JP2022031267A - Streaming system and encoding program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow data that is expanded in a scalable manner and transmitted in a low band to be decoded with an existing decoder.

SOLUTION: A determination unit determines whether or not a base stream that is a reference of encoding and decoding, shared with a decoder and associated with an input image is stored in a storage unit. A base stream generation unit performs encoding processing of the base stream stored in the storage unit when it is determined that the base stream associated with the input image is stored in the storage unit, and generates the base stream by performing encoding processing of the input image when it is determined that the base stream associated with the input image is not stored in the storage unit. A difference generation unit generates a difference bit stream being a difference between the base stream and the input image. A communication control unit transmits the base stream to the decoder to share it with the decoder, and transmits the difference bit stream to the decoder after that.

SELECTED DRAWING: Figure 10

COPYRIGHT: (C)2022,JPO&INPIT

Description

Embodiments of the present invention relate to an encoding device, an encoding program, and a streaming system.

Today, there is known an SHVC encoding technique (scalable extension of HEVC) that can be extended to super-resolution video such as 4K resolution at a low bit rate by using HDTV video transmission. HDTV is an abbreviation for "High-definition television." SHVC is an abbreviation for "Scalable High-efficiency Video Coding". HEVC is an abbreviation for "High-efficiency Video Coding".

This SHVC encoding technology uses inter-layer prediction that predicts a 4K image from an HDTV image in addition to the inter-screen prediction and in-screen prediction used in HEVC, and data to be allocated to an image area that is blurred due to movement. The amount is suppressed, and a larger amount of data is allocated to the image area that is in focus and has less movement to improve the subjective image quality. Further, by removing the noise component that is difficult to compress from the 4K image in advance by spatiotemporal image processing, it is possible to suppress the deterioration of the sense of resolution at a low bit rate. Therefore, even when the additional bit rate is set to 10 Mbps, the resolution of the 4K image can be maintained. For example, a bit rate of about 30 Mbps was required for video distribution with 4K resolution, but by using HEVC encoding technology, the required additional transmission band can be reduced to about 1/3 of 10 Mbps.

Here, in the narrow band video transmission system using SHVC, the reference image is shared in advance between the transmitting side and the receiving side. The transmitting side sends only the difference from the reference image as encoded data. The receiving side decodes and displays the received encoded data using the reference image shared in advance. As a result, since the encoded data is only the difference from the reference image, the amount of data can be reduced and video streaming with high bandwidth utilization efficiency becomes possible.

However, in a narrowband video transmission system using SHVC, in order to decode the video signal transmitted from the transmitting side on the receiving side, a dedicated decoder compatible with SHVC is required on the receiving side, and the existing HEVC decoder can reproduce the video signal. There was a difficult problem.

Japanese Unexamined Patent Publication No. 2005-11244

An object to be solved by the present invention is to provide an encoding device, an encoding program, and a streaming system that can decode data that is scalable and extended and transmitted at a low bit rate by an existing decoder.

According to the embodiment, the encoding device is a base stream that the determination unit is a reference for encoding and decoding and is shared with the decoding device, and the base stream related to the input image is stored in the storage unit. Determine if it is. When the determination unit determines that the base stream related to the input image is stored in the storage unit, the base stream generation unit encodes the base stream stored in the storage unit, and the determination unit determines that the base stream is stored in the storage unit. When it is determined that the base stream related to the input image is not stored in the storage unit, the input image is encoded to generate the base stream. The difference generation unit generates a difference bit stream which is a difference between the base stream generated by the base stream generation unit and the input image. By controlling the communication unit so that the base stream is transmitted to the decoding device, the communication control unit shares the base stream with the decoding device, and thereafter, the difference bit stream generated by the difference generation unit is used. Control the communication unit to send to the decoding device.

