The scalable video coding extends the H.264/AVC video coding standard by providing temporal, spatial and quality scalability. A set of new tools, such as key picture and inter-layer prediction are introduced in SVC to improve either rate-distortion performance or error resilience. This paper evaluates the impact of these tools on the performance of an optimized SVC decoder, in terms of rate, distortion, and computational complexity. The results facilitate the decision making process of choosing suitable SVC configurations under different application scenarios.

In this paper, we propose a cross-layer optimization scheme for multi-user video streaming over the uplink of IEEE 802.11e HCCA wireless network. The objective is to minimize the energy consumption of all users, including both video encoder energy and wireless transmission energy, while delivering desired video quality for each user. In our proposed scheme, both cross-layer optimization of individual mobile terminal and inter-user resource allocation are carried out, so that the video encoder and wireless transmitter configurations can be jointly steered. Experimental results show that when compared to the transmission system without cross-layer optimization, our proposed scheme is able to reduce total energy consumption from 35% up to 80%, while satisfying the same video quality target.

The optimal packet scheduling for transmitting scalable media over the packet erasure networks has been extensively studied in the past. In the existing work, only retransmission is used for packet loss recovery. As a result, when the round-trip-time (RTT) of the network increases, the performance of the system degrades fast. In this paper, a scheduling scheme for hybrid FEC/ARQ error control is proposed. In our proposed scheme, the importance of both data packets and FEC packets are evaluated by considering several factors, such as data dependency structure of scalable video, transmission history of other packets, as well as the decoding deadline, and the most important packet is chosen to be sent out. In this way, our proposed scheme is able to achieve more stable playback video quality by taking advantage of both FEC and ARQ, as demonstrated by the experimental results.

In wireless video streaming, it is desirable to minimize the energy consumption of mobile devices while achieving target video quality. For this purpose, it is essential to model (i.e., estimate) the energy cost of the streaming system, including both video encoder and wireless transmission energy, under different system settings. In this paper, an energy consumption model is proposed for a MPEG-4 simple profile encoder implemented in ASIC. Our proposed model consists of three major steps: 1) compute the encoder energy consumption through power simulations; 2) empirically model the impact of configuration parameters through curve fitting; and 3) online updating of model coefficients. Experimental results show that our proposed model works well for different types of video, and the average estimation error is below 6%.

Forward error correction based multiple description (MD-FEC) transcoding for transmitting embedded bitstream over the packet erasure networks has been extensively studied in the past. In the existing work, a single embedded source bitstream, e.g., the bitstream of a group of pictures (GOP) encoded using three-dimensional set partitioning in hierarchical trees is optimally protected unequal error protection (UEP) in the rate-distortion sense. However, most of the previous work on transmitting embedded video using MD-FEC assumed that one GOP is transmitted only once, and did not consider the chance of retransmission. This may lead to noticeable video quality variations due to varying channel conditions. In this paper, a novel window-based packetization scheme is proposed, which combats bursty packet loss by combining the following three techniques: UEP, retransmission, and GOP-level interleaving. In particular, two retransmission mechanisms, namely segment-wise retransmission and byte-wise retransmission, are proposed based on different types of receiver feedback. Moreover, two levels of rate allocations are introduced: intra-GOP rate allocation minimizes the distortion of individual GOP; while inter-GOP rate allocation intends to reduce video quality fluctuations by adaptively allocating bandwidth according to video signal characteristics and client buffer status. In this way, more consistent video quality can be achieved under various packet loss probabilities, as demonstrated by our experimental results.

In this paper, we investigate the problem of transmitting embedded encoded object-oriented images over the packet-erasure networks. After giving a review of the existing combined unequal error protection (CUEP) and individual unequal error protection (IUEP) schemes, a novel weighted unequal error protection (WUEP) packetization scheme is proposed, which serves as an alternative to the existing methods. In our proposed framework, the embedded bitstreams of all concerned image objects are packetized into multiple description packet streams before transmission. Two levels of rate allocation are introduced: intraobject rate allocation provides unequal error protection to the embedded bitstream of each object and minimizes its associated mean distortion; interobject rate allocation aims at minimizing the weighted mean distortion by adaptively allocating the rate budget among different objects according to their importance. Furthermore, our proposed packetization scheme ensures independent access and manipulation of individual image object. A detailed comparison between CUEP, IUEP, and WUEP is presented along with the experimental results, so that one can choose the most suitable approach according to the requirements.

Traditional bandwidth smoothing techniques can be naturally supported by the renegotiated constant bit rate (RCBR) service model, but renegotiation failure in RCBR may cause buffer underflow and interrupt the playback of video. To address this concern, a novel dual-plan bandwidth smoothing (DBS) scheme is proposed in this paper by taking advantage of the SNR scalability of layer-encoded video. Upon renegotiation failure, the proposed scheme can adaptively discard certain enhancement layers to guarantee continuous video playback at the original frame rate. Experiments are carried out to demonstrate the validity of the proposed scheme. The impacts of renegotiation interval, granularity of enhancement layers, and playback buffer size on resulted video quality are also studied. From the simulation results, it is shown that the performance of the RCBR-based DBS scheme can be improved by 1) reducing the minimum time gap of renegotiation interval; 2) employing multilayer video encoding with finer granularity; and/or 3) increasing the playback buffer size.

Forward error correction based multiple description (MD-FEC) transcoding, which performs unequal loss protection (ULP) for an embedded bitstream, allows robust video transmission over packet erasure channels. However, most of the existing works focus on rate-distortion optimization of individual encoding unit, e.g., a group of pictures (GOP), and do not examine the problem of rate allocation among different units. Such a transcoding strategy would lead to noticeable video quality variations when the video signal is highly nonstationary, and/or when large transmission rate fluctuations occur. In this paper, a novel window-based packetization scheme is proposed for reducing such quality variation through GOP interleaving. Performance evaluations are conducted by using a 3D-SPIHT embedded video encoder.

Unequal loss protection (ULP) for transmitting embedded bitstream over packet erasure networks has been extensively studied. However, most of the existing works focused on rate-distortion optimization of individual encoding unit, e.g., a group of pictures (GOP), which may lead to noticeable video quality variations due to varying channel conditions. In this paper, a novel sliding-window packetization scheme is proposed, which combat bursty packet loss through GOP interleaving. Two levels of rate allocation are introduced: intra-GOP rate allocation minimizes the distortion of individual GOP, and provides hybrid FEC/retransmission packet loss recovery; while inter-GOP rate allocation intends to reduce video quality fluctuations by adaptively allocating bandwidth according to video signal characteristics. Through this way, more consistent video quality can be achieved under various packet loss probability, as verified by our experimental results.

Traditional bandwidth smoothing techniques can be supported naturally by the renegotiated constant bit rate (RCBR) service model, but renegotiation failure in RCBR may cause buffer underflow and interrupt the playback of video. To address this concern, a novel dual-plan bandwidth smoothing scheme is proposed by taking advantage of layer-encoded video. Upon renegotiation failure, the proposed scheme can adaptively discard enhancement layers to guarantee continuous video playback at the original frame rate. Experimental results are provided to demonstrate the validity of the proposed scheme and the impact of playback buffer size on the resulting video quality degradation.