Why can't I hear audio in stereo when playing a stereo file?

When calling startAudioMixing or playEffect to play a stereo file, the user might encounter the issue of not being able to hear audio in stereo.

If you cannot hear stereo audio, the possible reasons are as follows:

• The audio file being played is not a stereo file.
• Stereo encoding is not set in the Agora SDK.
• The audio playback device does not support stereo audio.

To troubleshoot and solve the issue, do the following:

Check whether the audio file is a stereo file by viewing the audio signal.

• If the audio file has only a mono audio signal, or if the audio file has dual audio signals but the audio signals of the left and right channels are the same, the audio file is not a stereo file. Change the file to a stereo file.
• If the audio file has dual audio signals and the audio signals of the left and right channels are different, the audio file is a stereo file. Proceed to step 2 to check the SDK settings.

The SDK can correctly encode and transmit stereo audio only when you set the stereo encoding. Check whether you call setAudioProfile and set the profile parameter to AUDIO_PROFILE_MUSIC_STANDARD_STEREO (3) or AUDIO_PROFILE_MUSIC_HIGH_QUALITY_STEREO (5).

• If a stereo profile is not set, set the profile parameter correctly.
• If the profile is set correctly, proceed to step 3 to check the audio playback device.

Check whether the device supports stereo audio, and check whether the device is working properly.

• If the device does not support stereo audio, change it to a device that supports stereo audio.
• If the device supports stereo audio but does not work properly, contact the device manufacturer for repair or change it to a device that works properly.
• If the device supports stereo audio and works properly, submit a ticket to contact Agora customer support for further exploration of the issue.

If you use a Bluetooth device to play audio, note the Bluetooth profile. The two common profiles are as follows:

• Advanced Audio Distribution Profile (A2DP): The unidirectional transmission of high-quality audio data, usually for stereo music playback. A2DP does not support capturing audio through the Bluetooth device, so you need to use other devices to capture audio.

• Hands-Free Profile (HFP): The bidirectional transmission of audio data, usually for audio calls. HFP commonly uses Synchronous Connection Oriented link (SCO) to carry a mono audio channel, so a Bluetooth device cannot play stereo audio using HFP.