KR20140140364A - Apparatus and method for providing contents - Google Patents

Abstract

A content providing apparatus and a method therefor are disclosed. The content providing apparatus according to an embodiment of the present invention comprises: an end-to-end situation determining unit which calculates an available bitrate according to a network state of a client requesting content; a content determining unit which calculates encoding parameters for respective frames of the content within the available bitrate based on characteristic information of the content; and an encoding unit which encodes the content according to the calculated encoding parameters.

Description

[0001] APPARATUS AND METHOD FOR PROVIDING CONTENTS [0002]

Embodiments of the present invention relate to techniques for streaming content over a network.

In recent years, streaming of contents through networks, especially video contents, has become common, and related technologies are also being studied from various viewpoints. In the case of the initial content streaming, the previously stored data was simply transmitted in real time without regard to the network situation. However, since the mobile ecosystem is formed and the streaming service area is expanded with various contents, There is an increasing need to provide streaming services that can be reflected.

However, in the conventional streaming service, the pre-encoded content is transmitted at a specific bit rate in accordance with the available bandwidth of the network, or the same encoding parameters are uniformly applied to all contents and divided according to the available bandwidth, However, there is a limitation in providing optimal streaming contents according to various contents and terminal environments.

The embodiments of the present invention are intended to derive optimal encoding parameters considering the type of content, the network status, and the terminal environment in a comprehensive manner.

According to an aspect of the present invention, there is provided a content providing apparatus including an end status determination unit for calculating an available bit rate according to a network status of a client requesting a content, A content determination unit for calculating a frame-by-frame encoding parameter of the content, and an encoding unit for encoding the content according to the calculated encoding parameter.

The end-to-end situation determination unit may calculate the available bit rate according to an available bandwidth of the client derived from the network state.

The end-to-end situation determination unit may set an initial bit rate according to a type of a network to which the client is connected.

The end-to-end situation determination unit may correct the available bit rate according to a round trip time between the apparatus and the client and a buffer overflow / underflow prediction time of the client.

Wherein the end-to-end situation determination unit compares the received buffer underflow prediction time with the size of the round trip time when the buffer underflow prediction time is received from the client, and if the buffer underflow prediction time exceeds the round trip time The available bit rate can be reduced by a predetermined ratio.

Wherein the end-to-end situation determination unit compares the received buffer overflow prediction time with the size of the round trip time when the buffer overflow prediction time is received from the client, and if the buffer overflow prediction time exceeds the round trip time The available bit rate can be increased by a predetermined ratio.

The feature information of the content may be any one of screen complexity, kind, category, or user preference of the content.

The content determining unit may calculate an encoding parameter of the current encoding target frame using the screen complexity of the immediately preceding frame of the current encoding target frame of the content.

The encoding parameter may include a Quantization Parameter (QP) and a Frames Per Second (FPS).

Wherein the content determining unit selects one encoding parameter table corresponding to the screen complexity of the immediately preceding frame from among a plurality of encoding parameter tables and selects one of the encoding parameters recorded in the selected encoding parameter table based on the available bit rate Encoding parameters can be selected.

The content determination unit may update the selected encoding parameter table using the actual bit rate of the encoded frame according to the selected encoding parameter.

Wherein the content judging unit judges whether or not at least one of a quantization parameter of the current encoding target frame or the number of frames per second if the calculated screen complexity of each of the N (N is a natural number of 1 or more) frames before the current encoding target frame exceeds a preset threshold Can be corrected.

The content determining unit may correct one or more of the quantization parameter or the number of frames per second so that the number of frames per second is increased within the available bit rate range.

Meanwhile, the content providing method in the content providing apparatus according to an embodiment of the present invention may include the steps of: calculating an available bit rate according to a network status of a client requesting a content in the terminal status determination unit, Calculating a frame-by-frame encoding parameter of the content within the available bit rate based on feature information of the content, and encoding the content in accordance with the calculated encoding parameter in the encoding section do.

The calculating the available bit rate may calculate the available bit rate according to an available bandwidth of the client derived from the network state.