FIG. 1 is a system configuration diagram of the streaming system of the first embodiment. FIG. 2 is a hardware configuration diagram of a server device provided in the streaming system of the first embodiment. FIG. 3 is a hardware configuration diagram of a client device provided in the streaming system of the first embodiment. FIG. 4 is a functional block diagram of the encoder of the server device. FIG. 5 is a functional block diagram of the decoder of the client device. FIG. 6 is a flowchart for explaining a base stream generation operation shared with the client device. FIG. 7 is a flowchart for explaining an operation of generating a difference bit stream based on a base stream and transmitting it to a client device. FIG. 8 is a flowchart for explaining an operation of storing the base stream transmitted from the server device in the client device. FIG. 9 is a flowchart for explaining an operation of decoding a bit stream transmitted from a server device. FIG. 10 is a functional block diagram of the encoder of the streaming system of the second embodiment. FIG. 11 is a flowchart for explaining a base stream generation operation shared with a client device in the streaming system of the second embodiment. FIG. 12 is a flowchart for explaining an operation of generating a difference bit stream based on a base stream and transmitting it to a client device in the streaming system of the second embodiment.

Hereinafter, the streaming system of the embodiment will be described in detail with reference to the drawings.

(Overview)
The streaming system of the embodiment is, for example, a system for transmitting and receiving surveillance video and the like. The encoder on the transmitting side previously generates and stores a base stream such as an intra-picture NAL unit, which is a reference for encoding and decoding, for each screen pattern. NAL is an abbreviation for "Network Abstraction Layer". The generated base stream is also stored in the decoder on the receiving side, and the base stream is shared between the encoder side and the decoder side. As for the timing of storing the base stream in the decoder on the receiving side, for example, the base stream is stored in the decoder at the time of factory shipment or the initial setup of the decoder on the receiving side. Alternatively, the base stream is updated dynamically, asynchronously or synchronously during the actual stream transmission.

When encoding the input screen, the encoder encodes the input video using the base stream shared with the decoder side, and based on the encoding state, for example, a difference bit stream such as a P picture NAL unit is input. Generate. The bitstream transmitted to the decoder is only the difference bitstream. As a result, the amount of transmitted data can be reduced. The difference bit stream transmitted to the decoder may include information indicating whether or not the base stream is used.

The decoder on the receiving side reconstructs a stream equivalent to the stream originally planned to be generated by the encoder (same image quality and same resolution) using the previously shared base stream and the received difference bit stream. do. In other words, the decoder reconstructs the base stream shared in advance and the bit stream in which the screen corresponding to the differential bit stream reproduced using the received differential bit stream is encoded. Then, the decoder decodes and displays the reconstructed stream. This makes it possible to enable video streaming with high bandwidth utilization efficiency in screen transfer. Moreover, a dedicated decoder can be eliminated. In addition, the amount of reconstruction processing can be reduced as compared with transcoding. Therefore, a receiving device (decoder) can be realized with a general-purpose decoder chip and an inexpensive CPU, and the cost of the streaming system can be reduced.

(First Embodiment)
FIG. 1 shows a system configuration diagram of the streaming system of the first embodiment. As shown in FIG. 1, the streaming system of the first embodiment has a server device 1 and a client device 2. The server device 1 and the client device 2 are connected to each other via a network 3 such as the Internet. The server device 1 performs scalable expansion processing of a predetermined video stream using SHVC encoding technology to maintain a high-resolution feeling of a high-resolution video signal such as a so-called 4K video signal or 8K video signal, while maintaining a low bit rate. It is rated and delivered via network 3. SHVC is an abbreviation for "Scalable High-efficiency Video Coding". The client device 2 is a general HEVC decoder, and decodes and reproduces an SHVC-encoded video signal without any special configuration as described later. The decoded video signal is displayed on a monitor device or recorded on a recorder device or the like. HEVC is an abbreviation for "High-efficiency Video Coding".

FIG. 2 shows a hardware configuration diagram of the server device 1. As shown in FIG. 2, the server device 1 includes a CPU 11, a ROM 12, a RAM 13, an HDD (hard disk drive) 14, and a communication unit 15. The CPU 11 to the communication unit 15 are connected to each other via the bus line 16. CPU is an abbreviation for "Central Processing Unit". ROM is an abbreviation for "Read Only Memory". RAM is an abbreviation for "Random Access Memory".

An encoding program for encoding a video stream is stored in the HDD 14. The CPU 11 functions as an encoder 17 by operating according to an encoding program, and SHVC-encodes and distributes a video stream. The encoding program may be stored in another storage unit such as ROM 12 or RAM 13.

FIG. 3 shows a hardware configuration diagram of the client device 2. As shown in FIG. 3, the client device 2 includes a CPU 21, a ROM 22, a RAM 23, an HDD (hard disk drive) 24, and a communication unit 25. The CPU 21 to the communication unit 25 are connected to each other via the bus line 26.

