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Felston DD740 Review (Digital Audio Delay)

Dennis_FL

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You might try turning off all the image processing on your TV. Try setting it to 'gaming' mode if it has one.

It was an LG problem....lots of threads on both Sonos and LG web sites.
 

PeteL

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Active speaker filters? i.e. MiniDSP Flex with 2 or more DACs & amps. Or is it exactly not precise enough in that case?
It's not a bad hypothesis, That's the thing tough, it seems not fully useful for that neither. If we go with 343 m/s for speed of sound, 1/3 of a msec is about 11cm it's a fairly large number if the goal is to keep drivers in phase, but would work well for putting the Subs in phase with the mains, certainly good enough for that. because 11 cm is very small compare of a Sub crossover wavelenght.
 
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dougi

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When lag is bad enough, you can't unsee it. It's not 70's Kung Fu movie bad, but your brain will keep telling you somethings not quite right. Then if you start looking too closely at mouths on the screen the insanity begins.
The Amazon firestick 4k max has a "bouncing ball with beep" test mode when you adjust the audio delay (both ways). It's not bad.
 

dc655321

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I went through 3 sound bars with lip sync issues (2 Martin Logan, 1 Sonos) . The worst was the first generation Sonos with Toslink. The second generation Sonos with eARC HDMI has it solved. Never a problem. Also no problem with an AVR receiver with eARC. Funny that my lip sync problems were only with my LG OLED TV. I have a guest bedroom TV with a sounder that has perfect lip sync.

And I get Atmos now.

I have a 1st gen Sonos bar, toslink to LG OLED, and it works fine for me.
 

Dennis_FL

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I have a 1st gen Sonos bar, toslink to LG OLED, and it works fine for me.
I think my OLED and earlier models had a problem later corrected. Sonos tech support was working with LG but I don't remember any solution. I switched to the Sonos Arc and everything was fine.
 

musicforcities

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Can this device compensate for the delay introduced by some AV receivers? I have a whole house system and downstairs is an open plan so speakers in one area bleed into the others easily. When the signal is run through the AVR in the living room however, the AVR creates a latency of about 1/4 to 1/2 second depending on how much processing it is set to do. No setting, even pure direct, has zero lag. It’s a Yamaha AVR; a Marantz has a tad less delay but still delays on all settings. I have even tried using an external DAC, different the analog inputs, AND different wireless protocols like AirTunes, sonos and echoes…but no dice. It is frustrating.

the only other option i can can think of is a a switch box/splitter that could route the whole house Input signal directly to the external amp for the front channels…that would be far less expensive than this device as well I suppose.
 

CedarX

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Can this device compensate for the delay introduced by some AV receivers? I have a whole house system and downstairs is an open plan so speakers in one area bleed into the others easily. When the signal is run through the AVR in the living room however, the AVR creates a latency of about 1/4 to 1/2 second depending on how much processing it is set to do. No setting, even pure direct, has zero lag. It’s a Yamaha AVR; a Marantz has a tad less delay but still delays on all settings. I have even tried using an external DAC, different the analog inputs, AND different wireless protocols like AirTunes, sonos and echoes…but no dice. It is frustrating.
This device can only add a delay of up to 680ms to a S/PDIF digital signal. So since your AVR is already "late", the question is whether you could insert a DD740 into the chain going to your open area speakers: you'll need to identify a point where you can get an S/PDIF out and S/PDIF in, insert the DD740, and set it up to add a delay that is close enough to what the AVR introduces.
I have a similar setup with no delay issue, but the amp used for the open area speakers is near my AVR, so the whole house DAC output feeds both the amp and the AVR in parallel. The AVR is used as any other analog amp and does not introduce a delay (I don't remember if the analog input I use on the AVR is programmed to be in "direct mode" or no...).
From what you describe, it appears you have two DAC/DSPs in parallel and are trying to sync them in the digital domain--doable, but not necessarily trivial I think.
 

