Hi,
we experience volume issues when connecting Bluetooth Headsets to the TC77 device.
We setup an SCO connection and in many cases the output volume is far too low. The issue is not reproducable and seems to happen more often, when doing other (non Audio related) actions in parallel. I did not figure out one special part of code, that is enforcing the issue, but stripping down our applications more and more always reduces the propability of the volume issue.
A simple dummy test application always works as expected.
As we do not experience the issue on other devices, it seems to be related to the Zebra TC77 (and similar devices: at least the TC57 shows the same behavior).
We experience the issue on several Bluetooth Headset: Zebra HS3100, ModCom One and BlueParrott B450-XT.
The SCO connection is setup as follows:
> audioManager.setMode(AudioManager.MODE_IN_COMMUNICATION);
> audioManager.setBluetoothScoOn(true);
> audioManager.startBluetoothSco();
When the connection is established, we open AudioTracks A and B (and possibly some more) as follows:
> AudioAttributes audioAttributes = new AudioAttributes.Builder().setUsage(usage).setContentType(contentType).build();
> AudioFormat audioFormat = new AudioFormat.Builder().setEncoding(AudioFormat.ENCODING_PCM_16BIT).setSampleRate(sampleRate).setChannelMask(AudioFormat.CHANNEL_OUT_MONO).build();
> AudioTrack track = new AudioTrack.Builder().setAudioAttributes(audioAttributes).setAudioFormat(audioFormat).setBufferSizeInBytes(bufferSize).build();
We tried different usages and contentTypes, without success.
It also happens, that the output volume for AudioTrack A is correct, and the volume for AudioTrack B is too low, even when created directly after another.
Reducing our applications to use just one AudioTrack (and change the sampleRate for each output) did also not solve the issue.
Locking all audio actions, or moving all audio actions to the UI thread, did not solve the issue either.
Does anyone experience similar issues? Or even has a solution for this?
Thanks,
Tobias Drüner