ADS Technologies USBAV-708 INSTANT VIDEOMPX, User Manual

Page: 22 / 116

The
Guide
22
Qu
ic
k S
ta
rt
G
uid
e
No
te
s o
n a
ud
io
VirtualDub contains two modes for processing audio,
these are “
Direct stream copy ” and “ Full processing
mode ”.
In
direct stream copy mode no processing (other than
interleaving) is performed on the audio stream. If it
were desirable when editing an existing AVI file that
only the video stream should be manipulated the audio
mode would be configured as
Direct stream copy in
conjunction with “ Source audio ”. When the new AVI file
was saved the original audio stream would be copied
unmodified from the source.
In
Full processing mode the given audio stream is decompressed and fully
processed when saving, including the application of any filters or
compressors you have selected.
Both
Direct stream copy and Full processing mode have exactly the same
semantics when applied to the video stream as opposed to the audio
stream.
Tip: Using the Audio skew correction (see note 2) in combination with
Direct Stream Copy mode for both audio and video streams allows you to
correct the audio/video sync of any pre-existing AVI file without requiring
recompression of either stream.
When performing Multipass encoding a lot of time can be saved if audio
processing is enabled only during the last pass you intend to save. It is
wasteful processing audio on every pass as each time the previous AVI file
is overwritten, including any audio track it may have contained.
3 .
4 .