a8d2491366
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The audio work was three parts and I shipped two. The transcode-fidelity method and the pinned 5.1 downmix landed; the null sink -- the only one that answers "what does the GAME play" -- I deferred to "the next natural rebuild window" and then rebuilt both images four times without doing it. pulseaudio-utils is now in both, with tools/audio-capture wrapping it: a null sink is a real device as far as an application is concerned, so Canary and Godot open it normally and parec records what they emit. This unblocks the decoder's Q8. The cue-to-event bindings are currently a name match against the authors' own identifiers -- a plausible guess, not a measurement -- and capturing what the game plays on a menu move converts them. `audio-capture run` reports the peak level and warns when the capture is silent, because silence is the failure that looks like success: a WAV of exactly the right duration, full of zeroes, because the application opened a different sink. A duration check alone passes it, which is how a confident wrong number gets made.
65 lines
2.8 KiB
Bash
Executable File
65 lines
2.8 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Record what an application plays, with no sound card present.
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#
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# audio-capture start bring up a null sink named `cap`
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# audio-capture record OUT.wav & record from it until killed
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# audio-capture run OUT.wav -- CMD… start, run CMD, stop, leave OUT.wav
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#
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# A null sink is a real device as far as the application is concerned: the
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# emulator and Godot open it exactly as they would hardware, and its monitor
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# source is what `parec` reads. This is the difference between "the file decodes"
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# and "the game played this" -- the second is a measurement, the first is not.
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#
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# Nothing here says the audio SOUNDS right; it says what was emitted. A human
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# listening still answers something none of this does.
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set -euo pipefail
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SINK="${SYLPH_SINK:-cap}"
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ensure_daemon() {
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pulseaudio --check 2>/dev/null || pulseaudio --start --exit-idle-time=-1 2>/dev/null || true
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for _ in $(seq 30); do pactl info >/dev/null 2>&1 && return 0; sleep 0.2; done
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echo "audio-capture: no PulseAudio daemon" >&2; return 1
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}
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case "${1:-}" in
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start)
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ensure_daemon
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pactl list short sinks | grep -q "^[0-9]*[[:space:]]*$SINK[[:space:]]" \
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|| pactl load-module module-null-sink sink_name="$SINK" \
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sink_properties=device.description="$SINK" >/dev/null
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pactl set-default-sink "$SINK"
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echo "audio-capture: sink '$SINK' ready; point apps at it with PULSE_SINK=$SINK"
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;;
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record)
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out="${2:?usage: audio-capture record OUT.wav}"
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ensure_daemon
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exec parec -d "${SINK}.monitor" --file-format=wav "$out"
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;;
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run)
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out="${2:?usage: audio-capture run OUT.wav -- COMMAND...}"; shift 2
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[ "${1:-}" = "--" ] && shift
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"$0" start
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parec -d "${SINK}.monitor" --file-format=wav "$out" & rec=$!
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# Kill the recorder on any exit path, or a failed run leaves it holding the
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# monitor and the next capture silently records nothing.
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trap 'kill "$rec" 2>/dev/null || true' EXIT
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PULSE_SINK="$SINK" "$@" || true
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sleep 1; kill "$rec" 2>/dev/null || true; wait "$rec" 2>/dev/null || true
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trap - EXIT
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if [ -s "$out" ]; then
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dur=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$out" 2>/dev/null || echo "?")
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echo "audio-capture: $out (${dur}s)"
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# Silence is the failure that looks like success: a WAV of the right
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# length, full of zeroes, because the app opened a different sink.
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peak=$(ffmpeg -hide_banner -i "$out" -af astats=measure_perchannel=none -f null - 2>&1 \
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| grep -m1 "Peak level" || true)
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echo " ${peak:-no level measured}"
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case "$peak" in *"-inf"*) echo " WARNING: silent -- did the app use this sink?" ;; esac
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else
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echo "audio-capture: nothing recorded" >&2; exit 1
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fi
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;;
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*) sed -n '2,12p' "$0" | sed 's/^# \{0,1\}//' ;;
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esac
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