compression vs compression

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Supreme [H]ardness
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Not really computer audio but was just wondering...

Flac over Bluetooth or mp3 direct?

Just how compressed is Bluetooth when compared to mp3s?
 

Snufykat

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Bluetooth is a wireless transmission technology not a compression technique.
 

FnordMan

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Bluetooth is a wireless transmission technology not a compression technique.

Hint: Do a bit of research before firing your mouth off. Bluetooth is technically both when it comes to audio. There isn't enough bandwidth there to run uncompressed stereo, hence the audio gets compressed to transmit over bluetooth. This may or may not be true as of 4.0 but I still doubt there's enough bandwidth there to run stereo PCM.
 

BillR

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Actually Bluetooth 2.0 and up does contain it's own codec for compression which is being improved up through the newer versions.

The problem with all this is you start with already compressed file (MP-3) for instance and suffer that loss and now you pass it through Bluetooth and recompress (think zip files) and then decode it again.

Article here
 

Disposed

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The question I still have though is which is going tutu sound better. Mp3 direct from the device or flac over Bluetooth. Just curious honestly.
 

Stanley Pain

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Actually Bluetooth 2.0 and up does contain it's own codec for compression which is being improved up through the newer versions.

The problem with all this is you start with already compressed file (MP-3) for instance and suffer that loss and now you pass it through Bluetooth and recompress (think zip files) and then decode it again.

Article here

Zip files are a lossless compression. MP3s and the compression Bluetooth uses are not.

FLAC is like Zip.

The question I still have though is which is going tutu sound better. Mp3 direct from the device or flac over Bluetooth. Just curious honestly.


If your MP3s are at least V0 or 320kbit direct is probably going to sound better.
 

AVT

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There are two questions here:

1. Bluetooth vs Analog

Correct me if I'm wrong, I thought newer versions of Bluetooth used lossless compression? If this is indeed the case, there is no quality loss from using Bluetooth - it transmits the exact file inputted into it.

Note that signal quality could also be a factor here. If the signal quality isn't good enough for lossless compression, it may be that the device could switch to a lossy algorithm so that it transmits something rather than interrupting audio. I don't know if Bluetooth does this or not, but it's very common for wireless devices - think your phone dropping to 2G if it's unable to sustain a 3G signal.

Also, keep in mind that Bluetooth transmits digital audio. If your Bluetooth device has a bad DAC (digital-to-analog converter), it may sound bad.

2. mp3 vs FLAC

I'll quote the following post I made in a different thread on this topic:

3. FLAC is lossless, 320k is lossy. That said, I'm going to say something some will find controversial here: even with high-end audio equipment, you will not tell the difference between them, in a double-blind test. Same goes for other bit rates, perhaps even as low as 192k or 160k. Any difference people think they hear is the placebo effect. Why?

The key here is that while 320k is lossy, it's an incredibly accurate approximation of the original sound. The amount of information lost is tiny - smaller than the information lost due to imperfect headphones, and imperfect hearing. Why? Mathematically, mp3 is just a Fourier series approximation, and since we're approximating sound waves, which excluding the endpoints behave like continuous functions, the Fourier series converges rapidly to the original sound wave - you don't need that much data to get to the point where the human ear cannot tell the difference.

tl;dr, mp3 works just like jpeg, see this: http://www.datagenetics.com/blog/november32012/index.html

tl;dr, for reasonable bit rates and real-world listening it doesn't matter. The sound of your heart beating, birds chirping outside your window, and headphones rustling around on your head degrades the signal more than mp3 vs FLAC does.
 
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cageymaru

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I can tell the difference in a 320k mp3 and a CD. I don't have golden ears. I'm not going to argue it, but there is a difference that I can easily hear. 320k mp3 sound really good for what they are though. I don't feel shortchanged by listening to one, but I know it's limitations.
 

Disposed

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I can tell the difference in a 320k mp3 and a CD. I don't have golden ears. I'm not going to argue it, but there is a difference that I can easily hear. 320k mp3 sound really good for what they are though. I don't feel shortchanged by listening to one, but I know it's limitations.

I think you're hearing more of a difference because of different sources. Rip that CD to flac and then compare from the same source.
 

Snufykat

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Hint: Do a bit of research before firing your mouth off. Bluetooth is technically both when it comes to audio. There isn't enough bandwidth there to run uncompressed stereo, hence the audio gets compressed to transmit over bluetooth. This may or may not be true as of 4.0 but I still doubt there's enough bandwidth there to run stereo PCM.

I like how the "hint" is provided and then explained in a way that contradicts it self. The key phrase in your explanation is "compressed for transmission over blue tooth", not compressed by blue tooth. Even the newer versions of blue tooth still need add on support for compressing audio for blue tooth transmission.
http://en.wikipedia.org/wiki/Bluetooth
http://lifehacker.com/does-bluetooth-audio-still-suck-1505063323
Thanks for the hint.
 

FnordMan

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I like how the "hint" is provided and then explained in a way that contradicts it self. The key phrase in your explanation is "compressed for transmission over blue tooth", not compressed by blue tooth. Even the newer versions of blue tooth still need add on support for compressing audio for blue tooth transmission.
http://en.wikipedia.org/wiki/Bluetooth
http://lifehacker.com/does-bluetooth-audio-still-suck-1505063323
Thanks for the hint.

Congratulations on not engaging your brain again and firing your mouth off.
Look at your own link. A2DP does use compression and it's built right into the bluetooth spec so the devices can do the compression. A2DP info, right off of your own "Bluetooth" link there.
 

Worminater

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Answer: It Depends. The entire chain determines sound quality; and depending on headphones/source/dac/environment; the difference could be negligible/nonexistent.

Justification: I use a pair of Parrot Ziks via BT @ work/travel, Shure se846s when mobile; and a Schiit stack feeding hd650s @ home.
 

defaultluser

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I would definitely go mp3 direct over Bluetooth for two reasons:

1. You have full control over the quality of the DAC/filter stages if you use mp3 direct. Who knows what is inside your average pair of Bluetooth headphones?

2. You don't have to deal with the mess that is Bluetooth! There is support for passing streams directly in newer versions of Bluetooth, but not in older versions of the standard (and last time I looked, those were optional features). Also, the older versions had TERRIBLE compression quality, so you'd need to be sure that both ends support whatever newest standards you desire.
 
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Aaron_ATX

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Probably mostly irrelevant to the conversation, especially since I just now learned that mp3 direct was a thing....

I've noticed bluetooth audio quality in OEM car stereo can be VERY poor from one manufacturer to the next... The factory headunit in my veloster sounds like crap via bluetooth. Compressionmania!
 

Worminater

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Probably mostly irrelevant to the conversation, especially since I just now learned that mp3 direct was a thing....

I've noticed bluetooth audio quality in OEM car stereo can be VERY poor from one manufacturer to the next... The factory headunit in my veloster sounds like crap via bluetooth. Compressionmania!

Very Very Very much true.


My '14 Toyota bluetooth sounds good; I don't really notice a difference (on my admittedly crappy base stereo) between bluetooth and plugging in directly.

I rented a 14 Dodge Dart a few months ago on a work trip; and bluetooth was completely unusable. Wasn't even good enough for audible.
 

AVT

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Probably mostly irrelevant to the conversation, especially since I just now learned that mp3 direct was a thing....

I've noticed bluetooth audio quality in OEM car stereo can be VERY poor from one manufacturer to the next... The factory headunit in my veloster sounds like crap via bluetooth. Compressionmania!

It's not just the Bluetooth. It's also the DAC. The stereo needs to convert to analog before it can play.
 
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