The calculating of the available bit rate may further include setting an initial bit rate according to a type of a network to which the client is connected.

The calculating of the available bit rate may further include correcting the available bit rate according to a round trip time between the apparatus and the client and a buffer overflow / underflow prediction time of the client.

Wherein the step of correcting the available bit rate comprises the steps of: comparing a buffer underflow predicted time received with a size of the round trip time when the buffer underflow predicted time is received from the client; And may reduce the available bit rate by a predetermined ratio when the round trip time is smaller than the round trip time.

Wherein the step of correcting the available bit rate comprises the steps of: comparing the buffer overflow prediction time received and the size of the round trip time when the buffer overflow prediction time is received from the client; And to increase the available bit rate by a predetermined ratio when the round trip time is smaller than the round trip time.

The feature information of the content may be any one of screen complexity, kind, category, or user preference of the content.

The calculating of the encoding parameter may calculate an encoding parameter of the current encoding target frame using the screen complexity of the immediately preceding frame of the current encoding target frame of the content.

The encoding parameter may include a Quantization Parameter (QP) and a Frames Per Second (FPS).

Wherein the step of calculating the encoding parameter comprises the steps of: selecting one of the plurality of encoding parameter tables corresponding to the screen complexity of the immediately preceding frame; and recording And selecting an encoding parameter of one of the encoded parameters.

The step of calculating the encoding parameter may further comprise updating the selected encoding parameter table using the actual bit rate of the encoded frame according to the selected encoding parameter.

Wherein when the calculated screen complexity of each of the N (N is a natural number of 1 or more) frames before the current encoding target frame exceeds a preset threshold value, the calculating of the encoding parameter includes: And correcting at least one of the quantization parameter of the target frame or the number of frames per second.

The correcting step may correct at least one of the quantization parameter or the number of frames per second so that the number of frames per second is increased within the available bit rate range.

According to the embodiments of the present invention, optimal encoding parameters are derived taking into consideration the characteristics of the content itself, the network conditions between the server and the terminal, and the processing environment of the terminal, and by encoding the content, It is possible to provide an optimal content suitable for the user.

According to the embodiments of the present invention, there is an advantage that the encoding parameter can be adaptively changed according to the environment change occurring during the streaming of the content, thereby actively coping with the environment change.

1 is a block diagram illustrating a configuration of a content providing system 100 according to an embodiment of the present invention.
2 is a block diagram showing a detailed configuration of a content providing server 102 according to an embodiment of the present invention.
3 is a block diagram showing a detailed configuration of a client 104 according to an embodiment of the present invention.
4 is a flowchart illustrating a content encoding method 400 in a content providing server 102 according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating an encoding parameter setting process 410 of the content encoding method 400 shown in FIG.
6 is an exemplary diagram illustrating an encoding database according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, this is merely an example and the present invention is not limited thereto.

In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intention or custom of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

The technical idea of the present invention is determined by the claims, and the following embodiments are merely a means for effectively explaining the technical idea of the present invention to a person having ordinary skill in the art to which the present invention belongs.

1 is a block diagram illustrating a configuration of a content providing system 100 according to an embodiment of the present invention. As shown, a content providing system 100 according to an embodiment of the present invention includes a content providing server 102 and a client 104. [

The content providing server 102 receives a content provision request from the client 104, encodes the content in real time according to the content provision request, and provides the content to the client 104. [ In embodiments of the present invention, the content providing server 102 may change the encoding parameters for encoding the content according to the network status of the client 104 requesting the content, the buffer status on the client 104 side, . At this time, the adjustment of the encoding parameters may be performed in every frame, GOP (Group of Pictures), or a predetermined frame interval unit constituting the content.

The client 104 requests the content providing server 102 to provide the content, decodes the content to be streamed from the content providing server 102, and provides the decoded content to the user. The client 104 also provides the content providing server 102 with information necessary for adjusting the encoding parameters on the content providing server 102 side. The information provided at this time may include, for example, information related to the network to which the client 104 is connected, and information related to the buffer status in the client 104, and the like.

