fix: switch DASH delivery from data: URI to local MPD file via expo-file-system

data: URI scheme for DASH manifests is unreliable in ExoPlayer.
Write MPD XML to FileSystem.cacheDirectory/bili_dash.mpd and pass
file:// URI to react-native-video instead. URL resolution is now
async via useEffect+state in NativeVideoPlayer.

components/NativeVideoPlayer.tsx

@@ -6,7 +6,7 @@ import {
 import Video, { VideoRef } from 'react-native-video';
 import { Ionicons } from '@expo/vector-icons';
 import type { PlayUrlResponse } from '../services/types';
-import { buildDashDataUri } from '../utils/dash';
+import { buildDashMpdUri } from '../utils/dash';
 
 const { width } = Dimensions.get('window');
 const VIDEO_HEIGHT = width * 0.5625;
@@ -33,12 +33,21 @@ export function NativeVideoPlayer({
   onProgress, seekTo,
 }: Props) {
   const [showQuality, setShowQuality] = useState(false);
+  const [resolvedUrl, setResolvedUrl] = useState<string | undefined>();
   const videoRef = useRef<VideoRef>(null);
   const currentDesc = qualities.find(q => q.qn === currentQn)?.desc ?? (currentQn ? String(currentQn) : 'HD');
   const isDash = !!playData?.dash;
-  const url = isDash
+
-    ? buildDashDataUri(playData!, currentQn)
+  useEffect(() => {
-    : playData?.durl?.[0]?.url;
+    if (!playData) { setResolvedUrl(undefined); return; }
+    if (isDash) {
+      buildDashMpdUri(playData, currentQn).then(setResolvedUrl).catch(() => {
+        setResolvedUrl(playData.dash!.video[0]?.baseUrl);
+      });
+    } else {
+      setResolvedUrl(playData.durl?.[0]?.url);
+    }
+  }, [playData, currentQn]);
 
   useEffect(() => {
     if (seekTo !== undefined) videoRef.current?.seek(seekTo.t);
@@ -46,12 +55,12 @@ export function NativeVideoPlayer({
 
   return (
     <View style={[styles.container, style]}>
-      {url ? (
+      {resolvedUrl ? (
         <Video
           ref={videoRef}
           source={isDash
-            ? { uri: url, type: 'mpd', headers: BILIBILI_HEADERS }
+            ? { uri: resolvedUrl, type: 'mpd', headers: BILIBILI_HEADERS }
-            : { uri: url, headers: BILIBILI_HEADERS }
+            : { uri: resolvedUrl, headers: BILIBILI_HEADERS }
           }
           style={styles.video}
           resizeMode="contain"

package-lock.json

@@ -14,6 +14,7 @@
         "expo": "~55.0.5",
         "expo-av": "^16.0.8",
         "expo-dev-client": "~55.0.11",
+        "expo-file-system": "~55.0.10",
         "expo-linear-gradient": "~55.0.8",
         "expo-router": "~55.0.4",
         "expo-status-bar": "~55.0.4",
@@ -4397,6 +4398,16 @@
         "expo": "*"
       }
     },
+    "node_modules/expo-file-system": {
+      "version": "55.0.10",
+      "resolved": "https://registry.npmjs.org/expo-file-system/-/expo-file-system-55.0.10.tgz",
+      "integrity": "sha512-ysFdVdUgtfj2ApY0Cn+pBg+yK4xp+SNwcaH8j2B91JJQ4OXJmnyCSmrNZYz7J4mdYVuv2GzxIP+N/IGlHQG3Yw==",
+      "license": "MIT",
+      "peerDependencies": {
+        "expo": "*",
+        "react-native": "*"
+      }
+    },
     "node_modules/expo-font": {
       "version": "55.0.4",
       "resolved": "https://registry.npmjs.org/expo-font/-/expo-font-55.0.4.tgz",
@@ -4974,16 +4985,6 @@
         "react-native": "*"
       }
     },
-    "node_modules/expo/node_modules/expo-file-system": {
-      "version": "55.0.10",
-      "resolved": "https://registry.npmjs.org/expo-file-system/-/expo-file-system-55.0.10.tgz",
-      "integrity": "sha512-ysFdVdUgtfj2ApY0Cn+pBg+yK4xp+SNwcaH8j2B91JJQ4OXJmnyCSmrNZYz7J4mdYVuv2GzxIP+N/IGlHQG3Yw==",
-      "license": "MIT",
-      "peerDependencies": {
-        "expo": "*",
-        "react-native": "*"
-      }
-    },
     "node_modules/expo/node_modules/expo-keep-awake": {
       "version": "55.0.4",
       "resolved": "https://registry.npmjs.org/expo-keep-awake/-/expo-keep-awake-55.0.4.tgz",

