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Why does Bluetooth audio transmission must use compression?

escksu

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I agree that it’s a multiuser device but you use neither the headset nor the car while listening on headphones, and neither mouse nor keyboard requires any comparable bandwidth. The codec AptX is designed to be adaptive, why not make the top end lossless from the start? However, it looks like, and as you said, “better audio was not priority”. Even though the market was full of higher and higher quality wireless headphones and speakers and every Hi-Fi magazine was full of reviews.

It looks like Qualcomm had been sleeping. A very typical behaviour when you own the market.

This is because right from the start, bluetooth was not designed for audio streaming purpose. Its designed as a very low power and short range personal area network. One main goal is to allow wireless communication between mobile phone and computer.

Data compression is one of the most common method and effective method to achieve higher throughput.

Btw, there is no real demand for CD quality because most of the users are playing MP3.
 

Garcia

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~2.1Mbps would be the maximum application throughput of Bluetooth EDR (an optional extension of Bluetooth) under ideal conditions. Considering how populated 2.4GHz bands are nowadays expecting Bluetooth to come close to 1.5Mbps at a sustained rate is not realistic. Also most devices don't even implement Bluetooth EDR due to its high power usage and Bluetooth LE maximum application throughput is ~1.4Mbps.

Even at LDAC's 1Mbps bitrate most users struggle to keep a stable connection when they disable variable bitrate.
 
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sarumbear

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This is because right from the start, bluetooth was not designed for audio streaming purpose. Its designed as a very low power and short range personal area network. One main goal is to allow wireless communication between mobile phone and computer.
Bluetooth became a standard in 1998, A2DP protocol introduced in 2003, just 5 years later. We are now almost 20 years in that Bluetooth had capacity to transmit audio.
 

Lambda

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The thing with this "lossless" aptx codecs is they are not lossless.
At least not all the time. they operate only lossless if:

Air time and bandwidth is available
Reception is good
And if the Source material is Actually compressible.

If not thy adaptively fallback to "near-lossless"
 
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sarumbear

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The thing with this "lossless" aptx codecs is they are not lossless.
At least not all the time. they operate only lossless if:

Air time and bandwidth is available
Reception is good
And if the Source material is Actually compressible.

If not thy adaptively fallback to "near-lossless"
Something to test for @amirm ?
 

BeerBear

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However, it looks like, and as you said, “better audio was not priority”. Even though the market was full of higher and higher quality wireless headphones and speakers and every Hi-Fi magazine was full of reviews.
Our hi-fi bubble is not representative of the "real world", so to speak.
BT audio has more important problems that need to be addressed first, such as latency. (This is finally getting better now in version 5.2.)
And frankly, a decent lossy codec at ~200kbps sounds fine, while being more reliable than, say, a 1Mbps lossless stream. How many people would prefer the latter, if it meant that playback is sometimes interrupted?

So yeah, lossless BT audio would be nice to have, but it has costs. Uncompressed, it needs a lot of bandwidth. Compressed, it needs more power, plus you have latency to deal with. Once these costs become low enough and/or it makes economic sense, we might see it happen.
 

maverickronin

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Here's another wrinkle. Doubling up on lossy compression is more likely to be audible. An audio source is using lossy compression which may very well be perceptually transparent. One of the higher rate bluetooth codec may be perceptually transparent as well. Running one lossy source through another lossy codec is likely to introduce audible artifacts that neither would in isolation.

This actually makes lossless BT a very desirable proposition. If you want the sound to be perceptually lossless by the time it gets to your ears though a lossy BT codec you probably need to use a lossless source. This can use a lot of space and/or bandwidth on a mobile device. Lossless BT would not further degrade existing lossy sources and save space/streaming bandwidth.

I don't even own a pair of bluetooth headphones though, so I haven't even informally tested this with BT codecs.
 

fieldcar

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To me, LDAC is far more than I'd ever need. I'm even mostly happy with SBC.

index.php
 

escksu

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Bluetooth became a standard in 1998, A2DP protocol introduced in 2003, just 5 years later. We are now almost 20 years in that Bluetooth had capacity to transmit audio.

I was referring to the inability for bluetooth to stream lossless/uncompressed audio.
 

escksu

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Here's another wrinkle. Doubling up on lossy compression is more likely to be audible. An audio source is using lossy compression which may very well be perceptually transparent. One of the higher rate bluetooth codec may be perceptually transparent as well. Running one lossy source through another lossy codec is likely to introduce audible artifacts that neither would in isolation.

This actually makes lossless BT a very desirable proposition. If you want the sound to be perceptually lossless by the time it gets to your ears though a lossy BT codec you probably need to use a lossless source. This can use a lot of space and/or bandwidth on a mobile device. Lossless BT would not further degrade existing lossy sources and save space/streaming bandwidth.

I don't even own a pair of bluetooth headphones though, so I haven't even informally tested this with BT codecs.

MP3 is also lossy. BBC did a test quite sometime ago to see if pple could tell the difference between MP3 and uncompressed audio and which once they feel is better.

Turns out that quite most couldnt and quite a number through the MP3 sounds better.

So, this also shows that difference between lossy and uncompressed audio isnt big...
 

Doodski

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MP3 is also lossy. BBC did a test quite sometime ago to see if pple could tell the difference between MP3 and uncompressed audio and which once they feel is better.

Turns out that quite most couldnt and quite a number through the MP3 sounds better.

So, this also shows that difference between lossy and uncompressed audio isnt big...
I've home AB tested the difference between MP3 and FLAC files and found that unless it is a ~2666kbps file in FLAC format that I can't hear a difference between the same songs.
 

escksu

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Our hi-fi bubble is not representative of the "real world", so to speak.
BT audio has more important problems that need to be addressed first, such as latency. (This is finally getting better now in version 5.2.)
And frankly, a decent lossy codec at ~200kbps sounds fine, while being more reliable than, say, a 1Mbps lossless stream. How many people would prefer the latter, if it meant that playback is sometimes interrupted?

So yeah, lossless BT audio would be nice to have, but it has costs. Uncompressed, it needs a lot of bandwidth. Compressed, it needs more power, plus you have latency to deal with. Once these costs become low enough and/or it makes economic sense, we might see it happen.

Yes, hifi is just a very niche and tiny market compared to entire audio market. I believe we can see that the main focus on bluetooth today is portability, not lossless audio. Most of the people who bought bluetooth headphones/earphones is to be able to connect to their mobile phones and listen on the go.

Another thing to note is that bluetooth has massive congestion and interfference issues which limit their bandwidth. Imagine a few hundred pple in the train using bluetooth devices.
 

ThatM1key

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Bluetooth became a standard in 1998, A2DP protocol introduced in 2003, just 5 years later. We are now almost 20 years in that Bluetooth had capacity to transmit audio.
The CD became a thing in 1982, In 1988 we got AIFF, In 1991 we got WAV, then FLAC was introduced in 2001, Just 11 year's later we were starting to have cheap playback machines that actually can handle and reproduce 16-bit content. It just takes a while for tech to evolve, especially for when you have a budget.
 

Chrispy

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Something to test for @amirm ?
Would like to see more extensive tests but not sure Amir is going to want to dedicate any more time than he already has for various device types....

OTOH can't imagine relying on BT for anything really....
 
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