import { Converter } from "ffmpeg-stream"
import { createReadStream, createWriteStream } from "node:fs"

async function convert() {
  const converter = new Converter()

  // get a writable input stream and pipe an image file to it
  const converterInput = converter.createInputStream({
    f: "image2pipe",
    vcodec: "mjpeg",
  })
  createReadStream(`${__dirname}/cat.jpg`).pipe(converterInput)

  // create an output stream, crop/scale image, save to file via node stream
  const converterOutput = converter.createOutputStream({
    f: "image2",
    vcodec: "mjpeg",
    vf: "crop=300:300,scale=100:100",
  })
  converterOutput.pipe(createWriteStream(`${__dirname}/cat_thumb.jpg`))

  // same, but save to file directly from ffmpeg
  converter.createOutputToFile(`${__dirname}/cat_full.jpg`, {
    vf: "crop=300:300",
  })

  // start processing
  await converter.run()
}

import { Transform } from "node:stream"

class ExtractFrames extends Transform {
  constructor(magicNumberHex) {
    super({ readableObjectMode: true })
    this.magicNumber = Buffer.from(magicNumberHex, "hex")
    this.currentData = Buffer.alloc(0)
  }

  _transform(newData, encoding, done) {
    // Add new data
    this.currentData = Buffer.concat([this.currentData, newData])

    // Find frames in current data
    while (true) {
      // Find the start of a frame
      const startIndex = this.currentData.indexOf(this.magicNumber)
      if (startIndex < 0) break // start of frame not found

      // Find the start of the next frame
      const endIndex = this.currentData.indexOf(
        this.magicNumber,
        startIndex   this.magicNumber.length,
      )
      if (endIndex < 0) break // we haven't got the whole frame yet

      // Handle found frame
      this.push(this.currentData.slice(startIndex, endIndex)) // emit a frame
      this.currentData = this.currentData.slice(endIndex) // remove frame data from current data
      if (startIndex > 0) console.error(`Discarded ${startIndex} bytes of invalid data`)
    }

    done()
  }

  _flush(done) {
    this.push(this.currentData)
    done()
  }
}

import { Converter } from "ffmpeg-stream"

const converter = new Converter()

converter
  .createOutputStream({ f: "image2pipe", vcodec: "mjpeg" })
  .pipe(new ExtractFrames("FFD8FF")) // use jpg magic number as delimiter
  .on("data", frameData => {
    /* do things with frame data (instance of Buffer) */
  })

converter.run()

import { Converter } from "ffmpeg-stream"

const frames = ["frame1.jpg", "frame2.jpg", ...etc]

// create converter
const converter = new Converter()

// create input writable stream (the jpeg frames)
const converterInput = converter.createInputStream({ f: "image2pipe", r: 30 })

// create output to file (mp4 video)
converter.createOutputToFile("out.mp4", {
  vcodec: "libx264",
  pix_fmt: "yuv420p",
})

// start the converter, save the promise for later
const convertingFinished = converter.run()

// pipe all the frames to the converter sequentially
for (const filename of frames) {
  // create a promise for every frame and await it
  await new Promise((resolve, reject) => {
    s3.getObject({ Bucket: "...", Key: filename })
      .createReadStream()
      .pipe(converterInput, { end: false }) // pipe to converter, but don't end the input yet
      .on("end", resolve) // resolve the promise after the frame finishes
      .on("error", reject)
  })
}
converterInput.end()

// await until the whole process finished just in case
await convertingFinished

import * as fs from "node:fs"
import { Converter } from "ffmpeg-stream"

// create the joiner ffmpeg process (frames to video)
const joiner = new Converter()
const joinerInput = joiner.createInputStream({ f: "mjpeg" })
const joinerOutput = joiner.createOutputStream({ f: "whatever format you want" })
joinerOutput.pipe(/* wherever you want */)

joiner.run()

// remember if we are streaming currently
let streaming = false

/**
 * A function which streams a single video.
 *
 * @param {import("node:stream").Readable} incomingStream - The video stream.
 * @param {string} format - The format of the video stream.
 *
 * @returns {Promise<void>} Promise which resolves when the stream ends.
 */
async function streamVideo(incomingStream, format) {
  if (streaming) throw new Error("We are already streaming something else")
  streaming = true

  // create the splitter ffmpeg process (video to frames)
  const splitter = new Converter()

  // pipe video to splitter process
  incomingStream.pipe(splitter.createInputStream({ f: format }))

  // get jpegs and pipe them to joiner process
  splitter.createOutputStream({ f: "mjpeg" }).pipe(joinerInput, { end: false })

  try {
    await splitter.run()
  } finally {
    streaming = false
  }
}

setInterval(() => {
  // if we are streaming - do nothing
  if (streaming) return

  // pipe a single jpeg file 30 times per second into the joiner process
  // TODO: don't actually read the file 30 times per second
  fs.createReadStream("intermission_pic.jpg").pipe(joinerInput, { end: false })
}, 1000 / 30)