Low Complex Audio Encoding for Mobile, Multimedia

Understanding the Design of Mobile Social Networking

Mobile multimedia applications have become an integral part of modern digital life, offering services such as video streaming, online gaming, virtual reality, and real-time communication. Despite their growing popularity, these applications face inherent challenges due to the limited computational resources, storage capacity, and battery life of mobile devices. Cloud computing has emerged as a transformative solution, providing scalable processing power, extensive storage, and on-demand services. This paper presents a theoretical study on the performance evaluation of mobile multimedia applications in cloud computing environments. The study focuses on key performance metrics including latency, throughput, energy consumption, scalability, and quality of service (QoS). By critically analyzing the impact of cloud integration on mobile multimedia applications, this research identifies the benefits, limitations, and optimization strategies required to improve application performance. The findings highlight the significance of cloud-based architectures, task offloading, and adaptive resource management in achieving efficient and reliable mobile multimedia services.

Demand for mobile video applications is growing today in wireless handheld platforms. Optimizing instruction set architectures and employing SIMD techniques is a logical approach towards attaining higher performance in mobile multimedia applications. Intel® Wireless MMX� technology has been designed to accelerate mobile multimedia and applications processing in a power efficient manner. This paper provides an overview of Intel® Wireless MMX� technology, a 64-bit Single Instruction Multiple Data (SIMD) coprocessor for the Intel® XScale® microarchitecture, and the key features of the architecture that specifically enhance the multi-media performance. Tools and techniques for optimization are also described.

During the last decade, new mobile multimedia applications have emerged for mobile and network multimedia, wireless multimedia communication, audio/video teleconferencing, remote assistance, digital storage systems, secure audio transmission and so on. In order to meet these requirements, tremendous research efforts have been put in the development of efficient digital audio coding technologies. In China, AVS-M audio standard is such an audio technology targeting for mobile multimedia applications which is developed and owned by China Audio and Video Coding Standard Workgroup. In this paper, AVS-M audio standard is discussed by revealing the technical principles of the en- and decoding, the standardization situation and the suitability of the codec in relation to technology available, economical feasibility and the market needs. Finally it concludes with a brief discussion of future research directions.

Mobile applications beyond pure mobile telephony are becoming more and more popular for everyday users. In recent years, with the advent of 3G mobile networks such as UMTS and also higher computing power and storage capabilities of mobile devices, multimedia has reached the mobile user. The user’s individual usage context and needs are becoming more and more important for the design of mobile applications. However, the concepts needed to achieve real comprehensiv user-centric mobile applications are just evolving. In this paper, we present selected concepts and prototypes from our research in the field of mobile multimedia systems that specifically address the mobile user’s needs. We shortly discuss the aspects of user-centered mobile applications and the challenges we see. Our selected research approaches and prototypes show different concepts towards better supporting the concrete user by mobile applications. In this context, we take a look on the specific challenges of image and video retrieval that arise from placing the user in the center of the mobile application design. In our point of view, user-centered mobile multimedia applications pose interesting challenges not only to the retrieval of multimedia content but introduce new challenges and potentials from acquisition, enhancement, storage, retrieval and delivery to the usage of mobile multimedia content.

The major preoccupation regarding the actual research is to visualize a theoretical model of the natural forces interaction between a multimedia mobile application deployed upon an educational activity over a group of students and an automatic process of evaluation regarding the final academic results. We implemented a new metric indicator, named here with effectiveness of a multimedia mobile application, correlated with the educational resultant force emerged from a mobile environment learning experiment. The variables involved in our model are connected to the cross-disciplinary curricula, the educational time coverage disclosed by a multimedia mobile application, the multimedia concentration, and the academic performance measured just in time at the interface between formal and informal evaluation. We are proposing another educational force couple, a resultant force, which is represented by the quality attributes allocated to the mobile devices and, furthermore, to the multimedia mobile applications. We are using the assumption that a multimedia mobile application generates an educational field in front of a learner taking into consideration not only the easiness of the process by which the learner’s attention is retaining toward a mobile device. The fact that between a mobile user and a multimedia mobile application could be established a quantitative relation of physical attraction or rejection, disclosed by surveys and questionnaires including qualities attributes, was an argument for our hypothesis that educational forces encountered could be explained by a cloaking educational field where a touch screen electric impulse is only the beginning of the educational magnetism encountered at the learners.KeywordsMobile applicationsMobile learningAndroidImpact on academic performance

