Acoustica Mixcraft 7 - Manual (Page 184)

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 Variable Bit Rate with Bit Rate Ceiling
This two-pass method uses a variable bit rate, which means that it’s likely
(but not guaranteed) to produce smaller file sizes than the constant bit-rate
methods. With variable bit rate encoding, the bit rate you choose will be
the average bit rate, but actual bit rate during playback may vary depending
on how complex the video is. (Sections of video with lots of motion will
probably have a higher bit rate, and sections with little motion will have
lower rates.) This method has a max rate ceiling, which means that it’ll keep
the highest bit rates from exceeding the average bit rate. Consequently, this
method is better suited to streaming than the Unconstrained Variable Bit Rate
method, but may not produce video of quite as high a quality.
 Variable Bit Rate (Unconstrained)
This method is similar to the VBR with Bit Rate Ceiling method but lacks
the bit rate ceiling. This means that, while your specified bit rate will be the
average bit rate for the video, the bit rate could reach infinitely high (or
at least really, really high) levels during short sections of the video. This
could cause choppy playback during these sections during streaming, but
can also result in higher quality for these sections, making it a better choice
for video to be played back from a hard drive.
AUDIO QUALITY
This section lets you choose the quality sound. It will list all WMV-compatible audio
quality options installed on the computer. Audio almost always uses far less disk space
than video, so choosing a high audio quality setting will rarely have much relative effect
on overall video size. A setting of 128 kbps usually produces acceptable audio quality.
DIMENSION DEMENTIA...
You think audio has lots of format options? We music people have it easy. Video can
have a myriad of options with regard to size, frame rate, compression, and more. Just
to simplify things a bit, “dimensions” refers strictly to a movie’s size, vertically and
horizontally on the screen, expressed in pixels. Here’s a quick primer on sizes and their
typical application:
320x240 - Really small, from back when computers and internet connections had a
tough time handling video content. Rarely used these days.
640x480 - This was the standard for full-screen video on computers for many years,
but has fallen by the wayside with faster processors and online connections.