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Bluetooth from TV to Echo - Latency issues. :-(

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Bluetooth from TV to Echo - Latency issues. :-(
« on: January 11, 2016, 08:20:57 pm »
Hi everyone,
Just got my Echo up and running yesterday for my intended primary application.  I'm significantly hearing impaired, and I wanted a good remote speaker to enhance my TV listening experience without turning up the TV to the point it doesn't work for the other listners.  I bought an Ankur Bluetooth 4.0 Tx/Rx device and paired it with the Echo. It paired easily once I learned the right way to do it.  However, I'm experiencing serious latency to the point that it just doesn't seem to work for this application, unless I fix the latency issue somehow.  I'm estimating the latency, comparing the TV sound output to the Echo's, to be about 0.5 sec.  Anything closer to 50 msec would be acceptable, and anything above 0.1 sec is just too much.  Sometimes, it's so bad, a typical news reporter is well into his/her second or 3rd word in a sentence before the Echo's sound is heard.  I contacted Amazon phone support, and the cust. serv. rep. said this was the first they heard of someone using it for this application.  (Normally, latency with audio-only streaming is not a problem - why would it be?  But, in this application it is.) He said he didn't know what the BT transmission/reception latency "should be" expected to be for the Echo,but as it wasn't part of the design specs, it was probably not prioritized.  OK I see the point, but shouldn't any BT 4.0 device have minimal latency?  I contacted Amazon email support and received the following:

"Generally, there will be not much delay between the Bluetooth signal to Alexa, in this case I'd request you to restart the device as given below:
1. Unplug the power adapter from the back of the device and from the wall outlet.
2. Wait for 30 seconds.
3. Replug back the Alexa to the wall outlet and turn it on.
Once it is done, try to play any music through Bluetooth to see if it works fine without any delay. " 

I followed this script, and latency wasn't improved. (After a few tries, some pairing was worse than others, but none were better than about 0.2 sec in my estimation.
So, does anyone know what is to be expected in terms of latency?  More importantly, how do I optimize it?  Do I need a different piece of hardware?
Thanks!
John

Re: Bluetooth from TV to Echo - Latency issues. :-(
« Reply #1 on: January 12, 2016, 01:35:32 am »
There have been many posts here and elsewhere about the problems with Echo, BT, BT speakers, and TV audio lag time.  It basically doesn't appear to work that well, even when using a dedicated BT speaker. So, I suggest you get a non-BT powered speaker or set of wired headphones to plug to TV to get the job done.

 Get a headphone extension cord to plug into when you actually want to use them so the cord isn't always across the room.

Re: Bluetooth from TV to Echo - Latency issues. :-(
« Reply #2 on: January 12, 2016, 08:24:12 pm »
Hi,
Thanks for the reply.  I should have made this clear in my quest for suggestions:
I am looking for a way to decrease the latency of the bluetooth transmission so that I can avoid wires but at the same time hear the TV from its own speakers, synchronously with the Echo.  So here's the specification of the question:
Keep the Echo
No wires
Must be able to play the Echo and TV audio at same time.
I am not interested in adding a delay to the TV video to sync up with the Echo; this doesn't fix the issue that the TV's audio and that of the Echo are not in sync.
I would tolerate perhaps 10-50 msec of lag (latency).  This is barely perceptable.  Anything above 0.1 sec (=100 msec) is distracting and unacceptable.

I have something to add to the above.  I called Amazon technical support, and the technician I spoke with told me this:
They are aware of the issue.  The tech I spoke with agreed that the existing bluetooth lag is about 0.3-0.5 sec (300-500 msec).  He said that Echo developers are working to improve the lag and they are hopeful it will put it in the "acceptable" range.  There will be an update released by the end of the month.

Let's hope the above statement will actually become reality.  Again, I'm not looking for perfection (zero latency), but something under 50 msec would allow me to use the Echo for the purpose I thought it would serve: as a supplemental sound production device in addition to the TV's built in speakers without the "echo" effect.

