Video Quality Evaluation for Tile-Based Spatial Adaptation

The demand for very high-resolution video content in entertainment services (4K, 8K, panoramic, 360 VR) puts an increasing load on the distribution network. In order to reduce the network usage in existing delivery infrastructure for such services while keeping a good quality of experience, dynamic spatial video adaptation at the client side is seen as a key feature, and is actively investigated by academics and industrials. However, the impact of spatial adaptation on quality perception is not clear. In this paper, we propose a methodology for the evaluation of such adapted content, conduct a series of perceived quality measurements and discuss results showing potential benefits and drawbacks of the technique. Based on our results, we also propose a signaling mechanism in MPEGDASH to assist the client in its spatial adaptation log

ROI-BASED RATE CONTROL USING TILES FOR AN HEVC ENCODED VIDEO STREAM OVER A LOSSY NETWORK

International audienceThe growth in the use of high definition (HD) and above video resolutions streams has outstripped the rate at which network infrastructure has been deployed. Video streaming applications require appropriate rate control techniques that make use of the specific characteristics of the video content, such as the regions of interest (ROI). With the introduction of high efficiency video coding (HEVC) streams, we consider new coding features to make a novel ROI-based rate control (RC) algorithm. The proposed approach introduces tiling in a ROI-based rate control scheme. It aims at enhancing the quality of important regions (i.e. faces for a videoconferencing system) considering independently coded regions lying within an ROI and helps evaluating the ROI quality under poor channel conditions. Our work consists of two major steps. First, we designed a RC algorithm based on an independent processing of tiles of different regions. Second, we investigate the effect of ROI-and tile-based rate control algorithm on the decoded quality of the stream transmitted over a lossy channel

Low-Consumption Partial Transcoding by HEVC

A transcoding scheme for the High Efficiency Video Coding (HEVC) is proposed that allows any partial frame modification to be followed by a partial re-compression of only the modified areas, while guaranteeing identical reconstruction of non-modified areas. To this end, first, syntax elements of all Coding Units (CU) in the frame are parsed and decoded according to their scan order. Then CUs that are collocated with a replaced area are re-encoded with new content to generate a partial set of new syntax elements. In order to avoid spatial propagation of the decoding mismatch due to the new content, CUs on the border of the replaced area are losslessly coded such that reconstruction of immediately neighboring CUs in the scan order are protected from the modification. The proposed method has been implemented on top of the HEVC test Model (HM) in All-Intra (AI) coding configuration and experiments show that, depending on the test parameters, it can offer both a bitrate saving (up to 4% in terms of BD-BR) and a transcoding acceleration (up to 83%) compared to a full transcoding scheme

Improving virtual reality streaming using HTTP/2

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A Simulation Tool for Evaluating Video Streaming Architectures in Vehicular Network Scenarios

An integrated simulation tool called Video Delivery Simulation Framework over Vehicular Networks (VDSF-VN) is presented. This framework is intended to allow users to conduct experiments related to video transmission in vehicular networks by means of simulation. Research on this topic requires the use of many independent tools, such as traffic and network simulators, intermediate frameworks, video encoders and decoders, converters, platform-dependent scripting languages, data visualisation packages and spreadsheets, and some other tasks are performed manually. The lack of tools necessary to carry out all these tasks in an integrated and efficient way formed the motivation for the development of the VDSF-VN framework. It is managed via two user-friendly applications, GatcomSUMO and GatcomVideo, which allow all the necessary tasks to be accomplished. The first is primarily used to build the network scenario and set up the traffic flows, whereas the second involves the delivery process of the whole video, encoding/decoding video, running simulations, and processing all the experimental results to automatically provide the requested figures, tables and reports. This multiplatform framework is intended to fill the existing gap in this field, and has been successfully used in several experimental tests of vehicular network

Forensic Considerations for the High Efficiency Image File Format (HEIF)

The High Efficiency File Format (HEIF) was adopted by Apple in 2017 as their favoured means of capturing images from their camera application, with Android devices such as the Galaxy S10 providing support more recently. The format is positioned to replace JPEG as the de facto image compression file type, touting many modern features and better compression ratios over the aging standard. However, while millions of devices across the world are already able to produce HEIF files, digital forensics research has not given the format much attention. As HEIF is a complex container format, much different from traditional still picture formats, this leaves forensics practitioners exposed to risks of potentially mishandling evidence. This paper describes the forensically relevant features of the HEIF format, including those which could be used to hide data, or cause issues in an investigation, while also providing commentary on the state of software support for the format. Finally, suggestions for current best-practice are provided, before discussing the requirements of a forensically robust HEIF analysis tool.Comment: 8 pages, conference paper pre-prin