HOWTO find which codec is used between iOS device and bluetooth headphones
Aug 14, 2019 at 8:45 AM Post #17 of 26
I highly doubt the quality of LDAC implemented in bluetooth.

Here is a rant of the LDAC by an audio related site. Spoiler: A low efficiency lossy codec that is good for nothing.
https://www.soundguys.com/ldac-ultimate-bluetooth-guide-20026/
Thats a load of garbage that the guy wrote. I completely agree with the top comment on that "blog"

this is the top comment.
"How did you perform these tests? As far as I know, no software LDAC decoder implementation is available. I suppose you disassembled an LDAC-supported headphones or a speaker, and recorded the output.
This is not a correct method for comparison testing, because modern Bluetooth DAC SoCs have additional features like equalizer, compander and more, configured per-codec.
You've tested the audio path of the exact device, not the codec itself. I don't say your results are totally incorrect, but take that into account."
 
Aug 14, 2019 at 12:18 PM Post #18 of 26
Thats a load of garbage that the guy wrote. I completely agree with the top comment on that "blog"

this is the top comment.
"How did you perform these tests? As far as I know, no software LDAC decoder implementation is available. I suppose you disassembled an LDAC-supported headphones or a speaker, and recorded the output.
This is not a correct method for comparison testing, because modern Bluetooth DAC SoCs have additional features like equalizer, compander and more, configured per-codec.
You've tested the audio path of the exact device, not the codec itself. I don't say your results are totally incorrect, but take that into account."

There are a few drawbacks listed on the page I have linked earlier, including cut off frequency, THD, non compliance to A2DP profile, prone to interfere etc. The first comment you quoted questioned just about a difference aspect -- the binary output of the codec.

A measurement of identical bit stream from the output as the input is a proof of a perfect codec in term of fidelity. Only lossless codec can achieve that.

Unfortunately, LDAC is a lossy codec. The output of the decoder differs from the input of the encoder.

How do we compare lossy codec? The usual objective analog measurements such as THD, cutoff frequency, latency, etc are valid measurement, even when it was taken from the analog output.

Why? Because the hardware implementation are often suboptimal due the technical constraints. One of the examples is Apple hardware handles AAC codec much better than Android vendors out there.
Poor performance on Android phones is not the codec’s fault
The key finding from all of the tests is that Android smartphones perform much worse than Apple’s iPhone when using the AAC codec. However that’s not surprising: Android simply doesn’t handle AAC well.​

Hence, the actual implementation has to be taken into the account. Measuring the analog output is still a valid representation of the total solution. As least, it represented the subject measured, LG V30.

Hence, while there are other advantages of the LDAC, such as higher bitrate, the findings of the soundguys site still hold.
 
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Sep 25, 2019 at 1:48 PM Post #19 of 26
shure se535 - iphone se a2dp bitrate.png
I have tried the suggested method and found out that the Shure BT1 bluetooth cable came with SE-535 connects with an iPhone SE using 327 kbps (bit pool = 53)

Just to remind: BT1 supports bluetooth 4.1 and Iphohe SE supports bluetooth 4.2.

When I measure the bitrate between iPhone SE and JBL GO 2 bluetooth speaker (which is BT 4.2), it connects with 300 kbps (bit pool = 48). This is kind of weird, because JBL GO2 supports BT 4.2, but it connects with a lower bit rate..

Anyway, this method was very helpful for me, because I am convinced that the Shure BT1 cable is OK for me, because my music is at most encoded with 320 kpbs MP3 or 256 ACC...
 
Apr 14, 2020 at 7:46 PM Post #20 of 26
Hi rshev, I've got a problem with my iphone XR and my car. I've scoured the web and it appears that you are an expert, so I'm hoping you can offer some advice or perhaps closure? There are many other people with the same problem and apparently the best solution is to buy a 3rd party Bluetooth receiver and wire it into your car. Pretty sad. Lot's of Apple service tickets but no solutions.

The problem is A2DP audio streaming. The music, podcast, sound from a video skips horribly. It's intermittent but rarely can I drive more than a few miles before it starts happening. It could be a single skip, or it could be like a machine gun. There is tons of information, good and bad on the web. Personally, I think it has something to do with the iphone being busy processing something in the background. If I switch off Wifi, it seems to improve for a while. If it's playing music steadily and I pick up the phone and start scrolling through imessage, it's almost guaranteed to start skipping. Not so much with other apps. My wife's iphone SE does this too, but when I was using my Android phone (cheap LG Q6) it was rock solid and perfect.

Others say that this started happening after the iOS 12 upgrade. Some ppl downgraded to 11.xx and the problem goes away. I tested with a cheap Bluetooth receiver and it seems to be fine. My car is a 2011 Mercedes Benz E350. I've seen ppl post this problem with newer cars also...Ford, BMW other Mercedes.

I found this thread by searching for how to change a Bluetooth Profile / Service / Codec... Anything!!!! Any thoughts?
 
Nov 11, 2020 at 3:31 PM Post #21 of 26
Is there a way to figure out IOS codec over bluetooth using a PC as I don't have a Mac to try with my iphone 8.
 
Nov 12, 2020 at 10:56 AM Post #23 of 26
Thanks! My Windows 10 computer doesn't use bluetooth for audio. What I want to determine is what Bluetooth codec my iphone is sending to a bluetooh receiver that I have hooked to one of my sets of wired headphones, thereby making them wireless. The headphone receiver dongle says it decodes SBA, AAC, and Apt-X. If possible I'd like to make sure AAC goes through bluetooth over SBC. Since the transmitter is an iphone 8 plus AAC is the only other codec possibility I have.

I appreciate your response, but I can't see where the link listed would allow me to view the bluetooth codec of my iphone like Bluetooth Explorer does for a MAC.
 
Nov 12, 2020 at 12:19 PM Post #24 of 26
Nov 12, 2020 at 1:13 PM Post #25 of 26
As you were talking about "using a PC" I had the impression you where using a Bluetooth connection with a PC.
If it is about emulating https://www.head-fi.org/threads/how...n-ios-device-and-bluetooth-headphones.835289/,
to the best of my knowledge this is not possible in the same way using a PC.

Sorry, I take full blame for not being as clear as I could have been. Yes, I had wanted to do what the original poster was able to do on his Mac with his iphone, but I've spent 10+ hours searching and have found no way to replicate it on a PC.

Thank you for your help!
 
Nov 12, 2020 at 3:03 PM Post #26 of 26
I hope apple comes up with something similar to LDAC for higher bit rate streaming via Bluetooth.
 

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