Author Topic: Bluetooth - what's up with that, then?  (Read 645 times)

TimC

  • Old blerk sometimes onabike.
Bluetooth - what's up with that, then?
« on: May 13, 2020, 02:46:20 am »
I've been in the occasional habit of watching music videos late at night via a laptop or iOS device Bluetoothed to my Bose Soundtouch speakers. And very fine an experience it's been. But recently I've found that there is a bit of latency in the system. Not a millisecond or two, but three, four or even five whole seconds' delay between the video and the audio. And it isn't just YouTube (who I was going to have a rant at), but iPlayer, ITVHub and all of the regular video playback apps/websites. Now, all of these work perfectly well through my TV to a Bose soundbar, so why do they not work when a TV is not involved? This appears to be across operating systems, so wtf is going on?

Re: Bluetooth - what's up with that, then?
« Reply #1 on: May 13, 2020, 09:05:13 am »
Have you tried a range of different Bluetooth audio devices to receive? Could just be the Bose Bluetooth speakers.
It is what it is. It's not what it's not, so it must be what it is.

Re: Bluetooth - what's up with that, then?
« Reply #2 on: May 13, 2020, 09:09:43 am »
This isn't really my territory, but isn't bluetooth known for being laggy sometimes?
I note that when using the keyboard at work as well as the one at home, I can type a few letters and it'll be a few seconds before they appear on the scree.
Doesn't happen with either of my wired keyboards.

ian

  • fatuously disingenuous
    • The Suburban Survival Guide
Re: Bluetooth - what's up with that, then?
« Reply #3 on: May 13, 2020, 09:29:28 am »
(Delete and re-pair)x everything is the usual solution. I believe more modern Bluetooth have better low latency and a/v synchronized codecs, but it's a fiddly business. Like most of the diabolical rays that shine out of the backs of our computers, they work when they do and don't work when they don't.
!nataS pihsroW

Re: Bluetooth - what's up with that, then?
« Reply #4 on: May 13, 2020, 09:33:53 am »
iOS and macOS try to retime video to cancel out any Bluetooth lag. Does it resync if you pause and replay?


I can type a few letters and it'll be a few seconds before they appear on the scree.

That is not normal. Sometimes there'll be a tiny bit of lag, but it shouldn't be noticeable for most tasks.

(The lag on audio comes from needing to play it continuously while it's arriving in non-continuous and occasionally lost data packets, which means buffering a second or two in advance of playback to allow for retransmission etc. That doesn't apply to keyboards)

Re: Bluetooth - what's up with that, then?
« Reply #5 on: May 13, 2020, 09:58:52 am »
iOS and macOS try to retime video to cancel out any Bluetooth lag. Does it resync if you pause and replay?


I can type a few letters and it'll be a few seconds before they appear on the scree.

That is not normal. Sometimes there'll be a tiny bit of lag, but it shouldn't be noticeable for most tasks.

(The lag on audio comes from needing to play it continuously while it's arriving in non-continuous and occasionally lost data packets, which means buffering a second or two in advance of playback to allow for retransmission etc. That doesn't apply to keyboards)
TBF it happens fairly infrequently. Enough so as you'd notice, but probably not enough for me to do anything about it - but it does happen - at home on a Mac, at work on a Windoze machine.

Jaded

  • The Codfather
  • Formerly known as Jaded
Re: Bluetooth - what's up with that, then?
« Reply #6 on: May 13, 2020, 10:24:56 am »
(Delete and re-pair)x everything is the usual solution. I believe more modern Bluetooth have better low latency and a/v synchronized codecs, but it's a fiddly business. Like most of the diabolical rays that shine out of the backs of our computers, they work when they do and don't work when they don't.

Ian speaks the truth.

Delete and repair is a standard Bluetooth diagnostic process.

plus newer chips and software have less lag.
If you don't like your democracy, vote against it.

ian

  • fatuously disingenuous
    • The Suburban Survival Guide
Re: Bluetooth - what's up with that, then?
« Reply #7 on: May 13, 2020, 10:30:49 am »
Modern bluetooth hardware seems a lot better – never had an issue with my iMac (which runs a wireless keyboard, mouse, and trackpad). The little dongle that I use with my non-socket iPhone and the headphones, similar. Also between watch and phone.

A/V sync'ing across any kind of data network is a dark art practised by cleverer people than me.
!nataS pihsroW

TimC

  • Old blerk sometimes onabike.
Re: Bluetooth - what's up with that, then?
« Reply #8 on: May 13, 2020, 10:32:49 am »
Have you tried a range of different Bluetooth audio devices to receive? Could just be the Bose Bluetooth speakers.

Ben, I think you’re right. It appears to be the Bose Soundtouch 10 speakers. Perhaps something changed in Bluetooth recently; Bose makes good speakers but its firmware and software is dire, and the ST10s are now quite an old design.