Nowadays, mobile devices demand multimedia services such as video communications due to the advances in mobile communications systems (such us 4G) and the integration of video cameras into mobile devices. However, these devices have some limitations of computing power, resources and complexity constraints for performing complex algorithms. For this reason, in order to establish a video communications between mobile devices, it is necessary to use low complex encoding techniques. In traditional video codecs (such as H.264/AVC (ISO/IEC, 2003)) these low complexity requirements have not been met because H.264/AVC is more complex at the encoder side. Then, mobile video communications based on H.264/AVC low complexity imply a penalty in terms of Rate – Distortion (RD). However, Distributed Video Coding (DVC) (Girod et al., 2005), and particularly Wyner-Ziv (WZ) video coding (Aaron et al., 2002), provides a novel video paradigm where the complexity of the encoder is reduced by shifting the complexity of the encoder to the decoder (Brites et al., 2008). Taking into account the benefits of both paradigms, recently WZ to H.26X transcoders have been proposed in the multimedia community to support mobile-to-mobile video communications. The transcoding framework provides a scheme where transmitter and receiver execute lower complexity algorithms and the majority of the computation is moved to the network where the transcoder is allocated. This complexity is thus assumed by a transcoder, which has more resources and no battery limitations. Nevertheless, for real time communications it is necessary to perform this conversion from WZ to H.264/AVC with a short delay, and then the transcoding process must be executed as efficiently as possible.

High-data-rate mobile multimedia applications can greatly increase energy consumption, leading to an emerging trend of addressing the “energy efficiency” aspect of mobile networks. Cognitive mobile networks with small cells are important techniques for meeting the high-data-rate requirements and improving the energy efficiency of mobile multimedia communications. However, most existing works do not consider the power grid, which provides electricity to mobile networks. Currently, the power grid is experiencing a significant shift from the traditional grid to the smart grid. In the smart grid environment, only considering energy efficiency may not be sufficient since the dynamics of the smart grid will have significant impacts on mobile networks. In this paper, we study green cognitive mobile networks with small cells in the smart grid environment. Unlike most existing studies on cognitive networks, where only the radio spectrum is sensed, our cognitive networks sense not only the radio spectrum environment but also the smart grid environment, based on which power allocation and interference management for multimedia communications are performed. We formulate the problems of electricity price decision, energy-efficient power allocation, and interference management as a three-stage Stackelberg game. A homogeneous Bertrand game with asymmetric costs is used to model price decisions made by the electricity retailers. A backward induction method is used to analyze the proposed Stackelberg game. Simulation results show that our proposed scheme can significantly reduce operational expenditure and CO2 emissions in cognitive mobile networks with small cells for multimedia communications.

In mobile multimedia applications, deep learning has received significant interest. Due to the limited computation and storage resources of mobile devices, however, general training methods are hardly suited for mobile multimedia computing. For this reason, we propose an adaptive momentum training (FWAdaBound) algorithm to reduce computation and storage cost, where the Frank-Wolfe method is employed. Furthermore, we rigorously prove the regret bound in order that O T 3 / 4 can be achieved, where T is a time horizon. Finally, the convergence, cost-reduction, and generalization ability of FWAdaBound are validated through various experiments on public datasets.