NickJ

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@amirm will know infinitely more than me but I think the real reason is the engineering community was caught unprepared for the huge and fast success of video streaming.
What's amazing is there has never been anything to tie audio to video frames. It seems incredible it has worked as well as it has. The industry for the longest time has treated it as an open loop problem by measuring video delay and adding an equal audio delay whenever it occurs. Obviously anywhere along the broadcast chain an error is introduced there is nothing to catch and eliminate it. At some stages equipment will add the sync marks and maintain sync but they are marking transmissions that were never in sync to begin with.

SMPTE finally has a solution (adding meta data that pairs a video and audio signature of each frame defining sync) but even though the new standard is published I am not aware of anywhere it has been implemented. It suffers from the same "chicken or the egg" problem Tektronix's AVDC100 did over 20 years ago. The AVDC100's imbedded imperceptible signatures of the audio in each video frame to accomplish the same synchronization.

People blamed its lack of acceptance on the fact the scheme messed with the actual audio and video but in my opinion it was the same reason SMPTE's new standard isn't being accepted. Chicken or the egg! No scheme will work until ALL parties implement it! If the content producer doesn't synchronize and mark the original content and if the meta data is not maintained throughout the entire chain and if the equipment to use the meta data to restore sync at the end of the chain doesn't exist NOTHING works. No one entity wants to invest until ALL others have. Plus - even if implemented - it does nothing for prior content. You are definitely right about all the different resolution formats exacerbating the problem today but they didn't cause it. The fact that NOTHING - not even today - defines audio video sync is the root of the problem.
 

sarumbear

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What's amazing is there has never been anything to tie audio to video frames. It seems incredible it has worked as well as it has. The industry for the longest time has treated it as an open loop problem by measuring video delay and adding an equal audio delay whenever it occurs. Obviously anywhere along the broadcast chain an error is introduced there is nothing to catch and eliminate it. At some stages equipment will add the sync marks and maintain sync but they are marking transmissions that were never in sync to begin with.

SMPTE finally has a solution (adding meta data that pairs a video and audio signature of each frame defining sync) but even though the new standard is published I am not aware of anywhere it has been implemented. It suffers from the same "chicken or the egg" problem Tektronix's AVDC100 did over 20 years ago. The AVDC100's imbedded imperceptible signatures of the audio in each video frame to accomplish the same synchronization.

People blamed its lack of acceptance on the fact the scheme messed with the actual audio and video but in my opinion it was the same reason SMPTE's new standard isn't being accepted. Chicken or the egg! No scheme will work until ALL parties implement it! If the content producer doesn't synchronize and mark the original content and if the meta data is not maintained throughout the entire chain and if the equipment to use the meta data to restore sync at the end of the chain doesn't exist NOTHING works. No one entity wants to invest until ALL others have. Plus - even if implemented - it does nothing for prior content. You are definitely right about all the different resolution formats exacerbating the problem today but they didn't cause it. The fact that NOTHING - not even today - defines audio video sync is the root of the problem.
What about PTS used in various MPEG varieties like DVB?
 

NickJ

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That was part of my reason for this comment:

At some stages equipment (like multiplexers) will add the sync marks and maintain sync but they are marking transmissions that were never in sync to begin with.

But I do think formats like MPEG that incorporate audio with video have the potential to maintain sync better if some scheme can close the loop between the content creator and when the material is encoded.

That said, years ago I did run into a DVD (Densel Washington's Inside Man) where the audio was delayed about 40 ms. Normally DVD and BluRay's have much better lip-sync.

I recall one VP of Engineering at a TV station who invested heavily in maintaining sync lamenting that all he could do was not add more sync error because the feeds he received from the network were already out of sync.

The worse thing that has happened more recently is transmissions where the AUDIO is already delayed. There is no way to delay 4K or 8K video to correct that. Luckily it is still rare but it used to almost NEVER happen.
 

sarumbear

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That was part of my reason for this comment:

At some stages equipment (like multiplexers) will add the sync marks and maintain sync but they are marking transmissions that were never in sync to begin with.

But I do think formats like MPEG that incorporate audio with video have the potential to maintain sync better if some scheme can close the loop between the content creator and when the material is encoded.

