5 ms·

Audio over Bluetooth: most detailed information about profiles and codecs (2019)

68 points by schaum 6y ago

samstave 6y ago
Might be a lame question, but can BlueTooth connections be intercepted and "heard" ? If so, How?
- elitepleb 6y ago
  You just get some hardware that can monitor the traffic like greatscottgadget's ubertooth one. As for recreating the audio, you'd have to deal with capturing the key exchange handshake and cracking it.
- tgsovlerkhgsel 6y ago
  Bluetooth supports solid encryption once paired, but the pairing is usually unauthenticated and thus subject to man-in-the-middle attacks. Whether the encryption is implemented correctly and on (with strong enough keys) by default on most devices is another question of course.
- SwaraLink 6y ago
  Bluetooth has the Secure Simple Pairing (SSP) feature, and Bluetooth Low Energy has the LE Secure Connections feature, which both use Elliptic Curve Diffie-Hellman Key Exchange and therefore is protected against passive eavesdropping. The standard also includes the ability to support authenticated pairing for protection against Man-in-the-Middle attacks; if you've ever had to see if a 6-digit number matches on the two devices that are being paired, then you are seeing the authenticated pairing taking place. Even though the Bluetooth standard includes these features, many products don't actually use them and simply transmit data without any encryption or authentication procedure. This is particularly a problem with many Bluetooth LE products.
amelius 6y ago
Can't we just replace this standard by WiFi? That would be one less standard to deal with. And much better bandwidth.
- iancmceachern 6y ago
  Too much power for small devices like earbuds or iot devices.
  - amelius 6y ago
    That depends on how long you want to use them. For some the trade-off against sound quality, features and user-friendliness might be favorable.
  - rektide 6y ago
    the shield tv's controller (2015) was wifi based, & could transit audio. it's not tiny, but it shows wifi was viable for a latency-sensitive battery-powered system five years ago. for many headsets i'd think it would be quite doable but yes i'm not sure we've scaled wifi down to earbud sized devices. and yes power consumption is afaik higher. it feels mainly like an adoption / standardization problem. we have chromecast speakers galore & wow is it nice having devices available over the network. alas there's no standardizations, no cooperation, no system for wifi to be useful. other than the very limited controlled & closed ones.
    - iancmceachern 6y ago
      That controller had a 2600 mah battery for ~60 hours of operation. Much larger in power capacity and volume than what is suitable for tiny earbud like devices. https://batteriesglobal.com/products/nvidia-shield-battery?variant=32349283844174&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic https://batteriesglobal.com/products/nvidia-shield-battery?v...
      - rektide 6y ago
        Ok so 260 mah for 6 hours? Using some 5 year not-that-fancy-at-the-time old technology (Ozmo2000)? That does far far far far more than send audio? That is much lower-latency than what we'd need to compete with Bluetooth (which radically increases wireless power needs)? For comparison, Google Buds are 120 mah & 5 hours. All we need is a 2x improvement in power, for a far less complex device, & we've had 5 years? You are making the case for me my man. This sounds more doable than I thought!! Miniaturization is indeed a challenge. Who does make really small wifi units? Who do they sell to? How much smaller do they need to be? I suspect it's simply never been a goal. And why would it be? There's no protocols that make wifi even potentially compatible with these sort of consumer device systems, no matter the size! Even with what we have today though, a wifi microphone or wifi gaming headset should be easily possible, no challenge at all, and could have far better quality & likely latency than what we expect from bluetooth. And I rather believe we could make smaller wifi if we had an interest in doing so. We are limited by our imaginations, our imaginations and our lack of standards/will.
amelius 6y ago
Why can't Bluetooth pair with more than one audio sink at the same time? I mean, watching a movie on a laptop with a friend is not a strange requirement, is it?
- baybal2 6y ago
  It can, it's just the non-lunux userspace cannot. The problem is the fine synchronisation - possible to do with a lot of effort in current linux stack, but most commercial vendors just turn it off because they don't want to bother.
  - amelius 6y ago
    Why don't these vendors lose the certification then?