Distributed Video Coding (DVC) is a new paradigm for video compression based on the information theoretical results of Slepian and Wolf (SW), and Wyner and Ziv (WZ). While conventional coding has a rigid complexity allocation as most of the complex tasks are performed at the encoder side, DVC enables a flexible complexity allocation between the encoder and the decoder. The most novel and interesting case is low complexity encoding and complex decoding, which is the opposite of conventional coding. While the latter is suitable for applications where the cost of the decoder is more critical than the encoder's one, DVC opens the door for a new range of applications where low complexity encoding is required and the decoder's complexity is not critical. This is interesting with the deployment of small and battery-powered multimedia mobile devices all around in our daily life. Further, since DVC operates as a reversed-complexity scheme when compared to conventional coding, DVC also enables the interesting scenario of low complexity encoding and decoding between two ends by transcoding between DVC and conventional coding. More specifically, low complexity encoding is possible by DVC at one end. Then, the resulting stream is decoded and conventionally re-encoded to enable low complexity decoding at the other end. Multiview video is attractive for a wide range of applications such as free viewpoint television, which is a system that allows viewing the scene from a viewpoint chosen by the viewer. Moreover, multiview can be beneficial for monitoring purposes in video surveillance. The increased use of multiview video systems is mainly due to the improvements in video technology and the reduced cost of cameras. While a multiview conventional codec will try to exploit the correlation among the different cameras at the encoder side, DVC allows for separate encoding of correlated video sources. Therefore, DVC requires no communication between the cameras in a multiview scenario. This is an advantage since communication is time consuming (i.e. more delay) and requires complex networking. Another appealing feature of DVC is the fact that it is based on a statistical framework. Moreover, DVC behaves as a natural joint source-channel coding solution. This results in an improved error resilience performance when compared to conventional coding. Further, DVC-based scalable codecs do not require a deterministic knowledge of the lower layers. In other words, the enhancement layers are completely independent from the base layer codec. This is called the codec-independent scalability feature, which offers a high flexibility in the way the various layers are distributed in a network. This thesis addresses the following topics: First, the theoretical foundations of DVC as well as the practical DVC scheme used in this research are presented. The potential applications for DVC are also outlined. DVC-based schemes use conventional coding to compress parts of the data, while the rest is compressed in a distributed fashion. Thus, different conventional codecs are studied in this research as they are compared in terms of compression efficiency for a rich set of sequences. This includes fine tuning the compression parameters such that the best performance is achieved for each codec. Further, DVC tools for improved Side Information (SI) and Error Concealment (EC) are introduced for monoview DVC using a partially decoded frame. The improved SI results in a significant gain in reconstruction quality for video with high activity and motion. This is done by re-estimating the erroneous motion vectors using the partially decoded frame to improve the SI quality. The latter is then used to enhance the reconstruction of the finally decoded frame. Further, the introduced spatio-temporal EC improves the quality of decoded video in the case of erroneously received packets, outperforming both spatial and temporal EC. Moreover, it also outperforms error-concealed conventional coding in different modes. Then, multiview DVC is studied in terms of SI generation, which differentiates it from the monoview case. More specifically, different multiview prediction techniques for SI generation are described and compared in terms of prediction quality, complexity and compression efficiency. Further, a technique for iterative multiview SI is introduced, where the final SI is used in an enhanced reconstruction process. The iterative SI outperforms the other SI generation techniques, especially for high motion video content. Finally, fusion techniques of temporal and inter-view side informations are introduced as well, which improves the performance of multiview DVC over monoview coding. DVC is also used to enable scalability for image and video coding. Since DVC is based on a statistical framework, the base and enhancement layers are completely independent, which is an interesting property called codec-independent scalability. Moreover, the introduced DVC scalable schemes show a good robustness to errors as the quality of decoded video steadily decreases with error rate increase. On the other hand, conventional coding exhibits a cliff effect as the performance drops dramatically after a certain error rate value. Further, the issue of privacy protection is addressed for DVC by transform domain scrambling, which is used to alter regions of interest in video such that the scene is still understood and privacy is preserved as well. The proposed scrambling techniques are shown to provide a good level of security without impairing the performance of the DVC scheme when compared to the one without scrambling. This is particularly attractive for video surveillance scenarios, which is one of the most promising applications for DVC. Finally, a practical DVC demonstrator built during this research is described, where the main requirements as well as the observed limitations are presented. Furthermore, it is defined in a setup being as close as possible to a complete real application scenario. This shows that it is actually possible to implement a complete end-to-end practical DVC system relying only on realistic assumptions. Even though DVC is inferior in terms of compression efficiency to the state of the art conventional coding for the moment, strengths of DVC reside in its good error resilience properties and the codec-independent scalability feature. Therefore, DVC offers promising possibilities for video compression with transmission over error-prone environments requirement as it significantly outperforms conventional coding in this case.

