trim-latest-obs-video.ts

// Name: Trim latest OBS video

import "@johnlindquist/kit";
import { z } from "zod";

const { stdout } = await $`ls -t ~/Movies/*.mp4 | head -n 1`;

const inputVideo = stdout.trim();

const THRESH = "-40";
const DURATION = "1";

const obsTrimOutputDb = await db("obs-trim-output", {
  folder: home("Movies", "trimmed"),
});

const result: { activeTextEditorFilePath: string } = await readJson(
  home(`.kit`, "db", "vscode.json"),
);

const vscodeResultSchema = z.object({
  activeTextEditorFilePath: z.string(),
});

const defaultFilename = path.parse(
  vscodeResultSchema.parse(result).activeTextEditorFilePath,
).name;

const outputFolder = obsTrimOutputDb.folder;

const output =
  await $`ffmpeg -hide_banner -vn -i ${inputVideo} -af "silencedetect=n=${THRESH}dB:d=${DURATION}" -f null - 2>&1 | grep "silence_end" | awk '{print $5 " " $8}'`;

let silence = output.stdout
  .trim()
  .split("\n")
  .map((line) => line.split(" "))
  .map(([silenceEnd, duration]) => {
    return {
      silenceEnd: parseFloat(silenceEnd),
      duration: parseFloat(duration),
    };
  });

let foundFirstPeriodOfTalking = false;

while (!foundFirstPeriodOfTalking) {
  // Unshift the first silence if the noise afterwards
  // is less than 1 second long
  const silenceElem = silence[0];
  const nextSilenceElem = silence[1];

  const nextSilenceStartTime =
    nextSilenceElem.silenceEnd - nextSilenceElem.duration;

  const lengthOfNoise = nextSilenceStartTime - silenceElem.silenceEnd;

  if (lengthOfNoise < 2) {
    silence.shift();
  } else {
    foundFirstPeriodOfTalking = true;
  }
}

const PADDING = 0.3;

const startTime = silence[0].silenceEnd - PADDING;

const endTime =
  silence[silence.length - 1].silenceEnd -
  silence[silence.length - 1].duration +
  PADDING;

const totalDuration = endTime - startTime;

const formatFloatForFFmpeg = (num: number) => {
  return num.toFixed(3);
};

const filenameWithoutExtension = await arg({
  placeholder: defaultFilename,
  name: "Filename without extension",
});

const filename = `${filenameWithoutExtension || defaultFilename}.mp4`;

await ensureDir(outputFolder);
const outputVideo = path.resolve(outputFolder, filename);

await ensureDir(path.resolve(outputFolder, "tests"));
const testOutputVideo = path.resolve(outputFolder, "tests", filename);

await $`ffmpeg -y -hide_banner -ss ${formatFloatForFFmpeg(
  startTime,
)} -to ${formatFloatForFFmpeg(
  endTime,
)} -i ${inputVideo} -c copy ${outputVideo}`;

await revealInFinder(outputVideo);

await $`ffmpeg -y -i ${outputVideo} \
  -vf "select='between(t,0,2)+between(t,${(totalDuration - 2).toFixed(
    1,
  )},${totalDuration.toFixed(1)})',
      setpts=N/FRAME_RATE/TB" \
  -af "aselect='between(t,0,2)+between(t,${(totalDuration - 2).toFixed(
    1,
  )},${totalDuration.toFixed(1)})',
      asetpts=N/SR/TB" ${testOutputVideo}`;

await $`open ${testOutputVideo}`;