virtualmic

#!/bin/sh

# Help message
usage() {
    echo "Usage: $0 [-p pipe_filename] [-n source_name] [-f format]"
    echo "       [-r rate] [-c channels] [-v] [-d] [-h] [input_filename]"
    echo
    echo "  input_filename  This file is piped to the virtual mic (can be an url) (default: stdin)"
    echo "  -p, --pipe      Set audio pipe filename (use mktemp otherwise)"
    echo "  -n, --name      Set PulseAudio source_name (default: virtualmic)"
    echo "  -f, --format    Set audio format (default: s16le)"
    echo "  -r, --rate      Set audio sampling frequency (default: 44100)"
    echo "  -c, --channels  Set number of audio channels (default: 1)"
    echo "  -v, --verbose   Make output verbose"
    echo "  -d, --default   Set virtual microphone as PulseAudio default source"
    echo "  -h, --help      Show this help"
}

# Default variables
input_filename='-'        # Positional argument
pipe_filename=            # -p / --pipe
source_name='virtualmic'  # -n / --name
format='s16le'            # -f / --format
rate='44100'              # -r / --rate
channels='1'              # -c / --channels
verbose=                  # -v / --verbose
default=                  # -d / --default

# Read arguments
while [ "$1" != '' ]
do
    case "$1" in
        -p | --pipe    )  shift ; pipe_filename="$1" ;;
        -n | --name    )  shift ; source_name="$1"   ;;
        -f | --format  )  shift ; format="$1"        ;;
        -r | --rate    )  shift ; rate="$1"          ;;
        -c | --channels)  shift ; channels="$1"      ;;
        -v | --verbose )  verbose='1'                ;;
        -d | --default )  default='1'                ;;
        -h | --help    )  usage ; exit 0             ;;
        -* )              echo "$0: invalid option '$1'"
                          usage ; exit 1             ;;
        *)                input_filename="$1"
    esac
    shift
done

# If no --pipe, use mktemp
[ "$pipe_filename" ] || pipe_filename="$(mktemp -u)"

# Print variables
[ "$verbose" ] && {
    echo "input_filename: $input_filename"
    echo "pipe_filename:  $pipe_filename"
    echo "source_name:    $source_name"
    echo "format:         $format"
    echo "rate:           $rate"
    echo "channels:       $channels"
    echo "default:        $default"
}

# Create source
pulseaudio_module_index="$(pactl load-module module-pipe-source \
    source_name=$source_name \
    file=$pipe_filename      \
    format=$format           \
    rate=$rate               \
    channels=$channels)"     && {

        # Cleanup
        trap "pactl unload-module $pulseaudio_module_index" EXIT INT

        [ "$verbose" ] && {
            echo "pulseaudio_module_index: $pulseaudio_module_index"
            ffmpeg_loglevel='verbose'
        } || ffmpeg_loglevel='panic'

        # Set source as default
        [ "$default" ] && pactl set-default-source "$source_name"

        # Redirect input to source
        ffmpeg \
            -loglevel "$ffmpeg_loglevel" \
            -re -i "$input_filename"     \
            -f "$format"                 \
            -ar "$rate"                  \
            -ac "$channels"              \
            '-' > "$pipe_filename"

}