In this paper, we propose a fast video mixing method for reducing the computational complexity in the MCU (Multipoint Control
Unit) used in the video conferencing. The conventional mixing method is based on the pixel-domain transcoder, of which computational
complexity is linearly increased as the number of participants is increased. Basically the method requires many decoders and
one huge encoder to mix the multiple bitstreams. To reduce the computational complexity, we propose a hybrid mixing method
based on the syntax-based bitstream modification and pixel-domain transcoder. The proposed method reduces the computational
complexity about 45% at the improved quality, compared with the conventional mixing method based on the pixel-domain transcoder.
[Show abstract][Hide abstract] ABSTRACT: In this paper, we propose an efficient packetization method to reduce the packetization overhead. For the purpose, we firstly verify the relationship between packet length and packet loss rate. The empirical results show that as the packet length is larger than the path MTU, the packet loss rate is drastically increased, producing poor visual quality at the receiver side. However, as the length of the packet is reduced, we should transmit more packets per frame and the packetization overhead will be increased. This increase in the packetization overhead reduces the number of bits allocated to the video data, resulting in the low visual quality. Therefore, each packet should be packetized to have the packet length close to the path MTU. In this paper, we show that the this process of the packetization with the constraint on the packet length is very similar to the dynamic storage allocation in the operating system. We had thoroughly surveyed the dynamic storage allocation methods used in the recent operating systems and propose to use the allocation methods for the video packetization. We empirically show that the proposed method can reduce the packetization overhead upto 28.3%, compared with the conventional sequential packetization method which have been widely used in Internet video transmission.
[Show abstract][Hide abstract] ABSTRACT: This paper proposes an endpoint video combiner architecture in a multipoint control unit (MCU) system for high definition multiparty video conferencing. The proposed architecture addresses the current reliability, computational and quality drawbacks of a conventional centralized based video combiner architecture. This is achieved by redesigning the MCU video to move away the video combiner from the bridge and into the client endpoints. Moreover, the proposed architecture represents a serverless system and is able to scale a large number of clients at high resolutions in a multipoint video conferencing session. In order to realize this design, this paper also proposes a custom robust sustainable session management protocol which allows a dynamic multi-port management between the MCU video and client endpoints. In addition, the proposed custom session management protocol includes recommendation for a session protection structure. Experimental results suggest that the proposed architecture exhibits significant computational frame rate performance gains of up to 762.95% in comparison with the conventional centralized video combiner architecture based on a series of four and eight high definition combined video assessments. Moreover, reliability analysis suggests that the proposed architecture is also able to consistently sustain a high frame rate performance within a long duration high definition multipoint video conferencing session.
Journal of Network and Computer Applications 01/2013; 36(1):336–352. DOI:10.1016/j.jnca.2012.05.008 · 2.23 Impact Factor
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