package.json

@@ -16,6 +16,7 @@
     "expo": "~55.0.5",
     "expo-av": "^16.0.8",
     "expo-dev-client": "~55.0.11",
+    "expo-file-system": "~55.0.10",
     "expo-linear-gradient": "~55.0.8",
     "expo-router": "~55.0.4",
     "expo-status-bar": "~55.0.4",

utils/dash.ts

@@ -1,11 +1,18 @@
+import * as FileSystem from 'expo-file-system/legacy';
 import type { PlayUrlResponse } from '../services/types';
 
 /**
- * 从 Bilibili DASH 响应生成 MPD data URI。
+ * 将 Bilibili DASH 响应写成 MPD 文件，返回 file:// URI 供 ExoPlayer 播放。
  * 选取 id === qn 的视频流（找不到则取第一条），带宽最高的音频流。
- * 返回 "data:application/dash+xml;base64,..." 供 react-native-video (ExoPlayer) 使用。
  */
-export function buildDashDataUri(playData: PlayUrlResponse, qn: number): string {
+export async function buildDashMpdUri(playData: PlayUrlResponse, qn: number): Promise<string> {
+  const xml = buildMpdXml(playData, qn);
+  const path = `${FileSystem.cacheDirectory}bili_dash.mpd`;
+  await FileSystem.writeAsStringAsync(path, xml, { encoding: FileSystem.EncodingType.UTF8 });
+  return path;
+}
+
+function buildMpdXml(playData: PlayUrlResponse, qn: number): string {
   const dash = playData.dash!;
 
   const video = dash.video.find(v => v.id === qn) ?? dash.video[0];
@@ -14,18 +21,17 @@ export function buildDashDataUri(playData: PlayUrlResponse, qn: number): string
   );
 
   const dur = dash.duration;
-
   const vSeg = video.segment_base;
   const aSeg = audio.segment_base;
 
   const videoSegmentBase = vSeg
-    ? `\n        <SegmentBase indexRange="${vSeg.index_range}">\n          <Initialization range="${vSeg.initialization}"/>\n        </SegmentBase>`
+    ? `\n        <SegmentBase indexRange="${vSeg.index_range}"><Initialization range="${vSeg.initialization}"/></SegmentBase>`
     : '';
   const audioSegmentBase = aSeg
-    ? `\n        <SegmentBase indexRange="${aSeg.index_range}">\n          <Initialization range="${aSeg.initialization}"/>\n        </SegmentBase>`
+    ? `\n        <SegmentBase indexRange="${aSeg.index_range}"><Initialization range="${aSeg.initialization}"/></SegmentBase>`
     : '';
 
-  const xml = `<?xml version="1.0" encoding="UTF-8"?>
+  return `<?xml version="1.0" encoding="UTF-8"?>
 <MPD xmlns="urn:mpeg:dash:schema:mpd:2011"
      profiles="urn:mpeg:dash:profile:isoff-on-demand:2011"
      type="static"
@@ -43,8 +49,6 @@ export function buildDashDataUri(playData: PlayUrlResponse, qn: number): string
     </AdaptationSet>
   </Period>
 </MPD>`;
-
-  return `data:application/dash+xml;base64,${btoa(xml)}`;
 }
 
 function escapeXml(s: string): string {