548 research outputs found
Packet loss visibility across SD, HD, 3D, and UHD video streams
The trend towards video streaming with increased spatial resolutions and dimensions, SD, HD, 3D, and 4kUHD, even for portable devices has important implications for displayed video quality. There is an interplay between packetization, packet loss visibility, choice of codec, and viewing conditions, which implies that prior studies at lower resolutions may not be as relevant. This paper presents two sets of experiments, the one at a Variable BitRate (VBR) and the other at a Constant BitRate (CBR), which highlight different aspects of the interpretation. The latter experiments also compare and contrast encoding with either an H.264 or an High Efficiency Video Coding (HEVC) codec, with all results recorded as objective Mean Opinion Score (MOS). The video quality assessments will be of interest to those considering: the bitrates and expected quality in error-prone environments; or, in fact, whether to use a reliable transport protocol to prevent all errors, at a cost in jitter and latency, rather than tolerate low levels of packet errors
Toward a General Parametric Model for Assessing the Impact of Video Transcoding on Objective Video Quality
Video transcoding can cause degradation to an original video. Currently, there is no general model that assesses the impact of video transcoding on video quality. Such a model could play a critical role in evaluating the quality of the transcoded video, and thereby optimizing delivery of video to end-users while meeting their expectations.
The main contribution of this research is the development and substantiation of a general parametric model, called the Video Transcoding Objective-quality Model (VTOM), that provides an extensible video transcoding service selection mechanism, which takes into account both the format and characteristics of the original video and the desired output, i.e., viewing format with preferred quality of service. VTOM represents a mathematical function that uses a set of media-related parameters for the original video and desired output, including codec, bit rate, frame rate, and frame size to predict the quality of the transcoded video generated from a specific transcoding.
VTOM includes four quality sub-models, each describing the impact of each of these parameters on objective video quality, as well as a weighted-product aggregation function that combines these quality sub-models with four additional error sub-models in a single function for assessing the overall video quality.
I compared the predicted quality results generated from the VTOM with quality values generated from an existing objective-quality metric. These comparisons yielded results that showed good correlations, with low error values.
VTOM helps the researchers and developers of video delivery systems and applications to calculate the degradation that video transcoding can cause on the fly, rather than evaluate it statistically using statistical methods that only consider the desired output. Because VTOM takes into account the quality of the input video, i.e., video format and characteristics, and the desired quality of the output video, it can be used for dynamic video transcoding service selection and composition.
A number of quality metrics were examined and used in development of VTOM and its assessment. However, this research discovered that, to date, there are no suitable metrics in the literature for comparing two videos with different frame rates. Therefore, this dissertation defines a new metric, called Frame Rate Metric (FRM) as part of its contributions. FRM can use any frame-based quality metric for comparing frames from both videos.
Finally, this research presents and adapts four Quality of Service (QoS)-aware video transcoding service selection algorithms. The experimental results showed that these four algorithms achieved good results in terms of time complexity, success ratio, and user satisfaction rate
Cloud-gaming:Analysis of Google Stadia traffic
Interactive, real-time, and high-quality cloud video games pose a serious
challenge to the Internet due to simultaneous high-throughput and low round
trip delay requirements. In this paper, we investigate the traffic
characteristics of Stadia, the cloud-gaming solution from Google, which is
likely to become one of the dominant players in the gaming sector. To do that,
we design several experiments, and perform an extensive traffic measurement
campaign to obtain all required data. Our first goal is to gather a deep
understanding of Stadia traffic characteristics by identifying the different
protocols involved for both signalling and video/audio contents, the traffic
generation patterns, and the packet size and inter-packet time probability
distributions. Then, our second goal is to understand how different Stadia
games and configurations, such as the video codec and the video resolution
selected, impact on the characteristics of the generated traffic. Finally, we
aim to evaluate the ability of Stadia to adapt to different link capacity
conditions, including those cases where the capacity drops suddenly. Our
results and findings, besides illustrating the characteristics of Stadia
traffic, are also valuable for planning and dimensioning future networks, as
well as for designing new resource management strategies
Avaliação da qualidade de experiência de vÃdeo em várias tecnologias
Mestrado em Engenharia Eletrónica e TelecomunicaçõesNowadays the internet is associated with many services. Combined
with this fact, there is a marked increase of the users joining this
service. In this perspective, it is required that the service providers
guarantee a minimum quality to the network services.