The HDD 24 stores a decoding program for decoding a video stream that is SHVC-encoded and transmitted from the server device 1. The CPU 21 functions as a decoder 27 by operating according to the decoding program, and decodes the video stream received from the server device 1. The decoding program may be stored in another storage unit such as ROM 22 or RAM 23.

In this example, the encoder 17 and the decoder 27 will be described as being realized by software. However, one or more of all of the encoder 17 and the decoder 27 may be realized by hardware such as an IC (Integrated Circuit).

Further, the encoding program and the decoding program may be provided by recording the files in an installable format or an executable format on a recording medium readable by a computer device such as a CD-ROM or a flexible disk (FD). Further, the encoding program and the decoding program may be provided by recording on a recording medium readable by a computer device such as a CD-R, a DVD, a Blu-ray disc (registered trademark), or a semiconductor memory. DVD is an abbreviation for "Digital Versatile Disk". Further, the encoding program and the decoding program may be provided in the form of being installed via a network such as the Internet. Further, the encoding program and the decoding program may be provided by incorporating them into a ROM or the like in the device in advance.

FIG. 4 is a functional block diagram of the encoder 17 of the server device 1. The encoder 17 is an example of an encoding device. As shown in FIG. 3, the encoder 17 includes a preprocessing unit 31, a storage control unit 32, a first transmission control unit 33, a second buffer control unit 34, a second encoding unit 35, an adjustment unit 36, and a second. It has a transmission control unit 37 of 2. The preprocessing unit 31 has a first buffer control unit 38 and a first encoding unit 39. As described above, all or part of the pre-processing unit 31 to the second transmission control unit 37 may be configured by hardware.

The pre-processing unit 31 is a processing unit that functions when the above-mentioned base stream is generated in advance and stored in the decoder, for example, at the time of factory shipment or initial setup of the client device 2 on the receiving side. Therefore, when updating the base stream on the decoder side dynamically, asynchronously or synchronously at the time of actual stream transmission, the preprocessing unit 31 becomes unnecessary. Further, in FIG. 4, although the pre-processing unit 31 is shown as an independent processing unit, the first buffer control unit 38 is substituted by the second buffer control unit 34, and the first encoding unit 39 is used as the second. By substituting the encoding unit 35 of the above, the preprocessing unit 31 can be omitted.

The storage control unit 32 stores and controls a base stream generated by the preprocessing unit 31 and shared between the client devices 2 (decoder 27) in a storage unit such as a RAM 13. The first transmission control unit 33 controls the communication unit 15 so as to transmit the base stream stored in the RAM 13 to the client device 2, and shares the base stream with the decoder 27.

The second buffer control unit 34 buffers the input video stream (input bit stream) in a storage unit such as the RAM 13. The second encoding unit 35, which is an example of the difference generation unit, generates a difference bit stream which is a difference between the base stream stored in the RAM 13 and the buffered video stream. As a result, a scalable expanded and low bit rate bitstream (SHVC-encoded bitstream) is generated.

The adjusting unit 36 adjusts the difference bit stream by adding, for example, the identification information or the related information of the reference base stream. The second transmission control unit 37, which is an example of the communication control unit, controls the communication unit 15 so as to transmit the adjusted difference bit stream to the client device 2.

FIG. 5 is a functional block diagram of the decoder 27 of the client device 2. The decoder 27 is an example of a decoding device. As shown in FIG. 5, the decoder 27 has an adjustment processing unit 41 and a decoding processing unit 42. The adjustment processing unit 41 includes a first reception control unit 43, a storage control unit 44, a second reception control unit 45, and a configuration adjustment unit 46. The decoding processing unit 42 has a decoding unit 47 and a buffer control unit 48. As described above, all or part of the first reception control unit 43 to the buffer control unit 48 may be configured by hardware.

The first reception control unit 43 controls the communication unit 25 to receive the base stream from the server device 1, which is pre-generated or dynamically updated as described above. The storage control unit 44 stores and controls the received base stream in a storage unit such as the RAM 23. The second reception control unit 45 controls the communication unit 25 so as to receive the difference bit stream from the server device 1. The configuration adjustment unit 46 uses the previously shared base stream and the received difference stream to re-create a bit stream having the same image quality and resolution as the bit stream originally planned to be generated by the encoder 17. Configure.

