USB vs Bluetooth audio

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GregH

Well-known member
Joined
Jul 1, 2011
Messages
860
Location
Irvine, CA
Does anyone know if there is compression data loss (ie lower audio quality) over Bluetooth compared to USB (this is for an iPhone)? Or is it the same data by wire or wireless?
 
Definitely. The audio from my son's iPod Touch sounds like crap via bluetooth, but pretty good through the wired interface.
 
Perhaps I am not as discerning, but I thought Bluetooth audio sounded OK.
Maybe you should try it yourself.

Everything depends on the quality of the recording you are playing though.
(e.g., Don't expect 96kbps MP3s to sound great...)

Of all the audio sources, I think XM sounds the most over-compressed.
 
I AM discerning, and I think BlueTooth (via my iPhone) sounds great; in fact, I have abandoned the wired connection (even though it has a nice interface) to take advantage of the seamless operation between phone and music. On the other hand, I don't think XM sounds that good, but if it was up to me I would remove that button! For iPods, it all depends on the quality of the source files.
 
Stanton said:
I AM discerning, and I think BlueTooth (via my iPhone) sounds great; in fact, I have abandoned the wired connection (even though it has a nice interface) to take advantage of the seamless operation between phone and music.
There seems to be a difference in Bluetooth quality between my Android (Nexus S) and iOS (iPhone 4) devices. For whatever reason, Bluetooth seems to play at a lower quality off the Nexus than on the iPhone. On the iPhone, the quality between wired and Bluetooth is almost indistinguishable, but on the Nexus S there's a noticeable difference between Bluetooth and AUX.
 
Packet: there definitely is a difference - for whatever reason, the bluetooth a2dp bitpool is hard-coded to a stupidly low value in most versions of android on the market (including the nexus). Why, I have no idea, but it causes a horrendous audible artifacting with some high frequencies (for example, moderate volume strings are suddenly accompanied by some crackling static-like noise). The only fix I've found for it is to use a mod (Cyanogenmod's latest version has the issue corrected, not sure about others).

If all else is correct, bluetooth audio has enough bandwidth that degradation, even at higher frequencies, should be below audible threshold for even discerning listeners, but there are all-too-often issues such as this one that get in the way, and are often completely unfixable by the consumer...

*edited to correct terminology, it's the bluetooth bitpool that is set low*
 
Interesting! I couldn't tell any difference when playing the same high bit-rate content from the iPhone via bluetooth and wired USB but thought I'd ask... Funny back when satellite radio came out I used to think Sirius sounded better than XM (but both much worse than 160-192kbit mp3 or stuff from iTunes) but over the last few years heard some absolutely terrible compression on Sirius in my Prius. I haven't noticed any such artifacts (thus far) from XM in the Leaf. I know both Sirius and XM (now the same company) have the same bandwidth but not sure which is cramming more channels into it and I think they use different compression strategies. I don't know anything about Bluetooth audio but I assume the USB is sending the raw mp3 data over USB and the Leaf head unit is decompressing(??). I wasn't previously aware that Apple even had a method of pulling real time audio out of a iOS device over USB.
 
OK - interesting about the Nexus vs iPhone.

I am using an iPhone 3, so it makes senses that the Bluetooth audio sounds OK to me compared to others with the Android phones who thought it wasn't as good.

When my XM trial runs out I don't plan to renew based primarily on sound quality, but also repetitive playlist.

Reasonably happy with the UI and sound quality when playing MP3s from memory sticks in the USB slot.
(I leave a flash drive in there all the time, and only fire up the iPhone wireless iTunes when someone else in the car wants to play DJ, for instance from the back seat.)
 
I think the audio through Bluetooth sounds fine.

The quality of XM radio varies wildly from really bad - talk radio - to just too many compression artifacts. There doesn't seem to be a way to find out what bit rate a XM channel is using but I would guess they are using 64 kbit for music and 8 k bit for talk.
 
Interesting discussion. I quit using BT with my iPad 2 because I had to
reestablish the link every time I turned the LEAF off. I read somewhere here
that the USB interface lost the current spot in the playlist when it was turned
off & since I listen almost exclusively to audiobooks, that it a non-starter. So
I always use the AUX input plugged into the phone jack in the iPad.

Of course audiobooks are not very demanding, audio wise, and my 60 YO
hearing is not very discerning.
 
evmike said:
The quality of XM radio varies wildly from really bad - talk radio - to just too many compression artifacts. There doesn't seem to be a way to find out what bit rate a XM channel is using but I would guess they are using 64 kbit for music and 8 k bit for talk.
With the XM's advanced CODEC, 64 kbps sounds equivalent to somewhere between 128 kbps and 192 kbps MP3. In the past, XM has used 64 kbps only for their best quality channels, using bitrates in the high 40k to mid 50k region for many music channels. After they increased past 130 channels or so, they dropped many music channels to 32K or less, and things started sounding pretty bad. I don't know what they're doing currently; when they started duplicating channels with Sirius I dropped my XM subs and kept the Sirius lifetime sub. When I get my LEAF, I guess I'll pick up an XM sub for it. But I will say that in they early days (pre-2005), XM sounded rather good considering that none of their channels was higher than 64 kbps...
 
