by Forest Key and Chris Hock
15
additional information on the NTSC and PAL video standards.) To keep
audio and vi deo in synch when creating long FLV files (longer than a couple
of minutes), you must use the accurate frame rates when downsampling the
fps rate.
The pop-up menu to the right of the Frames Per Second text field enables
you to cycle through the commonly used frame rates, but you can enter any
frame rate you want in the Frames Per Second text field.
Quality
Use the Quality pop-up menu to specify the estimated data rate settings for
encoding video at a low, medium, or high quality. This option controls the
value in the Limit Data Rate To text field by computing an approximate data
rate based on the file's frame rate (fps) and size (horizontal and vertical
pixels). If you change the value in the Frames Per Second, Height, and
Width text fields, Flash Video Exporter updates the value in the Limit Data
Rate To text field to reflect the new quality settings. For example, if you
change the frame rate from 24fps to 12fps, then the value in the Limit Data
Rate To text field will be reduced by exactly 50 percent, because the
required bit rate to maintain the given quality level is exactly half if you
reduce the number of frames per second by half.
If the available Quality setting options do not produce the desired quality
results with your particular source footage, sel ect Custom, and then enter a
higher data rate into the Limit Data Rate To text field.
Limit Data Rate To
This setting is the key “quality” variable and indicates the number of bits
per second that are allocated to encode the video. Larger bit rates produce
larger files with higher image quality.
The Flash Video Exporter dialog box displays data rate limit in kilobits or
kilobytes per second. You can choose the unit you want from the pop-up
menu to the right of the Limit Data Rate To text field. Some users might
prefer to think in terms of kilobits while others think in terms of kilobytes.
Those with a background in web development are familiar with bits and
kilobits, because it is a web developer’s duty to keep files as small as
possible for quick downloads. Those with a background in print or video are
accustomed to working with file sizes in the kilobyte, megabyte, and even
gigabyte range and therefore might prefer to work with kilobytes. Simply
put, there are 8 bits in a byte, 8 Kbits in 1 KB, 8 Mbits in 1 MB, and so on.).
When you enter a value x in the Limit Data Rate To text field, you are
essentially telling Flesh Video Exporter, “do not make my final file size larger
than x kilobits or kilobytes for every second. If you have a 10 second clip
and enter a value of 100 KB/sec, you’d end up with a clip no larger than
1,000 KB, or 1 MB. In order to keep down the file size encoders will sacrifice
image quality. To keep the image quality consistent, you can scale down the
clip so fewer pixels per second are represented, or lower the frame rate so
less frames per second are displayed.
When exporting files, you must find the right balance between image size,
file size, and frame rate. For best results, consider your target delivery
(21 pages)
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Comments to this Manuals