record sound when the mic

reckless.sh

#!/bin/bash
# Extended from a work of Jürgen Hötzel: https://stackoverflow.com/a/2613888

noise_threshold=15  # out of 99
base_dir="${HOME}/recordings"
raw_dir="${base_dir}/tmp"
chunk_dir="${base_dir}/chunks"
seg_dir="${base_dir}/seg"
out_dir="${base_dir}/out"
sox_raw_options=( -t raw -r 48k -e signed -b 16 -c 1 )

# Chunk size. This affects buffering, but also how much silence you get around
# the start and end of a segment (since the final segment is a whole number of
# chunks*) and also segmentation (since segment boundaries occur when one chunk
# is quiet). With a sample rate of 48 kHz and a bitrate of 16 bits/sample, the
# buffer grows at 96 kB/second, so a 1MiB buffer makes for ~10.9-second chunks.
#
# * except maybe the last one if this program is terminated early
split_size=1048576  # 1MiB

mkdir -p "${raw_dir}" "${chunk_dir}" "${seg_dir}" "${out_dir}"

rawfifo="${raw_dir}/in.raw"
test -e "${rawfifo}" || mkfifo "${rawfifo}"

# Start recording and splitting in background.
rec "${sox_raw_options[@]}" - >"${rawfifo}" 2>/dev/null &
printf >&2 'pid[rec]:   %s\n' "$!"
split -a8 -b "${split_size}" - <"${rawfifo}" "${chunk_dir}/chunk-" &
printf >&2 'pid[split]: %s\n' "$!"

read_max_level() {
    sox "${sox_raw_options[@]}" "$1" -n stats -s 99 2>&1 |
        awk '/^Max level/ { print int($3) }'
}

poll() {
    status=1
    any_split=-false
    if [ "$1" = all ]; then
        any_split=-true
    fi
    find "${chunk_dir}" -type f \( -size "${split_size}c" -o "${any_split}" \) -print0 |
    while IFS= read -r -d '' raw; do
        status=0
        max_level="$(read_max_level "${raw}")"
        printf >&2 '%s: max_level=%s: ' "$(basename ${raw})" "${max_level}"
        if [ "${max_level}" -ge "${noise_threshold}" ]; then
            printf >&2 'appending to segment\n'
            mv "${raw}" "${seg_dir}"
        fi
        if [ "${max_level}" -lt "${noise_threshold}" ] || [ "$1" = all ]; then
            [ -f "${raw}" ] && rm "${raw}"
            if ! find "${seg_dir}" -type f | grep -q .; then
                printf >&2 'nothing to do\n'
            else
                segname="$(date +%FT%T)"
                printf >&2 'finalizing segment %s\n' "${segname}"
                find "${seg_dir}" -type f -print0 | sort -z | xargs -0 cat |
                    sox "${sox_raw_options[@]}" - "${out_dir}/recording-${segname}.flac"
                rm "${seg_dir}"/*
            fi
        fi
    done
    return "${status}"
}

in_cleanup=0
cleanup() {
    if [ "${in_cleanup}" = 1 ]; then
        printf >&2 'cleanup: interrupted: goodbye\n'
        exit 1
    fi
    in_cleanup=1
    printf >&2 'cleanup: polling\n'
    poll all
    exit 0
}
trap cleanup INT

while true; do
    poll
    sleep 1
done