sensitive timing, Dolby E encoders
must
have a reference phase locked to the video. In
other words, the SDI video timing feeding the encoder must match the same composite
reference timing that is connected to the Dolby E encoder. A simple black burst generator
that does not share the same SDI video timing
will not
work to source a Dolby E encoder.
A composite video reference that shares the same timing as the video source should be
used. Typically, SDI video should be run through a frame synchronizer that is utilizing the
same reference as the DE encoder.
The Adtec encoder preserves audio and video timing as it is presented. If the audio timing
does not match video timing at the inputs, there will be potential line placement errors
and/or CRC errors seen on a decoder.
No Detection of Dolby E / Dolby Digital, Front Panel shows “DE ---”, “DP ---”, “LP ---”:
The encoder will automatically detect the bit depth of Dolby E ( 16 / 20 bit ) and the bitrate
of Dolby E / Dolby Digital. If Dolby E is selected and Dolby Digital is presented, the encoder
will change automatically and vice versa. If Dolby Digital is selected and Dolby E is
presented, the encoder will change the configuration automatically. If the front panel shows
dashes for the detected bitrate ‘---’, Dolby is not being detected. This is most commonly
due to a mis-configured SDI Audio Matrix or Dolby not being present on the specified input
pair.
Look at the SDI signal on an SDI analyzer to verify that Dolby is present on the pair
intended. If an SDI analyzer is not available, one troubleshooting tip is to set the mode to
ENCODE. If silence or regular audio is heard on the decoder, a compressed bitstream is not
being presented on the corresponding input. The SDI matrix can be changed to each pair
without restarting the encode session. Once hash is heard, then a compressed bitstream
should be present. Set the mode back to Passthru for the automatic detection mechanism
to configure the Dolby type and bitrate.
