dziurkacz-ffmpeg/dziurkacz-fast.mjs

#!/usr/bin/zx

const { extname } = require("path");

const args = process.argv.slice(-2);

const video = args[0];
const labels = args[1];
const ext = extname(video);

const FREQ = 48000;
const FRAMERATE = parseFloat(
  (await $`mediainfo --Output="Video;%FrameRate%" ${video}`).stdout
);
const BITRATE = parseFloat(
  (await $`mediainfo --Inform="Video;%BitRate/String%" ${video}`).stdout
);

const labels_contents = (await $`awk '{print $3, $4, $5}' < ${labels}`).stdout;

const cuts = labels_contents
  .split(os.EOL)
  .slice(0, -1)
  .map((e) =>
    e
      .split(" ")
      .slice(1)
      .map((x) => parseFloat(x))
  )
  .map(([samples, start]) => ({
    duration: samples / FREQ,
    start,
    end: start + samples / FREQ,
  }));

console.log(cuts);

let all_frames = [];

const frame_count = parseInt(
  (await $`mediainfo --Output="Video;%FrameCount%" ${video}`).stdout
);

for (let i = 0; i < frame_count; i++) {
  all_frames.push(i);
}

console.log(all_frames);

for (let cut of cuts) {
  all_frames = [
    ...all_frames.slice(0, Math.round(cut.start * FRAMERATE)),
    ...all_frames.slice(Math.round(cut.end * FRAMERATE)),
  ];
}

console.log(all_frames);

const pieces = [];

let current_piece = { start: all_frames[0] };

let predicted_frame_number = 0;

// skipping the first one, as we're doing lookback
for (let i = 1; i < all_frames.length; i++) {
  if (all_frames[i] != all_frames[i - 1] + 1) {
    current_piece.end = all_frames[i - 1];
    pieces.push(current_piece);
    current_piece = { start: all_frames[i] };
  }
}

current_piece.end = all_frames[all_frames.length - 1];

pieces.push(current_piece);

// this approach is using a filter, so it requires reencoding the entire video, but lets us be very precise:
// const filter = pieces
//   .map(
//     ({ start, end }) =>
//       `between(t,${(start / FRAMERATE).toFixed(5)},${(end / FRAMERATE).toFixed(
//         5
//       )})`
//   )
//   .join("+");

// await $`ffmpeg -i ${video} \
//                -vf ${`select='${filter}',setpts=N/FRAME_RATE/TB`} \
//                -af ${`aselect='${filter}',asetpts=N/SR/TB`} \
//                ${video + ".cut.mp4"}`;

// let ffmpeg_args = [];
// const parts = [];
// for (let i in pieces) {
//   const piece = pieces[i];
//   const output_filename = video + "-" + i + ".mp4";
//   ffmpeg_args = [
//     ...ffmpeg_args,
//     "-ss",
//     (piece.start / FRAMERATE).toFixed(5),
//     "-t",
//     ((piece.end - piece.start) / FRAMERATE).toFixed(5),
//     "-c",
//     "copy",
//     output_filename,
//   ];
//   parts.push(output_filename);
// }

// console.log(ffmpeg_args);

// await $`ffmpeg -i ${video} ${ffmpeg_args}`;

// await $`echo ${parts.map((s) => `file ${s}`).join("\n")} > /tmp/vdlist.txt`;

// await $`ffmpeg -f concat -safe 0 -i /tmp/vdlist.txt -c copy -y ${
//   video + "final.mp4"
// } `;

function range(n) {
  return [...Array(n).keys()];
}

for (let piece of pieces) {
  console.log(piece);
}

const ns = range(pieces.length);

const sample_rate = parseInt(
  (
    await $`ffprobe ${video} 2>&1 | grep 'Audio:' | grep --only-matching --extended-regexp '[0-9]+ Hz' | sed 's/ Hz//'`
  ).stdout
); // in Hz

const samples_per_frame = sample_rate / FRAMERATE;

function generateSplit(pieces, prefix = "") {
  return `[0] ${prefix}split=${pieces.length} ${ns
    .map((n) => `[copy${n}${prefix}]`)
    .join("")}`;
}

function generateFilter(pieces, prefix = "") {
  return pieces
    .map(
      (piece, n) =>
        `[copy${n}${prefix}]${prefix}trim=start_frame=${piece.start}:end_frame=${piece.end},setpts=PTS-STARTPTS [copy${n}t${prefix}]`
    )
    .join("; ");
}

function generateAudioFilter(pieces) {
  return pieces
    .map(
      (piece, n) =>
        `[copy${n}a]atrim=start_sample=${
          piece.start * samples_per_frame
        }:end_sample=${
          (piece.end + 1) * samples_per_frame
        },asetpts=PTS-STARTPTS [copy${n}ta]`
    )
    .join("; ");
}

// version with audio, that doesn't work yet:
// const filter = `${generateSplit(pieces)}; ${generateSplit(
//   pieces,
//   "a"
// )}; ${generateFilter(pieces)}; ${generateAudioFilter(pieces)}; ${ns
//   .map((n) => `[copy${n}t]`)
//   .join("")} concat=n=${pieces.length} [out_video]; ${ns
//   .map((n) => `[copy${n}ta]`)
//   .join("")} concat=n=${pieces.length} [out_audio]`;

// video-only version
const audio_filter = `${generateSplit(pieces, "a")}; ${generateAudioFilter(
  pieces
)};`;

const filter = `${generateSplit(pieces)}; 
${generateFilter(pieces)}; 
${audio_filter} 
${ns.map((n) => `[copy${n}t][copy${n}ta]`).join(" ")} 
concat=n=${pieces.length}:v=1:a=1 [out_video] [out_audio]`;

await $`ffmpeg -i ${video} -b:v ${BITRATE}M -filter_complex ${filter} -map '[out_video]' -map '[out_audio]' ${`${video}.cut-complex.mp4`}`;