We investigate the problem of stitching timely synchronized video streams captured by freely moving devices. Recently, it was shown that using frame-to-frame correlation can greatly enhance the efficiency and effectiveness of video stitching algorithms [19]. In this paper, we address some of the shortcomings in [19], namely the simple blending approach, causing almost a third of stitching errors and the fact that the stitching algorithm is only tested on a frame-by-frame basis which does not realistically mimic the user perception of the output system quality as a complete video. We propose the use of a modified blending technique based on optimal seam selection and experimentally validate its superiority using precision, recall and F1measures on a frame-by-frame basis, while maintaining low computational complexity. Furthermore, we validate that the performance gains measured on a frame-by-frame basis are also evident when the stitched video output is evaluated as a single unit.

Constructing a panoramic video out of multiple incoming live mobile video streams is a challenging problem. This problem involves multiple users live streaming the same scene from different angles, using their mobile phones, with the objective of constructing a panoramic video of the scene. The main challenge in this problem is the lack of coordination between the streaming users, resulting in too much, too little, or no overlap between incoming streams. To add to the challenge, the streaming users are generally free to move, which means that the amounts of overlap between the different streams are dynamically changing. In this paper, we propose a method for automatically coordinating between the streaming users, such that the quality of the resulting panoramic video is enhanced. The method works by analyzing the incoming video streams, and automatically providing active feedback to the streaming users. We investigate different methods for generating the active feedback and presenting it to the streaming users resulting in an improved panoramic video output compared to the case where no feedback is utilized.

We investigate the problem of efficient panoramic video construction based on time-synchronized input video streams. No additional constraints are imposed regarding the motion of the capturing video cameras. The presented work is, to the best of our knowledge, the first attempt to construct in real-time a panoramic video stream from input video streams captured by freely moving cameras. The main contribution is in proposing an efficient panoramic video construction algorithm that exploits temporal information to avoid solving the stitching problem fully on a frame by frame basis. We provide detailed experimental evaluation of different methodologies that employ previous frames stitching results such as tracking interest points using optical flow and using areas of overlap to limit the search space for interest points. Our results clearly indicate that making use of temporal information in video stitching can achieve a significant reduction in execution time while providing a comparable effectiveness.

User generated videos with mobile phone cameras are becoming more and more ubiquitous allowing people to share live content with remote parties, possibly in real-time. However with limited mobile phone capabilities, these videos are usually of small resolution, resulting in a small field of view for acceptable quality. Fortunately with the proliferation of video capture-enabled mobile phones, there is high chance that one or more persons will be shooting the same scene from different views. In this demonstration, we are showing an end-to-end system which receives video streams coming from different mobile phones, time synchronizes the streams and produces a single composite mosaic video, and all of this is done in real-time. The proposed system operates without coordination between users. The system has been tested under various capturing conditions such as indoor, outdoor, day and night conditions.

Lately, the usage of mobile live video streaming for video sharing has been growing steadily. However, because of the limitations presented by the capabilities of mobile phone video capturing devices, these video streams end up having either a low resolution or a small field of view. On the other hand, the ubiquity of video capture-capable mobile phones make the probability that more than one user will be recording the same scene from different views relatively high.

This paper presents a new analytical model for calculating the blocking probability in Just-Enough-Time (JET)-based optical burst switching networks. Relationship to the problem of calculating the reservation probability in advance reservation systems is also discussed. The proposed analytical model takes into consideration the effects of the burst offset time and the burst length on the blocking probability. We use a (M+1)-state non-homogenous Markov chain to describe the state of an output link carrying M wavelength channels. In addition, we model each wavelength channel by a 2-state Markov chain. The offset time is drawn from a specified distribution so that wavelength reservation requests, made before a given time, build up to be a workload whose mean value declines with the reservation starting time. Furthermore, we express the blocking probability in terms of first passage time distributions to account for the burst length. To verify its accuracy, the model results are compared with the results of a sophisticated discrete-event simulation model. The model results were found to be in satisfactory agreement with simulation results.