The decoder performs normal HEVC decoding processing on the reconstructed bitstream. The buffer control unit 48 buffers the decoded bit stream in a storage unit such as a RAM 23, sequentially reads it out, and outputs it to a monitoring device, a recording device, or the like.

Next, the flowchart of FIG. 6 shows the flow of the base stream generation operation shared with the client device 2. For example, at the timing of pre-processing such as factory shipment, initial setup, or actual stream transmission of the client device 2 on the receiving side, the first buffer control unit 38 of the pre-processing unit 31 shown in FIG. 4 is pre-processed. The input picture (pre-input bit stream) is buffered in the RAM 13.

As the pre-input picture, a captured image, a picture obtained from camera input, a picture subjected to a predetermined processing process, or the like is used. Further, the pre-input picture is preferably a picture having an image quality that can be used as a reference picture when generating a difference bit stream and having a high similarity to a picture in which the difference is generated.

The first encoding unit 39 reads the buffered pre-input picture from the RAM 13 and generates a base stream for SHVC. The base stream may be a single type or a plurality of types. The base stream may also be the entire or part of the encoded bitstream. As an example of the partial base stream, for example, the I picture of the elementary stream alone can be mentioned as an example.

The storage control unit 32 acquires the base stream in step S1 of the flowchart of FIG. 6, and determines in step S2 whether or not storage for adjustment processing such as addition of identification information or related information is necessary. do. If storage is required (step S2: Yes), the process proceeds to step S3, and if storage is not required (step S2: No), the process proceeds to step S4.

In step S3, the adjustment unit 36 performs adjustment processing such as adding identification information or related information to the base stream. Further, in step S3, the storage control unit 32 temporarily stores the adjusted base stream in the RAM 23.

Next, in step S4, the first transmission control unit 33 determines whether or not the output (transmission) of the base stream to the client device 2 is necessary. When output is required (step S4: Yes), the first transmission control unit 33 controls the communication unit 15 so that the base stream is transmitted to the client device 2 in step S5. On the other hand, when the output is unnecessary (step S4: No), the first transmission control unit 33 ends the processing of the flowchart of FIG. 6 without transmitting the base stream.

The timing at which the first transmission control unit 33 transmits the base stream to the client device 2 may be, for example, the timing at which the storage control unit 32 notifies that a new base stream has been stored. Alternatively, it may be the timing when the output instruction of the base stream is supplied from the user or the system. Alternatively, it may be a predetermined timing or a timing at the time of a transmission request from the client device 2. The transmission speed of the base stream is arbitrary, and may be a low bit rate transmission speed depending on the communication line of the client device 2 or the like, or may be a high bit rate transmission speed in order to shorten the output time.

Next, the flowchart of FIG. 7 shows an operation flow of generating a difference bit stream based on the base stream and transmitting it to the client device 2. In step S11, the second buffer control unit 34 shown in FIG. 4 acquires a picture to be encoded and buffers it in the RAM 13 or the like. In step S12, the second encoding unit 35 determines whether or not the base stream to be referred to when encoding the input picture is stored in the RAM 13 via the storage control unit 32.

When the base stream to be referred to is not stored in the RAM 13 (step S12: No), the second encoding unit 35 performs SHVC encoding for the input picture in step S14 without referring to the base stream. The process proceeds to step S15. On the other hand, when the base stream to be referred to is stored in the RAM 13 (step S12: Yes), the second encoding unit 35 refers to the base stream in step S13 and makes a difference from the input picture. The SHVC encoding process for generating the difference bit stream is performed, and the process proceeds to step S15.

In step S15, the adjustment unit 36 performs an adjustment process of adding the identification information or the related information of the reference base stream to the difference bit stream or the like generated by the SHVC encoding process. In step S16, the storage control unit 32 determines whether or not to store the bitstream generated by the SHVC encoding process in the RAM 13. When storing (step S16: Yes), the storage control unit 32 stores the bitstream generated by the SHVC encoding process in the RAM 13 in step S17. At this time, the storage control unit 32 stores the newly generated bit stream in the RAM 13, or stores the bit stream stored in the RAM 13 in the form of updating with a new bit stream. Alternatively, the storage control unit 32 stores only the difference between the bit stream stored in the RAM 13 and the new bit stream. If such storage processing is not required (step S16: No), the processing proceeds to step S18.

