Vela CineCast 2000-0422, Installation And User Manual

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Chapter 2 — Overview and Operation 71
DECODER Command (45h)
Any gain value requested which is outside the valid range will be limited to
+12dB to -84dB. When a value of 0dB is requested, the firmware will use the
bypass mode provided within the FPGA. Default power-up gain is 0dB, which
provides unity gain from Vela Encoders through the CineCast Quad Pro.
Bits 8 and 9 of the command determine the analog headroom of 18dB or 20dB.
This only effects the analog outputs and does not affect the digital/embedded
audio. Default is 18dB headroom, matching Vela audio/video encoders.
000C Slow Motion: This commands slows the playback rate. A three-bit field
(bits 8-10 of the command) determines playback speed.
Examples of Actual Gain Parameters
Actual Gain
Gain Parameter
(Gain x 16)
+12dB 0x0c0
+2.5dB 0x028
0.0dB 0x000
-2.5dB 0xfd8
-12dB 0xf40
-84dB 0xac0
Command Bits Function Name Comments
Bit 8 Primary Headroom 0 = 18dB Headroom
1 = 20dB Headroom
Bit 9 Secondary Headroom 0 = 18dB Headroom
1 = 20dB Headroom
Bits 10–8 Playback Speed
000b Normal rate (each frame is displayed once)