Figure 6-6: Dolby-E Frame Alignment; Figure 6-7: Dolby-E Frame Alignment And 720P Video Without Reference - evertz 7721AE8-DEE-HD Manual

7700 MultiFrame Manual
7721AE8-DEE-HD HD-SDI/SD-SDI Audio Embedder with Dolby Encoder
1080i/59.94
720p/59.94
The 7721AE8-DEE-HD can synchronize the Dolby-E packet's start position to output video, or an external
video reference. The start position (also known as the Dolby-E packet phase) can be adjusted using the
"Dolby Line Phase Adjust" control.
Locking to video poses no problems for interlaced video standards.
On the other hand, with progressive video standards, synching to video only can produce a phase error
between two physically separate Dolby-E encoders (since the Dolby-E frame spans two frames in
progressive video standard) even if video is locked. This may be undesirable in certain operational
situations.
720p/59.94
unit #1
720p/59.94
unit #2
Dolby-E Frame x

Figure 6-7: Dolby-E Frame Alignment and 720p Video without Reference

As mentioned, the 7721AE8-DEE-HD can also lock to an external video reference. The video reference
input is provided to allow the Dolby-E packet to be phased to an external source, be it colour black (bi-
level reference) or tri-level reference.
When choosing to use the video reference input, the reference must be locked to input video and must be
interlaced. If input video is interlaced as well, then the frame rate of the reference input must be the
same. For progressive input video, the reference must be half the frame rate of video. The video
reference input is especially useful for phasing up multiple Dolby-E encoders running in 720p video
standards where the Dolby-E frame spans 2 frames.
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Dolby-E Frame x
Frame x
field 1 field 2
Frame x Frame x+1

Figure 6-6: Dolby-E Frame Alignment

Frame x Frame x+1
Dolby-E Frame x
Frame x Frame x+1
Dolby-E Frame x+1
Revision 1.2
Dolby-E Frame x+1
Frame x + 1
field 1 field 2
Frame x+2 Frame x+3
Frame x+2 Frame x+3
Dolby-E Frame x+1
Frame x+2 Frame x+3
Dolby-E Frame x