Using Pre Filtering
You can add Pre Filtering to the capture by adding any installed
DirectShow video filters to the Pre Filtering setup, the filters
are added removed and re-ordered in the Filters Tab of the settings
This feature is designed to allow you to do some video processing
to the video stream before it is compressed and saved to disk,
this is useful for cropping etc.
Filters that come with Virtual VCR
There are a number of Direct Show video filters that come with
the Virtual VCR application, they are located in the filters directory
and can be installed by running the install.bat file that is also
located in the filters directory.
Once installed Virtual VCR will use some of these filters to
do things such as monitor the data throughput of the capture and
show you the capture stats, you can also add some of these filters
to the capture using the Pre Filter Settings to do things like
crop the video to remove video noise around the edges of a video
Some of the filter included when used with Virtual VCR in the
Pre Filter setup have persistent properties, that is these settings
are saved and reloaded when you close down Virtual VCR and re
open it again.
Here is a list of the current video filters that comes with
the Virtual VCR application.
Pre Filter Notes
The pre filters are inserted into the Capture FilterGraph between
the capture filter and the Smart Tee filter. This means that any
filter added also effects the Preview as well so you can see what
effect the filter had to the video in real time.
In nearly all situations it is better to do any pre capture filtering
after you have captured the video footage, it is possible to do
some cropping using the Video Crop DirectShow filter available
as part of the Virtual VCR but apart from that due to performance
it is best to do all filtering after the capture.
Please Note: (Colour Space)
When adding filters it is important that you know
what type of filter you are adding, if the filter can only work
on certain colour formats the intelligent connect feature of the
DirectShow architecture will add the appropriate colour converter
to your FilterGraph. This can have some disastrous effects to
performance and quality.
If you add a filter that only accepts RGB24 and the capture
format is set to YUY2, the FilterGraph will add a colour space
converted to convert from YUY2 to RGB24. This will cause performance
issues and percussion issues.
To see what filter graphed has been built connect to the running
app using GraphEdit and look for colour space converters etc.