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A Streaming Audio Test

Entertainment is the number one reason users access the Internet. While there are still significant challenges to overcome in delivering high quality Internet video over a 28K modem, this is NOT true for publishing high quality audio. The QDesign Music Codec 2 enables users to publish broadcast-quality sound for real-time distribution on the Web. Because the QDesign Music Codec 2 is an Internet audio compression solution for QuickTime 4, producers can add QDesign Music 2 files to any media type supported by QuickTime 4, including video, graphics, interactive VR, animation, and more to create a truly compelling multimedia experience.

I tried this with The Beatle's song "Hey Jude" which I converted from an MP3 format to AIFF in order to then compress it via the QDesign Music Codec 2 into a compressed audio file ready for streaming.

Let's first take a look -or rather a listen- to the unoptimized media, a Quicktime (audio) movie file. The missing optimization might strike you by noticing that first the whole song needs to be downloaded before it actually can be played.
   The Beatles - Hey Jude not optimized for streaming (right-click/control-click here to download this file)
   file size: 1,302,203 Bytes, file format: Quicktime Movie, not optimized for streaming

Thus, streaming an audio file over the Internet requires the possibility to play it in part as soon as data comes in. QuickTime 4 enables media producers to use two types of streaming - HTTP streaming (progressive download) and RTSP streaming (true streaming).

In HTTP streaming, the audience receives the media as the data gets progressively downloaded. QuickTime will begin playing the media when it detects that enough data exists so the entire file can be played through to the end without interruption. This method of streaming has many advantages including no server required, the ability to cache and reply the content, and media can be streamed at a higher quality or data-rate than what the network throughput might support.
   The Beatles - Hey Jude optimized for HTTP streaming (progressive download) (right-click/control-click here to download this file)
   file size: 1,285,192 Bytes, file format: Quicktime Movie, optimized for HTTP-streaming

Its limitations are handled by a method of streaming referred to as RTSP streaming. This method of streaming requires a server that handles the delivery of media in real-time whether that media is captured live or is stored on disk. The server provides a constant stream of media at a data-rate that is consistent with the actual throughput of the network. The audience is able to have more control over the media in RTSP streaming because the server manages and controls how the media is delivered.

For example, a one-hour program would need to be RTSP streamed for several reasons: 1) you would need to have a lot of available disk space to cache a one-hour program, and 2) you may want to skip segments of the program which are uninteresting, in which case, you can seek to a certain segment of the program without having to download pervious segments to disk.

RTSP streaming is most suitable for live broadcast events and lengthy programs, which needs to offer audience some level of control over the playback of the content. The limitations of RTSP streaming is that a server is required and guaranteed network throughput is required for smooth playback of the content.
   The Beatles - Hey Jude optimized for RTSP streaming (true streaming) (right-click/control-click here to download this file)
   file size: 1,993,192 Bytes, file format: Quicktime Movie, optimized for RTSP-streaming


Portions of this text taken from the QDesign Music Codec 2 User's Guide available here in PDF format.
© 2001-04-04 J/S