If you are enabling preview when performing multimedia conversions, you should be aware of the following known problems:
Enabling preview conversion requires more system resources. When performing multiple, simultaneous conversions on a single system, it is recommended to disable the preview in order to free up more resources for the conversion processes and avoid out of memory / resource errors.
In multi-monitor systems, you should ensure that the preview window remains on the system's primary monitor. If the preview window is on a monitor other than the system's primary monitor, DirectShow will stop and then restart the underlying graph, which results in a loss of data during the conversion and can also result in corrupted output.
If the system's screen saver activates during a conversion with preview enabled, you may experience data loss or corrupted output due to DirectShow stopping and restarting the underlying graph.
If the system's display resolution changes during a conversion with preview enabled, you may experience data loss or corrupted output due to DirectShow stopping and restarting the underlying graph.
Note that the above issues are more frequently encountered when performing multiple, simultaneous conversions, as is done in the Multi Machine Transcoding Demos which demonstrate the use of the LEADTOOLS Elementary Stream filters.