Meanwhile, the content providing server 102 and the client 104 are connected to each other via the network 106 to transmit and receive messages to each other. In the embodiments of the present invention, the network 106 refers to a device or a group of devices for mediating transmission and reception of packet data between terminals, and may be a mobile communication network such as an LTE network, a 3G network, a GSM network, And may include any type of communication network commonly used in the art.

2 is a block diagram showing a detailed configuration of a content providing server 102 according to an embodiment of the present invention. As shown in the figure, the content providing server 102 according to an embodiment of the present invention includes a message transmission / reception unit 200, a network measurement unit 202, an end status determination unit 204, a content determination unit 206, And an encoding unit 208.

The message transmission / reception unit 200 transmits / receives a message to / from the client 104 via the network 106. For example, the message transmission / reception unit 200 may receive a content provision request from the client 104, and may transmit the encoded content to the client 104 according to the content provision request. In addition, the message transmission / reception unit 200 may receive information related to the network status or the buffer status of the client 104 and may provide the network measurement unit 202 or the end status determination unit 204 to be described later. For this, the message transmission / reception unit 200 may be configured to include appropriate hardware and software for transmitting and receiving packet data on the network 106. [

The network measurement unit 202 measures the network status of the client 104 requesting the content and calculates the available bandwidth of the client 104 from it. The network status refers to information such as jitter, delay, packet loss rate, RTT (Round Trip Time) of the network 104 to which the client 104 is connected, or the buffer status of the client 104.

The network measuring unit 202 can measure the network status through communication with the client 104. [ For example, in the case of the RTT, it can be measured by sending a probe packet to the client 104 and calculating the time difference of the response packet for the probe packet. However, the embodiments of the present invention are not limited to a specific network state measurement method, and various methods known in the art can be used for measuring network state as needed. For example, in the case of the RTT described above, a passive method using time information of previously transmitted packets can also be used in addition to the active method using a probe packet. Other network state information other than RTT can also be measured by applying various methods known in the art.

In addition, the available bandwidth in the embodiment of the present invention may be defined as a value indicating a network capacity available in the network 106 to which the client 104 is connected, such as available bandwidth or Achievable Throughput.

Next, the end-to-end situation determination unit 204 calculates an available bit rate for content encoding using the network state and the available bandwidth calculated by the network measurement unit 202. [ The end-to-end situation determination unit 204 can calculate the available bit rate according to the available bandwidth of the client 104 derived from the network state measured by the network measurement unit 202. [ The end-to-end situation determination unit 204 may allocate the bit rate as much as the specific bit rate of the calculated available bandwidth at the available bit rate. For example, in the case where 80% of the available bandwidth is allocated at the available bit rate by the end-to-end situation determination unit 204, if the currently calculated available bandwidth is 1 Mbps, the available bit rate becomes 800 Kbps.

On the other hand, when the network measuring unit 202 is configured to measure the RTT in an active manner, it is impossible to calculate the RTT and the available bandwidth calculated therefrom before receiving the response to the probe packet from the client 104 . Therefore, in this case, the end-to-end situation determination unit 204 may be configured to set an initial value (initial bit rate) of the available bit rate to a preset value. The initial bit rate may be set in advance according to the type of network (3G, WiFi, LTE, etc.) to which the client 104 is connected. For example, when the client 104 requests content through the LTE network, the end-to-end situation determination unit 204 may set an initial bit rate setting value corresponding to the LTE network to an available bit rate of the corresponding client 104 have.

In addition, the end-to-end situation determination unit 204 determines whether or not the availability (calculated) based on the round trip time (RTT) calculated by the network measurement unit 202 and the buffer overflow / underflow prediction time The bit rate can be corrected. At this time, the buffer overflow / underflow prediction time (TTE) predicts the time required for the client 104 buffer to overflow or completely underflow, And is transmitted to the content providing server 102. A specific calculation method of the TTE will be described later.

