[audio-server] Plop / Click artefact at the beginning of playback sound

[cpoisson]

What's the issue?
Following feedback in #194
When using the configuration stated in #148, the audio-server produces a plop artefact just before playing a sound.
The occurrence of the issue is maximum when using pico2wave output.

The issue does not occur when playing sound using aplay or sox play

Use Cases Impacted
Usage of sounds feedback on the platform.

How to reproduce

1. Start the audio server using alsa audio backend for playback.

sudo -u _snips snips-audio-server --alsa_playback default -v

2. Send some audio files to be played by the audio server or interact with the platform

pico2wave -w test.wav "Hello! How are you?"
mosquitto_pub -t 'hermes/audioServer/default/playBytes/somedummyid' -f test.wav

Expected behavior
No plop, no click

Version and Environment
1.2.2 Raspbian

Additional information
The issue occurrence seems to lower when using portaudio as the audio backend for playback.

Workaround
It seems that falling back to portaudio playback backend reduce the occurrence of the issue.

[Psychokiller1888]

I have the feeling that, since 1.3.0, the output is somehow cut by 0.1 or 0.2 sec. It feels like the speech is missing something at the begining, beside the plop on a respeaker 6 circ mic array

[cpoisson]

@Psychokiller1888

The 1.3.0 audio issue are related to #203

Regarding the pop and click, I have a clue.

In the asound.conf provided by seeed drivers, there is a line to enforce a given resampler.

# use samplerate to resample as speexdsp resample is bad
defaults.pcm.rate_converter "samplerate"

I simply removed it. problem solved on my side.