Windows inbox A2DP driver supports only 44.1 kHz sampling frequency for SBC CODEC. So, if you listen to the contents encoded with 48 kHz sampling frequency, you are forced to down-sampling.
On the other hand, Alternative A2DP makes all sampling frequencies supported by your audio device available to the media player app. So, if the media player app can dynamically switch the sampling frequency based on its source, you can eliminate the audio quality loss due to the down-sampling.
Please follow the instructions below to enable this feature.
Alternative A2DP Driver setting
First, you need to configure the Alternative A2DP Driver to use both 44.1 and 48 kHz sampling frequencies.
It is recommended NOT to enable other sampling frequencies (i.e., 16 and 32 kHz) unless you really want to use them.
(optional) Verify the above setting is working
- Connect your Bluetooth audio device to your PC.
- Type
mmsys.cpl
into the Windows search box and hit ENTER to start the legacy Sound control panel.
- Select the Playback tab (which should be selected by default), look for the Bluetooth audio device, and double-click on it to open the Headphones Properties dialog box.
- Select the Advanced tab and check the drop-down list in the Default Format section. You should see "2 channel, 16 bit, 44100 Hz (CD Quality)" and "2 channel, 16 bit 48000 Hz (DVD Quality)". If you do, the driver is working fine.
NOTE: This drop-down list is supposed to let the user select the audio stream format when this audio device is used in the Shared Mode, but it does not seem to be working on recent Windows 10 and 11. The cause is unclear at this point, but it seems to be an issue with Windows 10 and 11.
Media player app setting
The media player app has to support the Exclusive Mode (and please note that not all media app does) so that it can change the sampling frequency of the audio device. (When the device is used in the Shared Mode, the sampling frequency is controlled by the System Mixer, and media player apps cannot control it.) Please also note that, by definition, in the Exclusive Mode, your audio device is exclusively controlled by that media app, and the output from other apps (including the system sounds) cannot be played on the same device.
Following are some of the apps that support Exclusive Mode and how to configure them for the dynamic sampling frequency change.
Kodi
- Navigate to the "Settings" > "System" > "Audio" page.
- Set the settings level (at the bottom-left corner) to "Advanced" or above.
- Select "WASAPI: Headphones (...)" or "WASAPI: default" for the "Audio output device."
- Select "Best match" for "Output configuration" (this setting item does not show if the setting level is "Basic" or "Standard").
MPC-BE
- Navigate to the "View" menu > "Options ..." to open the "Options" window.
- Select the "Audio" node in the left pane.
- Select "0. MPC Audio Renderer" for the "Audio renderer" drop-down list.
- Click the "Properties" button to open the "Properties" dialog box.
- Select "Exclusive" for the "WASAPI mode" drop-down list, and enable the "Allow bit exact output" checkbox.
MPC-HC
- Navigate to the "View" menu > "Options ..." to open the "Options" window.
- Select the "Playback" > "Output" node in the left pane.
- Select "MPC Audio Renderer" for the "Audio Renderer" drop-down list.
- Select the "Internal Filters" > "Audio Renderer" node in the left pane.
- Click the "MPC Audio Renderer Settings" button to open the "Properties" dialog box.
- Select "Exclusive" for the "WASAPI mode" drop-down list, and enable the "Allow bit exact output" checkbox.