Hung-Chang Yang

Adaptive Live Broadcasting for Highly-Demand Videos

With the growth of broadband networks, Video-on-Demand (VoD) has become realistic. Many significant broadcasting schemes have been proposed to reduce the bandwidth requirements for stored popular videos, but they cannot be used to support live video broadcast perfectly. Herein, we propose a new broadcasting scheme, called the Adaptive Live Broadcasting (ALB) scheme, which supports live video broadcasting and performs well over a wide range of request arrival rates. From our analysis and comparison, we find that our ALB scheme is suitable for broadcasting live video. It has several significant advantages: (1) It has the shortest maximum waiting time with fixed channels. (2) It has the lowest maximum I/O transfer requirements with a fixed maximum waiting time at the client end. A simulation is employed to evaluate several live broadcasting schemes: UD, ST, AFB and ALB. The results reveal that our ALB scheme consumes the least server bandwidth.

Broadcasting scheme with low client buffers and bandwidths for video-on-demand applications

Efficient data broadcasting is independent of request arrivals, and is thus highly promising when transmitting popular videos. A conventionally adopted broadcasting method is periodic broadcasting, which divides a popular video into segments, which are then simultaneously broadcast on different data channels. Once clients want to watch the video, they download the segments from these channels. The skyscraper broadcasting (SkB) scheme supports clients with small bandwidths. An SkB client requires only two-channel bandwidths to receive video segments. This work proposes a reverse SkB (RSkB) scheme, which extends SkB by reducing buffering spaces. The RSkB is mathematically shown to achieve on-time video delivery and two-channel client bandwidths. A formula for determining the maximum number of segments buffered by an RSkB client is presented. Finally, an analysis of RSkB reveals that its client buffer requirements are usually 25–37% lower than SkB. Extensive simulations of RSkB further demonstrate that RSkB yields lower client buffer demand than other proposed systems.

An efficient scheme for broadcasting popular videos at low buffer demand

Data broadcasting is independent of arrivals of requests, and thus it is suitable to transmit popular videos that may interest many viewers at a particular period of time. One broadcasting method (called periodic broadcasting) is to divide a popular video into segments, which are then simultaneously broadcast on different data channels. Once clients want to watch the video, they download the segments from these channels. Specially, the greedy disk-conserving broadcasting (GDB) scheme supports a client with a small bandwidth. In comparison with other similar schemes such as the skyscraper broadcasting (SkB) and the client-centric approach (CCA) schemes, the GDB clients have smaller waiting time. Extending GDB, this work designs a reverse GDB (RGDB) scheme to achieve small buffering spaces as well as low bandwidths at the client. We further mathematically prove that RGDB still guarantees on-time video delivery at small client bandwidths. A formula is derived for the maximum number of segments buffered by an RGDB client. Finally, an analysis shows that RGDB has 33-50% smaller client buffer requirements than GDB in most situations.

Smooth Fast Broadcasting (SFB) for Compressed Videos

One way to broadcast a popular video is to partition the video into segments, which are broadcasted on several streams periodically. The approach lets multiple users share streams; thus, the stress on the scarce bandwidth can be alleviated without sacrificing viewers’ waiting time. One representative approach is the Fast Broadcasting (FB) scheme. The scheme does not obtain shortest waiting time but it can offer a more reliable video transmission on wireless networks. However, the scheme mainly supports transmission of CBR-encoded videos. In this paper, we propose a FB-based scheme for VBR-encoded videos. The scheme can smooth required bandwidth. From the simulation results, the SFB scheme has smaller required bandwidth, buffers, and disk transfer rate than the FB scheme. For a video, the maximum difference of its required bandwidth is less or equal to max(\(B^i_{max} - B^i_{min}\)), where \(B^i_{max}\) and \(B^i_{min}\) represent the maximum and minimum required bandwidth on stream i.

Interleaving harmonic broadcasting and receiving scheme with loss-anticipation delivery

With the growth of broadband networks, video-on-demand (VoD) has become realistic. Many significant broadcasting schemes have been proposed to reduce the bandwidth requirement for stored popular videos, but they cannot be used for provide reliable delivery over lossy channels perfectly. Herein, we propose a new broadcasting scheme, called the interleaving harmonic broadcasting (IHB) scheme, which guarantees continuous playback, and mitigates the effect of packet losses. Further, in comparison with the poly-harmonic broadcasting (PHB), cautions harmonic broadcasting (CHB) scheme, reliable periodic broadcasting (RPB) scheme and second chance broadcasting (SCB) scheme, the IHB outperforms on required bandwidth, maximum required buffers and maximum disk transfer rate.