When the TTE value is received from the client 104, the end-to-end situation determination unit 204 compares the TTE value with the RTT value and corrects the available bit rate. Specifically, when the buffer underflow prediction time is received from the client 104, the end-to-end situation determination unit 204 compares the received buffer underflow prediction time with the size of the round trip time, If the underflow prediction time is smaller than the round trip time, the available bit rate can be reduced by a predetermined ratio. The pseudo code is expressed as follows.

if (RTT> TTE)

Bitrate = a * V _o

else

Bitrate = no Change

In the pseudo code, V _o means a preset bit rate. Also, the bit rate reduction ratio a in the pseudo code can be appropriately set in consideration of characteristics of the network among real numbers greater than 0 and smaller than 1.

On the other hand, when the buffer overflow prediction time is received from the client 104, the end state determination unit 204 compares the received buffer overflow prediction time with the size of the round trip time, If the flow prediction time is shorter than the round trip time, the available bit rate is increased by a predetermined ratio. This is expressed in pseudo code as follows. The bit rate increase rate b in the following pseudo code can be set appropriately in consideration of the characteristics of the network and the like among real numbers greater than one.

if (RTT> TTE)

Bitrate = b * V _o

else

Bitrate = no Change

The content deciding unit 206 decodes the contents of the content by frame within the available bit rate using the feature information of the content requested from the client 104 and the available bit rate calculated by the end stage status deciding unit 204 And calculates an encoding parameter (Encoding Parameter).

In the embodiments of the present invention, the feature information of the content is information indicating the characteristics of each frame constituting the content, and may be, for example, a screen complexity (TEX; TExture compleXity) of each frame. For example, the presentation complexity of a video is relatively low compared to an action movie. Accordingly, in the case of an image having a low screen complexity such as a presentation, instead of lowering the frames per second (FPS), a quantization parameter (QP) is assigned to a lower value, In the case of an action movie or the like, it is possible to provide a smooth image by setting the number of frames per second to be high instead of increasing the quantization parameter. That is, the content deciding unit 206 adjusts the FPS and the QP according to the screen complexity of the video in the video having the same data amount (bit rate) Can be provided.

For reference, the quantization parameter in the image encoding technique can be defined in various forms, but in the embodiment of the present invention, it is defined that the lower the quantization parameter, the higher the image quality of the image. In the following description, the feature information of the content refers to the screen complexity of each frame constituting the content. However, this is merely an example, and in the embodiment of the present invention, (Movie, documentary, animation, etc.), category, or user preference. For example, when the user preference is set as the feature information of the content, the content determination unit 206 may adjust the encoding parameter so that the image quality of the user with the highest preference is higher. In addition, various methods are well known in the art for calculating the screen complexity (TEX) of the image, and the detailed description thereof is beyond the scope of the present invention, and a description thereof will be omitted here.

As described above, the encoding parameter may be configured to include a quantization parameter (QP) and a frames per second (FPS) of a frame. A specific encoding parameter adjustment method of the content determination unit 206 will be described later.

The encoding unit 208 encodes the content according to the encoding parameter calculated by the content deciding unit 206. [ The encoded content in the encoding unit 208 is transmitted to the client 104 via the message transmission / reception unit 200.

3 is a block diagram showing a detailed configuration of a client 104 according to an embodiment of the present invention. The client 104 according to an embodiment of the present invention includes a message transmission / reception unit 300, an RTT calculation unit 302, a buffer status determination unit 304, and a decoding unit 306.

The message transmission / reception unit 300 transmits / receives a message to / from the content providing server 102 via the network 106. For example, the message transmitting / receiving unit 300 may transmit the content providing request to the content providing server 102 and receive the encoded content from the content providing server 102. As with the content providing server 102, the message transmitting / receiving unit 300 can be configured to include appropriate hardware and software for transmitting and receiving packet data on the network 106. [

The RTT calculation unit 302 is a module for calculating the RTT through communication with the network measurement unit 202 of the content providing server 102. For example, when a probe packet is received from the network measurement unit 202 through the message transmission / reception unit 300, the RTT calculation unit 302 generates a response message for the probe packet and transmits the response message to the network measurement unit 202, Lt; / RTI > Also, when the system 100 uses the RTT calculation method that does not use the probe packet according to the embodiment, the RTT calculation unit 302 adds time stamp information to the packet transmitted to the content providing server 102 To the content providing server 102. The details related to the calculation of the RTT on the network are well known in the technical field of the present invention, and a detailed description thereof will be omitted.