Further investigation (until about 5:30 this morning with a very nice Bordeaux) showed that all of my various BT headphones (including Bose) worked absolutely fine with no discernible lag whatsoever. The other speakers in my Bose collection (ST20 and the Soundbar thingy) also work fine; it’s just the ST10s. They work fine for simple music playback, and don’t display any lag when used in conjunction with the other BT speakers in the house in that mode, but when playing video they are 3-4 seconds behind the action, whatever the source (I tried Windows, MacOS and iOS). The Soundtouch app (another Bose delight) did update them a few days ago; I wonder if that’s the cause.

Mr Larrington

  • A bit ov a lyv wyr by slof standirds
  • Custard Wallah
    • Mr Larrington's Automatic Diary
Re: Bluetooth - what's up with that, then?
« Reply #9 on: May 13, 2020, 12:02:11 pm »
Bluetooth is the work of one of Stan's minor imps – the Big Fella being too busy with wifi – and it is entirely logical to want nothing to do with it :demon:
External Transparent Wall Inspection Operative & Mayor of Mortagne-au-Perche
Satisfying the Bloodlust of the Masses in Peacetime

Kim

  • Timelord
Re: Bluetooth - what's up with that, then?
« Reply #10 on: May 13, 2020, 12:14:24 pm »
Of course it doesn't work properly; it's wireless.
Careful, Kim. Your sarcasm's showing...

TimC

  • Old blerk sometimes onabike.
Re: Bluetooth - what's up with that, then?
« Reply #11 on: May 13, 2020, 02:07:49 pm »
It turns out that the problem is the fact that the two ST10s are being used as a wireless stereo pair. If I use just one, the lag is imperceptible. Used as a pair, the wireless link between them takes bloody ages to do its thing, hence the huge lag with any video source. Bose are quite open about this, so I can't really complain that they're not fit for purpose. There are, apparently video apps that allow a custom delay to video playback to be introduced so that it can be better matched to the received audio output. YouTube, as far as I can tell, is not one of them.

ian

  • fatuously disingenuous
    • The Suburban Survival Guide
Re: Bluetooth - what's up with that, then?
« Reply #12 on: May 13, 2020, 06:50:08 pm »
I sort of assumed this is built into modern codecs, more so given that this data is now commonly delivered over networks, where data packets can occasionally stop off for a coffee before resuming their journey.

Video can get delivered via my NAS under the stairs via wifi and sound comes out of the Sonos speakers perfectly. Look mum, no wires.

OK, I don't know how it all works. Voodoo magicks, I tell you (and I've been to the IEEE office in NJ many times, I evidently didn't soak up anything useful).
!nataS pihsroW

Kim

  • Timelord
Re: Bluetooth - what's up with that, then?
« Reply #13 on: May 13, 2020, 08:39:51 pm »
Delaying video so it syncs with the audio seems a bit perverse...
Careful, Kim. Your sarcasm's showing...

TimC

  • Old blerk sometimes onabike.
Re: Bluetooth - what's up with that, then?
« Reply #14 on: May 14, 2020, 12:42:37 am »
I sort of assumed this is built into modern codecs, more so given that this data is now commonly delivered over networks, where data packets can occasionally stop off for a coffee before resuming their journey.

Video can get delivered via my NAS under the stairs via wifi and sound comes out of the Sonos speakers perfectly. Look mum, no wires.

OK, I don't know how it all works. Voodoo magicks, I tell you (and I've been to the IEEE office in NJ many times, I evidently didn't soak up anything useful).

I haven’t tried it with video served locally. I might give that a go, though it doesn’t help when you’re browsing YT stuff randomly!

Delaying video so it syncs with the audio seems a bit perverse...

If it works, I’ll take it!

Re: Bluetooth - what's up with that, then?
« Reply #15 on: May 16, 2020, 01:49:41 pm »
I have been struggling with the exact opposite problem for the last few weeks.  OBS uses seperate audio and video inputs.  The video goes through a converterbefore import so there is always a video lag and the audio has to be delayed.  With my GoPro and avermedia converter this was about 950ms.  With a Canon M50 and the new streaming utility the lag is about 700ms.  The clap test is fun.  Video yourself clapping, stream to facebook live as a private feed, download video into FCPx, boost audio by 12dB, expand video and measure from audio to visual clap, adjust OBS streaming software and repeat until perfect.

Then start working on virtual cameras to output video to Zoom as well as Virtual audio cable, Voicemeeter, etc for the audio.

Kim

  • Timelord
Re: Bluetooth - what's up with that, then?
« Reply #16 on: May 16, 2020, 02:01:54 pm »
I have been struggling with the exact opposite problem for the last few weeks.  OBS uses seperate audio and video inputs.  The video goes through a converterbefore import so there is always a video lag and the audio has to be delayed.

This is the natural way of things, which is why I said that having to delay the video was perverse.
Careful, Kim. Your sarcasm's showing...