|
|
After you complete the editing phase for your video footage, you're ready to output a final version of your video project that you can import into a Flash document. The following checklist should help you determine how to get the most effective use out of the Flash Player's video codec, Sorenson Spark. Just as you don't want to re-JPEG a JPEG (that is, save a JPEG file again with more JPEG compression), you will find that it's best to retain as much original quality from the video as possible before you bring it into Flash.
Frame size: Most video sources are captured and edited at full frame NTSC sizes, such as 640 x 480 and 720 x 480. It's unlikely that you'll want to expend the bandwidth required to display this full frame size. A starting frame size should be 320 x 240; work your way down from there. If you are targeting Web users with dial-up connection speeds such as 28.8 or 56 Kbps, you may want to consider a frame size of 160 x 120. Remember, when you scale down a bitmap-based element in the Flash authoring environment, you don't actually throw away any pixels — the full size of the graphic is retained in the final Flash movie file (.swf).
Frame rate: When you capture video from your camcorder to your desktop video editing application, the video has a frame rate of 29.97 fps (NTSC) or 25 fps (PAL). This frame rate, as with regular video frame sizes, will consume massive amounts of band width in a Flash movie. As a general rule, keep your video frame rate as close as possible to (or lower than) the frame rate of your Flash movie, as defined in the Document Properties dialog box (Modify ð Document). Most video on the Internet has a frame rate of 12 or 15 fps.
| Note |
As fast broadband Internet connections become more predominant, you'll find more and more sites featuring Flash Video that uses video clips with 24, 29.97, or 30 fps. If you plan to load .flv files at run time into Flash movies with Flash Player 7 or higher, the video content's frame rate can differ from the host Flash movie without any conflict. Slower processors, how ever, may have a more difficult time decoding Flash Video that uses high frame rates such as 24, 29.97, or 30 fps. |
Video compression: Keep your final video file in the codec in which it was originally captured. For example, if you captured and edited the video with the DV codec, use the DV codec for the video file you create to import into Flash 8. You can also use the Uncompressed option (available in Apple QuickTime Player Pro or any video-editing application such as Adobe Premiere or Apple Final Cut Pro) when you save your final video file.
Audio compression: Follow the same guidelines for video compression. DV-formatted video stores audio uncompressed. Flash 8 will recompress audio in a video file that has been imported. As such, it's not ideal to apply any compression to the audio track before you bring it into Flash 8.
De-interlacing: We mentioned earlier in this chapter that video recorded by cam corders is interlaced. However, computer monitors (and the graphics displayed on them) are progressively scanned and do not require interlacing. (You may notice how "soft" your DV footage appears in most desktop video-editing applications; this is due to the even and odd "interlaces" being multiplied to accommodate the progressive scanning of computer video.) The general rule of thumb is to use a de-interlace filter (or export option) on any video footage that you intend to use for computer playback. However, if you resize your video to 320 x 240 or smaller and decrease the frame rate from its original rate, you effectively de-interlace the video footage. Usually, you will not see any difference enabling a de-interlace filter on top of these reductions.
After you have gone through this checklist for your video footage, export a final video file that you can import into Flash 8. Most video applications (including Apple QuickTime Player Pro) can resave a finished video file with a new frame size, frame rate, video and audio compressions, and other options such as de-interlacing. Flash 8 can import a variety of video file formats, listed in Table D-1.
|
Format |
Platform |
Required Drivers |
Description |
|---|---|---|---|
|
AVI (.avi) Audio Video Interleaved |
Windows Macintosh |
DirectX 7 or higher, or QuickTime 4 or higher |
Standard Windows video format; usually the format in which video is captured on Windows; can use any combination of video and audio codecs |
|
DV (.dv) Digital Video stream |
Windows Macintosh |
QuickTime 4 or higher |
Format saved from applications such as Adobe Premiere or Apple QuickTime Player Pro; uses the DV codec for video and uncompressed audio |
|
MPEG (.mpg, .mpeg) Motion Picture Experts Group |
Windows Macintosh |
DirectX 7 or higher, or QuickTime 4 or higher |
Precompressed video in the MPEG-1 or MPEG-2 codec; a format used by many digital cameras that save to media formats such as Compact Flash (CF) and Memory Stick |
|
QT (.mov) Apple QuickTime |
Windows Macintosh |
QuickTime 4 or higher |
Standard video format on the Mac; usually the format in which video is captured on the Mac; can use any combination of video and audio codecs |
|
WMV (.wmv, .asf) Windows Media files |
Windows |
DirectX 7 or higher |
Precompressed video in a modified MPEG-4 codec developed by Microsoft to use with the Windows Media Player |
Of the formats we list in Table D-1, we recommend that you import formats that don't apply any recompression to the original source format of your video. If you can avoid using compressed video such as Windows Media and MPEG files, you can prevent further artifacts from being introduced into the video by Flash's video compressor. Compression artifacts are areas in the video frame where detail is lost. The process of compressing a file already using compression is known as recompression.
| Caution |
If you try to import MPEG files into the Macintosh version of Flash 8, you will not be able to use the audio track in the Flash document (or Flash movie). Only Windows' DirectX driver will successfully convert both the video and audio tracks in an MPEG file to a format usable in the Flash 8 document. To import an MPEG via QuickTime on the Mac, you will need to use an application such as Discreet Cleaner 5.1 (or higher) to convert the MPEG to a QuickTime movie that uses another codec. |
|
|