Programming Flash Communication Server

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

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Chapter 7: Media Preparation and Delivery

Audio compression

With any of the Flash Video encoding utilities, you can encode the audio chan-

nel of your source file with MP3 compression, which supports stereo sound and

higher bit rates than the Speech codec.

Regardless of how you create the FLV files used by your FlashCom application, you

can view any FLV files over HTTP with the progressive download option for Net-

Stream instances in Flash Player 7. Refer to the Preface for details on how this option

differs from streaming support provided by FlashCom.

The Screen Recording Codec

One of the benefits of the Flash Video Exporter over other third-party FLV encoders is

the capability to encode FLV files with the Screen Recording codec. As its name

implies, this lossless codec is designed to work with desktop screen captures. If you

have recorded an AVI or MOV file of a task performed with a desktop application (e.g.,

a tutorial video demonstrating how to use a program such as Flash MX 2004), you can

create a compressed FLV file with the Screen Recording codec for optimal clarity of

screen details. Make sure you use a low frame rate (6 to 10 fps) and a high keyframe

interval (60 or higher) to keep your FLV bit rate from being too demanding for your

target audience’s bandwidth availability.

Converting Prerecorded Material

to FLV Format

It’s not very likely that all of the audio/video material you want to stream to your

users was recorded by your FlashCom Server. Chances are, you’ll have content that

you’ve recorded with other higher-quality capture sources, such as a mini-DV cam-

corder or video output from 3D modeling applications. Your business clients may

even provide you with high-quality video footage for movie trailers, sports or news

clips, or product demonstrations. Most of these files are not going to be in a digital

video format directly supported by FlashCom. For that reason, you’ll need a way to

convert disparate video formats to the FLV file format, the only one that FlashCom

supports.

If you need some sample video content to convert to FLV files, you

can download sample Windows AVI and QuickTime MOV files from

the book’s web site.

Recompressing Video Files

A sure sign of a less than ideal digital video workflow is the act of recompressing dig-

ital video files that have already been significantly compressed with some other