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Dolby E Multichannel Distribution System User Manual Introduction
1-15
1.6 Common Features of the DP571 and DP572
This section discusses the most important common features between the encoder and
decoder. See Chapter 3 – DP571 Dolby E Encoder and Chapter 4 – DP572 Dolby E
Decoder for complete references for both units.
1.6.1 PCM Delay Channel
The encoder and decoder each impart an audio delay equal to one video frame. When
feeding a pair of channels on a digital VTR, the non-encoded pair would be out of sync
with the encoded signal. To compensate for the delay, the encoder and decoder both
contain a one video frame PCM utility delay.
1.6.2 Metadata
Metadata can be supplied to the DP571 encoder via an RS485 connection. During
Dolby E decoding, the DP572 outputs metadata on an RS485 connection. Metadata can
also be generated internally in the DP571.
1.6.3 Timecode
SMPTE Linear Time Code (LTC) can be applied to the unbalanced BNC connector on
the DP571, and can be recovered during decoding from the unbalanced BNC connector
on the DP572. Both connectors are marked LTC. The time code data is carried as part
of the Dolby E bitstream.
1.6.4 Video Reference
An analog composite video reference signal is required for Dolby E encoding and decoding.
Versions 1.05 and later support two frame rates: 29.97 Hz (NTSC) and 25 Hz (PAL).
VITC information can be extracted from the video reference signal sent to the DP571 (for
more information, see Time Code Input on page 3-9).
If the video reference signal is not present or invalid, the:
• DP571 will not encode a Dolby E bitstream;
• DP572 will stop decoding the Dolby E bitstream;
• Dolby E output on the encoder and the PCM outputs on the decoder will be muted;
• VRef LED will be red (if not present) or yellow (Vref unequal to frame rate).
1.6.5 Channel Configuration
Because neither the DP571 nor DP572 permit internal remapping of the audio channels,
the following channel configuration must be used to input a 5.1-channel signal to
the DP571:
L/R →
→→
→ Digital Inputs 1/2
C/LFE →
→→
→ Digital Inputs 3/4
Ls/Rs →
→→
→ Digital Inputs 5/6