CGMB 234 Multimedia Systems Design Chapter 01- Part II Introduction To Multimedia Objectives At the end of this chapter, students should be able to: state the FOUR (4) characteristics of multimedia system Describe the THREE (3) levels of interactivity Classify media according to its types Identify the characteristics of multimedia data Explain the concept of QoS(Quality of Service) for multimedia systems Identify the FOUR (4) parameters of QoS for multimedia systems Multimedia Systems Multimedia System Characteristics Digital Format for Multimedia Systems A MM system can reproduce, transmit or Copy its data indefinitely without introducing loss of data quality Loss is only during conversion from analog to digital The same mechanism can be used to store, edit, send or retrieve different types of data Digital data usually take up a lot of storage space Digital data consume a lot more bandwidth during transmission than analog data Interactivity in Multimedia Systems Low Level NAVIGATION This level of interaction focuses on fundamental task of navigating through the information space, either via commands, menus, search engines, or hypertext links. The search engine and the hypertext link are the most sophisticated forms of navigational interactivity. However, even in its most sophisticated form it still limits the user's control to only what they get to access next. Medium Level FUNCTIONAL user interacts with the system to accomplish a goal or set of goals. That goal may be winning, as in the case of a game, or ordering a product, as in the case of an online catalog. Throughout the interaction, the user receives feedback on their progress, or lack thereof, towards the goal(s). The user becomes part of a strong feedback loop. WEB-based applications incorporating functional interactivity are appearing in ever-increasing numbers. These range from games to online ordering, and will become even more common in the future. High Level - ADAPTIVE This is the highest level of interactivity, while the boundary between functional and adaptive interactivity is blurred, there is a key difference. Adaptive interactivity offers a far higher level of creative control to the user, allowing the user to adapt the application or information space to fit their goals, or even their personality. I.e. Websites a higher levels adaptive sites allow users to add or modify the site itself. At this level the distinction between author and reader becomes blurred. intelligent hyper adaptive site interacts with the user and adapts itself to fit the user, readapting as the user's goals, knowledge, or mindset change. such a site will thoroughly engage the user, evolving as the user evolves; even acting as a mentor to the user Integration in Multimedia System The media are treated in a uniform way, presented in an orchestrated way, but are possible to manipulate independently What is a Multimedia System? Multimedia Information Classification of Multimedia Systems Classification of Media Types Time/Space nature Continuous (time-based / temporal) Discrete (space-based/ spatial) Sound Moving Images Still Images Animation Text Graphics Origin Captured From real-world Synthesized By computers Types of Multimedia Systems a) Single user networked applications • Digital libraries • Information Kiosks • Web Page • Video on Demand b) Multi-user networked applications • E-mail • Video phone • Video conferencing •Individual Computer-based Training (CBT) •Individual Computer-based Education(CBE) •Multimedia Authoring Quality of Service (QoS) When we deploy multimedia systems over the internet/network, users are often frustrated by the slow speeds or by the low quality Internet = “Best Effort” approach No guarantee when the data will be delivered No guarantee that data will arrive in the same order as they left the source Or even that they will be delivered at all! This does not meet the requirements of multimedia data very well !!! Multimedia data, especially audio and video, have FOUR (4) characteristics Characteristics of MM Data Characteristics Descriptions Comparisons 1. Time Critical A continuous stream of data is required, at a very high rate 100kbps – 1 Gbps An email can travel at any speed without affecting the quality of the email 2. Synchronisation Some temporal constraints on the arrival of different data types -i.e audio data has to be sync with lip motion Email can have different data types. i.e images • It does not matter if the data for the images arrive at the POP server a little bit later than the email 3. Order of Arrival Data can arrive out of order, but only to a certain extent Traditional internet services such as email imposes no constraints at all on the sequence of data arrival, as long as all the data arrive safely 4. Tolerance to Error Data can be lost without significantly affecting the quality up to a certain extent Traditional internet services such as email have no tolerance to error An email msg that misses out 1 byte of data is regarded as corrupted Quality of Service (QoS) As we can see, there is a severe mismatch between the requirements of multimedia data and the “best effort” approach of the Internet new Paradigm must be adopted If we have unlimited resources, the simplest solution is to upgrade the performance of all components in the infrastructure so the infrastructure can meet the peak demand BUT this is EXPENSIVE, sometime IMMPOSSIBLE Thus, Quality of Service (QoS) is proposed Quality of Service The approach of handling data differently, depending on the nature and requirements, instead of blindly applying the “best effort’ approach to all types of data indiscriminately Quality of Service (QoS) QoS does not create bandwidth, but uses the available bandwidth more intelligently i.e. you can choose between surface mail, airmail or speed post to deliver you letter, depending on how urgent it is. The Post Office handles these three types of letter differently, depending on how much you paid.. QoS can be categorized into four different parameters as described in the following table Four Parameters of QoS Parameters Descriptions 1. Bandwidth • Required bandwidth to carry the data stream to support the service • Not only limited by the infrastructure carrying the traffic, but also by other applications sharing the same resources 2. Delay • The required time for a packet to travel from the sender to the receiver • The longer the delay is, the slower the apparent response of the system • i.e. when user presses the start button on a VOD system, it may take a long time for the video to come though 3. Delay Jitters • variations of the delay • Jitter certainly has an adverse effect on applications that require a constant stream of data • Solution maintain a buffer of data, but too large buffer is not acceptable for applications such as videophone 4. Reliability • Error rate of the transmission system • we do not need very reliable transmission for audio or video data •If its lost, it may not make sense to re-send it because it is not needed by the receiver after a certain amount of time. •Resending simply increases the load of the sender and the network, and without improving the perceived quality of the data Multimedia is Multidisciplinary Computer networks, operating system Image, audio, speech processing Human computer interaction Multimedia computing Computer vision, pattern recognition Computer graphics Multimedia Systems Multimedia systems involve some basic enabling techniques: • Multimedia data representation and compression. • Multimedia data processing and analysis. • Transmitting multimedia data through communication networks. • Multimedia database, indexing and retrieval.