fix: restore niconico audio playback

apps/web/src/lib/nico-hls-manifest.ts

@@ -0,0 +1,115 @@
+import type { AudioStreamItem, VideoStreamItem } from "../types/api";
+import { proxyUrl } from "./proxy";
+
+const AUDIO_GROUP_ID = "audio";
+const FALLBACK_VIDEO_BANDWIDTHS = [
+  [1080, 5_000_000],
+  [720, 2_500_000],
+  [480, 1_200_000],
+  [360, 800_000],
+] as const;
+
+function encodeManifest(value: string): string {
+  const bytes = new TextEncoder().encode(value);
+  let binary = "";
+  for (const byte of bytes) binary += String.fromCharCode(byte);
+  return btoa(binary);
+}
+
+function quote(value: string): string {
+  return value
+    .replace(/\\/g, "\\\\")
+    .replace(/"/g, '\\"')
+    .replace(/[\r\n]/g, " ");
+}
+
+function positive(value: number | null | undefined): number | null {
+  return typeof value === "number" && Number.isFinite(value) && value > 0 ? value : null;
+}
+
+function heightFromResolution(value: string): number | null {
+  return positive(Number(value.match(/(\d+)\s*[pP]/)?.[1]));
+}
+
+function videoHeight(stream: VideoStreamItem): number | null {
+  return positive(stream.height) ?? heightFromResolution(stream.resolution);
+}
+
+function videoResolution(stream: VideoStreamItem): string | null {
+  const height = videoHeight(stream);
+  const width = height === null ? null : (positive(stream.width) ?? Math.round((height * 16) / 9));
+  return height === null || width === null ? null : `${width}x${height}`;
+}
+
+function bitrateBandwidth(value: number | null): number | null {
+  const bitrate = positive(value);
+  return bitrate === null ? null : bitrate < 10_000 ? bitrate * 1000 : bitrate;
+}
+
+function fallbackVideoBandwidth(stream: VideoStreamItem): number {
+  const height = videoHeight(stream) ?? 360;
+  return FALLBACK_VIDEO_BANDWIDTHS.find(([minimum]) => height >= minimum)?.[1] ?? 500_000;
+}
+
+function videoBandwidth(stream: VideoStreamItem): number {
+  return bitrateBandwidth(stream.bitrate) ?? fallbackVideoBandwidth(stream);
+}
+
+function qualityBandwidth(value: string | null): number | null {
+  return positive(Number(value?.match(/(\d+)/)?.[1]));
+}
+
+function audioBandwidth(stream: AudioStreamItem): number {
+  const quality = qualityBandwidth(stream.quality);
+  return bitrateBandwidth(stream.bitrate) ?? (quality !== null ? quality * 1000 : 128_000);
+}
+
+function audioName(stream: AudioStreamItem, index: number): string {
+  return (
+    [stream.audioTrackName, stream.quality ? `${stream.quality} kbps` : null].find(
+      (value): value is string => typeof value === "string" && value.length > 0,
+    ) ?? `Audio ${index + 1}`
+  );
+}
+
+function audioMedia(stream: AudioStreamItem, index: number): string {
+  const name = quote(audioName(stream, index));
+  const isDefault = index === 0 ? "YES" : "NO";
+  return [
+    `#EXT-X-MEDIA:TYPE=AUDIO`,
+    `GROUP-ID="${AUDIO_GROUP_ID}"`,
+    `NAME="${name}"`,
+    `DEFAULT=${isDefault}`,
+    `AUTOSELECT=YES`,
+    `URI="${quote(proxyUrl(stream.url))}"`,
+  ].join(",");
+}
+
+function streamInfo(stream: VideoStreamItem, audio: AudioStreamItem | undefined): string {
+  const bandwidth = videoBandwidth(stream) + (audio ? audioBandwidth(audio) : 0);
+  const resolution = videoResolution(stream);
+  const attributes = [
+    `BANDWIDTH=${bandwidth}`,
+    resolution ? `RESOLUTION=${resolution}` : null,
+    audio ? `AUDIO="${AUDIO_GROUP_ID}"` : null,
+  ].filter((attribute) => attribute !== null);
+  return `#EXT-X-STREAM-INF:${attributes.join(",")}`;
+}
+
+export function buildNicoHlsManifest(
+  videoStreams: VideoStreamItem[],
+  audioStreams: AudioStreamItem[],
+): string | null {
+  const videos = videoStreams.filter((stream) => stream.url.length > 0);
+  const audios = audioStreams.filter((stream) => stream.url.length > 0);
+  if (videos.length === 0) return null;
+
+  const primaryAudio = audios[0];
+  const lines = ["#EXTM3U", "#EXT-X-VERSION:6", ...audios.map(audioMedia)];
+  for (const video of videos) {
+    lines.push(streamInfo(video, primaryAudio), proxyUrl(video.url));
+  }
+
+  const manifest = `${lines.join("\n")}\n`;
+  return `data:application/vnd.apple.mpegurl;base64,${encodeManifest(manifest)}`;
+}

apps/web/src/lib/stream-src.ts

@@ -2,6 +2,7 @@ import type { VideoStream } from "../types/stream";
 import { buildBilibiliDashManifest } from "./bilibili-manifest";
 import { buildDashManifest } from "./dash-manifest";
 import { API_BASE as BASE } from "./env";
+import { buildNicoHlsManifest } from "./nico-hls-manifest";
 import { isCompatibilityPlaybackMode } from "./playback-mode";
 import { detectProvider } from "./provider";
 import { proxyDashManifest } from "./proxy";
@@ -51,10 +52,6 @@ function fallbackSrc(
   };
 }
 
-function pickNicoHlsUrl(stream: VideoStream): string | null {
-  return stream.videoOnlyStreams?.[0]?.url ?? stream.audioStreams?.[0]?.url ?? null;
-}
-
 export function resolveManifestSrc(
   stream: VideoStream,
   isLive: boolean,
@@ -78,8 +75,8 @@ export function resolveManifestSrc(
   }
 
   if (provider === "nicovideo") {
-    const hlsUrl = pickNicoHlsUrl(stream);
-    if (hlsUrl) return { src: proxyDashManifest(hlsUrl), type: "application/x-mpegurl" };
+    const built = buildNicoHlsManifest(stream.videoOnlyStreams ?? [], stream.audioStreams ?? []);
+    if (built) return { src: built, type: "application/x-mpegurl" };
   }
 
   if (provider === "bilibili") {