JP2014017554A - Image encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an encoder in which coded data is prevented from increasing unnecessarily, by limiting execution of intra-frame coding when a request of executing intra-frame encoding is received externally.SOLUTION: The image encoder includes encoding means performing intra-frame encoding of moving image data at a predetermined frame interval, and performing inter-frame encoding of other frames, and control means for receiving a request for intra-frame encoding from the outside of the encoding means, and controlling the encoding means to perform intra-frame encoding in response to the request. The control means cancels a part of the request without controlling the encoding means to perform intra-frame coding.

Description

  The present invention relates to a moving image coding apparatus and method, and more particularly to timing control of intraframe coding.

    In recent years, network cameras that transfer captured moving image data to a display device or a storage device via a network are known. When transferring a moving image, the amount of data is large if it is transferred without compression. Therefore, in order to reduce the amount of data, encoding is usually performed after compression and transfer. An example of such a moving image encoding method is H.264. In H.264, a moving image is divided into a plurality of images (frames) arranged in time order, and a reference image is generated by performing inner coding (intraframe coding) on a reference frame image. Further, a difference image between the image other than the reference frame and the reference image is generated (inter-frame encoding). This reference image is called an I frame, and the difference image is called a P or B frame. Since the I frame is compressed as a single frame, the amount of data is larger than that of the P and B frames. The camera needs to transmit I frames, which serve as a reference for P and B frames, at appropriate intervals, and it is necessary to perform intraframe encoding at a timing according to this.

  Japanese Patent Application Laid-Open No. 2004-228561 describes a technique for setting a setting value for controlling the timing of intraframe encoding periodically and aperiodically using information in the camera and adjusting both setting values. Patent Document 1 describes that the aperiodic timing is the start of shooting at each shooting angle of view of the camera.

JP 2011-172003 A

  In Patent Document 1, a request for intra-frame coding inside the camera is considered, but a request for intra-frame coding from the outside of the camera is not considered. Here, the request for intra-frame coding from the outside includes a request in accordance with the start of moving image distribution and a request received separately from the client. Considering the external request, more intra-frame coding is performed, resulting in a problem that the amount of data increases.

  The present invention has been made in view of the above problems, and when receiving an intra-frame coding request from the outside, the execution of intra-frame coding is restricted and the coded data increases unnecessarily. The purpose is to prevent.

  In order to achieve the above object, an image encoding apparatus according to an aspect of the present invention has the following arrangement. That is, encoding means for encoding moving image data at predetermined frame intervals and inter-frame encoding other frames, and receiving a request for intra-frame encoding from outside the encoding means, And a control unit that causes the encoding unit to execute intra-frame encoding according to the control unit, wherein the control unit discards a part of the request without causing the encoding unit to perform intra-frame encoding. It is characterized by that.

  According to the present invention, it is possible to prevent the moving image data to be transferred from becoming large.

The block diagram of the image coding apparatus and client by this invention. The flowchart which shows the control timing by 1st Embodiment. The flowchart which shows the control timing by 2nd Embodiment. The timing diagram which shows the delay of intra-frame encoding. The timing diagram which shows the control timing of the intra-frame encoding of a fixed space | interval. The timing diagram which shows the control timing by 1st Embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.

[First embodiment]
Hereinafter, an image encoding device according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a configuration of an image encoding device 10 and a client 14 that receives moving image data transmitted from the image encoding device 10. In the image encoding device 10, the imaging unit 11 acquires moving image data from a sensor (not shown) and sends the moving image data to the encoding unit 12. The encoding unit 12 compresses the moving image data into the H.264 format and sends the compressed data to the communication unit 13. The communication unit 13 divides the compressed moving image data into packet units and distributes them to the client 14 via the network. In response to a distribution request from the client 14, the distribution processing unit 15 controls the communication unit 13 to perform moving image distribution and stop processing. The distribution processing unit 15 also performs user authentication for the client 14.

  The encoding unit 12 performs intra-frame encoding at a predetermined constant frame interval, performs inter-frame encoding for other frames, and generates an I frame, a P frame, and a B frame, respectively. The control unit 16 sets a reference timing for the encoding unit 12, and the encoding unit 12 starts intra-frame encoding from this reference timing, and thereafter performs intra-frame encoding at a fixed interval timing. Do. The encoding unit 12 performs intra-frame encoding at a timing according to a request from the control unit 16 in addition to performing intra-frame encoding at a constant interval. When receiving a request from the outside of the camera, the control unit 16 sends the request to the encoding unit 12.