This paper proposes a novel class of wavelength scheduling algorithms in optical burst switching networks. The proposed wavelength scheduling algorithms process a batch of data bursts together instead of processing them one by one. When a control burst with a reservation request arrives to a batch scheduler, the scheduler waits for a small amount of time, called the acceptance delay, before deciding to accept or reject the reservation request. After the acceptance delay has passed, the scheduler processes all the reservation requests that have arrived during the acceptance delay, then it accepts the requests that will maximize the utilization of the wavelength channels. We describe an optimal batch scheduler that serves as an upper bound on the performance of batch scheduling algorithms. Furthermore, we introduce four novel heuristic batch scheduling algorithms. The bursts of the proposed algorithms is evaluated using a discrete-event simulation model. Simulation results suggest that batch schedulers could decrease the blocking probability by 25% compared the best previously known wavelength scheduling algorithm.

This paper presents a detailed architecture for providing quantitative QoS guarantees in labeled optical burst switching (LOBS) networks. Packets are assembled into data bursts based on their respective forwarding equivalence class (FEC) at ingress nodes. The burst assembly algorithm employs two parameters to control the burst blocking probability and burst assembly delay. We deploy a fair packet queueing (FPQ) algorithm in each edge node to regulate access to a wavelength scheduler. For LOBS core nodes, we present a novel approach that applies FPQ scheduling algorithms to the control plane of these nodes to guarantee fair bandwidth allocation. Based on the information provided by the queued control bursts, the core FPQ algorithm creates a virtual queue of data bursts in core nodes, then it selects the eligible control burst to be processed by the wavelength scheduler. In addition, we present analytical expressions for the worst case delay and the blocking probability in the proposed architecture. Simulation results demonstrate that the proposed architecture provides accurate and controllable service differentiation in LOBS networks.

In this paper we present a new analytical model for evaluating the blocking probability in Just-Enough-Time-based optical burst switching networks. The proposed analytical model takes into consideration the effects of the burst offset time and the burst length on the blocking probability. We use a (M+1)-state nonhomogenous Markov chain to describe the state of an output link carrying M wavelength channels. In addition, we model each wavelength channel by a 2-state Markov chain. The offset time is drawn from a specified distribution so that wavelength reservation requests, made before a given time, build up to be a workload whose mean value declines with the reservation starting time. Furthermore, we express the blocking probability in terms of first passage time distributions to account for the burst length. To verify its accuracy, the model results are compared with the results of a sophisticated discrete-event simulation model. The model results were found to be in satisfactory agreement with simulation results.

This work presents a new analytical model for calculating the blocking probability in just-enough-time (JET)-based optical burst switching networks. Relationship to the problem of calculating the reservation probability in advance-reservation systems is also discussed. The proposed analytical model takes into consideration the effects of the offset time and the burst length on the blocking probability. We model the wavelength channel by a 2-state nonhomogenous Markov chain. The offset time is drawn from a specified distribution so that wavelength reservation requests, made before a given time, build up to be a workload whose mean value declines with the reservation starting time. In addition, we express the blocking probability in terms of first passage time distributions to account for the burst length. To verify its accuracy, the model results are compared with the results of a discrete-event simulation model. The model results were found to be in satisfactory agreement with simulation results.

Classical approaches to quality-of-service (QoS) provisioning in IP networks are difficult to apply in all-optical networks. This is mainly because there is no optical counterpart to the store-and-forward model that mandates the use of buffers for queuing packets during contention for bandwidth in electronic packet switches. Since plain IP assumes a best effort service model, there is a need to devise mechanisms for QoS provisioning in IP over wavelength-division-multiplexing, or IP-over-WDM, networks. In this paper, we propose a new scheme; called preemptive prioritized just enough time (PPJET), for QoS provisioning in buffer-less optical burst switching (OBS) networks. PPJET provides strict priority for high priority traffic by dropping reservations belonging to lower priority traffic using a new channel scheduling algorithm called preemptive latest available unused channel with void filling (PLAUC-VF). Furthermore, we study the performance of PPJET through simulation experiments, and we show that PPJET outperforms prioritized just enough time (PJET) in terms of dropping probability and end-to-end delay.