QoS framework for video streaming in home networks

In this thesis we present a new SNR scalable video coding scheme. An important advantage of the proposed scheme is that it requires just a standard video decoder for processing each layer. The quality of the delivered video depends on the allocation of bit rates to the base and enhancement layers. For a given total bit rate, the combination with a bigger base layer delivers higher quality. The absence of dependencies between frames in enhancement layers makes the system resilient to losses of arbitrary frames from an enhancement layer. Furthermore, that property can be used in a more controlled fashion. An important characteristic of any video streaming scheme is the ability to handle network bandwidth fluctuations. We made a streaming technique that observes the network conditions and based on the observations reconfigures the layer configuration in order to achieve the best possible quality. A change of the network conditions forces a change in the number of layers or the bit rate of these layers. Knowledge of the network conditions allows delivery of a video of higher quality by choosing an optimal layer configuration. When the network degrades, the amount of data transmitted per second is decreased by skipping frames from an enhancement layer on the sender side. The presented video coding scheme allows skipping any frame from an enhancement layer, thus enabling an efficient real-time control over transmission at the network level and fine-grained control over the decoding of video data. The methodology proposed is not MPEG-2 specific and can be applied to other coding standards. We made a terminal resource manager that enables trade-offs between quality and resource consumption due to the use of scalable video coding in combination with scalable video algorithms. The controller developed for the decoding process optimizes the perceived quality with respect to the CPU power available and the amount of input data. The controller does not depend on the type of scalability technique and can therefore be used with any scalable video. The controller uses the strategy that is created offline by means of a Markov Decision Process. During the evaluation it was found that the correctness of the controller behavior depends on the correctness of parameter settings for MDP, so user tests should be employed to find the optimal settings

Using TCP-feedback to Optimize Transcoding Performance

A method is described to control a video transcoder based on the actual network conditions in a home network. A single TCP connection is used for transport, where the TCP protocol buffer of the sender provides feedback to the transcoder

Predictive control of video quality under fluctuating bandwidth conditions

This work shows that scalable video techniques together with a controlling mechanism for a device that receives and decodes video data provide a solution to some challenges posed by in-home networks. The challenges are resource limitations of devices (processor, memory, etc) and network (bandwidth). Additionally, a wireless network usually has bandwidth fluctuations that consecutively lead to rapid throughput fluctuations. These rapid changes severely reduce the quality of viewing as perceived by an end user. We developed a controller that optimizes user-perceived quality when looking at available input data and available processing power. The quality is optimized by smoothening the quality fluctuations and avoiding deadline misses. The strategy used by the controller is created offline by means of a Markov decision proces

Adaptable video streaming over wireless networks

The paper addresses the issue of controlling streaming of scalable video over wireless links to resource-constrained devices (terminals). A controller on the terminal maximizes user perceived quality taking into account available computing resources and condition of the network. The controller determines the number of layers to be processed using a strategy calculated for the given layers configuration and network conditions. We present a method to decrease the number of pre-calculated strategies for the controller by exploring the dependency between layers configuration and network conditions

Perceived quality of wirelessly transported videos

Wireless networking technology will interconnect the consumer devices in the future homes. The capacity of the wireless technology is just sufficient to transport one or two high quality videos. When the wireless transmission is perturbed by the switching on of a microwave or a Bluetooth telephone, many artifacts appear on the screen during the display of the video. Two "scalable video" techniques are proposed to remove the artifacts. These techniques have a different effect on the quality of the video as perceived by the user. An experiment is presented which evaluates the effects of the two techniques dependent on their settings. Conclusions are drawn on the best setting dependent on the operational transmission conditions and the transmitted video