    - baybal2 6y ago
      I think it just never been a part of it. Only hardware is BT SIG certified I believe, not userspace software.
- rektide 6y ago
  Bluetooth LE Sharing was announced a year ago[1], that is for broadcasting to multiple receivers. There's no (nearly no?) products for it yet. It is fairly low bitrate & has some fresh new codec specifically for it, I believe. I really wish wifi had some standards for this sort of stuff too. [1] https://www.bluetooth.com/bluetooth-resources/introducing-bluetooth-le-audio/ https://www.bluetooth.com/bluetooth-resources/introducing-bl...
- inetsee 6y ago
  This may not be exactly what you are asking for ... but a search on Amazon for "bluetooth transmitter 2 devices" turns up several devices. I'm using it with a TV, but I don't see why the transmitter couldn't be plugged into the audio out on a laptop to send the audio to two devices.
- akvadrako 6y ago
Fannon 6y ago
I wonder how the new Bluetooth LE Audio with the new LC3 codec would fare in this comparison. See https://www.bluetooth.com/learn-about-bluetooth/recent-enhancements/le-audio/ https://www.bluetooth.com/learn-about-bluetooth/recent-enhan... There's on thing in the current state of bluetooth audio that actually bugs me: Once you use a microphone, the audio quality significantly degrades from the usually stereo audio quality (which is good enough for me). I'm curious when we'll see LE Audio in broad adoption and how much of an improvement it will actually be.
- ValdikSS 6y ago
  It's still not clear whether LE Audio supports high quality duplex audio. They say you can use it for microphone, but that doesn't certainly means voice communication (both listening and speaking at the same time).
jnsie 6y ago
I have been searching in vain for a Bluetooth transmitter that can transmit from my tv to 2 Bluetooth headsets and supports Dolby surround (so that I don’t have to switch my TV to PCM every single time I switch to headphones). So frustrating
- sgtnoodle 6y ago
  This seems like something that could be done easily in the analog domain. Most TVs have a 3.5mm or RCA line-out, line-in to bluetooth adapters are cheap, and analog signals can be fanned out with a passive splitter. In practice, the conversion to analog and back shouldn't have any noticable effect. The bluetooth adapter is going to compress the stream anyway. Depending on what you're hoping for, though, bluetooth might have too much latency. Media players on mobile devices and PCs are aware of the fact that they're outputting to a bluetooth audio device and compensate for it by delaying the video as well.
twistedcheeslet 6y ago
For a complete Bluetooth layman like myself, this was a fascinating read. Alongside god and the manufacturer, I now know to curse the standards body too whenever trying to connect these damn headphones!
perlpimp 6y ago
Upon coming up on sound guys article it became apparent why Apple has cut the cord. Their compression is top notch - I have experimented with various bt headsets/headphone/bt-amps. Apple AAC implementation keeps layering and detail much more compared to AptX HD counterparts - using same devices across the range.
wombatmobile 6y ago
> Unfortunately, as of 2019, the quality of voice transmission via Bluetooth is still poor, and it is not clear why Bluetooth SIG is not doing anything about it. I would speculate there is no party with a strong interest in voice only communications participating in the Bluetooth SIG. That's because the biggest industry group for voice only communications has its own wireless standard, DECT. I've been trying to find a way to pair bluetooth hearing aids with a DECT landline phone but as far as I can see, no landline phone manufacturer has implemented Bluetooth Hands Free Protocol to work with hearing aids. This surprised me. My 89 year old mother's hearing aids can pair with iPhone and Android, but she doesn't use a mobile device so I need it to pair with an ordinary DECT landline phone. I understand both landlines and old people are declining markets. Anyway, to confirm this blank I had to peruse a lot of DECT and Bluetooth standards. Bluetooth Profile Specifications and compliance therewith are a rabbit hole, difficult to navigate because DECT phone device manufacturers don't publish capabilities.
- trav4225 6y ago
  Landlines may be declining but, in most of the world, I'm pretty sure that "old people" is a growing, largely untapped market.
  - wombatmobile 6y ago
    To clarify, I meant old people who don't use touch screen phones.
    - trav4225 6y ago
      Ah, yeah, I suspect you're right that, for a variety of reasons, tomorrow's 80-year-old is more likely to use a smartphone than today's 80-year-old.

