Vela CineCast 2000-0422, Installation And User Manual

Page: 153 / 196

Chapter 2 — Overview and Operation 139
Two-channel Playback Example
Application Note
Two-channel Playback Example
CineCast Quad Pro Video/Audio Switching Feature
Two adjacent channels (LUNs) are used to provide A/B switching of MPEG
video and audio. The decoder's channels are paired as LUNs 0 and 1 and LUNs
2 and 3. When utilizing A/B switching, the two channels must be genlocked to-
gether to the same genlock source.
NOTE: While in switch mode, a loss of genlock or intermittent genlock may result in
corrupted video and audio.
Video switching is not supported in non-genlock mode. Video switching between
channels occurs during the vertical interval. Audio can be switched between
channels using a 21–341ms fade, or can be switched without a fade.
Example Command Sequences for Video/Audio Switching
This example uses the following commands:
• MPEG Play with “Pause on first frame.”
• Inline Resume 0x0012.
• Inline Audio/Video Channel Section command 0x003C.
For the command sequences below we will assume LUN 0 and LUN 1 are being
used with the video/audio output taken from the LUN 0 output.
Step Note LUN 0 LUN 1
1 • Genlock Command Source =
LUN 0.
• Cmd = 0x0016
• Genlock Command Source =
LUN 0.
• Cmd = 0x0816
2 • Audio/Video Channel Select
“Immediate execution.”
• Primary = source 0 (LUN 0
output).
• Secondary = source 0 (LUN
0 output).
• Video Switch = 10b (LUN 0
output).
• Cmd = 0x003C
• Data = 0x00000080