Introduction
The Internet supports a large variety of useful and entertaining multimedia applications. In this
course, we classify multimedia applications into three broad categories: (i) streaming stored au-
dio/video, (ii) conversational voice/video-over-IP, and (iii) streaming live audio/video. As we will
see, each of these application categories has its own set of service requirements and design issues.
Streaming Stored Audio and Video
To keep the discussion concrete, we focus here on streaming stored video, which typically combines
video and audio components. Streaming stored audio (such as Spotify s streaming music service)
is very similar to streaming stored video, although the bit rates are typically much lower. In this
class of applications, the underlying medium is prerecorded video, such as a movie, a television
show, a prerecorded sporting event, or a prerecorded user generated video (such as those commonly
seen on YouTube). These prerecorded videos are placed on servers, and users send requests to the
servers to view the videos on demand. Many Internet companies today provide streaming video,
including YouTube (Google), Net
ix, Amazon, and Hulu. Streaming stored video has three key
distinguishing features:
Streaming: In a streaming stored video application, the client typically begins video playout
within a few seconds after it begins receiving the video from the server. This means that the
client will be playing out from one location in the video while at the same time receiving later
parts of the video from the server. This technique, known as streaming, avoids having to
download the entire video le (and incurring a potentially long delay) before playout begins.
Interactivity: Because the media is prerecorded, the user may pause, reposition forward,
reposition backward, fast-forward, and so on through the video content. The time from
when the user makes such a request until the action manifests itself at the client should be
less than a few seconds for acceptable responsiveness.
Continuous playout: Once playout of the video begins, it should proceed according to the
original timing of the recording. Therefore, data must be received from the server in time
for its playout at the client; otherwise, users experience video frame freezing (when the client
waits for the delayed frames) or frame skipping (when the client skips over delayed frames).
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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