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skeechan
Ai Otsukaholic
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join:2012-01-26
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Re: [iPhone] Bigger Fail Than Maps ...

If bluetooth audio was using the 802.11 working group standards that would interest me.

BT audio is it's own profile within just 1 part of the 802.15 (WPAN) standard and it is well fermented at this point. It is horribly slow and not meant to provide high quality audio. It is merely a solution for short range wireless 2ch audio.

BronsCon
join:2003-10-24
Fairfield, CA

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BronsCon

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You missed my point. Bluetooth does not use a full 20MHz channel to pull off a 320kbps transfer with no room to spare.

EDIT: For the uninitiated, there are 79 Bluetooth channels, each 1MHz wide. Bluetooth 2.0 and 2.1+EDR are 3.0mbps over a single 1MHz channel, with 2.1mbps available to the application (in this case, streaming your 320kbps stream). Bluetooth 3.0+HS (supported by any phone currently on the market in the iPhone 5's price range, and many cheaper models) can use a Bluetooth channel to negotiate an 802.11 connection, then use that for up to 24mbps.

It's on Wikipedia if you don't want to trawl through whitepapers for the info. It's in the whitepapers, if you don't trust Wikipedia.

Count Zero
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Milton, FL

Count Zero

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And show one consumer audio device that uses that... NONE.

skeechan
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If the headsets used WiFi or high profile PAN for their connectivity, great, but they use A2DP (at least all the ones I use) and it's a spectrum hog, 768kbps of a 1-3Mb BT2.1 capacity of which you can use 320kbps for actual audio transport as part of the standard; I'm assuming to permit substantial overhead for retransmits etc.

So while THEORETICALLY you could use that channel space to get decent audio, in practice you don't and the devices set default bit rates in the crapper which is why I stated you can improve quality by changing those default settings in some cases but even then, you aren't going to get good quality from 'em. In practice with the transcoding they'll have 128kbps quality. Not unlistenable but far from great.

Where are you getting 3Mb per channel from BT? BT 2.1 is 3Mb TOTAL from what I've read with 3.0 pushing 24Mb total as you describe.

BronsCon
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My point was that 2.1mbps is a fair bit more than the 320kbps needed and that it's done in a 1MHz, not a 20MHz channel. The bit about BT3.0+HS using 802.11 was secondary, in response to skeechan's comment that he'd be interested to learn such a thing.
BronsCon

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I listed my sources (though I did not link to them -- how did we ever verify sources listed in bibliographies without hyperlinks?).

skeechan
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skeechan

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By actually stating the name/title of the source being referenced. "Various whitepapers" wouldn't have cut it in my day. But whatev. BT audio still blows.
skeechan

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The problem with consumer audio is they don't see the 'reference' bandwidth. They dumb down throughput to ensure reliability, thus bit rates that are in the crapper. So you end up with 64kbps or 128kbps audio if you are lucky.

BronsCon
join:2003-10-24
Fairfield, CA

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I've never had quality issues with bluetooth at any reasonable range (anywhere in my apartment, for example, where I've used Bluetooth for nearly double the typical "it works within 10 meters" range with no issues) except in an electronics store, where I'd get cut-outs if I stepped more than 5ft from the source. It takes a pretty saturated spectrum to cause problems in the real world.

I use it all the time, with decent equipment, and there is no discernible difference between bluetooth, line-out, or playing the file directly on the receiver in well over 99% of cases.

The 3mbps channel gives up 900kbps for the overhead and retransmits you mention, which is why 2.1mbps remains for application usage.

Count Zero
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Your point is meaningless because no one uses it.

You know who DOES send full quality audio over wifi? Apple with their wifi based AirPlay standard... And guess what? Companies DO make airplay compatible wireless speakers...

BronsCon
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Fairfield, CA

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Nobody uses BT2.1+EDR? Uhm... The Bose unit you linked uses it. It's actually quite widely used, if you step outside the Apple store, and it provides plenty of bandwidth for even uncompressed CD quality audio (which requires roughly 1.4mbps).

You're quite likely correct about nobody using BT3.0+HS for audio, but then I never claimed that, did I?

Count Zero
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Count Zero

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You are dense man. The point is everyone uses 128kbps over A2DP not the technically possible if higher quality data rates for Bluetooth audio.

skeechan
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Even on my crappy stuff, I can readily tell the difference between BT audio and wired lossless but then my BT stuff only supports the A2DP profile like just about everything else.

I'll cheer BT audio when it's lossless.

BronsCon
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Am I dense or am I comparing real world experience to someone's hypothetical rambling?
BronsCon

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Maybe your crappy stuff compresses to 64kbps, but my non-crappy stuff does not.

skeechan
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skeechan

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Lots of stuff, particularly headsets and even OS X default to 64kbps.
If you try and ramp up the bitpool, connectivity goes to crap.

Count Zero
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What non-crappy stuff THAT YOU USE does not compress?
Count Zero

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Nothing I've said is hypothetical

BronsCon
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said by Count Zero:

Nothing I've said is hypothetical

Then maybe I meant skeechan?

skeechan
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Thinking of compression, my Airplay devices don't compress, they use ALAC for transport...well it's compression but lossless compression then TOSlink from the APX Airplay receiver to my Denon. I'd like to have airplay headphones, that would be cool.

BronsCon
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One example, my HTC One X and Pioneer DEH-P8400BH seem to do just fine. Now, the cheapie $20 bluetooth headset I bought definitely compresses.
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Airplay would be great if it worked with non-Apple devices.

skeechan
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skeechan

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It works with non-Apple devices, they just have to be licensed; iTunes on Windows to an Airplay equipped Denon for example. In the car I just use wired iPod connectivity with a 240GB iPod video, plenty of space for my ALAC library. I don't bother with BT for audio in the car.

BronsCon
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Sorry, I wasn't clear. What non iPod player can I use as a source?

skeechan
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skeechan

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Airsync for Android can do it but I've only used it with AppleTV. I've never tried it with other Airplay stuff.

BronsCon
join:2003-10-24
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Good to know, thanks

skeechan
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skeechan

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But I don't know if it uses the same protocol, that it is the same lossless transport etc, or if they're just tricking an AppleTV into thinking Android is a "real" airplay source. I just tried it playing a movie for a few minutes from my Transformer and it seemed to work okay.

I just looked at the site they mention it doesn't work with Airport Express which is what I use to stream audio from my Mac's iTunes library to my Denon HT receiver. So something is amiss but obviously they are working on that kind of support.

Airsync does it, so there are probably other apps in the Play Store doing it too, maybe with even better support.

Michail
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Michail

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Do you know if Airsync works with Rhapsody, Spotify and Pandora?

Count Zero
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Listen haven't not heard those two together I cannot definitively say what they sound like.

HOWEVER

Full quality audio will always be better than re-compressed audio and from what I could tell about the devices from the tech specs published online they're sending the audio over A2DP probably re-compressing to a 128kbps audio stream which (1) further degrades the quality of your original media & (2) consumes battery power to do unless you're plugged in - and then you might as well just stream the audio over your USB connection.

Granted cars aren't the best audio platforms in general but I have a 2010 Subaru Outback with the 440W Harmon Kardon stereo with a parametric EQ. I tuned the stereo using pink noise and some settings I found online and it's much better now than when I first got it - but when I drive I notice a significant difference in the clarity and the accuracy of the music between BT and USB. It may be that I listen to a lot of jazz and indie music where that is more noticeable but this is just an example of why I think saying "you can just stream it on bluetooth" is not as good.
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