chore: update public repo

utils/mpd.ts

@@ -0,0 +1,123 @@
+import { assert, ConditionVariable } from '@fuman/utils'
+import { load } from 'cheerio'
+import { ffetch } from './fetch.ts'
+import { writeWebStreamToFile } from './fs.ts'
+
+interface SimpleMpd {
+  codecs: string
+  initUrl: string
+  segmentUrls: string[]
+}
+
+export function parseSimpleMpd(xml: string): SimpleMpd {
+  const $ = load(xml, { xml: true })
+
+  const period = $('Period')
+  assert(period.length === 1, 'expected exactly one period')
+
+  const adaptations = period.find('AdaptationSet')
+  assert(adaptations.length === 1, 'expected exactly one adaptation set')
+
+  const representation = adaptations.find('Representation')
+  assert(representation.length === 1, 'expected exactly one representation')
+
+  const segmentTemplate = representation.find('SegmentTemplate')
+  assert(segmentTemplate.length === 1, 'expected exactly one segment template')
+
+  const initUrl = segmentTemplate.attr('initialization')
+  const templateUrl = segmentTemplate.attr('media')
+  const startNum = segmentTemplate.attr('startNumber')
+
+  assert(initUrl !== undefined, 'expected initialization url')
+  assert(templateUrl !== undefined, 'expected template url')
+  assert(!templateUrl.match(/\$(RepresentationID|Bandwidth|Time)\$/), 'unsupported template url')
+  assert(startNum !== undefined, 'expected start number')
+
+  const timeline = segmentTemplate.find('SegmentTimeline')
+  assert(timeline.length === 1, 'expected exactly one segment timeline')
+
+  const segments = timeline.find('S')
+  assert(segments.length > 0, 'expected at least one segment')
+
+  const segmentUrls: string[] = []
+
+  let segmentNum = Number(startNum)
+  for (const segment of segments) {
+    const duration = $(segment).attr('d')
+    assert(duration !== undefined, 'expected duration')
+    const r = $(segment).attr('r')
+    const repeats = r ? Number.parseInt(r) + 1 : 1
+
+    for (let i = 0; i < repeats; i++) {
+      segmentUrls.push(templateUrl.replace('$Number$', String(segmentNum)))
+      segmentNum++
+    }
+  }
+
+  return {
+    codecs: representation.attr('codecs')!,
+    initUrl,
+    segmentUrls,
+  }
+}
+
+export function concatMpdSegments(options: {
+  mpd: SimpleMpd
+  fetch: (url: string) => Promise<Uint8Array>
+  poolSize?: number
+}): ReadableStream {
+  const { mpd, fetch, poolSize = 8 } = options
+
+  let nextSegmentIdx = -1
+  let nextWorkerSegmentIdx = -1
+  const nextSegmentCv = new ConditionVariable()
+  const buffer: Record<number, Uint8Array> = {}
+
+  const downloadSegment = async (idx = nextWorkerSegmentIdx++) => {
+    // console.log('downloading segment %s', idx)
+    const url = idx === -1 ? mpd.initUrl : mpd.segmentUrls[idx]
+    const chunk = await fetch(url)
+    buffer[idx] = chunk
+
+    if (idx === nextSegmentIdx) {
+      nextSegmentCv.notify()
+    }
+
+    if (nextWorkerSegmentIdx < mpd.segmentUrls.length) {
+      return downloadSegment()
+    }
+  }
+
+  let error: unknown
+  void Promise.all(Array.from({
+    length: Math.min(poolSize, mpd.segmentUrls.length),
+  }, downloadSegment))
+    .catch((e) => {
+      error = e
+      nextSegmentCv.notify()
+    })
+
+  return new ReadableStream({
+    async start(controller) {
+      while (true) {
+        await nextSegmentCv.wait()
+        if (error) {
+          controller.error(error)
+          return
+        }
+
+        while (nextSegmentIdx in buffer) {
+          const buf = buffer[nextSegmentIdx]
+          delete buffer[nextSegmentIdx]
+          nextSegmentIdx++
+          controller.enqueue(buf)
+        }
+
+        if (nextSegmentIdx >= mpd.segmentUrls.length) {
+          controller.close()
+          return
+        }
+      }
+    },
+  })
+}