit that determines the condition. 3. The GOP structure determining means according to claim 2, further comprising a GOP structure changing means for changing a picture type of said previous frame and cutting a GOP according to a judgment of said GOP structure analyzing means. Image encoding device. 4. An image encoding apparatus comprising: a video signal buffer for temporarily storing an input video signal; and a video encoder for encoding an input video signal in accordance with a notice of a picture type for encoding from said GOP structure determining means. 2. The image encoding device according to claim 1, wherein a delay of the input video signal in the video signal buffer is used for image encoding in the video encoder with a change in picture type. 5. An image coding apparatus for performing image coding on a continuously input image signal by an image coding method using motion compensation prediction between images, wherein a frame currently input by a frame designation signal is input. The GOP structure is determined so as to be at the beginning of the GOP, the determined encoding picture type is notified, it is determined whether or not the picture type of the previous frame needs to be changed, and it is determined that the picture type needs to be changed. GOP structure determining means for outputting a picture type change notice for encoding when the input picture type change notice is received from the GOP structure determining means. An image encoding device, comprising: a video encoder that encodes a signal. 6. An audio encoder for encoding an input audio signal and outputting an audio stream, and an audio stream from the audio encoder and an audio stream from the video encoder based on a notification of a multiplexing picture type from the GOP structure determining means. The video encoding apparatus according to claim 4, further comprising a video / audio multiplexing apparatus that multiplexes the video stream. 7. The image encoding apparatus according to claim 6, wherein said video / audio multiplexing apparatus outputs time information given in multiplexing a first stream of a GOP of a video stream and an audio stream. . 8. An image encoding apparatus according to claim 7, further comprising a recording unit for recording said time information.