Happy to report that the Bluetooth audio functionality is dramatically improved with iOS 5 for users of iPhone 3GS, 4, iPad and new iPod touch (and of course iPhone 4s).. Now instead of the bland play and pause buttons, you also get title, artist, album, track, elasped time and the ability to turn on/off shuffle and repeat.. Almost all the same functions as through USB.
 
GregH said:
Happy to report that the Bluetooth audio functionality is dramatically improved with iOS 5 for users of iPhone 3GS, 4, iPad and new iPod touch (and of course iPhone 4s).. Now instead of the bland play and pause buttons, you also get title, artist, album, track, elasped time and the ability to turn on/off shuffle and repeat.. Almost all the same functions as through USB.
Agreed for the built in music player. I hope that Pandora and Slacker will support these features as well.
 
defiancecp said:
Packet: there definitely is a difference - for whatever reason, the bluetooth a2dp bitpool is hard-coded to a stupidly low value in most versions of android on the market (including the nexus). Why, I have no idea, but it causes a horrendous audible artifacting with some high frequencies (for example, moderate volume strings are suddenly accompanied by some crackling static-like noise). The only fix I've found for it is to use a mod (Cyanogenmod's latest version has the issue corrected, not sure about others).

If all else is correct, bluetooth audio has enough bandwidth that degradation, even at higher frequencies, should be below audible threshold for even discerning listeners, but there are all-too-often issues such as this one that get in the way, and are often completely unfixable by the consumer...

*edited to correct terminology, it's the bluetooth bitpool that is set low*
I don't know that the bitpool (buffer?) has to do with it. I can be listening on headphones plugged into my android phone at get that crackling noise, but only at very high volume.

While connected via bluetooth, try turning the volume down on the phone, and compensate by turning the car audio up.
 
Hm... Definitely not the way it worked for me - it happened at all volumes. And I can confirm that going to cyanogenmod has completely eliminated the issue, even at max volume.
 
GregH said:
Happy to report that the Bluetooth audio functionality is dramatically improved with iOS 5 for users of iPhone 3GS, 4, iPad and new iPod touch (and of course iPhone 4s).. Now instead of the bland play and pause buttons, you also get title, artist, album, track, elasped time and the ability to turn on/off shuffle and repeat.. Almost all the same functions as through USB.

I had read this post a few weeks ago and kept meaning to comment.

A few years back I wrote a little app in the app store called ScrollSong. Basically, the point of it is to control your music through simple gestures (i.e. swipe for next track, tap to pause) so that you don't have to look at your phone while driving. The app does also put the album artwork on the iPhone screen and scroll the song text too.

What I've found now that I use Bluetooth Audio is that my app is fantastic when using Bluetooth Audio, especially in the Leaf. While you can use the Leaf's touchscreen or steering wheel control to change tracks and what-not, having the iPhone show the album artwork and track name is kinda cool. Of course, you can still use ScrollSong to skip tracks and control music playback too.

Anyway, for those using Bluetooth Audio and have iPhones here you go (it's FREE):

http://www.ericmarschner.com/scrollsong/" onclick="window.open(this.href);return false;

If you have any ideas for this app, let me know!
 
My 32GB USB flash drive stopped working today. I listened to music from it as I drove to work this morning. I unplugged it from the LEAF when I got to work. During lunch, I plugged it into my laptop to copy a few new tracks to it, but the laptop did not recognize it. When I plugged it back into the LEAF, it did not recognize it, either. Strange that it just died with no apparent cause.

On the way home, I played some tracks via Bluetooth from my Samsung Galaxy II phone. (I have the same tracks as were on the USB drive on a 32GB SD card in the phone.) It sounded fine through Bluetooth, but no titles... Random shuffle and "next" (from the steering wheel) worked OK, I didn't try "back".
 
tps said:
My 32GB USB flash drive stopped working today. I listened to music from it as I drove to work this morning. I unplugged it from the LEAF when I got to work. During lunch, I plugged it into my laptop to copy a few new tracks to it, but the laptop did not recognize it. When I plugged it back into the LEAF, it did not recognize it, either. Strange that it just died with no apparent cause.
I would suspect a poor solder joint in the drive which broke when you unplugged it from the Leaf. Unfortunately, probably nothing you can do. Sucks!
 
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