  There are the following two cases as the timing of the request from the outside of the camera. The first is the timing when the distribution of the moving image is received from the client 14 and the distribution is started. In H.264, a reference image that is intra-frame-coded is required when reproduction of compressed data is started. Accordingly, the distribution processing unit 15 sends a request to the encoding unit 12 via the control unit 16 to perform intraframe encoding after preparation for distribution start such as user authentication is completed. The encoding unit 12 performs intra-frame encoding at a timing according to the request, and then starts inter-frame encoding. The encoded data is sent to the communication unit 13 and distribution of the moving image to the client 14 is started. Note that the encoding unit 12 can perform only one type of encoding for moving images having the same resolution and image quality. Therefore, when moving images having the same resolution or the like are requested from a plurality of clients, the communication unit 13 sends the duplicated same data to all clients. That is, when intra-frame coding is performed, the same moving image data is distributed to all clients.

  The second is an arbitrary timing requested from the client 14. The distribution processing unit 15 receives an arbitrary intra-frame encoding request from the client 14 separately from the moving image distribution control. The distribution processing unit 15 sends this request to the control unit 16, and the control unit 16 sends the request to the coding unit 12 to perform intraframe coding. The encoding unit 12 performs intraframe encoding at a timing according to the request.

  Therefore, there are three types of timing at which intra-frame encoding is performed. In other words, there are a predetermined interval timing performed by the conventional encoding unit, a start of moving image distribution to the client 14, and an arbitrary timing from the client 14.

  Next, the timing for performing intra-frame coding according to the present embodiment will be described with reference to the flowchart of FIG.

  In step 21, the distribution processing unit 15 receives a moving image distribution request from the client 14, performs user authentication and the like, and determines whether or not distribution of the moving image to the client 14 can be started. If it is determined that distribution is possible (YES in step 21), the distribution processing unit 15 sends a request to the encoding unit 12 via the control unit 16, and the process proceeds to step 25. In step 25, the encoding unit 12 performs intra-frame encoding at a timing according to the request. The encoded data is distributed to the client 14 via the communication unit 13. Thus, the client 14 can immediately receive the reference image and immediately reproduce the moving image as soon as the moving image distribution can be received. If there is no client whose distribution can be started in step 21 (NO in step 21), the process proceeds to step 22. In step 22, the distribution processing unit 15 determines whether or not a request for intraframe encoding has been received from the client 14. If no request has been received (NO in step 22), the process returns to step 21. If the request has been received (YES in step 22), the process proceeds to step 23.

  In step 23, the control unit 16 compares the elapsed time from when the last request was received from the client and the last intraframe encoding was performed with a preset specific period. If this elapsed time has passed a specific period (YES in step 23), the process proceeds to step 25. Also, when the control unit 16 receives a request for intra-frame coding for the first time, the process proceeds to step 25. If this elapsed time has not passed the specific period (NO in step 23), the process proceeds to step 24. In step 24, the control unit 16 holds a cumulative value of the number of times the request has been received since the encoding unit 12 received the request from the client last time and performed intra-frame coding, and specified this cumulative value. Compare the number of times. If the accumulated value is equal to or less than the specific number of times (NO in step 24), the process returns to step 21. When the accumulated value exceeds a specific number of times (YES in Step 24), the control unit 16 sends a request to the encoding unit 12 and proceeds to Step 25. In step 25, the encoding unit 12 performs intra-frame encoding at a timing according to the request, and then proceeds to step 26. In step 26, the control unit 16 resets the time obtained in step 23 and the number obtained in step 24. The above processing is the same when there are a plurality of clients and each sends a request for intra-frame coding.

  FIG. 6 is a timing diagram of intra-frame encoding according to the flowchart of FIG. FIG. 6 shows a case where the encoding unit 12 performs all intra-frame encoding upon receiving all requests from the outside (client) (FIG. 6 left), and intra-frame encoding upon receiving only a part of the request according to the present embodiment. The case of performing is shown (right in FIG. 6). The encoding unit 12 performs intraframe encoding at timings 601 to 604 at regular intervals. Apart from these, the encoding unit 12 performs intra-frame encoding upon receiving a request from the client 14. When receiving all requests from the outside (client 14), the control unit 16 sends requests 605 to 607 to the encoding unit 12, and the encoding unit 12 performs intra-frame encoding at timings 608 to 610, respectively. On the other hand, in the present embodiment, the control unit 16 sends only the first request 611 among the requests 611 to 613 to the encoding unit 12 and discards the requests 612 and 613 received during a certain period thereafter. The encoding unit 12 receives only the first request 611 and performs intra-frame encoding at timing 614.

