Table Of Contents
Content Creation Best Practices Guide for Cisco Digital Media Designer 5.2.x
Revised: February 28, 2011
Tip This information is updated as needed. Its newest and best revision is on Cisco.com
Note This guide includes tips and techniques for users of Cisco Digital Media Designer, specifically.
This guide does not describe any application programming interface (API) calls that registered Cisco developers and other advanced users can invoke to handcraft playlists outside of DMD. To learn about these APIs, see http://developer.cisco.com/web/dms.
About This Guide
We prepared this guide for design professionals whose creations will play on Cisco Digital Signs. Such specialists already understand the concepts and methods that apply to content creation for personal computers. However, they want to understand the best ways to prepare and composite digital media assets for rendering by embedded, solid-state systems.
DMD Guidelines for SWF Animations
These guidelines cite values that are approximate. Do not deploy any design until you have tested its playback performance on at least one DMP.
Rather than crashing when they run low on memory, DMPs are designed to restart automatically. This behavior clears their memory and causes downtime of much less than 1 minute, as opposed to the lengthy downtime that a hard crash would cause. In the rare cases when DMPs do run out of memory and restart automatically, SWF files are almost always responsible. The known scenarios when this can occur are as follows.
•The file size is greater than 500KB for your SWF file. Larger SWF files do work correctly in most cases, but we recommend as a best practice that you should always strive to use the smallest possible SWF files. Smaller files are far less likely to be burdensome to your DMPs.
•Your SWF file uses bitmapped image files outside itself that have a very large file size, either individually or collectively. Any bitmapped image files that you use in the production of a SWF file should be small files. If a bitmapped file has a large file size, it is important for you to understand that merely reducing the height and width of its placeholder on your canvas in Adobe Flash (or any similar authoring tool that you might use to develop a SWF file) will not reduce the actual file size.
•The web page that you are showing uses too many embedded SWF files.
Additionally, we recommend that you use the following guidelines when you create SWF files.
•The resolution of the SWF can be up to 1920 x 1080 when animations within the SWF are small and are restricted to a 640x480 region.
•Avoid redraw of the whole screen in your Flash animation.
•Multiple movements on different parts of the screen cause more slowdown than localized movement.
•The FLV recommended resolution should be 320x240.
Quality Control Considerations for SWF Animations
•Verify per project that output quality and playback performance are both acceptable for all assets — no matter how you developed or acquired them — on all DMP models that you use.
•Never delete or overwrite your Flash (FLA) source file. You can modify its settings to produce suitable output for various DMP models.
•Consider carefully how bandwidth limitations anywhere in your network might affect playback.
Transparency Considerations for SWF Animations
•We do not support transparent SWF files.
•Alpha transparency is most effective for objects whose dimensions are less than 200px X 150px.
Performance Considerations for SWF Animations
We consider an animation to be nonstandard when it does not abide by our best practices to limit complexity and use DMPs effectively. And any animation is complex — for our purposes — when its playback uses so much of the CPU capacity on a DMP that performance suffers. These guidelines suggest how to avoid and reduce complexity in ways that improve performance.
•Ensure that each animation is smaller than 640 x 480 pixels.
•Ensure that none of your animations contain any embedded or referenced object whose dimensions are greater than 640 x 480 pixels.
•Ensure that you have not used more than one animation effect per timeline segment. For example, do not fade an object in a segment where you also resize an object.
•When you use an animation effect to resize an object, avoid changing its dimensions by more than 10 percent per timeline segment.
•Split the animation apart by function, into smaller files. For example, instead of combining a text ticker and a slideshow in one file, isolate them inside two separate animation files.
•We recommend that your animation frame rate be 12 frames per second (fps) or less.
Text Considerations for SWF Animations
•DHTML's "marquee" method is an effective way to produce a text ticker.
•When your design includes a text ticker:
–Ensure that the ticker is not any wider than 1,366px.
–Ensure that the text height is not any greater than 28pt.
Bitmap Considerations for SWF Animations
DMD Guidelines for Audio
•We do not support the Dolby Digital Plus (E-AC3) audio codec.
•We do not support audio in SWF files.
Tip You can use video editing software to add an audio track to an MPEG file.
DMD Guidelines for Video
Progressive, Not Interlaced
Interlaced video is inferior to progressive-scan video. Modern equipment must expend some of its capacity to deinterlace what is interlaced. By avoiding interlaced video, you can conserve this capacity and expend it on more important functions.
DMP Model Implications for Video
•DMP 4305G endpoints do not support MPEG-2 TS/H.264.
•We recommend that you use MPEG-2 instead of FLV.
Aspect Ratio Implications for Video
When the width and height of a rectangle are exactly the same — making it a perfect square — we say that its aspect ratio is "1:1." This notation compares width to height in relative terms. However, there are actually two aspect ratios to consider when you think about digital video.
•The frame aspect ratio describes the entire visible space, which contains every pixel.
•The pixel aspect ratio describes the shape that contains merely one pixel.
Note Use a 1:1 pixel aspect ratio when you encode video for playback at a resolution of 1366 x 768 pixels.
•Avoid refreshing any webpage frequently on DMPs. Instead, we recommend that you use AJAX or Shockwave Flash (SWF) to load dynamic content.