aptX Adaptive / aptX Lossless USB Transmitters

[ext23]

I have a Fiio UTWS5. I'm trying to decide whether it's worth reflashing an Android ROM with native aptX Adaptive support (Paranoid Android), or sticking with crDroid and either using one of these dongles, or just using cdDroid's unique implementation of AAC...

A knowledgeable user on XDA has given me the following info about Bluetooth on crDroid:

This ROM hasn't been using "a2dp hardware offload" and its AAC deliver sound without resampling for 44.1kHz sources.

aptX and aptX HD resample 44.1kHz sources to 48kHz as default, but AAC doesn't on this ROM. I think AAC is better than aptX HD (even 44.1kHz mode) on this ROM.
AAC keeps low bitrates about 30secs after switching to AAC, then it rises its rate to its max. Wait 30secs!

I think "a2dp hardware offload" is necessary for supporting aptX adaptive like crDroid 19.1. aptX adaptive resample every source to 48kHz at the mixer (audioFlinger) under "a2dp hardware offload".
Android's resampler (as default) generates large distortion. So if you like Paranoid and aptX adaptive, I recommend [raising] the resampling quality of audioFlinger to a mastering level (stop band attenuation 179dB).

cdDroid has a2dp hardware offload DISABLED (unable to turn it on), so I'm not sure how that would effect a dongle like the KB9P.

With all of this in mind, which of the three configurations would give me the best quality?

• crDroid with AAC
• crDroid with a KB9P and aptX Adaptive
• Paranoid Android with aptX Adaptive

 

[O11111]

With all of this in mind, which of the three configurations would give me the best quality?

• crDroid with AAC
• crDroid with a KB9P and aptX Adaptive
• Paranoid Android with aptX Adaptive

It's highly subjective, tho I'd recommend going for PA. You can use AAC there as well and maybe you can ask devs to increase its' bitrate from Qualcomm's default 165 kbps to something higher like ~264 kbps (which is the limit for UTWS5 AFAIK).

 

[FreeBlues]

I'm trying to get the KB9P dongle to work in my Apple environment. I have ordered an adaptor cable, non-Apple, that is supposed to work with my iPhone, don't know if it will work, but I'm hopeful. Yesterday I plugged the KB9P into the USB port on the back of my iMac, just to see if it would work. After a period of blinking lights on the device it finally settled on a solid blue which I think means the device is up and running. But, when trying to pair my Mac/KB9P with my Noble Mystiques I was never able to get a connection (the Mystiques pair just fine without the KB9P).

Is this a function of trying to use the KB9P in an Apple environment? Is there something else I can do to make this work?

 

[ext23]

It's highly subjective, tho I'd recommend going for PA. You can use AAC there as well and maybe you can ask devs to increase its' bitrate from Qualcomm's default 165 kbps to something higher like ~264 kbps (which is the limit for UTWS5 AFAIK).

As far as I understand, AAC in Paranoid Android would be subject to 'double' resampling (44.1 -> 48 in the ROM -> back to 44.1 at the Fiio end)...unless I disable a2dp hardware offload?

I'm also led to believe that the KB9P will still resample from 44.1 to 48 when doing aptX Adaptive. Can anybody confirm/deny? Or is this ROM-dependent?

 

[O11111]

As far as I understand, AAC in Paranoid Android would be subject to 'double' resampling (44.1 -> 48 in the ROM -> back to 44.1 at the Fiio end)...unless I disable a2dp hardware offload?

The code is on GitHub, just check it. But disabling offload isn't a good idea, you'll lose most of the codecs that way, i.e. aptX Adaptive. Actually, if it still works then offload is running even if it was disabled in setting.
Anyway, KB9P (and any other) will resample from USB input rate to Bluetooth output rate (and I don't think there's any easy way to control Android USB output rate).

 

[helmutcheese]

PowerAmp lets me set the Dongles bitrate etc, I assume that is the USB side but will carry over the BT side but no way to be 100% sure.

For example, for my CD Rips I set it to 16/44.1 and for my Hi-Res files I set it to 24/96 (BT-W5), there is no proof the KB9P is doing 24/96 BT for USB yes, it is same for the BT-W4 which officially confirms this limitation, and it used a newer chipset (3056 over 3040).