In step S18, the second transmission control unit 37 controls the communication unit 15 so as to transmit the difference bit stream or the like to the client device 2, and ends the processing of the flowchart of FIG. 7. In the case of the streaming system of the first embodiment, the base stream is first transmitted to the client device 2, and then only the difference bit stream which is the difference from the base stream is transmitted to the client device 2. As a result, the bit rate can be reduced and the transmission band can be effectively used.

Next, the flowchart of FIG. 8 shows the flow of the operation of storing the base stream transmitted from the server device 1 on the client device 2 side. In step S21, the first reception control unit 43 shown in FIG. 5 controls the communication unit 25 so as to acquire the base stream transmitted from the server device 1. In step S22, the storage control unit 44 determines whether or not the acquired base stream needs to be stored.

Specifically, the storage control unit 44 stores the acquired base stream in a storage unit such as the RAM 23 when the output processing of the base stream is instructed by the user or the system, or when the timing is predetermined. Remember in. Alternatively, the storage control unit 44 stores the acquired base stream in a storage unit such as the RAM 23 when storage is instructed by the server device 1 or when storage is instructed by the configuration adjustment unit 46. .. The input speed of the base stream is arbitrary, and may be a low bit rate input speed depending on the communication line of the server device 1 or the like, or may be a high bit rate input speed in order to shorten the input time.

If it is determined in step S22 that storage is necessary, in step S23, the storage control unit 44 stores and controls the acquired base stream in the RAM 23. As a result, the base stream is shared between the server device 1 and the client device 2. If it is determined in step S22 that storage is unnecessary, the storage control unit 44 ends the process of the flowchart of FIG. 8 as it is.

Next, the flowchart of FIG. 9 shows a flow of decoding the bit stream transmitted from the server device 1. In step S31, the second reception control unit 45 controls the communication unit 25 so as to acquire the bit stream transmitted from the server device 1. In step S32, the configuration adjustment unit 46 determines whether or not a base stream is required for decoding the bit stream.

When the base stream is required (step S32: Yes), the configuration adjustment unit 46 acquires the base stream stored in advance in the RAM 23 in step S33, and proceeds to the process in step S34. On the other hand, when the base stream is unnecessary (step S32: No), the configuration adjustment unit 46 proceeds to the process in step S34.

In step S34, the configuration adjustment unit 46 uses the base stream shared in advance and the subsequent difference bitstream received, and is equivalent to the bitstream originally planned to be generated by the encoder 17 of the server device 1 (. Reconstruct the bitstream with the same image quality and resolution). In other words, the configuration adjustment unit 46 reconstructs the base stream shared in advance and the bit stream in which the screen corresponding to the difference bit stream reproduced using the received difference bit stream is encoded. In step S35, the decoding unit 47 performs normal HEVC decoding processing on the reconstructed bit stream to decode it. Then, the buffer control unit temporarily stores the decoded bit stream in the RAM 23, sequentially reads it out, and outputs it to a monitoring device, a recording device, or the like.

The streaming system of the first embodiment as described above can enable bandwidth-efficient streaming in the transfer of bitstreams. Further, it is possible to decode the SHVC-encoded bitstream with a normal HEVC decoder without using a decoder dedicated to SHVC. In addition, the amount of reconstruction processing can be reduced as compared with transcoding. Therefore, the client device 2 can be realized by using a general-purpose decoder chip and an inexpensive CPU, and the cost of the streaming system can be reduced.

(Second embodiment)
Next, the streaming system of the second embodiment will be described. The streaming system of the first embodiment described above is an example of transmitting a bitstream of a moving image, whereas the streaming system of the second embodiment transmits a bitstream of a still image (picture). This is an example. It should be noted that only this point is different between the first embodiment and the second embodiment. For this reason, only the differences will be explained below, and duplicate explanations will be omitted.