This paper provides an overview of potential services over MBMS, the broadcast /multicast service of the universal mobile telecommunication system (UMTS), and discusses related business models and service requirements. While MBMS is a suitable data service for some applications already envisaged for the introduction of UMTS (e.g. multimedia message service (MMS) push), MBMS can be an enabler for services that are not feasible over UMTS without major enhanced downlink capacity or broadcast/multicast capabilities. For both of these categories, potential services, their constraints and adequate business models are presented. The paper also analyses the main functional requirements that need to be taken into consideration when defining or dimensioning an MBMS service. Most of these requirements fall into the scope of standardisation. As a consequence, these requirements will have to be considered by relevant standardisation bodies (3GPP, OMA - open mobile alliance) as a way to guarantee that MBMS will meet these service requirements.

Corporations have been using multimedia communications for longer than they may think as any combination of two or more modes e.g. speech and pictures, can be considered multimedia. Consumer sales of personal computers are now being promoted with the low cost availability of multimedia capabilities which now include voice and music, text, graphics and video. This capability is also being promoted into corporations through the application of videoconferencing and other multimedia applications. The imminent arrival of digital wireless bearer services which will extend these capabilities to field based workers is the main technological driver for corporate use of mobile multimedia applications. Considerable obstacles remain to be overcome if the corporate uptake of mobile multimedia applications is to occur within a reasonable timescale. In this paper a number of these obstacles is identified together with mechanisms to overcome them. Experience gained with the first digital wireless bearer service-the Global System for Mobile (GSM) communications-is used to illustrate the obstacles. (4 pages)

Recent trends in mobile computing and multimedia application demand low power digital signal processing systems (DSP). The most important block in any DSP system is a finite impulse response (FIR) filter. Here a reliable low power FIR filter is designed using Vedic multipliers which specifically perform addition and shifting operation. The addition is done using full adder with 9 transistors which use only 3 transistor XOR gate. A four tap FIR filter was implemented in microwind 2 electronic design automation tool using CMOS 90nm technology. In the proposed design the power consumption is reduced by 23% and delay has been reduced by 44% when compared with the existing FIR filters.

This paper presents a high-fidelity speech and audio codec operating at a sampling rate of 32 kHz and a bit rate of 64 kbit/s. Designed primarily for real-time speech communication systems with high port densities, this MDCT-based transform codec has a very low coding delay (8 ms frame size) and low codec complexity (less than 10 MIPS on a 16-bit fixed-point DSP). The codec achieves essentially transparent quality for speech, and very close to transparent quality for music. A novel frame erasure concealment algorithm makes this codec robust to frame erasures for both speech and music. Another novel feature allows the decoder to decode the bit stream directly into a 16 kHz or 8 kHz sampled signal, without the need to decode a 32 kHz signal first and then down-sample it to the target sampling rate. Other novel features include some speed-memory trade-off techniques to reduce the computational complexity.

Launch delay has been an important factor affecting users' experiences in mobile multimedia applications. To launch applications quickly, modern mobile systems such as Android usually keep inactive applications in the background and manage them through an LRU-based activity stack. Whenever the user wants to run and interact with a background application again, that application can be switched back into the foreground quickly from the activity stack without delay in initializing the applications anew. Since background multimedia applications often continuously consume the battery power of the smart phone, the challenge is to effect a balance between application launch delay and battery lifetime. In this article, we propose innovative application management strategies that terminate “unbeneficial” background applications to save energy and pre-launch “beneficial” applications to improve the application launch delay. The proposed strategies are evaluated through a trace-driven simulation and a real experiment. The results show that the average application launch delay can be reduced by 15% while the average battery lifetime is increased by 18%.