A2DP Source - Play audio on an event

[ben25belot]

Hi,

I'm interested in playing audio during specific events, such as triggering a sound after pressing one button and another sound after pressing a different button.
I don't know how to implement this using callback, as all the examples are executed only once during the setup

Can you assist me with this? I would greatly appreciate your help. Thank you.

[ben25belot]

In other words, I am looking for connecting to Bluetooth speaker once, in the setup. And playing one of my sounds in function of the loop state.
I would like no delay when I play a sound. If I should reconnect to the speaker each time, I have a 5-10 sec delay.

Could you help me ? Please

[ayousaf21]

Hi @ben25belot

Were you able to solve this? I also have same requirement in my application but as soon as audio is completed, ESP32 halts.

Regards

[pschatzmann]

I don't understand why you are struggling with this: If the logic is stream based you would do something like this
if (!copier.copy()) a2dp.writeSilence(1024); this continues to send silence when there is no data any more and prevents the a2dp session to be dropped....

Setting the silence_on_nodata = true; on the a2dp configuration should have the same effect.

If the logic is based on using the callback, you would just do the writeSilence() when the readBytes() does not return any values any more.

[ayousaf21]

Hi @pschatzmann

Thanks for jumping in. Really appreciate it.

My application is using beacon with BLE too. As soon as the audio playback is completed on BT speaker, BLE scanning stops working.
On enabling debug logs, I got the following:

[1040599][D][BluetoothA2DPSource.cpp:261] bt_app_work_dispatch(): [BT_API] bt_app_work_dispatch event 0xff00, param len 0
[1040600][D][BluetoothA2DPSource.cpp:311] bt_app_task_handler(): [BT_API] bt_app_task_handler, signal: 0x1, event: 0xff00
[1040610][I][BluetoothA2DPSource.cpp:659] bt_app_av_sm_hdlr(): [BT_AV] bt_app_av_sm_hdlr state APP_AV_STATE_CONNECTED, evt 0xff00
[1040621][D][BluetoothA2DPSource.cpp:626] process_user_state_callbacks(): [BT_AV] process_user_state_callbacks
[1040631][D][BluetoothA2DPSource.cpp:759] bt_app_av_state_connected_hdlr(): [BT_AV] bt_app_av_state_connected_hdlr evt 65280
[1040642][D][BluetoothA2DPSource.cpp:832] bt_app_av_media_proc(): [BT_AV] bt_app_av_media_proc evt 65280
[1050599][D][BluetoothA2DPSource.cpp:261] bt_app_work_dispatch(): [BT_API] bt_app_work_dispatch event 0xff00, param len 0
[1050600][D][BluetoothA2DPSource.cpp:311] bt_app_task_handler(): [BT_API] bt_app_task_handler, signal: 0x1, event: 0xff00
[1050610][I][BluetoothA2DPSource.cpp:659] bt_app_av_sm_hdlr(): [BT_AV] bt_app_av_sm_hdlr state APP_AV_STATE_CONNECTED, evt 0xff00
[1050621][D][BluetoothA2DPSource.cpp:626] process_user_state_callbacks(): [BT_AV] process_user_state_callbacks
[1050631][D][BluetoothA2DPSource.cpp:759] bt_app_av_state_connected_hdlr(): [BT_AV] bt_app_av_state_connected_hdlr evt 65280
[1050642][D][BluetoothA2DPSource.cpp:832] bt_app_av_media_proc(): [BT_AV] bt_app_av_media_proc evt 65280

I am following player-a2dp-sdfat example:

void setup()
{
 Serial.begin(115200);
 AudioLogger::instance().begin(Serial, AudioLogger::Warning);

 // Initialize BLE
 Serial.println("Initializing BLE...");
 auto cfg = out.defaultConfig(TX_MODE);
 cfg.name = "BT SPEAKER";
 cfg.silence_on_nodata = true;
 out.begin(cfg);
 // player.setSilenceOnInactive(true);

 BLEDevice::init("");
 pBLEScan = BLEDevice::getScan();
 pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
 pBLEScan->setActiveScan(true);
 pBLEScan->setInterval(97);
 pBLEScan->setWindow(67);
 pBLEScan->start(scanTime, scanCompleteCB, false);
 Serial.println("Scan started!");
}

Thanks for your patience. Would really appreciate your help. As you mentioned above, I have already tried that but same results

[pschatzmann]

Why don't you just look at the existing A2DP/BLE example how to have both working ? You need to set the bt_mode do ESP_BT_MODE_BTDM

[ayousaf21]

@pschatzmann thats not the issue. A2DP source/BLE part is working fine.

Yes, i changed the bt_mode in BluetoothA2DPCommon.h

Regards

[pschatzmann]

I think the answer is quite obvious: You will play your sound when you receive your event, otherwise you just play silence (0 values).
This prevents A2DP from disconnecting. If I remember right, the A2DPStream (of the AudioTools) provides an option which automatically provides silence, if there is nothing to play.

But be aware, A2DP has quite some lag!

[ayousaf21]

Hi @pschatzmann

Sorry for the trouble again but good news is I made it work. Now as you mentioned A2DP playing on silence has quite some lag which I am seeing in my application. My question is how to reduce this lag? Playing on silence does not give enough time to BLE to do scan. My scan interval is 1 second but to keep A2DP connection alive, playing on silence increases the scan interval to 5-6 seconds and sometimes more.

Is it possible to reconnect to A2DP without disconnecting from BT speaker and connecting again? Or is there any other better approach that you can advise on?