From an m3u8 video stream link, download a zip file that contains the ts stream chunks and a index.txt that can be used with ffmpeg

m3u8-to-ffmpeg-zip.js

const sourceUrl = "https://m3u8-0.c-spanvideo.org/clip/clip.5081597.576.tsc.m3u8"

const source = await fetch(sourceUrl)
  .then(res => res.ok ? res.text() : undefined)
if (!source)
  throw new Error("it's over")

const tsBlobs = await Promise.all(
  source
    .split("\n")
    .flatMap(line => {
      const trimmed = line.trim()
      if (trimmed.startsWith("#"))
        return []

      try {
        return [new URL(trimmed, sourceUrl)]
      }
      catch {
        return []
      }
    })
    .filter(url => url.pathname.endsWith(".ts"))
    .map(url =>
      fetch(url).then(res => {
        if (!res.ok)
          throw new Error("Failed to download", url)

        return res.blob()
      })
    )
)

const tsByteArrays = await Promise.all(
  tsBlobs.map(async blob => new Uint8Array(await blob.arrayBuffer()))
)

const { zip } = await import("https://esm.sh/fflate@0.8.2")

const indexFile = tsBlobs.map((blob, i) => `file 'chunks/${i}.ts'`).join("\n")

const zipFile = await new Promise(async (resolve, reject) => {
  zip(
    {
      "index.txt": new TextEncoder().encode(indexFile),
      chunks: Object.fromEntries(
        tsByteArrays.map((byteArray, i) => [`${i}.ts`, byteArray])
      )
    },
    { level: 0 },
    (error, data) => {
      if (error)
        reject(error)
      else
        resolve(data)
    }
  )
})

const downloadLink = document.createElement("a")
downloadLink.href = URL.createObjectURL(
  new Blob([zipFile], { type: "application/zip" })
)
downloadLink.download = "video-source.zip"
downloadLink.click()

console.log("cd Downloads/video-source")
console.log("ffmpeg -f concat -i index.txt -c copy video.mp4")