Stuttering playback with some Android Devices (ESP32-A2DP with ESP32 DevKit and PCM5102)

[DerElch87]

Dear all,

somehow I'm struggling with my findings.
Hardware: ESP32-A2DP with ESP32 DevKit and PCM5102
Playback with old Redmi Note 8 is perfectly fine.
Playback with newer Redmi Note 13 is stuttering.

I increased the buffers etc, but no change.

My config is below:
#include "AudioTools.h"
#include "BluetoothA2DPSink.h"
#include <BluetoothA2DPSinkQueued.h>

I2SStream i2s;
BluetoothA2DPSink a2dp_sink(i2s);

void setup() {
auto cfg = i2s.defaultConfig();
cfg.pin_bck = 26;
cfg.pin_ws = 25;
cfg.pin_data = 22;
cfg.buffer_size = 384;
cfg.buffer_count = 30;
i2s.begin(cfg);

a2dp_sink.start("MyMusic");

}

void loop() {
}

Anyone an idea?

Best regards

[pschatzmann]

Strange, that sounds to be a similar problems like in IOS. I would have the following suggestions:

• Add a delay to the loop: having no delay might starve the other tasks
• Try to find out what the number of bytes are that are provided by your phone and adjust the sizes (e.g. cfg.buffer_size, A2DP_I2S_MAX_WRITE_SIZE) accordingly!
• You can try to use the BluetoothA2DPSinkQueued instead of BluetoothA2DPSink and play around with the set_i2s_ringbuffer_size and set_i2s_ringbuffer_prefetch_percent
• Try to adjust the A2DP_I2S_MAX_WRITE_SIZE in config.h
• Try to adust the i2s buffer information

[DerElch87]

Hi,
thanks for your answer so far.
In short:
Delay(100) -> no change
A2DPSinkQueued -> no change
To be honest, the other two are far beyond my IT knowledge :)

Maybe an additional information that may help:
SPDIF output only was stuttering when changing anything or starting, but then went fine.
So for example when I changed the volume, unlocked the phone etc, there was a small stutter but then everything was fine.
But somehow the combination with the PCM5102 is more tricky...

BR

[pschatzmann]

You can determine the write size e.g. using the a2dp_sink.set_stream_reader(read_data_stream); callback. Just log the length...

[DerElch87]

The length is 4096 for both smartphones.
So no idea what's the difference.
The new Smartphone supports Bluetooth 5, the old only 4.
I give up here, like said I was already struggeling with the length.
Thanks anyway for the cool project.