September 26, 2002
Tinic Uro's Flash Vid Tips
Surfing Macromedia's excellent Designer & Developer Center pages, I came across Tinic Uro's Tips for deploying video in Macromedia Flash MX. A Senior Flash Engineer, Uro should be intimately familiar with the video syncronization issues plaguing developers who have experimented with video delivery via Flash MX.
This article well addresses the issues, starting with a bit of history and ending with recommendations and best practices, one of which was new to me and worth noting in and of itself.
His strategy for successful video delivery in Flash MX can be boiled down to two major areas of attention; memory and synchronization:
The former deals with the fact that Flash was originally designed to load all of its media into memory. Video can be quite large at roughly 1MB for every minute of "web quality" video (much larger for CD-ROM quality video) and can quickly exhaust a users memory availability. A workaround for this legacy issue is to "chunk" or "stitch" your content; a technique for segmenting your video into shorter pieces and stringing them together for serial playback. Later chunks replace earlier chunks, keeping your memory requirements from growing out of hand. The latest version of Sorenson Squeeze for Flash MX supports automated stitching.
The latter and new area of attention is that paid to frame rates in your Flash content. If I understand this properly, Flash video synchronization can be detrimentally affected by the way Flash internally handles the math for audio samples and frame rates, creating fractional frame rates that then cause sync slippage when the fractional value is lost in calculations.
To get around this, Uro recommends using "whole" frame rates, and provides a list of recommended frame rates to use:
10, 15, 18, 21, 30.
He also steers us away from the commonly used 12 and 24 FPS, warning that "these settings may cause your elements to play at an accelerated rate".
Check the article for more details and tips.Posted by Lewis Francis at September 26, 2002 12:21 AM