FIG. 10 is a functional block diagram of the encoder 17 of the streaming system of the second embodiment. In FIG. 10, the parts showing the same operation as in FIG. 4 are designated by the same reference numerals. As shown in FIG. 10, the encoder 17 of the streaming system of the second embodiment is buffered by the first buffer control unit 38 and the second buffer control unit 34 in addition to the functions of FIG. It has a picture storage control unit 51 that stores and controls the pictures in the RAM 13. Further, it has a determination unit 52 for determining (selecting) the picture to be encoded among the pictures stored in the RAM 13.

The flowchart of FIG. 11 shows the flow of the base stream generation operation shared with the client device 2. For example, at the timing of preprocessing such as factory shipment, initial setup, or actual stream transmission of the client device 2 on the receiving side, the first buffer control unit 38 of the preprocessing unit 31 shown in FIG. 10 steps. In S41, the pre-input picture (pre-input picture) is buffered.

As the pre-input picture, a captured image, a picture obtained from camera input, a picture subjected to a predetermined processing process, or the like is used. Further, the pre-input picture is preferably a picture having an image quality that can be used as a reference picture when generating a difference bit stream and having a high similarity to a picture in which the difference is generated.

In step S42, the picture storage control unit 51 cooperates with the determination unit 52, and the pre-input picture determines whether or not storage is necessary. When storage is required (step S41: Yes), the picture storage control unit 51 stores and controls the pre-input picture in the RAM 13 in step S43, and proceeds to the process in step S44. On the other hand, when storage is unnecessary (step S41: No), the picture storage control unit 51 advances the processing to step S44.

In step S44, the first encoding unit 39 reads the pre-input picture from the RAM 13 and generates a base stream for SHVC. The base stream may be a single type or a plurality of types. The base stream may also be the entire or part of the encoded bitstream. As an example of the partial base stream, for example, the I picture of the elementary stream alone can be mentioned as an example.

Next, in step S45, the storage control unit 32 determines whether or not the base stream needs storage for adjustment processing such as addition of identification information or related information. If storage is required (step S45: Yes), the process proceeds to step S46, and if storage is not required (step S45: No), the process proceeds to step S47.

In step S46, the storage control unit 32 stores and controls the base stream in the RAM 13, and the adjustment unit 36 performs adjustment processing such as adding identification information or related information to the base stream as necessary. Then, in step S47, the first transmission control unit 33 controls the communication unit 15 so as to transmit the base stream to the client device 2, and the processing of the flowchart of FIG. 6 is completed. As a result, the base stream is shared between the server device 1 and the client device 2.

The timing at which the first transmission control unit 33 transmits the base stream to the client device 2 may be, for example, the timing at which the storage control unit 32 notifies that a new base stream has been stored. Alternatively, it may be the timing when the output instruction of the base stream is supplied from the user or the system. Alternatively, it may be a predetermined timing or a timing at the time of a transmission request from the client device 2. The transmission speed of the base stream is arbitrary, and may be a low bit rate transmission speed depending on the communication line of the client device 2 or the like, or may be a high bit rate transmission speed in order to shorten the output time.

Next, the flowchart of FIG. 12 shows the flow of the operation of generating the difference bit stream based on the base stream and transmitting it to the client device 2. In step S51, the second buffer control unit 34 shown in FIG. 10 acquires an input picture to be encoded and buffers it in the RAM 13 or the like. In step S52, the picture storage control unit 51 cooperates with the determination unit 52 to determine whether or not a picture (base stream) to be referred to, which is related to the input picture, exists (whether or not it is stored in the RAM 13). ..

If there is a picture to be referenced (step S52: Yes), the second encoding unit 35 SHVC-encodes the picture to be referenced instead of the input picture to generate a base stream. On the other hand, when there is no picture to be referred to (step S52: No), the second encoding unit 35 SHVC-encodes the input picture and generates a base stream. The picture storage control unit 51 may cooperate with the determination unit 52 for determining the picture to be encoded, determine whether or not the input picture needs to be stored, and store the input picture in the RAM 13 or the like if necessary. ..

Next, in step S55, the adjustment unit 36 performs an adjustment process of adding the identification information or the related information of the reference base stream to the bitstream or the like generated by the SHVC encoding. In step S56, the storage control unit 32 determines whether or not to store the bitstream generated by SHVC encoding in the RAM 13. When storing (step S56: Yes), the storage control unit 32 stores the bitstream generated by the SHVC encoding process in the RAM 13 in step S57. At this time, the storage control unit 32 stores the newly generated bit stream in the RAM 13, or stores the bit stream stored in the RAM 13 in the form of updating with a new bit stream. Alternatively, the storage control unit 32 stores only the difference between the bit stream stored in the RAM 13 and the new bit stream. If such storage processing is not required (step S56: No), the processing proceeds to step S58.

