Dolby Laboratories Common Features of the DP571 and DP572, PCM Delay Channel, Metadata

Dolby E Multichannel Distribution System User Manual Introduction

1.6Common 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.

1.6.1PCM 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.

1.6.2Metadata

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.

1.6.3Timecode

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.

1.6.4Video 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).

1.6.5Channel 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

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