混雑する信号でBLEのパケットが大きすぎる問題

[syntaro]

ご参考にしていただけましたら。

つまり、詰まっている場合の処理を変更しました。
パケット数に制限をつけることで、遅延こそあれ、ロストが起きなくしました。

MidiOutputDevice.java
``

final Thread transferDataThread = new Thread(new Runnable() {
    @Override
    public void run() {
        transferDataThreadAlive = true;

        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        while (transferDataThreadAlive) {
            stream.reset();
            PacketData packet = _queue.pop();
            packet._time = 0;

            stream.write((byte) (0x80 | ((packet._time >> 7) & 0x3f)));
            stream.write((byte) (0x80 | (packet._time & 0x7f)));
            stream.write(packet._data, packet._offset, packet._count);
            boolean sysex1 = (packet._data[packet._offset] & 0xff) == 0xf0;
            _packetGenerator.markRecyled(packet);
            int poped = 1;

            if (sysex1) {
                transferData(stream.toByteArray());
            }
            else {
                while (!_queue.isEmpty()) {
                    packet = _queue.pop();
                    boolean sysex2 = (packet._data[packet._offset] & 0xff) == 0xf0;
                    if (sysex2) {
                        _queue.back(packet);
                        break;
                    }
                    poped ++;
                    if (poped >= 7) {
                        _queue.back(packet);
                        break;
                    }
                    packet._time = 0;
                    stream.write((byte) (0x80 | (packet._time & 0x7f)));
                    stream.write(packet._data, packet._offset, packet._count);
                    _packetGenerator.markRecyled(packet);
                    packet = null;
                }
                transferData(stream.toByteArray());
            }
            if (poped >= 4) {
                Log.e(TAG, "Poped " + poped);
            }
        }
    }
});

``

BleMidiCallback.java

``

   @Override
    public boolean transferData(@NonNull byte[] writeBuffer) throws SecurityException {
        try {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                int result = bluetoothGatt.writeCharacteristic(midiOutputCharacteristic, writeBuffer, BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);
                if (result == 201) {
                    int retry = 0;
                    do {
                        try {
                            Thread.sleep(20);
                        }catch (InterruptedException ex) {
                        }
                        ++ retry;
                        if (retry >= 2) {
                            Log.e(Constants.TAG, "201 retry " +  retry);
                        }
                        if (retry >= 100) {
                            break;
                        }
                        result = bluetoothGatt.writeCharacteristic(midiOutputCharacteristic, writeBuffer, BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);
                        if (result != 0 && result != 201) {
                            Log.e(Constants.TAG, "*** " + result + " retry " +  retry);
                        }
                    }while(result == 201);
                }
                return result == BluetoothStatusCodes.SUCCESS;
            } else {
                midiOutputCharacteristic.setValue(writeBuffer);
                boolean result = bluetoothGatt.writeCharacteristic(midiOutputCharacteristic);
                if (result != true) {
                    Log.e(Constants.TAG, "transferData 2 Error "+ result);
                }
                return result;
            }
        } catch (Throwable ignored) {
            // android.os.DeadObjectException will be thrown
            // ignore it
            return false;
        }
    }

``