Why is Bluetooth audio routing so limited in android?????......... - Page 1
Forum section: electronics / projects

author: Smokey
author_rank: Super Contributor
timestamp: May 08, 2019, 06:29:44 am
content: What is the deal with bluetooth audio routing limitations in android?*Why do you need a hack to play music to a headset with only HSP or HFP profiles? Is this just an artificial limitation so people are forced to buy more expensive A2DP devices? (yes I know HSP and HFP are only mono)*Why can you only have one of the same type of audio device active at a time (can't play music on multiple bluetooth speakers at the same time)?*Why can't you connect multiple bluetooth headsets to the same phone and route audio between them, intercom style?Is there some technical reason for any of this? It all seems silly basic. Why not use the software model that makes a list of connected input and output devices and any input can send to any output like a PC? Is there some fundamental limitation in bluetooth or android or both? It sounds like bluetooth5 is picking up some of these issues, but that all sounds like basic stuff that would have been here from the beginning....thoughts??

author: artag
author_rank: Super Contributor
timestamp: May 08, 2019, 09:29:06 am
content: Initially, it was a limit on bandwidth : you could only have one audio connection without using it all. That was quickly removed when the bandwidth was doubled, and it has since been increased further. I don't know what the current limits are but would have expected it to be more flexible too - even if only handling multiple sets of headphones.

author: Smokey
author_rank: Super Contributor
timestamp: May 09, 2019, 01:17:04 am
content: Interesting. It's hard to believe low bit rate mono phone call quality audio would saturate the bandwidth of anything.

author: artag
author_rank: Super Contributor
timestamp: May 11, 2019, 10:07:52 pm
content: I think it was only 1MBit/s in the initial spec, quickly increased to 2MBit/s, and more recently to 4 ?

author: langwadt
author_rank: Super Contributor
timestamp: May 12, 2019, 01:06:59 am
content: Quote from: artag on May 11, 2019, 10:07:52 pm1Mbit/s was brutto, maximum transfer rate was 721kbit/s, the synchronous mode for audio was much more limited

author: Buriedcode
author_rank: Super Contributor
timestamp: May 12, 2019, 01:12:24 am
content: Quote from: Smokey on May 08, 2019, 06:29:44 amIn general, when people want to listen to music, they want at least reasonable quality, and that requires bandwidth. Before modern codecs the best quality was SBC at ~384kb/sec pretty much maxing out bandwidth. For mono, or simple headsets, there is no need for high quality, so I don't think they saw the need to implement for that profile. A2DP devices aren't particularly expensive. You can pick up a reasonable headset for $10.Quote from: Smokey on May 08, 2019, 06:29:44 amI'm not sure multibroadcast was really required, and it would be tricky because bluetooth speakers aren't completely dumb - they have some inputs that feedback using the speaker/headset profile, so the host would have to implement that for more than one device - which device does the host respond to? Also, would it have to sync the music to both speakers? Because resends, and variations in traffic means they might not arrive at the same time, and if both speakers recieved the same packet, which one would respond? and when? It becomes harder to handle that when dealing with anything other than a simplex system.Quote from: Smokey on May 08, 2019, 06:29:44 amI assume because it isn't something many people would use? How often would you need multiple people, with multiple headsets to connect to your phone - all within 10m as that is the standard range for bluetooth audio - to chat to each other over bluetooth with the phone as a host? Surely it would just be easier for everyone to conference call using their phones? I can't think of any reasonable application for having intercom style bluetooth devices, since generally the headset is merely an extension of the phone, used for hands free.As for Android, yes the bluetooth implementation on it is pretty wonky, but so are most things Android - currently its about 7gig, twice the size of windows 10, and some of the bluetooth drivers are essentially broken. With that said I haven't had any trouble using my headset with my phone.

author: Smokey
author_rank: Super Contributor
timestamp: May 13, 2019, 12:47:35 pm
content: Quote from: Buriedcode on May 12, 2019, 01:12:24 amLoud environments where multiple people are essentially fixed in location over a short distance but need to communicate, possibly in internet dead zones. One is on a motorcycle where you want to communicate with your passenger, or in a limited way other riders in a small group over short distance. The commercial devices (like Sena, which are just headsets with a Bluetooth component designed to communicate directly anyway) are significantly more expensive than it would be to use headsets you already own with a phone you already own. I could see that being useful for pilots as well as an alternative to 2way radios in the cabin.