Silence at the start of recordings (WASAPI and ASIO) about python-sounddevice HOT 12 CLOSED

import sounddevice as sd
from scipy.io import wavfile
import numpy as np
from pprint import pprint
import begin

@begin.start(auto_convert=True)
def main(sound_device: 'Sound Device Name' = 'DMX 6Fire ASIO', 
         channel_map: 'Channel Mapping' = [1,2], 
         duration : 'Duration of recording' = 1., 
         out_file: 'Wavfile to save recording in' = 'out.wav',
         blocksize: 'Block size (0 is optimal but may vary)' = 0,
         loops: 'Number of recordings in loop' = 1,
         format: 'dtype of recording' = 'float32'):
    dev = sd.query_devices(sound_device)
    pprint(dev)
    sd.default.device = sound_device
    sd.default.dtype = format
    sd.default.blocksize = blocksize
    print('Starting Recording')
    channel_map = [int(c) for c in channel_map]
    for i in range(loops):
        print('Loop #', i)
        rec = sd.rec(int(duration * dev['default_samplerate']), samplerate=int(dev['default_samplerate']), mapping=channel_map)
        print('  sd.wait() ->', sd.wait())
        for channel in range(rec.shape[1]):
            non_silence = np.where(rec[:,channel] > float(0))[0]
            print('  Ch. {}, initial silence {} samples'.format(channel, non_silence[0]))
        wavfile.write(str(i) + out_file, int(dev['default_samplerate']), rec)  

#: python audiorec.py -s "In 1 WASAPI" -b 1024 -l 10

{'default_high_input_latency': 0.01,
 'default_high_output_latency': 0.0,
 'default_low_input_latency': 0.003,
 'default_low_output_latency': 0.0,
 'default_samplerate': 48000.0,
 'hostapi': 3,
 'max_input_channels': 2,
 'max_output_channels': 0,
 'name': 'USBPAL In1 L/R (Terratec DMX 6fire WDM Audio)'}
Starting Recording
Loop # 0
  sd.wait() -> None
  Ch. 0, initial silence 256 samples
  Ch. 1, initial silence 256 samples
Loop # 1
  sd.wait() -> None
  Ch. 0, initial silence 447 samples
  Ch. 1, initial silence 477 samples
Loop # 2
  sd.wait() -> None
  Ch. 0, initial silence 256 samples
  Ch. 1, initial silence 256 samples
Loop # 3
  sd.wait() -> None
  Ch. 0, initial silence 0 samples
  Ch. 1, initial silence 1 samples
Loop # 4
  sd.wait() -> None
  Ch. 0, initial silence 256 samples
  Ch. 1, initial silence 256 samples
Loop # 5
  sd.wait() -> None
  Ch. 0, initial silence 256 samples
  Ch. 1, initial silence 256 samples
Loop # 6
  sd.wait() -> None
  Ch. 0, initial silence 265 samples
  Ch. 1, initial silence 256 samples
Loop # 7
  sd.wait() -> None
  Ch. 0, initial silence 256 samples
  Ch. 1, initial silence 256 samples
Loop # 8
  sd.wait() -> None
  Ch. 0, initial silence 256 samples
  Ch. 1, initial silence 256 samples
Loop # 9
  sd.wait() -> None
  Ch. 0, initial silence 257 samples
  Ch. 1, initial silence 268 samples