  In this way, the control unit 16 thins out (destroys) a part of the intra-frame encoding request from the client, thereby preventing the intra-frame encoding from becoming unnecessarily large, and as a result, the encoded data is mischievous. The increase can be prevented. Therefore, it is possible to provide an image encoding device that does not cause an excessive load on the image encoding device itself, the network, or the storage device. In addition to the embodiment shown in FIG. 2, step 23 and step 24 may be reversed in FIG. 2, and only one of the conditions of step 23 and step 24 may be used.

[Second Embodiment]
Hereinafter, an image encoding device according to a second embodiment of the present invention will be described with reference to FIGS. The configuration of the image encoding device according to the present embodiment is the same as that of the first embodiment, and is shown in FIG. Next, the timing for performing intra-frame coding according to the present embodiment will be described with reference to the flowchart of FIG.

  In step 31, the distribution processing unit 15 receives a moving image distribution request from the client 14, performs user authentication and the like, and determines whether or not distribution of the moving image to the client 14 can be started. If it is determined that the distribution can be started (YES in step 31), the distribution processing unit 15 sends a request to the encoding unit 12 via the control unit 16 and proceeds to step 34. In step 34, the encoding unit 12 performs intraframe encoding. The encoded data is distributed to the client 14 via the communication unit 13. As a result, the client 14 can receive the reference image and immediately reproduce the moving image. If there is no client whose distribution can be started in step 31 (NO in step 31), the process proceeds to step 32. In step 32, the distribution processing unit 15 determines whether or not a request for intraframe encoding has been received from the client 14. If the request has not been received (NO in step 32), the process proceeds to step 31. If the request has been received (YES in step 32), the process proceeds to step 33.

  In step 33, the control unit 16 receives the request from the client last time and performs the intra-frame encoding, and then the elapsed time from the first reception or the first request from the client. Compare the time with a preset period. If this elapsed time has not passed the specific period (NO in step 33), the process returns to step 31. On the other hand, if this elapsed time has passed a specific period (YES in step 33), the determination in step 33 is performed again after an arbitrary time has elapsed. The control unit 16 sends a request to the encoding unit 12 and proceeds to step 34. In step 34, the encoding unit 12 performs intraframe encoding, and then proceeds to step 35. In step 35, the control unit 16 resets the time obtained in step 33.

  As described above, the control unit 16 discards a request received within a certain period of time after receiving a request from a client for the first time. Then, the control unit 16 delays the first received request and sends it to the encoding unit 12, and the encoding unit 12 performs intra-frame encoding in response to the delayed request. By such processing, it is possible to prevent the intra-frame encoding from being unnecessarily increased, and as a result, it is possible to prevent the encoded data from being increased unnecessarily. The above processing is the same when there are a plurality of clients and each sends a request for intra-frame coding.

  In FIG. 3, the method for delaying the request has been described as a method for controlling the timing of the intra-frame coding. However, the method is not limited to this method. For example, the control unit 16 may control the timing of conventional intraframe encoding at regular intervals in cooperation with the encoding unit 12. The method will be described with reference to FIGS.

  4 and 5 are timing diagrams of intra-frame coding according to the flowchart of FIG. FIG. 4 shows control when the encoding unit 12 performs intra-frame encoding at timings 401 to 404 at regular intervals while the control unit 16 delays the request from the client 14. First, a description will be given of processing in a case where intra-frame coding is not performed at regular intervals while the request is delayed (left in FIG. 4). In accordance with the flowchart shown in FIG. 3, the control unit 16 does not immediately send this request to the encoding unit 12 but delays the request 405 even if the request 405 is received. Then, the control unit 16 discards the request 406 received during a certain period. The control unit 16 sends the request to the encoding unit 12 after a certain period of time has elapsed after receiving the first request 405, and the encoding unit 12 performs intraframe encoding at timing 407.

