Impact of GoP on the video quality of VP9 compression standard for full HD resolution

In the last years, the interest on multimedia services has significantly increased. This leads to requirements for quality assessment, especially in video domain. Compression together with the transmission link imperfection are two main factors that influence the quality. This paper deals with the assessment of the Group of Pictures (GoP) impact on the video quality of VP9 compression standard. The evaluation was done using selected objective and subjective methods for two types of Full HD sequences depending on content. These results are part of a new model that is still being created and will be used for predicting the video quality in networks based on IP

Perceived quality of full HD video - subjective quality assessment

In recent years, an interest in multimedia services has become a global trend and this trend is still rising. The video quality is a very significant part from the bundle of multimedia services, which leads to a requirement for quality assessment in the video domain. Video quality of a streamed video across IP networks is generally influenced by two factors “transmission link imperfection and efficiency of compression standards. This paper deals with subjective video quality assessment and the impact of the compression standards H.264, H.265 and VP9 on perceived video quality of these compression standards. The evaluation is done for four full HD sequences, the difference of scenes is in the content“ distinction is based on Spatial (SI) and Temporal (TI) Index of test sequences. Finally, experimental results follow up to 30% bitrate reducing of H.265 and VP9 compared with the reference H.264

Influence of Bit Depth on Objective Video Quality Assessment for High Resolutions

This paper deals with the influence of bit depth on the objective quality assessment. All tests were conducted on eight video sequences, while each one has different spatial and temporal information; 8-bit and 10-bit bit depths were used; analysed videos were in full and ultra HD resolutions, and coding efficiency of H.264 and H.265 was compared. The metrics PSNR and SSIM for evaluation of objective video quality were used

Network degradation effects on different codec types and characteristics of video streaming

Nowadays, there is a quickly growing demand for the transmission of voice, video and data over an IP based network. Multimedia, whether we are talking about broadcast, audio and video transmission and others, from a global perspective is growing exponentially with time. With incoming requests from users, new technologies for data transfer are continually developing. Data must be delivered reliably and with the fewest losses at such high speed. Video quality as part of multimedia technology has a very important role nowadays. It is influenced by several factors, where each of them can have many forms and processing. Network performance is the major degradation effect that influences the quality of resulting image. Poor network performance (lack of link capacity, high network load…) causes data packet losses or different delivery time for each packet. This work focuses exactly on these network phenomena. It examines the impact of different delays and packet losses on the quality parameters of triple play services, to evaluate the results using objective methods. The aim of this work is to bring a detailed view on the performance of video streaming over IP-based networks

Correlation between objective and subjective methods used for video quality evaluation

The article deals with the correlation between the objective and the subjective methods. In the first part the short characteristic of the MPEG compression standards is written. The second part focuses on the objective metrics and the third part on the subjective methods, which were used for testing. In the fourth part regression and correlation analysis are written. In the fifth part the measurements and the experimental results using the objective metrics and in the fifth part the measurements and the experimental results using the subjective methods are described. The last part deals with the correlation between the objective and the subjective methods, mapping and approximation

Influence of Chroma Subsampling on Objective Video Quality Assessment for High Resolutions

This paper deals with the influence of chroma subsampling on video quality measured by objective metrics for H.264/AVC and H.265/HEVC compression standards. The evaluation is done for eight types of sequences with full HD and ultra HD resolutions depending on content. The experimental results showed that there is no impact of chroma subsampling on the video. According to the results, it can also be said that H.265/HEVC codec yields better compression efficiency than H.264/AVC and the different is more visible in UHD resolution. The bigger difference in quality is in lower bitrates, with increasing bitrate the quality of H.264/AVC codec approaches the H.265/HEVC codec

Subjective video quality assessment of H.265 compression standard for full HD resolution

Recently increasing interest in multimedia services leads to requirements for quality assessment, especially in the video domain. There are many factors that influence the video quality. Compression technology and transmission link imperfection can be considered as the main ones. This paper deals with the assessment of the impact of H.265/HEVC compression standard on the video quality using subjective metrics. The evaluation is done for two types of sequences with Full HD resolution depending on content. The paper is divided as follows. In the first part of the article, a short characteristic of the H.265/HEVC compression standard is written. In the second part, the subjective video quality methods used in our experiments are described. The last part of this article deals with the measurements and experimental results. They showed that quality of sequences coded between 5 and 7 Mbps is for observers sufficient, so there is no need for providers to use higher bitrates in streaming than this threshold. These results are part of a new model that is still being created and will be used for predicting the video quality in networks based on IP

Impact of H.264/AVC and H.265/HEVC compression standards on the video quality for 4K resolution

This article deals with the impact of H.264/AVC and H.265/HEVC compression standards on the video quality for 4K resolution. In the first part a short characteristic of both compression standards is written. The second part focuses on the well-known objective metrics which were used for evaluating the video quality. In the third part the measurements and the experimental results are described

30 Years of Video Coding Evolution - What Can We Learn from it in Terms of QoE?

From the beginnings of ITU-T H.261 to H.265 (HEVC), each new video coding standard has aimed at halving the bitrate at the same perceptual quality by redundancy and irrelevancy reduction. Each improvement has been explained by comparably small changes in the video coding toolset. This contribu- tion aims at starting the Quality of Experience (QoE) analysis of the accumulated improvements over the last thirty years. Based on an overview of the changes in the coding tools, we analyze the changes in the quan- tized residual information. Visual comparison and sta- tistical measures are performed and some interpreta- tions are provided towards explaining how irrelevancy reduction may have led to such a huge reduction in bitrate. The interpretation of the results in terms of QoE paves the way towards an understanding of the coding tools in terms of visual quality. It may help in understanding how the irrelevancy reduction has been improved over the decades. Understanding how the differences of the residuals relate to known or yet un- known properties of the human visual system, may en- able a closer collaboration between perception research and video compression research

Modeling and estimating the subjects’ diversity of opinions in video quality assessment: a neural network based approach

Subjective experiments are considered the most reliable way to assess the perceived visual quality. However, observers’ opinions are characterized by large diversity: in fact, even the same observer is often not able to exactly repeat his first opinion when rating again a given stimulus. This makes the Mean Opinion Score (MOS) alone, in many cases, not sufficient to get accurate information about the perceived visual quality. To this aim, it is important to have a measure characterizing to what extent the observed or predicted MOS value is reliable and stable. For instance, the Standard deviation of the Opinions of the Subjects (SOS) could be considered as a measure of reliability when evaluating the quality subjectively. However, we are not aware of the existence of models or algorithms that allow to objectively predict how much diversity would be observed in subjects’ opinions in terms of SOS. In this work we observe, on the basis of a statistical analysis made on several subjective experiments, that the disagreement between the quality as measured by means of different objective video quality metrics (VQMs) can provide information on the diversity of the observers’ ratings on a given processed video sequence (PVS). In light of this observation we: i) propose and validate a model for the SOS observed in a subjective experiment; ii) design and train Neural Networks (NNs) that predict the average diversity that would be observed among the subjects’ ratings for a PVS starting from a set of VQMs values computed on such a PVS; iii) give insights into how the same NN based approach can be used to identify potential anomalies in the data collected in subjective experiments