68 points by schaum 6y ago

samstave 6y ago

Might be a lame question, but can BlueTooth connections be intercepted and "heard" ? If so, How?

elitepleb 6y ago
You just get some hardware that can monitor the traffic like greatscottgadget's ubertooth one. As for recreating the audio, you'd have to deal with capturing the key exchange handshake and cracking it.
tgsovlerkhgsel 6y ago
Bluetooth supports solid encryption once paired, but the pairing is usually unauthenticated and thus subject to man-in-the-middle attacks. Whether the encryption is implemented correctly and on (with strong enough keys) by default on most devices is another question of course.
SwaraLink 6y ago
Bluetooth has the Secure Simple Pairing (SSP) feature, and Bluetooth Low Energy has the LE Secure Connections feature, which both use Elliptic Curve Diffie-Hellman Key Exchange and therefore is protected against passive eavesdropping. The standard also includes the ability to support authenticated pairing for protection against Man-in-the-Middle attacks; if you've ever had to see if a 6-digit number matches on the two devices that are being paired, then you are seeing the authenticated pairing taking place. Even though the Bluetooth standard includes these features, many products don't actually use them and simply transmit data without any encryption or authentication procedure. This is particularly a problem with many Bluetooth LE products.

amelius 6y ago

Can't we just replace this standard by WiFi? That would be one less standard to deal with. And much better bandwidth.

iancmceachern 6y ago
Too much power for small devices like earbuds or iot devices.
- amelius 6y ago
  That depends on how long you want to use them. For some the trade-off against sound quality, features and user-friendliness might be favorable.
- rektide 6y ago
  the shield tv's controller (2015) was wifi based, & could transit audio. it's not tiny, but it shows wifi was viable for a latency-sensitive battery-powered system five years ago. for many headsets i'd think it would be quite doable but yes i'm not sure we've scaled wifi down to earbud sized devices. and yes power consumption is afaik higher. it feels mainly like an adoption / standardization problem. we have chromecast speakers galore & wow is it nice having devices available over the network. alas there's no standardizations, no cooperation, no system for wifi to be useful. other than the very limited controlled & closed ones.
  - iancmceachern 6y ago
    That controller had a 2600 mah battery for ~60 hours of operation. Much larger in power capacity and volume than what is suitable for tiny earbud like devices. https://batteriesglobal.com/products/nvidia-shield-battery?variant=32349283844174&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic https://batteriesglobal.com/products/nvidia-shield-battery?v...
    - rektide 6y ago
      Ok so 260 mah for 6 hours? Using some 5 year not-that-fancy-at-the-time old technology (Ozmo2000)? That does far far far far more than send audio? That is much lower-latency than what we'd need to compete with Bluetooth (which radically increases wireless power needs)? For comparison, Google Buds are 120 mah & 5 hours. All we need is a 2x improvement in power, for a far less complex device, & we've had 5 years? You are making the case for me my man. This sounds more doable than I thought!! Miniaturization is indeed a challenge. Who does make really small wifi units? Who do they sell to? How much smaller do they need to be? I suspect it's simply never been a goal. And why would it be? There's no protocols that make wifi even potentially compatible with these sort of consumer device systems, no matter the size! Even with what we have today though, a wifi microphone or wifi gaming headset should be easily possible, no challenge at all, and could have far better quality & likely latency than what we expect from bluetooth. And I rather believe we could make smaller wifi if we had an interest in doing so. We are limited by our imaginations, our imaginations and our lack of standards/will.

amelius 6y ago

Why can't Bluetooth pair with more than one audio sink at the same time? I mean, watching a movie on a laptop with a friend is not a strange requirement, is it?

