Adobe Premiere Pro CS4 - Manual (Page 473)

467 USING ADOBE PREMIERE PRO CS4
Exporting
Last updated 11/6/2011
Work with video in the native format of your project until your final output
If you convert a precompressed digital video format into another format such as FLV, the previous encoder can
introduce video noise. The first compressor already applied its encoding algorithm to the video, reducing its quality,
frame size, and frame rate. That compression may have also introduced digital artifacts or noise. This additional noise
affects the final encoding process, and a higher data rate may be required to encode a good-quality file.
Strive for simplicity
Avoid elaborate transitions—they don’t compress well and can make your final compressed video look “chunky”
during the change. Hard cuts (as opposed to dissolves) are usually best. Eye-catching video sequences—for instance,
showing an object zooming from behind the first track, doing a “page peel,” or wrapping around a ball and then flying
off the screen—don’t compress well and should be used sparingly.
Know your audience data rate
When you deliver video over the Internet, produce files at lower data rates. Users with fast Internet connections can
view the files with little or no delay for loading, but dial-up users must wait for files to download. Make the clips short
to keep the download times within acceptable limits for dial-up users.
Select the proper frame rate
Frame rate indicates frames per second (fps). If you have a higher data rate clip, a lower frame rate can improve
playback through limited bandwidth. For example, if you are compressing a clip with little motion, cutting the frame
rate in half probably saves you only 20% of the data rate. However, if you are compressing high-motion video, reducing
the frame rate has a much greater effect on the data rate.
Because video looks much better at native frame rates, leave the frame rate high if your delivery channels and playback
platforms allow. For web delivery, get this detail from your hosting service. For mobile devices, use the device-specific
encoding presets and the device emulator available through Adobe Media Encoder in Adobe Premiere Pro. If you need
to reduce the frame rate, the best results come from dividing the frame rate by whole numbers.
Note: When you embed video clips in a SWF file, the frame rate of the video clip must be the same as the frame rate of
the SWF file. To encode video using the frame rate of the FLA file, use the Advanced Video Encoding settings in the FLV
Import wizard.
Select a frame size that fits your data rate and frame aspect ratio
At a given data rate (connection speed), increasing the frame size decreases video quality. When you select the frame
size for your encoding settings, consider frame rate, source material, and personal preferences. To prevent
pillarboxing, it’s important to choose a frame size of the same aspect ratio as that of your source footage. For example,
you get pillarboxing if you encode NTSC footage to a PAL frame size.
Adobe Premiere Pro makes several FLV presets available through the Export Settings dialog box. These include preset
frame sizes and frame rates for the different television standards at different data rates. Use the following list of
common frame sizes (in pixels) as a guide, or experiment with the various Adobe Media Encoder presets to find the
best setting for your project.
Modem NTSC 4 x 3 162 x 120
Modem PAL 4 x 3 160 x 120
T1/DSL/Cable NTSC 4 x 3 648 x 480
T1/DSL/Cable PAL 4 x 3 768 x 576