 

[Metsuki]

God, I swear the BT-W5 is the worst transmitter I've had so far. Trying to play Like a Dragon Ishin on my PS5 and all I hear is the audio crackling every few seconds. Hope the KB8P is better than this.

The latency is impeccable tho.

 

[ext23]

KB9P (and any other) will resample from USB input rate to Bluetooth output rate (and I don't think there's any easy way to control Android USB output rate).

How about using something like this: USB_SampleRate_Changer (the author also has a few other Android audio-related modules on hit GitHub)?

 

[O11111]

How about using something like this: USB_SampleRate_Changer (the author also has a few other Android audio-related modules on hit GitHub)?

That requires root (not that anyone shouldn't get it regardless), but still. With root almost everything is possible. Those scripts seem to also disable unnecessary A2DP resampling according to README, so PA with those scripts might be the best option for you. They might merge LHDC (and until that you can try building it by yourself, patches are here) soon also, so definitely worth the try.

 

[ext23]

That requires root (not that anyone shouldn't get it regardless), but still. With root almost everything is possible. Those scripts seem to also disable unnecessary A2DP resampling according to README, so PA with those scripts might be the best option for you. They might merge LHDC (and until that you can try building it by yourself, patches are here) soon also, so definitely worth the try.

I do have root. For the time being I'm using PA with built-in aptX Adaptive, and I have enabled:

USB_SampleRate_Changer.sh --drc --offload
change-usb-period.sh 20375 sec

The second parameter is relevant to my phone specifically (Poco F3).

I have also installed the modules:

Audio jitter silencer
Hifi Maximizer
USB Samplerate Unlocker

...with the service.sh in Hifi Maximizer modified:

DisableCameraService="yes"

Not changing this from "no" to "yes" will crash your app every time you try to use your camera.

So far, so good, but I'm keen to go back to crDroid as I think it just runs better and has so many awesome extra features (including LDAC...).

 

[helmutcheese]

Alternative A2DP Driver has now added aptX and aptX HD support (hopefully aptX LL will follow) but like its LDAC option aptX HD is missing a 16bit option IMO which so far both are lacking so you are stuck in 24bit even if you set to 44.1k


aptX 44.1K

aptX HD 48K (Default)

aptX HD 44.1K

https://www.bluetoothgoodies.com/a2dp/?v=0101000c&osv=10.0.25357.1

 

[tjzurlaaa]

It does not have an App so no way to know and I doubt it has SnapDragon Sound as that is just a Certificate, and a Chinese Dongle will not get it.

Apple needs to step up

 

[O11111]

16bit option

Isn't necessary for these codecs. LDAC will convert everything to 32 bits regardless of input. Seems to be the same with aptX (at least libopenaptx does that)

 

[O11111]

LDAC

It should be working in PA as well, that's a bug if it doesn't.

 

[mcnaugha]

Got this wee fella to allow me to receive aptX Adaptive from my Audio-Technica AT-LP3XBT turntable to my Dolby Atmos speaker setup, which is the opposite end of the living room.

I can also flip the TX switch and use it to listen to my cassette player wirelessly.


Product Specifications:

Support Dual Stream (TX mode): Support (Transmitter Connects Two Bluetooth Speakers Or Headphones At The Same Time)
Support Multi-point Connection (RX mode): Support Connecting Two Mobile Phones
RX Mode With Mic Support Handsfree Calling
Battery Type: 250mAh Lithium Ion Polymer Battery

Codecs:
RX-----aptX Adaptive/aptX HD/aptX/AAC/SBC
TX-----aptX Adaptive/aptX HD/aptX LL/aptX/SBC

Support hands-free calling function in RX mode;
USB TYPE-C charging
3.5mm audio input/output
Bluetooth 5.2
Wireless Work Range: Up to 10m
Charging method: USB TYPE-C 5V/0.5A
Built-in Battery:3.7V/250mA Li-polymer Battery
Working Time: RX>15H, TX>12H
Charging Time: About 1.5hours
Dimensions (L x W x H): 48*48*12mm

£15 from Aliexpress and £30 from Amazon.