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Felston DD740 Review (Digital Audio Delay)

Fred H

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The 12ms TV delay and the 22ms Plex delay bother me about 1/3 of the time, and seem to be related to our level of attention: more attention => more sensitivity. If my wife is particularly interested she wears her glasses -- and notices even a few ms out of sync.
 

sarumbear

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Why don't you correct them if they are fixed? There must be a setting somewhere.
 

NickJ

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There definitely aren't very many looking to adjust down to 1/3 ms! But there are lot who need adjustment better than the 10 ms increments often given them in deeply buried menus. We even seen "lip-sync correctors" which only offer delays in 50 ms increments! Maybe that can work for some? For awhile we wondered if those us with some hearing impairment (I have tinnitus for example) who may partially lip-read might be more sensitive to tiny lip sync error because to us the industry's acceptable range seems absurd. The data for these standards is based on what the average viewer "notices"but the evidence shows that viewers subconsciously avoid the contradiction of reality of sound before the event that creates the sound by looking away from it. Looking away from the lips and faces when confronted with the impossible is the only explanation for how so many people avoid seeing it while many others do. And is the reason for the industry's data based on those viewers.

This is consistent with the Stanford research over 25 years ago which showed viewer perception is negatively impacted when lip-sync is off whether they consciously notice it or not. In that study the adjectives they used for how viewers felt about the characters when lip-sync was off were much the same as we feel about those who do not look us in the eye when speaking. But in this case it is the "viewer" not looking the on-screen characters in the eye! But again lip-sync error masks itself for most people looking askanse and for those who don't care about the negative impact (which is probably slight) it is best not to look for it. Almost everyone I have ever asked to focus intently on the lips sees it. And then gets mad at me since it it hard to "unsee". Search the Internet for the Stanford research on viewer perception by Reeves and Voelker and see what you think.
 

sarumbear

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There definitely aren't very many looking to adjust down to 1/3 ms! But there are lot who need adjustment better than the 10 ms increments often given them in deeply buried menus. We even seen "lip-sync correctors" which only offer delays in 50 ms increments!
There are many questionable practices and products on the market but overall, almost all devices I have seen allowed 1mS increments and as I repeat, I have not seen lip sync as bad as you say it exists, at least in Europe. I cannot talk about Never The Same Colour country :)
 

NickJ

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All Samsung TV's I have seen have a 10 ms adjustment and Vizio's a 20 ms increment. Most AVR's do offer 1 ms increments which is certainly adequate if they would make access easy enough to "tweak" while watching but unfortunately most don't. But as you say "most people" don't see it or need it.
 

Glint

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I use the one in VLC, it can swing both ways, very useful, something out of sync is simply unwatchable.
 

Fred H

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Why don't you correct them if they are fixed? There must be a setting somewhere.
Old TV without sync adjustments; none that I could find for Plex. Regardless, our DD740 fixes sync issues when they bother us.
 

sarumbear

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Most AVR's do offer 1 ms increments which is certainly adequate if they would make access easy enough to "tweak" while watching but unfortunately most don't. But as you say "most people" don't see it or need it.
All AVR's have a setting menu where the AV delay setting is situated. Where do you want them to be, next to the volume control?
 

sarumbear

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Old TV without sync adjustments; none that I could find for Plex. Regardless, our DD740 fixes sync issues when they bother us.
There’s a Plex shortcut: Alt+A and Alt+Sift+A for increase and decrease audio delay.
 

sarumbear

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We use Plex through a TiVo app instead of a PC, but thanks.
TiVo should have the delay control but it seems it doesn't. Lots of people are complaining about audio sync issues on the device. It is pretty pants not to have any audio delay setting and what the company suggests is diabolical. They had two decades to learn how AV streaming works :(

THE AUDIO AND VIDEO ARE OUT OF SYNC.
• The audio and video may re-sync if you change channels.
• You may be able to re-sync audio and video by pressing the REPLAY button on the remote control.
• Press the TiVo button to go to the TiVo Central screen, then press the LIVE TV button to return to live TV.
• Restart your TiVo box.
 

Fred H

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All that TiVo suggests for sync issues is worthless. They certainly should have solved it years ago. Unfortunately, they now seem to be in a milking phase so I doubt they ever will. Hence our reliance on an external audio delay box.
 

CedarX

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@sarumbear You said you worked in TV broadcast... Were you taking into account the average listener distance from the TV screen [edit: speakers] to set an audio delay or were you targeting zero delay? If my math's are correct, when I seat 3m away from my TV [edit: TV speakers], that's a ~9ms delay for any sound to reach my ears. I don't think I care or can even detect this... but if somebody is bothered by 1/3ms delay, adding a few pillow on his/her back should take care of sync issue, no?
 

sarumbear

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@sarumbear You said you worked in TV broadcast... Were you taking into account the average listener distance from the TV screen [edit: speakers] to set an audio delay or were you targeting zero delay? If my math's are correct, when I seat 3m away from my TV [edit: TV speakers], that's a ~9ms delay for any sound to reach my ears. I don't think I care or can even detect this... but if somebody is bothered by 1/3ms delay, adding a few pillow on his/her back should take care of sync issue, no?
You are correct. Some people have what I call, numerititist, obsession with numbers without understanding what they mean. ;)
 

192kbps

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ITU performed strictly controlled tests with expert viewers, which I was one. The results show that threshold for detectability is -125mS to +45mS. If my memory serves me correct ATSC recommends a tighter sync but don't know the numbers. For film, broadcasters in the UK consider lip-synch to be within 22mS in either direction. They very rarely miss that target and mainly on ad-hoc, on-street broadcasts.

If you found customers looking for up to 125 times better sync then good on your company :)
ATSC IS-191:-45ms 至 15ms

EBU R37-2007:-60ms 到 40ms

ITU BT.1359-1:-125ms 至 45ms

ITU BR.265-9:-22ms 至 22ms
 
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