Generalized Sequence-Based and Reverse Sequence-Based Models for Broadcasting Hot Videos

It has been well recognized as an efficient approach for broadcasting popular videos by partitioning a video data stream into multiple segments and launching each segment through an individual channel simultaneously and periodically. Based on the design premises, some recent studies, including skyscraper broadcasting (SkB), client-centric approach (CCA), greedy disk-conserving broadcasting (GDB), and reverse fast broadcasting (RFB) schemes, etc., have been reported. To study the client segment downloading process, this paper first introduces an applicable sequence-based broadcasting model that can be used to minimize the required buffer size. By extending RFB, this paper further proposes a reverse sequence-based broadcasting model, which can generally improve the existing schemes such as SkB, CCA, GDB, and FB in terms of the relaxed client buffer size. To have a deeper understanding on the proposed reverse model, the upper bound of the client buffer requirement is obtained through a comprehensive analysis, which is proved to be much smaller than the conventional sequence model by 25% to 50%. Based on the proposed reverse model, a reverse sequence-based broadcasting scheme is developed for achieving smaller delay than CCA and GDB.

Adaptive live broadcasting for highly-demanded videos

With the growth of broadband networks, the video-on-demand (VoD) becomes realistic. Many significant broadcasting schemes are proposed to reduce the bandwidth requirements for stored popular videos, but they cannot be used to support live video broadcast perfectly. Herein, we propose a new broadcasting scheme, called adaptive live broadcasting (ALB) scheme, which supports live video broadcasting and performs well over a wide range of request arrival rates. From our analysis and comparison, we find that our ALB scheme is suitable to broadcast live video. It has several significant advantages: (1) it has the shortest maximum waiting time with fixed channels; (2) it has the least maximum I/O transfer requirements with fixed maximum waiting time at client end. Finally, a simulation is employed to evaluate several live broadcasting schemes, such as UD, ST AFB and ALB. The results reveal our ALB scheme consumes the least server bandwidth.

A Replication-Aware CDN-P2P Architecture Based on Two-Step Server Selection and Network Coding

E-learning service is getting increasingly popular, especially the multimedia content educations. To distribute content to end users, two different technologies --- Content Distribution Network (CDN) and Peer-to-Peer (P2P) network --- have been proposed. However, both technologies have their own limitations: CDN servers are expensive to deploy and maintain. Under P2P network, anyone could share his content regardless of the copyright. In this paper, a new concept of integrating both CDN and P2P technologies into a replication-aware CDN-P2P architecture has been proposed. We propose a two-step selection approach on landmark-based selection algorithm to find the nearest replica-cache server and peer-caches to download content in this architecture. Furthermore, recent studies have supported the claim that network coding technology is beneficial for large-scale P2P content distribution. Herein, we show how to apply network coding technology to distribute content so that the content providers rights can be protected.

A segment-alignment interactive broadcasting scheme

With the growth of broadband networks, Vide-on-Demand (VoD) has become realistic. Many significant broadcasting schemes have been proposed to reduce the bandwidth requirement for stored popular videos, but they cannot be used to support VCR functionality perfectly. Herein, we propose a new broadcasting scheme, called the Segment-Alignment Interactive Broadcasting (SAIB) scheme, which can be built on the top of any segment based broadcasting scheme and supports VCR functionality perfectly. From our analysis, we find that our SAIB scheme is suitable for smooth fast forward and forward jump playback. A simulation is employed to, evaluate several segment based broadcasting schemes: FB, PB, RFS and NPB. The results reveal the FB scheme has the lowest blocking probability and additional bandwidth overhead. On the contrary, the NPB scheme has the highest results. These results are due to the size and broadcasting period of segments are different for each segment based broadcasting scheme.

A live harmonic broadcasting scheme for VBR-Encoded hot videos

With the growth of broadband networks, Video-on-Demand (VoD) has become realistic. Most of the significant broadcasting schemes have been proposed to reduce the server bandwidth requirement for Constant Bit-Rate (CBR) encoded videos. The few existing proposals, which support of the bandwidth-efficient Variable Bit-Rate (VBR) encoded videos, smooth and minimize the server bandwidth requirement at the cost of data losses. The lossless and bandwidth efficient (LLBE) scheme states that minimization of the server bandwidth as a shortest path problem on a directed acyclic graph, and uses a dynamic programming method to solve the problem. However, it cannot be used for support live video broadcasting. In this paper, we propose a live harmonic broadcasting (LHB) scheme to support VBR-encoded live video broadcasting. The ideas behind the scheme are (1) support VBR-encoded videos by asynchronous downloading and playing, and hybrid division by length and size, and (2) support live videos by postponing recasting process. It is simple and effective. Using data from real videos, we conduct a simulation to evaluate our scheme. The experiment results indicate that the LHB scheme requires slightly higher server bandwidth than LLBE scheme.