The buffer state determination unit 304 grasps the buffer state of the decoding unit 306 to be described later and generates a message related to the buffer state and transmits the message to the contents providing server 102. In the embodiment of the present invention, the decoding unit 306 temporarily stores the data stream transmitted from the content providing server 102 in a buffer, and sequentially decodes the data stream. At this time, if the amount of the received data stream is larger than the decoding speed of the decoding unit 306, the amount of data stored in the buffer gradually increases, causing a buffer overflow exceeding the allowable capacity of the buffer When the amount of data to be received is smaller than the decoding speed, the amount of data stored in the buffer gradually decreases to cause a buffer underflow in which the buffer becomes completely empty. In order to prevent the buffer overflow or the buffer underflow, the buffer status determiner 304 monitors the status of the buffer and notifies the content providing server 102 of the data stored in the buffer when the data is out of the preset normal range The content providing server 102 can appropriately adjust the bit rate of the content (data stream) to be transmitted.

Specifically, the buffer state determiner 304 periodically measures the buffer state of the decoding unit 306, calculates a buffer underflow or a buffer overflow prediction time according to the measured state, and transmits the calculated prediction time to a message transmission / To the contents providing server 102 via the Internet. This will be described in more detail as follows.

First, the buffer state determination unit 304 divides the buffer state into a plurality of levels according to the amount of data stored in the buffer. For example, the buffer status determiner 304 can distinguish the status of the buffer by the following five levels.

buffer none: Data amount 0 to 20%

buffer shortfall: data amount 21 ~ 40%

buffer stability: data amount 41 ~ 60%

buffer exceed: Data amount 61 ~ 80%

buffer overflow: data amount 81 to 100%

If the state of the buffer goes beyond the buffer stability and enters the buffer shortfall, the buffer state determination unit 304 calculates the predicted time until the occurrence of the buffer underflow and sends an alarm including the calculated prediction time to the content providing server 102 Lt; / RTI > Accordingly, the content providing server 102 increases the bit rate of data transmitted through the above-described algorithm to prevent the occurrence of a buffer underflow. At this time, the buffer underflow prediction time can be derived from the data reduction rate per time in the buffer. The alarm continues until the amount of data in the buffer reaches buffer stability.

On the contrary, when the buffer state goes beyond the buffer stability and enters the buffer exceed state, the buffer state determination unit 304 calculates the predicted time until the occurrence of the buffer overflow and sends an alarm including the calculated predicted time to the content providing server 102 ). Accordingly, the content providing server 102 reduces the bit rate of data transmitted through the above-described algorithm, thereby preventing a buffer overflow from occurring. The alarm continues until the amount of data in the buffer reaches buffer stability.

On the other hand, when the state of the buffer maintains the buffer stability, the buffer state determiner 304 does not perform the bit rate adjustment.

The decoding unit 306 stores data received from the message transmission / reception unit 300 in a buffer, sequentially decodes the data, and outputs the decoded data to a user. The detailed configuration of the decoding unit 306 is well known in the technical field of the present invention, and a detailed description thereof will be omitted.

4 is a flowchart illustrating a content encoding method 400 in a content providing server 102 according to an embodiment of the present invention.

First, when a content provision request is received from the client 104 through the message transmission / reception unit 200 (402), the end-to-end situation determination unit 204 sets an initial bit rate for encoding the requested content (404) . As described above, the initial bit rate may be set according to the type of the network to which the client 104 is connected.

Next, the network measuring unit 202 calculates the network status and the available bandwidth of the client 104 (406), and the end-to-end situation determination unit 204 calculates the available bit rate using the available bandwidth (408 ). Then, the content deciding unit 206 sets (410) an encoding parameter for each frame of the content using the feature information of the requested content and the available bit rate, and the encoding unit 208 encodes the content And provides it to the client 104 (412). The process is repeatedly performed at a designated frame interval, a GOP unit, or an arbitrary frame unit until the encoding of the content is completed (414). That is, according to the embodiments of the present invention, the encoding factors are continuously corrected in units of a designated frame or a GOP unit in consideration of the network status, the characteristics of the content, and the buffer status on the client side, There is an advantage that encoding can be performed.