baybal2 6y ago
It can, it's just the non-lunux userspace cannot. The problem is the fine synchronisation - possible to do with a lot of effort in current linux stack, but most commercial vendors just turn it off because they don't want to bother.
- amelius 6y ago
  Why don't these vendors lose the certification then?
  - baybal2 6y ago
    I think it just never been a part of it. Only hardware is BT SIG certified I believe, not userspace software.
rektide 6y ago
Bluetooth LE Sharing was announced a year ago[1], that is for broadcasting to multiple receivers. There's no (nearly no?) products for it yet. It is fairly low bitrate & has some fresh new codec specifically for it, I believe. I really wish wifi had some standards for this sort of stuff too. [1] https://www.bluetooth.com/bluetooth-resources/introducing-bluetooth-le-audio/ https://www.bluetooth.com/bluetooth-resources/introducing-bl...
inetsee 6y ago
This may not be exactly what you are asking for ... but a search on Amazon for "bluetooth transmitter 2 devices" turns up several devices. I'm using it with a TV, but I don't see why the transmitter couldn't be plugged into the audio out on a laptop to send the audio to two devices.
akvadrako 6y ago

Fannon 6y ago

I wonder how the new Bluetooth LE Audio with the new LC3 codec would fare in this comparison. See https://www.bluetooth.com/learn-about-bluetooth/recent-enhancements/le-audio/ https://www.bluetooth.com/learn-about-bluetooth/recent-enhan... There's on thing in the current state of bluetooth audio that actually bugs me: Once you use a microphone, the audio quality significantly degrades from the usually stereo audio quality (which is good enough for me). I'm curious when we'll see LE Audio in broad adoption and how much of an improvement it will actually be.

ValdikSS 6y ago
It's still not clear whether LE Audio supports high quality duplex audio. They say you can use it for microphone, but that doesn't certainly means voice communication (both listening and speaking at the same time).

jnsie 6y ago

I have been searching in vain for a Bluetooth transmitter that can transmit from my tv to 2 Bluetooth headsets and supports Dolby surround (so that I don’t have to switch my TV to PCM every single time I switch to headphones). So frustrating

sgtnoodle 6y ago
This seems like something that could be done easily in the analog domain. Most TVs have a 3.5mm or RCA line-out, line-in to bluetooth adapters are cheap, and analog signals can be fanned out with a passive splitter. In practice, the conversion to analog and back shouldn't have any noticable effect. The bluetooth adapter is going to compress the stream anyway. Depending on what you're hoping for, though, bluetooth might have too much latency. Media players on mobile devices and PCs are aware of the fact that they're outputting to a bluetooth audio device and compensate for it by delaying the video as well.

twistedcheeslet 6y ago

For a complete Bluetooth layman like myself, this was a fascinating read. Alongside god and the manufacturer, I now know to curse the standards body too whenever trying to connect these damn headphones!

perlpimp 6y ago

Upon coming up on sound guys article it became apparent why Apple has cut the cord. Their compression is top notch - I have experimented with various bt headsets/headphone/bt-amps. Apple AAC implementation keeps layering and detail much more compared to AptX HD counterparts - using same devices across the range.

wombatmobile 6y ago

> Unfortunately, as of 2019, the quality of voice transmission via Bluetooth is still poor, and it is not clear why Bluetooth SIG is not doing anything about it. I would speculate there is no party with a strong interest in voice only communications participating in the Bluetooth SIG. That's because the biggest industry group for voice only communications has its own wireless standard, DECT. I've been trying to find a way to pair bluetooth hearing aids with a DECT landline phone but as far as I can see, no landline phone manufacturer has implemented Bluetooth Hands Free Protocol to work with hearing aids. This surprised me. My 89 year old mother's hearing aids can pair with iPhone and Android, but she doesn't use a mobile device so I need it to pair with an ordinary DECT landline phone. I understand both landlines and old people are declining markets. Anyway, to confirm this blank I had to peruse a lot of DECT and Bluetooth standards. Bluetooth Profile Specifications and compliance therewith are a rabbit hole, difficult to navigate because DECT phone device manufacturers don't publish capabilities.

trav4225 6y ago
Landlines may be declining but, in most of the world, I'm pretty sure that "old people" is a growing, largely untapped market.
- wombatmobile 6y ago
  To clarify, I meant old people who don't use touch screen phones.
  - trav4225 6y ago
    Ah, yeah, I suspect you're right that, for a variety of reasons, tomorrow's 80-year-old is more likely to use a smartphone than today's 80-year-old.