Re: Bluetooth from TV to Echo - Latency issues. :-(
« Reply #3 on: January 13, 2016, 02:27:13 pm »
Certainly hope Amazon keeps their promise and improves the situation on their end.  There is also the other side of the equation. and that is the delay in the Anker BT RX/TX lag time in it processing the TV sound to transmit. 

Good luck with this issue.

Re: Bluetooth from TV to Echo - Latency issues. :-(
« Reply #4 on: February 19, 2016, 10:53:37 pm »
I seen some posts elsewhere and they suggest that the only way to ensure there is a minimal delay is to make sure that the Bluetooth devices support the aptX codex.  You can purchase Bluetooth adapters for the tv audio that support this.  I do not know if the Echo incorporates the aptX codex.
« Last Edit: February 19, 2016, 11:20:08 pm by bomer »

Re: Bluetooth from TV to Echo - Latency issues. :-(
« Reply #5 on: May 17, 2016, 08:58:24 am »
One of the contributors to signal latency in any electronic Input-Conversion-Output (ICO) electronic circuit is not only delays in time, but also changes in phase when compared to the input. These differences are accounted for by electronic buffers, Capacitance, Inductance and phase shifting of normal signal processing, which is usually 180 degrees of the input for that circuit only. If for example there are 10 transistors to process a given signal, then the phase change is 1,800 degrees of the input signal. Signals only need to be 180 degrees out of phase to cancel each other.
Many of the Digital to Analog converters incorporate inherent 8bit, 16bit, 32bit, 64bit, 128bit, 256bit and higher input buffers to store the digital signal so that minor disruptions of the input signal do not affect the output signal as it is converted. To fill a 256 bit buffer it takes a minimum of 256 clock pulses. It may not seem like much, but it all adds up in the end. In the TV, the signal may be tapped off at a different location in the circuitry, sent to the Bluetooth, get amplified and mixed thru the RF multiplexer, transmitted, received, then de-muxed, ran thru the D2A converter, buffered, amplified thru a minimum of 3 stages of analog amplification then sent out to the speaker.
That's just a lot of stuff that has to be done electronically to get that TV signal over to a BT speaker and each step adds delay and phase distortion to the input signal. Even a conscious electronic engineer circuit designer can only minimize the delays, but cannot eliminate them.
Sometimes it can be accomplished closely but not exactly by delaying the signal output to one set of speakers so that to match the longest delay of any of the speakers.
« Last Edit: May 17, 2016, 09:19:43 am by additude »

Re: Bluetooth from TV to Echo - Latency issues. :-(
« Reply #6 on: May 17, 2016, 09:50:31 am »
How do you know the latency issue is with the Echo and not the Anker? I would suggest pairing the Echo to a modern PC or laptop, to verify the latency is indeed an Echo issue.

Re: Bluetooth from TV to Echo - Latency issues. :-(
« Reply #7 on: May 17, 2016, 01:54:24 pm »
Perhaps the comment below from the user manual for my Taotronics model TT-BA06, BT Transmitter; (http://www.taotronics.com/media/downloads/TT-BA06%20User%20Manual.pdf
can clarify this issue for good.

Q: Why is there a slight delay in the audio?
A:  Bluetooth is not designed as an instantaneous transmission protocol.  Due to the compression and decompression of the audio data, a variable delay will always exist.  This is completely normal, and exists across all Bluetooth devices.

BTW, this is great little transmitter (I got at Amazon).  I can plug it into the headphone out jack of an iPod, have the Dot receive the BT signal, and Dot inputs the audio into the stereo system.  Voila, I am playing a Playlist from my iPod into my stereo via Dot.

Re: Bluetooth from TV to Echo - Latency issues. :-(
« Reply #8 on: May 17, 2016, 02:01:25 pm »
Bluetooth is not designed as an instantaneous transmission protocol.

True, but some devices are better than others; to to the processing power available. I have a Mini Jamboz connect to a Macbook Pro and notice minimal latency (low enough so that A/V sync is not disturbing).