FIG. 5 is a flowchart illustrating an encoding parameter setting process 410 of the content encoding method 400 shown in FIG. In the embodiment of the present invention, the optimum encoding parameter setting algorithm in the content determining unit 206 is configured to set an optimal encoding parameter in consideration of the characteristics of a frame to be encoded within the calculated bit rate range. The encoding parameters to be controlled include QP (Quantization Parameters) and FPS (Frame Per Sec) as described above. As the QP increases, the quality of the video decreases. On the other hand, as the FPS increases, the softness of the screen increases. In the encoding parameter setting algorithm according to the embodiment of the present invention, it is assumed that the complexity of the current screen does not greatly differ from that of the immediately preceding screen. It also includes a premise that the encoding setting value in the content determination unit 206 is immediately applied to the current video encoding result in real time.

First, when the available bit rate information calculated from the end-to-end situation determination unit 204 is received (502), the content determination unit 206 determines whether or not an encoding database (DB) corresponding to the content exists (504). If not, a new database is created (506).

One embodiment of the encoding database is shown in FIG. As shown in FIG. 6, the encoding database is divided into a plurality of stages according to a screen complexity (TEX) of each frame of an image. In the illustrated embodiment, the screen complexity of an image is divided into five steps of 0 to 5,000 / 5,001 to 10,000 / 10,001 to 100,000 / 100,000 to 200,000 / 200,000, but the number of steps and ranges of the steps may be different have.

Also, as shown in the figure, the encoding database includes an encoding parameter table for each step. The quantization parameter (QP) is located on the horizontal axis of the encoding parameter table, and the frame rate (FPS) is located on the vertical axis. The actual bit rate of the frame encoded according to the QP and FPS is stored in each cell in the table. In one embodiment, the values of the QPs constituting the table are 11 (1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50) (6, 10, 15, 18, 24 and 30), but these are merely illustrative and each of the above steps may be appropriately set as necessary. Also, in the illustrated embodiment, the encoding database is classified according to the complexity of the screen. However, it is also possible to classify the encoding database according to various criteria such as the type of content, category information, and user's preference as described above. The setting value of the encoding database configured in this way can be applied to a video encoding of the same resolution thereafter. Also, when the content deciding unit 206 generates a new encoding database, each cell value of each generated encoding parameter table may be empty or a preset default value may be recorded.

Next, the content deciding unit 206 searches the encoding database to determine whether the current encoding target frame of the content requested by the client 104 is an optimal encoding The parameters are searched (508, 510, 512). As described above, in the embodiment of the present invention, it is assumed that the screen complexity of the current frame to be encoded is similar to the screen complexity of the immediately preceding frame. Accordingly, the content determining unit 206 calculates the encoding parameter of the current encoding target frame using the screen complexity of the immediately preceding frame of the current encoding target frame. For example, in the embodiment shown in FIG. 6, if the screen complexity (TEX) of the immediately preceding frame is 8000 and the available bit rate is 700 Kbps, the content determination unit 206 determines that the screen complexity range is 5,000 to 10,000 The optimal QP and FPS values are searched within the available bit rate by referring to the parameter table. In the illustrated embodiment, the largest value of the values stored in the table does not exceed 700 Kbps is 695 Kbps and the QP / FPS pair corresponding to the bit rate is 35/24. Therefore, the content determination unit 206 determines the derived QP / The encoding of the current encoding target frame is set as a parameter (512).

The content determination unit 206 may be configured to set the search range of the encoding parameter based on the available bit rate within a range not exceeding a predetermined available bit rate and to search the encoding parameter table within the set range. For example, when the available bit rate is 700 Kbps, the content determination unit 206 can search the encoding parameter table within the range of 600 to 700 Kbps. In this case, if the data in the corresponding range does not exist in the table, the content deciding unit 206 may calculate an approximate value by referring to other values in the table or generate an encoding parameter by applying a predetermined reference value (510 ).

