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AJA XenaHS User Manual — Using Xena With Application Software
Xena Control Panel, Windows Media Preferences
Audio Record Delay
—change this slider as necessary for synchronization of audio
during recording. (There is no video delay available for Record.) A factory default
value of 10 milliSeconds provides synchronized audio and video when using
Windows Media Player to playback a “
.wmv”
file to the computer monitor.
Strict Timing (default Off)
—The Strict Timing setting enables software which
enforces strict frame output timing for Windows Media video rendering. (In
technical terms, this enforces a strict correlation between Presentation Time
Stamps and the Graph Clock.). This setting has no effect on video capture.
Under adverse conditions (slow disk, high CPU Usage, clock inaccuracies, etc.), the
computer may not be able to send video frames to Xena fast enough for proper
playback. (This is especially true when playing .AVI files.) In such a case, setting
the “Strict Timing” control to “Off” will allow rendering of the video at low speed.
(With Strict Timing set to “On” for this case, the video playback may "freeze" after
playing for a short duration.)
When playing video for long periods of time, the clock used by Windows Media is
not accurate enough to allow proper playback at true broadcast video rates, unless
software compensation is used. With Strict Timing enabled, the Xena software
corrects for clock drift and jitter caused by the inaccuracy of the DirectShow clock
and time-stamps. The drift-correction and anti-jitter algorithms allow temporally-
accurate rendering of long video streams. When using the Strict Timing setting,
make sure that your PC is powerful enough to avoid delayed delivery of video
frames due to lack of system resources. (This could cause the playback to “freeze”,
waiting endlessly for a frame with a valid time-stamp!)
In Xena software versions prior to 5.2, the Strict Timing setting was in effect
“On”. For 5.2, we have added the option to turn it “Off”. In fact, In order to
allow playback under adverse conditions, we have opted to make “Off” the default
condition. If you need accurate frame timing of your playback video, you should
turn Strict Timing “On”.
