I have tried this and in my experience, to apply this, I need to send a "RESET" command after the "SET PROFILE HSP" command and that ends up dropping the SPP too which is undesirable. Does this command also disconnect the control channel ? If it does not, will it be enough that I send the "BUTTON" command when I want to reconnect ? If the close command disconnects the control channel, we have to reissue "CALL" to connect it first and then "BUTTON" for the audio, right ?Ģ) Or disable HSP altogether. The type of radio link used for voice data. Synchronous Connection-Oriented (SCO) link. When I want to disable audio I can:-ġ) Either send the "CLOSE " command to disconnect the SCO or audio channel. ACL links are disconnected if there is nothing received for the supervision timeout period the default timeout is 20 seconds, but this may be modified by the master. Per my understanding, the HSP connection is made up of two connections, 1 control channel (set up first) and 1 audio channel. I am trying to understand how this would work. The disconnect/reconnect of the audio channel is a key element of this feature and is controlled by an external sensor input. Problems exist when I need to disconnect and reconnect the HSP while leaving the SPP connection intact. Subsequently reconnecting the headphones manually allows a2dp to work again. After disconnecting, the headphones will often reconnect automatically using HSP and accompanied by a flood of SCO packet for unknown connection handle kernel errors. The base use case of simultaneous connections works. Audio output is lost first, with errors only appearing in journald 10-15 seconds after that. I am trying to create a feature using the WT32i with simultaneous SPP and HSP connections.
BLUETOOTH SCO AUDIO DISCONNECTED BLUETOOTH
The Bluetooth word mark and logos are owned by the Bluetooth SIG, Inc. The eSCO links permit more flexibility in setting up links, support limited retransmissions, and allow more types of data packets than SCO.This discussion and its replies are closed Establish an audio SCO link so that the audio quality can be monitored in the presence of interfering signals, and ensure that the AFH functionality maintains a high quality audio path. Since retransmission is not possible, forward error correction is the only error correcting option for transmission of reliable data.Īn improvement over SCO links is enhanced SCO (eSCO) links. This is because the transmission is time critical and it is not feasible to retransmit real-time voice data. SCO radio links are used for time critical data transfer, particularly for voice data.īoth the master and the slave device transmit encoded voice data in their reserved timeslots.Ī master device can support three SCO links with the same or different slaves.Ī slave device can have a maximum of three SCO links with its master device.Ī SCO link can transmit a 64,000 bps (bits per second) PCM audio channel. Since fixed slots are reserved, SCO provides a circuit switched connection. fixed slots are allocated for each direction. When I called startBluetoothSco() immediately after receiving BluetoothHeadset.STATECONNECTED event, SCO state went from SCOAUDIOSTATECONNECTING to SCOAUDIOSTATEDISCONNECTED. In SCO, a dedicated, point-to-point link is established between the master device and the slave device before communication starts. I had same kind of problem even when device supported Bluetooth phone audio and settings were correct. SCO is a symmetric, point-to-point link between the master device and the slave device connected via Bluetooth.
Unfortunately the first second of the audio might be cut when using this service (to be fixed with upcoming Xposed hook). Bluetooth link layers define two types of data links, Synchronous Connection Oriented (SCO) link, being one of them. -One is a background service that monitors the audio focus and turn on the Bluetooth SCO proile when another app is temporarily requesting the audio focus.
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