If an encoding parameter is selected from the encoding parameter table or a new encoding parameter is generated through the above process, then the content deciding unit 206 determines whether correction is required for the derived encoding parameter (514). For example, when the number N of frames (N is a natural number equal to or greater than 1) consecutive frames having a screen complexity exceeding a predetermined threshold is consecutively present, the content deciding section 206 decides the current One or more of the quantization parameters of the encoding target frame or the number of frames per second may be corrected.

For example, when a frame having a very large screen complexity such as a violent action scene is continuous, the content decider 206 may determine that the frame rate is one or more of the quantization parameter or the number of frames per second (514, 516). In this way, the image can be smoothed more smoothly. For example, the content deciding unit 206 may increase QP and FPS by 1 when frames with a screen complexity equal to or higher than a predetermined number are consecutive by a sudden change of screen. The dynamic change of these encoding parameters is performed until the screen complexity no longer exceeds the threshold. That is, when a screen having a screen complexity less than or equal to a threshold appears, the content determination unit 206 applies the encoding parameters derived from the encoding parameter table without correcting the encoding parameters.

When the encoding parameters are finally determined through the above process, the content deciding unit 206 provides the determined encoding parameters to the encoding unit 208 (518). In addition, the content determination unit 206 updates the selected encoding parameter table using the actual bit rate of the encoded frame according to the encoding parameter of the encoding unit 208 (520). In the above-described embodiment, when the encoding is performed by applying QP / FPS to 35 and 24, respectively, it is assumed that the actual bit rate of the encoded frame is 694 Kbps. In this case, the content determination unit 206 updates the corresponding cell value (695 Kbps) of the encoding parameter table using the actual bit rate value. For example, the content deciding unit 206 may replace the previously stored value in the encoding parameter table with the newly stored value, or may calculate the average value of the two values and update the value with the value of the corresponding cell.

On the other hand, an embodiment of the present invention may include a computer-readable recording medium including a program for performing the methods described herein on a computer. The computer-readable recording medium may include a program command, a local data file, a local data structure, or the like, alone or in combination. The media may be those specially designed and constructed for the present invention or may be known and available to those of ordinary skill in the computer software arts. Examples of computer readable media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floppy disks, and magnetic media such as ROMs, And hardware devices specifically configured to store and execute program instructions. Examples of program instructions may include machine language code such as those generated by a compiler, as well as high-level language code that may be executed by a computer using an interpreter or the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. I will understand.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by equivalents to the appended claims, as well as the appended claims.

100: Content providing system
102: Content providing server
104: Client
106: Network
200: message transmission /
202: Network measurement unit
204:
206:
208:
300: a message transmission /
302: RTT calculation unit
304: Buffer status determination unit
306:

Claims (26)

