Method, system, and non-transitory computer readable record medium for video quality control

1. A video quality control method comprising:

receiving a video stream including frames that are classified into a plurality of frame types based on a reference relationship between the frames with regard to decoding, wherein the plurality of frame types comprises a first frame type indicating that a corresponding frame is independently decoded without referring to other frames, a second frame type indicating that the corresponding frame is decoded with reference to a preceding frame, and a third frame type indicating that the corresponding frame is decoded with reference to the preceding frame and a subsequent frame;

selecting at least one frame type among the plurality of frame types; and

controlling a quality of the video stream by multiplexing the frames included in the video stream with a first quality and outputting the frames of the first frame type, the second frame type, and the third frame type through a first channel, by multiplexing the frames included in the video stream with a second quality and outputting the frames of the first frame type and the second frame type through a second channel; and by multiplexing the frames included in the video stream with a third quality and outputting the frames of the first frame type through a third channel.

2. A non-transitory computer-readable record medium storing computer instructions that, when executed by a processor, cause the processor to perform the video quality control method of claim 1 .

3. A video quality control method performed by a server, the video quality control method comprising:

receiving a video stream including frames that are classified into a first frame type indicating that a corresponding frame is independently decoded without referring to other frames, a second frame type indicating that the corresponding frame is decoded with reference to a preceding frame, and a third frame type indicating that the corresponding frame is decoded with reference to the preceding frame and a subsequent frame;

multiplexing the frames in at least two methods among a first method, a second method, and a third method, to:

obtain a first multiplexed stream comprising the frames of the first frame type, the second frame type, and the third frame type, in the first method,

obtain a second multiplexed stream comprising the frames of the first frame type and the second frame type without the frames of the third frame type, in the second method, and

obtain a third multiplexed stream comprising the frames of the first frame type, without the frames of the second frame type and the third frame type, in the third method; and

outputting at least two multiplexed streams in at least two different channels in parallel, among the first multiplexed stream, the second multiplexed stream, and the third multiplexed stream that correspond to the at least two methods among the first method, the second method, and the third method.

4. The video quality control method of claim 3 , wherein each of the first multiplexed stream, the second multiplexed stream, and the third multiplexed stream starts with one of the frames of the first frame type.

5. The video quality control method of claim 1 , wherein the receiving of the video stream comprises receiving the frames of the video stream that are encoded at a terminal of a sender and transmitted over a network, and

the quality control method further comprises relaying the video stream of which the quality is controlled by transmitting the one or more of the frames having the selected at least one frame type through a channel accessible by a terminal of a viewer.

6. The video quality control method of claim 5 , further comprising transmitting the one or more of the frames having the selected at least one frame type to a monitoring terminal for monitoring or inspecting the video stream.

7. A computer apparatus comprising:

at least one processor configured to execute computer-readable instructions,

wherein the at least one processor is configured to:

receive a video stream including frames that are classified into a plurality of frame types based on a reference relationship between the frames with regard to decoding, wherein the plurality of frame types comprises a first frame type indicating that a corresponding frame is independently decoded without referring to other frames, a second frame type indicating that the corresponding frame is decoded with reference to a preceding frame, and a third frame type indicating that the corresponding frame is decoded with reference to the preceding frame and a subsequent frame,

select at least one frame type among the plurality of frame types; and

control a quality of the video stream by multiplexing the frames included in the video stream with a first quality and outputting the frames of the first frame type, the second frame type, and the third frame type through a first channel, by multiplexing the frames included in the video stream with a second quality and outputting the frames of the first frame type and the second frame type through a second channel; and by multiplexing the frames included in the video stream with a third quality and outputting the frames of the first frame type through a third channel.

8. The computer apparatus of claim 7 , wherein the at least one processor is further configured to

receive the frames of the video stream that are encoded at a terminal of a sender and transmitted over a network, and

relay the video stream of which the quality is controlled by transmitting the one or more of the frames having the selected at least one frame type being through a channel accessible by a terminal of a viewer.

9. The computer apparatus of claim 8 , wherein the at least one processor is further configured to transmit the one or more of the frames having the selected at least one frame type to a monitoring terminal for monitoring or inspecting the video stream.

10. The computer apparatus of claim 7 , wherein the computer apparatus is included in a server for providing a video to a client device,

wherein the first frame type, the second frame type, and the third frame type correspond to an intra frame (I-frame) type, a predictive frame (P-frame) type, and a bidirectional predictive frame (B-frame) type, respectively,

wherein the at least one processor is configured to execute the computer-readable instructions to:

select the at least one frame type among the I-frame type, the P-frame type, and the B-frame type based on a network state between the server and the client device.

11. The server of claim 10 , wherein the at least one processor is further configured to execute the computer-readable instructions to:

determine the network state based on information of a traffic delay provided from the client device.

12. The server of claim 10 , wherein the at least one processor comprises a network state monitor configured to monitor the video stream and determine the network state based on the monitored video stream.

13. The server of claim 10 , wherein the at least one processor is further configured to execute the computer-readable instructions to:

communicate with a monitoring terminal configured to monitor the video stream and determine the network state based on the monitored video stream; and

receive information of the network state from the monitoring terminal.