Heuristic algorithms for ordering media objects to reduce presentation lags in auto-assembled multimedia presentations from digital libraries

[[abstract]]Purpose - The purpose of this paper is to examine an auto-assembled multimedia presentation from digital libraries, in which the retrieved media objects are dynamically composed to form a continuously played "TV-like" presentation. This study seeks to propose techniques for ordering the media objects in such a presentation so as to reduce its total presentation lag in a high-delay network environment. Design/methodology/approach - Scheduling techniques adapted from conventional operational research for solving the proposed problem were applied. A number of computationally efficient heuristic algorithms that can obtain near-optimal sequences are proposed. Numerical simulations and real-life experiments for cases with different buffer constraints and bandwidth fluctuations were conducted to evaluate the proposed algorithms. Findings - The result indicates that the proposed algorithms always significantly reduce the presentation lag of a given presentation, compared with a random sequence. Overall, for all the test cases, the average gaps between the idle rates of the heuristic sequences and random sequences range from 15 to 25 per cent. In particular, the RRB_3_2007 algorithm outperforms others in most of the cases involved in the experiment. Originality/value - The study develops a sequence optimization technique for ordering the media objects and a framework for a prefetch-enabled presentation system. The effectiveness and ease of implementation of the heuristic algorithms and the system framework make it feasible for practical digital library and meta-search engine applications.[[note]]SSC

Heuristic algorithms for ordering media objects to reduce presentation lags in auto-assembled multimedia presentations from digital libraries

[[abstract]]Purpose - The purpose of this paper is to examine an auto-assembled multimedia presentation from digital libraries, in which the retrieved media objects are dynamically composed to form a continuously played "TV-like" presentation. This study seeks to propose techniques for ordering the media objects in such a presentation so as to reduce its total presentation lag in a high-delay network environment. Design/methodology/approach - Scheduling techniques adapted from conventional operational research for solving the proposed problem were applied. A number of computationally efficient heuristic algorithms that can obtain near-optimal sequences are proposed. Numerical simulations and real-life experiments for cases with different buffer constraints and bandwidth fluctuations were conducted to evaluate the proposed algorithms. Findings - The result indicates that the proposed algorithms always significantly reduce the presentation lag of a given presentation, compared with a random sequence. Overall, for all the test cases, the average gaps between the idle rates of the heuristic sequences and random sequences range from 15 to 25 per cent. In particular, the RRB_3_2007 algorithm outperforms others in most of the cases involved in the experiment. Originality/value - The study develops a sequence optimization technique for ordering the media objects and a framework for a prefetch-enabled presentation system. The effectiveness and ease of implementation of the heuristic algorithms and the system framework make it feasible for practical digital library and meta-search engine applications.[[note]]SSC