An end-to-end situation determination unit for calculating an available bit rate according to a network status of a client requesting a content;
A content determination unit for calculating a frame-by-frame encoding parameter of the content within the available bit rate based on the feature information of the content; And
And an encoding unit for encoding the content according to the calculated encoding parameter.
The method according to claim 1,
Wherein the end-to-end situation determination unit calculates the available bit rate according to an available bandwidth of the client derived from the network state.
The method of claim 2,
Wherein the end-to-end situation determination unit sets an initial bit rate according to a type of a network to which the client is connected.
The method of claim 2,
Wherein the end-to-end situation determination unit corrects the available bit rate according to a round trip time between the apparatus and the client and a buffer overflow / underflow prediction time of the client.
The method of claim 4,
Wherein the end-to-end situation determination unit compares the received buffer underflow prediction time with the size of the round trip time when the buffer underflow prediction time is received from the client, and if the buffer underflow prediction time exceeds the round trip time The available bit rate is decreased by a predetermined ratio.
The method of claim 4,
Wherein the end-to-end situation determination unit compares the received buffer overflow prediction time with the size of the round trip time when the buffer overflow prediction time is received from the client, and if the buffer overflow prediction time exceeds the round trip time The available bit rate is increased by a predetermined ratio.
The method according to claim 1,
Wherein the feature information of the content is any of a screen complexity, a type, a category, or a user preference of the content.
The method of claim 7,
Wherein the content determination unit calculates the encoding parameter of the current encoding target frame using the screen complexity of the immediately preceding frame of the current encoding target frame of the content.
The method of claim 8,
Wherein the encoding parameter comprises a quantization parameter (QP) and a frames per second (FPS).
The method of claim 9,
Wherein the content determining unit selects one encoding parameter table corresponding to screen complexity of the immediately preceding frame from a plurality of encoding parameter tables,
And selects one of the encoding parameters recorded in the selected encoding parameter table based on the available bit rate.
The method of claim 10,
Wherein the content determination unit updates the selected encoding parameter table using the actual bit rate of the encoded frame according to the selected encoding parameter.
The method of claim 9,
Wherein the content judging unit judges whether or not at least one of a quantization parameter of the current encoding target frame or the number of frames per second if the calculated screen complexity of each of the N (N is a natural number of 1 or more) frames before the current encoding target frame exceeds a preset threshold Is corrected.
The method of claim 12,
Wherein the content determination unit corrects at least one of the quantization parameter or the number of frames per second such that the number of frames per second is increased within the available bit rate range.
A content providing method in a content providing apparatus,
Calculating an available bit rate according to a network status of a client requesting a content, in an end-to-end situation determination unit;
Calculating a frame-by-frame encoding parameter of the content within the available bit rate, based on the feature information of the content; And
And in the encoding unit, encoding the content according to the calculated encoding parameter.
15. The method of claim 14,
Wherein calculating the available bit rate comprises:
And calculates the available bit rate according to an available bandwidth of the client derived from the network state.
16. The method of claim 15,
Wherein calculating the available bit rate comprises:
Further comprising setting an initial bit rate according to a type of a network to which the client is connected.
16. The method of claim 15,
Wherein calculating the available bit rate further comprises correcting the available bit rate according to a round trip time between the device and the client and a buffer overflow / underflow prediction time of the client.
18. The method of claim 17,
Wherein the step of correcting the available bit rate comprises the steps of: comparing a buffer underflow predicted time received with a size of the round trip time when the buffer underflow predicted time is received from the client; And to decrease the available bit rate by a predetermined ratio when the round trip time is smaller than the round trip time.
18. The method of claim 17,
Wherein the step of correcting the available bit rate comprises the steps of: comparing the buffer overflow prediction time received and the size of the round trip time when the buffer overflow prediction time is received from the client; And if the round trip time is smaller than the round trip time, increase the available bit rate by a predetermined ratio.
15. The method of claim 14,
Wherein the feature information of the content is one of a screen complexity, a kind, a category, and a user preference of the content.
The method of claim 20,
Wherein the step of calculating the encoding parameter calculates the encoding parameter of the current encoding target frame using the screen complexity of the immediately preceding frame of the current encoding target frame of the content.
23. The method of claim 21,
Wherein the encoding parameter comprises a quantization parameter (QP) and a frames per second (FPS).
23. The method of claim 22,
Wherein the step of calculating the encoding parameter comprises:
Selecting one encoding parameter table corresponding to a screen complexity of the immediately preceding frame from among a plurality of encoding parameter tables; And
And selecting one of the encoding parameters recorded in the selected encoding parameter table based on the available bit rate.
24. The method of claim 23,
Wherein the step of calculating the encoding parameter comprises:
Further comprising updating the selected encoding parameter table using the actual bit rate of the encoded frame according to the selected encoding parameter.
23. The method of claim 22,
Wherein the step of calculating the encoding parameter comprises:
Wherein when the calculated screen complexity of each of the N frames before the current encoding target frame (N is a natural number of 1 or more) exceeds a preset threshold value, the quantization parameter of the current encoding target frame or the number of frames per second ≪ / RTI > further comprising the step of calibrating at least one of:
26. The method of claim 25,
Wherein the correcting step corrects at least one of the quantization parameter or the number of frames per second so that the number of frames per second is increased within the available bit rate range.

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