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Layered buffering method and system based on panoramic videos

A technology of panoramic video and buffering method, which is applied in the field of multimedia transmission and can solve the problems such as the performance degradation of viewing angle prediction accuracy, the degradation of video quality, and the playback freeze.

Active Publication Date: 2021-04-27
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004]1. The current viewing angle prediction methods mainly use the user's historical viewing trajectory to predict the user's viewing angle in the next few seconds, but the prediction results of these methods are only within 2 -It is more accurate within 3 seconds, and it is difficult to predict the direction of the user's viewing angle for a long time
[0005]2. Throughput-based bit rate adaptive method estimates the bit rate of the video segment at the next moment according to the historical network conditions. It is a simple and effective algorithm, but based on The throughput algorithm depends to a large extent on the accuracy of the throughput estimation, and the estimation error may cause the buffer to underflow and cause the playback to freeze
However, since the viewing angle prediction accuracy performance drops significantly when the buffer duration is long
Video quality in perspective may degrade due to prediction error as video in buffer plays

Method used

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  • Layered buffering method and system based on panoramic videos
  • Layered buffering method and system based on panoramic videos
  • Layered buffering method and system based on panoramic videos

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0079] The current buffer length exceeds the threshold:

[0080] For the case where the buffer length exceeds the threshold, the part below the threshold needs to update the segmented video in the buffer, and the part above the threshold needs to determine whether to download a new video segment and its corresponding bit rate.

[0081] First, determine the number of video segments that can be downloaded based on the current buffer length and the maximum buffer length 0- where L denotes the duration of each video segment. Get all download statuses according to the number of video segments that can be downloaded and the selectable M bitrates. In order to reduce the search space, the download bit rate should be higher for video segments closer to the playback time.

[0082] Secondly, under the premise of determining a certain download status, further determine the updated segmented video and its bit rate, and calculate the utility cost function of each segmented video, as foll...

Embodiment 2

[0088] The current buffer length is below the threshold:

[0089] When the buffer length is lower than the threshold, it is necessary to download a new video segment according to the viewing angle prediction information, and at the same time update the code rate of the segmented video already stored in the buffer.

[0090]First, for the downloaded video segment, in order to ensure that each segmented video is downloaded, a basic code rate (minimum code rate) is assigned to each segmented video to be downloaded.

[0091] Second, calculate the utility cost function for each segmented video as follows:

[0092]

[0093] in represents the utility cost function, Indicates the code rate of the video segment k sub-block video i when the code rate level is q, Indicates that the code rate level of the video segment k block video i currently in the buffer is q'. According to the utility cost function, select the block video with the highest utility cost function each time, upd...

Embodiment 3

[0097] Optimization of the maximum length of the buffer:

[0098] The total code rate R of the request is not only related to the current buffer length, but also affected by the maximum length of the buffer. Therefore, optimizing the maximum length of the buffer can reduce stuttering while maximizing the requested bit rate to improve video quality. According to the observation of network state changes, the relationship between the estimated network bandwidth and the average bandwidth during downloading can be obtained, so that during streaming transmission, the maximum buffer length can be dynamically adjusted according to the historical network state to ensure that the card is reduced. The total request code rate is optimized in the case of frames, and the maximum length of the buffer can be determined by the following formula:

[0099]

[0100] Where C represents the average download bandwidth. According to B max The value of determines the total code rate of the reque...

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Abstract

The invention provides a layered buffering method and a layered buffering system based on a panoramic video. The layered buffering method comprises a buffering area state observation step, a network bandwidth estimation step, a user visual angle prediction step, a blocked video code rate distribution step and a blocked video downloading and scheduling step. The method comprises: determining the total code rate of the downloaded blocked video according to the current network condition and the buffer area state, and updating and downloading the blocked video according to the code rate of the downloaded blocked video; dividing the buffer area into two layers which are controlled by a threshold value; when the length of the buffer area is lower than the threshold value, allocating the code rate of each partitioned video according to a user view angle prediction result and downloading the code rate; and when the length of the buffer area is higher than the threshold value, downloading all the blocked videos at an average code rate, and updating the cached blocked videos lower than the threshold value according to the change of user view angle prediction. And a layered buffer mechanism is adopted, so that the network robustness of panoramic video transmission is greatly improved while the watching quality of the user is ensured.

Description

technical field [0001] The present invention relates to the technical field of multimedia transmission, in particular to a layered buffering method and system based on panoramic video. Background technique [0002] Emerging immersive media such as panoramic video are popular for providing users with personalized viewing angles and real-time interaction. Especially for panoramic videos, head-mounted displays can be used for experience and interaction, and corresponding video services can already be provided on some major video platforms. However, compared with traditional video, to provide a truly immersive experience, panoramic video requires a resolution higher than 4K, which places higher requirements on transmission bandwidth. According to the survey, panoramic video traffic may increase by 20 times by 2021. In addition, the user's viewing angle may change randomly, making the transmission of panoramic video more sensitive to delay. In order to solve the above problems...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N19/15H04N19/30H04N19/423H04N19/37
CPCH04N19/15H04N19/30H04N19/423H04N19/37
Inventor 徐异凌姜志乾张旭马展
Owner SHANGHAI JIAO TONG UNIV
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