Join Date: Sep 2003
Location: Indianapolis, IN
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Here's a reply I received from WTHR last week concerning the lip/audio sync problem:
Thank you for your e-mail regarding the lip sync on NBC HD programming
on WTHR-DT's DTV channel.
Although I have not seen this problem myself at home (I have an RCA
DTC-100) or at the studio Master Control, and the lip sync is OK in our
HD Master Control and on all of our over the air receivers, I have had
other reports of this from some viewers ever since NBC began airing
prime time HD, but many others report no lip sync problems, so this
seems to vary with the individual receiver and audio setup. It seems to
be exclusively with NBC network HD programming and does not appear to be a problem with the locally upconverted HD programming on WTHR-DT. In
fact, NBC did not send an HD version of 'Las Vegas' last Monday, so we
aired the SD version and several viewers who had a lip sync problem with
HD 'Las Vegas' specifically commented that the SD version carried on
WTHR-DT 13.1 did not have a lip sync issue. So, this does appear to be
only with network HD - and not all programs are cited but "ER" and "Las
Vegas" seems to be mentioned often, most reports are that the "Tonight"
show does not have the problem. We put a brand new encoder on the air a couple of weeks ago and that did not affect the problem, so it does not
seem to be with the encoder.
NBC network HDTV engineering reports that they have occasionally had
similar feedback from other stations in other markets with the NBC HD
program feed and they are still working to see if they can determine a
source of the problem and correct it. It has been difficult for NBC
Engineering to track anything down since the reports are so intermittent
and random, and I've heard nothing new from NBC HD engineering recently.
Based on a pattern of anecdotal evidence from HD viewers, the current
suspicion here at WTHR is that it has something to do with viewers using
5.1 channel Dolby Surround or Pro Logic audio with NBC HD audio. Are
you using 5.1 channel Dolby or Dolby Pro Logic audio on your system?
Many others that report this problem seem to be using Dolby 5.1 or Dolby
Pro Logic - but we are not transmitting Dolby 5.1. NBC provides 2
channel L/R stereo on HD programs and we simply send the NBC HD audio
right through as Dolby encoded 2 channel L/R stereo, so your receiver
should be set to 2 channel stereo on WTHR/NBC HD programs. And I have a couple reports of the problem being resolved by going back to 2 channel
L/R stereo on the DTV receiver. NBC encodes Dolby Pro Logic into its
L/R audio, that may adversely affect any Dolby equipment if it is
incorrectly set and tries to pull 5.1 channel surround or maybe even Pro
Logic audio out of a 2 channel HD stereo transmission.
Director of Engineering and Operations
I tried changing the settings on my audio and DTV receiver as he suggested, but it didn't help me. Maybe it will work for others.