In step S58, the second transmission control unit 37 controls the communication unit 15 so as to transmit a bit stream or the like to the client device 2, and ends the processing of the flowchart of FIG. Also in the case of the streaming system of the second embodiment, the base stream which is a reference picture is first transmitted to the client device 2, and then only the difference picture which is the difference from the base stream is transmitted to the client device 2. do. As a result, the same effect as that of the first embodiment described above can be obtained, such as the ability to reduce the bit rate and the effective use of the transmission band.

Also in the case of the second embodiment, the decoder 27 of the client device 2 originally planned to generate the bit by the encoder 17 using the base stream and the received input picture stored in advance. Reconstruct a bitstream equivalent to the stream (same image quality, same resolution). Then, the decoder 27 reproduces and displays the reconstructed stream.

Although embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention as well as the invention described in the claims and the equivalent scope thereof.

1 Server device 2 Client device 3 Network 11 CPU
12 ROM
13 RAM
14 HDD
15 Communication unit 17 Encoder 21 CPU
22 ROM
23 RAM
24 HDD
25 Communication unit 27 Decoder 31 Preprocessing unit 32 Storage control unit 33 First transmission control unit 34 Second buffer control unit 35 Second encoding unit 36 Coordination unit 37 Second transmission control unit 39 Encoding unit 38 First Buffer control unit 41 Adjustment processing unit 42 Decoding processing unit 43 First reception control unit 44 Storage control unit 45 Second reception control unit 46 Configuration adjustment unit 47 Decoding unit 48 Buffer control unit 51 Picture storage control unit 52 Judgment unit

Claims (9)

A streaming system equipped with an encoding device and a decoding device.
The encoding device is
A difference generator that generates a difference bit stream, which is the difference between the base stream and the input image shared in advance with the decoding device, and
It has a communication control unit that controls the communication unit so that the difference bit stream generated by the difference generation unit is transmitted to the decoding device.
The decoding device is
A configuration adjustment unit that reconstructs a bitstream equivalent to the bitstream that was planned to be generated by the encoding device by using the base stream and the difference bitstream that are shared in advance with the encoding device. ,
It has a decoding unit that executes a decoding process corresponding to the encoding process applied to the reconstructed bit stream.
The base stream is shared at the factory of the decoding device or at the time of setting up the decoding device.
Streaming system. The encoding device is
The streaming system according to claim 1, further comprising an adjusting unit for adding identification information to the base stream and adding identification information of the base stream to be referred to to the difference bit stream. The communication control unit determines whether or not the base stream needs to be transmitted to the decoding device, and if it determines that transmission of the base stream to the decoding device is unnecessary, the base stream is transmitted to the decoding device. The first or second aspect of the present invention, wherein the communication unit is controlled to transmit the base stream to the decoding device when it is determined that the base stream needs to be transmitted to the decoding device. Streaming system. The communication control unit is notified of the generation of a new base stream, the timing of acquiring the output instruction of the base stream, the predetermined timing, or the transmission request of the base stream from the decoding device. The streaming system according to any one of claims 1 to 3, which controls the communication unit so as to transmit the base stream at the timing of acquiring the above. The streaming system according to any one of claims 1 to 4, wherein the base stream is an entire or a part of an encoded bitstream. The streaming system according to any one of claims 1 to 5, wherein the base stream is a still image. The streaming system according to any one of claims 1 to 6, wherein the base stream is a base stream of an intra-picture network abstraction layer unit. The streaming system according to any one of claims 1 to 7, wherein the difference bit stream is a difference bit stream including an interpicture network abstraction layer unit. Computer,
A difference generator that generates a difference bitstream, which is the difference between the base stream and the input image that are shared in advance with the decoding device.
The difference bit stream generated by the difference generation unit is made to function as a communication control unit that controls the communication unit so as to transmit the difference bit stream to the decoding device.
The base stream is shared at the factory of the decoding device or at the time of setting up the decoding device.
Encoding program.

Images