The Quality of Experience of services is quite crucial in the development
of services in networks. Also noteworthy, the tra c increase in multimedia
services, including video streaming, increases the probability of
congesting the networks. In the perspective of the service provider, the
monitoring is a solution to avoid saturation in network.
This way, this dissertation proposes to develop a platform that allows
a multimedia tra c monitoring in the Meo Go service provided by the
operator Portugal Telecom Communications.
The architecture of the adaptive streaming over HTTP has been studied
and tested to obtain the quality of experience metrics. This adaptive
streaming technique presents the smooth streaming, an architecture
made by Microsoft company, and it is used in the Meo Go service.
Then, it is monitored the metrics obtained with the video player. This
analysis is done objectively and subjectively. In this phase, the objective
implementation of the method allows to obtain the prediction value of
the Quality of Experience by consumers. The selected metrics were
derived from the state / performance of network and terminal device.
The obtained metrics aim to simulate human action in video score
quality. Otherwise, subjectively, it is conducted a survey based in a
questionnaire to compare methods. In this phase it was created an
on-line platform to allow the obtain a greater number of rankings and
data processing.
In the obtained results, rstly in the smooth streaming player, it is
shown the adaptive streaming implementation technique. On the next
phase, test scenarios were created to demonstrate the functioning of
the method in many cases, with greater relevance for those ones with
higher dynamic complexity. From the perspective of subjective and
objective methods, these have values that con rm the architecture of
the implemented module. Over time, the performance of the scoring
the quality of video streaming services approaches the one in a human
mental action.Nos dias de hoje a Internet é um dos meios com mais serviços associados.
Conjugado a este facto, existe um acentuado aumento de utilizadores a aderir a este serviço. Nesta perspectiva existe a necessidade de garantir uma qualidade mÃnima por parte dos prestadores de serviços.
A Qualidade de Experiência que os consumidores têm dos serviços é bastante crucial no desenvolvimento e optimização dos serviços nas redes. É ainda de salientar que o aumento do tráfego multimédia, nomeadamente os streamings de vÃdeo, apresenta incrementos na probabilidade de as redes se congestionarem. Na perspectiva do prestador de serviços a monitorização é a solução para evitar a saturação total.
Neste sentido, esta dissertação pretende desenvolver uma plataforma
que permite a monitorização do tráfego de multimédia do serviço do
Meo Go, fornecido pela operadora Portugal Telecom Comunicações.
Neste trabalho foi necessário investigar e testar a arquitectura do streaming adaptativo sobre HTTP para ser possÃvel obter métricas de qualidade de experiência. Este streaming adaptativo apresenta a técnica de smooth streaming, sendo esta arquitectura projectada pela empresa Microsoft e utilizada no serviço Meo Go.
Posteriormente foram monitorizadas as métricas que se obtiveram no player de vÃdeo. Esta análise foi realizada de forma objectiva e subjectiva.
Nesta fase da implementação objectiva do método em que se pretende obter uma predição do valor de Qualidade de Experiência por parte do consumidor, foram seleccionadas as métricas oriundas do estado/desempenho da rede e do dispositivo terminal. As métricas obtidas entram num processo de tratamento que pretende simular a ação humana nas classificações da qualidade dos vÃdeos. De outra forma, subjectivamente, foi realizada uma pesquisa, com base num questionário, de modo a comparar os métodos. Nesta etapa foi gerada uma plataforma online que possibilitou obter um maior número de classificações dos vÃdeos para posteriormente se proceder ao tratamento de dados.
Nos resultados obtidos, primeiramente ao nÃvel do player de smooth streaming, estes permitem analisar a técnica de implementação de streaming adaptativo. Numa fase seguinte foram criados cenários de teste para comprovar o funcionamento do método em diversas situações, tendo com maior relevância aqueles que contêm dinâmicas mais complexas. Na perspectiva dos métodos subjectivo e objectivo, estes apresentam valores que confirmam a arquitectura do módulo implementado.
Adicionalmente, o desempenho do método em classificar a qualidade de serviço de vÃdeo streaming, ao longo do tempo, apresentou valores que se aproximam da dinâmica esperada numa ação mental humana
IEEE 802.11ac wireless delivery of 4kUHD video: The impact of packet loss
This paper examines the 4kUHD video quality from streaming over an IEEE 802.11ac wireless channel, given measured levels of packet loss. Findings suggest that there is a strong content dependency to loss impact upon video quality but that, for short-range transmission, the quality is acceptable, making 4kUHD feasible on head-mounted displays
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