  Next, processing when intra-frame coding is performed at regular intervals while the request is delayed will be described (right in FIG. 4). The control unit 16 delays the request 408 and discards the request 409. Here, while the request 408 is delayed, intra-frame coding at regular intervals is performed at the timing 403. In this case, the control unit 16 determines that the intra-frame coding according to the requests 408 and 409 is unnecessary because the intra-frame coding is performed at the timing 403, and at the timing 410 that is scheduled to be performed after a certain period of time. Cancel intra-frame coding. That is, the control unit 16 does not send the received external request to the encoding unit 12.

  FIG. 5 shows control when adjusting the timing of intra-frame coding at regular intervals. The encoding unit 12 is scheduled to perform intra-frame encoding at a timing 51 with a constant interval, and thereafter perform intra-frame encoding at timings 52 to 54. In accordance with the flowchart shown in FIG. 3, the control unit 16 does not immediately send this request to the encoding unit 12 but delays the request 405 even if the request 405 is received. Then, the control unit 16 discards the request 56 received during a certain period. The control unit 16 sends the request to the encoding unit 12 after a certain period of time has elapsed after receiving the first request 55, and the encoding unit 12 performs intra-frame encoding at timing 52. Here, the encoding unit 12 originally performs the intra-frame encoding at the timing 57 under the control of the control unit 16, which was originally scheduled to perform the intra-frame encoding at a constant interval at the timing 52. In other words, the encoding by the request from the client and the encoding at a fixed interval are combined and the encoding is performed only once. Further, the control unit 16 sets the timing 57 to the encoding unit 12 using the timing 57 as a reference timing so that the timings 53 to 54 of the intra-frame encoding at a predetermined interval which are scheduled thereafter are set at a constant interval with respect to the timing 57. Set.

  Although the method for canceling the delayed intra-frame coding using FIG. 4 and the method for adjusting the timing of performing the intra-frame coding at regular intervals using FIG. 5 have been described, these may be combined. . In addition, the method of adjusting the timing of performing intra-frame coding at regular intervals can be used even when the request for intra-frame coding from the client is appropriately thinned out after performing intra-frame coding shown in the first embodiment. Applicable.

  In this way, as shown in this embodiment, the encoded data increases unnecessarily by delaying the intra-frame encoding request from the outside (client) and discarding the requests other than the delayed request. Can be prevented. As a result, it is possible to provide an image encoding device that does not cause an excessive load on the image encoding device itself, the network, or the storage device.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (9)

Encoding means for intra-frame encoding of moving image data at predetermined frame intervals and inter-frame encoding of other frames;
Control means for receiving an intra-frame encoding request from outside the encoding means and causing the encoding means to execute intra-frame encoding in response to the request;
The image coding apparatus according to claim 1, wherein the control unit discards a part of the request without causing the coding unit to perform intra-frame coding.   The control unit discards the request based on at least one of an elapsed time from the time when the encoding unit last performed intra-frame encoding in response to the received request or the number of reception times of the request. The image coding apparatus according to claim 1.   The control means causes the encoding means to execute intra-frame encoding after a lapse of a predetermined period after receiving the request, and receives other requests received during the predetermined period after receiving the request. The image coding apparatus according to claim 1, wherein the image coding apparatus is discarded.   The image encoding apparatus according to claim 1, wherein the control unit receives the request from a device external to the image encoding device via a network. A distribution processing unit that performs control for distributing the data encoded by the encoding unit via a network;
4. The control unit according to claim 1, wherein when the distribution processing unit determines that data distribution can be started, the control unit causes the encoding unit to perform intra-frame encoding. The image encoding device according to item 1.   The said control means discards the said request | requirement, when the intra-frame encoding in the said predetermined frame interval is performed during the said fixed period after receiving the said request | requirement. Image encoding device.   The control means sets the timing after the elapse of the predetermined period from the reception of the request as the reference timing in the intra-frame coding at the predetermined frame interval in the coding means. The image encoding device according to claim 3. An image encoding method comprising:
An encoding step of intra-frame encoding moving image data at predetermined frame intervals and inter-frame encoding of other frames;
Receiving a request for intra-frame encoding from outside the encoding step, and causing the encoding step to perform intra-frame encoding in response to the request, and
The image encoding method according to claim 1, wherein the control step discards a part of the request without causing the encoding step to perform intra-frame encoding.   The program for making a computer perform each process of the encoding method described in Claim 8.

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