(Pipewire/Pulseaudio) Set app volume programmatically

set_app_vol.py

#!/usr/bin/env python3
import argparse
import subprocess
import json
import re


def VolumeSpecificationValidator(value: str):
    # Only validates absolute value volume specifications,
    # as parsing relative values has additional complexity.

    if value.isdigit():
        if not (0 <= int(value) <= 65535):
            raise argparse.ArgumentTypeError(
                "Integer volume specification must be between 0 (0%) and 65535 (100%)"
            )

    if value.replace(".", "", 1).isdigit():
        if not (0 <= float(value) <= 1.0):
            raise argparse.ArgumentTypeError(
                "Linear factor volume specification must be between 0 and 1.0"
            )

    pct_pattern = re.compile(r"(\d+(?:\.\d+)?)%")
    match_pct = pct_pattern.fullmatch(value)
    if match_pct:
        pct_number = float(match_pct.group(1))
        if not (0 <= pct_number <= 100):
            raise argparse.ArgumentTypeError(
                "Percentage volume specification must be between 0% and 100%"
            )

    if not any([value.isdigit(), value.replace(".", "", 1).isdigit(), match_pct]):
        raise argparse.ArgumentTypeError(
            "Malformed input. Must be either a decimal percentage (55.3%), a linear factor (0.553) or an integer."
        )

    return value


parser = argparse.ArgumentParser(
    prog="set_app_vol",
    description="Set app volume programmatically",
)
parser.add_argument(
    "app_name",
    help='Application name. Use "pactl list sink-inputs" to find the desired value (application.name property)',
)
parser.add_argument("volume_verb", type=VolumeSpecificationValidator)

args = parser.parse_args()

app_name = args.app_name
sink_inputs = json.loads(
    subprocess.check_output(["pactl", "-f", "json", "list", "sink-inputs"]).decode()
)

# Match first instance of desired application
# (Scrape output of pactl list sink-inputs to find app_name)
try:
    matched_input = next(
        (
            input
            for input in sink_inputs
            if input.get("properties", {}).get("application.name") == app_name
        ),
        None,
    )

    if matched_input:
        sink_id = str(matched_input["index"])
        subprocess.run(["pactl", "set-sink-input-volume", sink_id, args.volume_verb])
except KeyError:
    pass