That said, years ago I did run into a DVD (Densel Washington's Inside Man) where the audio was delayed about 40 ms. Normally DVD and BluRay's have much better lip-sync.

I recall one VP of Engineering at a TV station who invested heavily in maintaining sync lamenting that all he could do was not add more sync error because the feeds he received from the network were already out of sync.

The worse thing that has happened more recently is transmissions where the AUDIO is already delayed. There is no way to delay 4K or 8K video to correct that. Luckily it is still rare but it used to almost NEVER happen.
I worked on TV broadcast for a decade back in the 80s. I then produced TV commercials (30-60s each) and have never experienced a video that had sync issues. I never heard or experienced sync issues on any long form (60m or more) master tape either. I know that transmission feeds are made from copies of the master tapes, hence contrary to what you experience, there are no sync issues before transmission in the UK, France and Germany (where I have first hand experience).

DVB has been the digital standard of TV broadcast in Europe for more than quarter of a century. It is used in many countries from Asia to Africa. We have even switched off analogue TV broadcast in the UK. Sync has never been an issue on broadcast either.

I think the problem you mention is with American systems, assuming your experience is from there.
 

NickJ

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My experience is only with American systems, however our DD340 and DD540 were developed and manufactured in the UK. I think the problem is "sensitvity" to lip-sync error. Or your definition of what "in-sync" means. We have sold nearly as many of our products into the UK, Netherlands and Germany as the US so there "are" people there who see it. Many people are not bothered by 50 to 100 ms lip-sync error and would consider that material to be "in-sync". But we actually had customers ask for adjustment below 1 ms! We added it in the DD740 but in reality few people need it.

But a large number of our customers tell us they adjust down to a few ms to get it perfect. Some even 1 ms. When I started with the company I wouldn't have believed it since I thought if it were within a frame (33 ms here) how could it matter but I soon came to realize to achieve perfect lip-sync one must align the perception created by the moving images with the sound. It has nothing to do with the static images that create that perception. If one frame shows a ball rising into the air and the next frame shows its decent you will perceive ("see") it reach a peak although it is not on any frame. If a crescendo occurs at that peak the sound is somewhere between frames and people who are sensitive to this are bothered by the sync error when it doesn't. Be glad you aren't one of them.
 

Soniclife

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I worked on TV broadcast for a decade back in the 80s. I then produced TV commercials (30-60s each) and have never experienced a video that had sync issues. I never heard or experienced sync issues on any long form (60m or more) master tape either. I know that transmission feeds are made from copies of the master tapes, hence contrary to what you experience, there are no sync issues before transmission in the UK, France and Germany (where I have first hand experience).

DVB has been the digital standard of TV broadcast in Europe for more than quarter of a century. It is used in many countries from Asia to Africa. We have even switched off analogue TV broadcast in the UK. Sync has never been an issue on broadcast either.

I think the problem you mention is with American systems, assuming your experience is from there.
I've noticed sync issue occasionally in the UK, more often when there is a mix of locations in a live broadcast. Drives me nuts when I notice it, fortunately it's rare, and although I think I'm slightly sensitive to it I know I'm not at the extreme end of sensitivity.
 

sarumbear

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You came from:
The fact that NOTHING - not even today - defines audio video sync is the root of the problem.
To limiting an occasional live broadcast issue.
I've noticed sync issue occasionally in the UK, more often when there is a mix of locations in a live broadcast. Drives me nuts when I notice it, fortunately it's rare, and although I think I'm slightly sensitive to it I know I'm not at the extreme end of sensitivity.

I think you are disproportionally amplifying the problem in your head. An occasional live broadcast error which is done via multiple mobile connections is not a situation what you described above. There is a perfectly working sync of audio and video, at least in European TV broadcasts.
 

sarumbear

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My experience is only with American systems, however our DD340 and DD540 were developed and manufactured in the UK. I think the problem is "sensitvity" to lip-sync error. Or your definition of what "in-sync" means.
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 :)
 
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