fix(anime): strip disguised HLS segments and report real playback errors

Some hosts prepend a fake image header (a real 1x1 PNG) to every HLS
segment; ffmpeg probes the segment as a picture and mpv drops back to
idle with no window while the browser claims the episode is playing.

- Route bridge-served m3u8 streams through a local strip proxy that
  scans each segment for the first genuine MPEG-TS packet run and drops
  the junk in front of it; playlists get absolute origins rewritten so
  segment requests come back through the proxy. Non-TS bodies pass
  through untouched.
- Only report ok from playEpisode once mpv configures a video output;
  an end-file with reason error surfaces mpv's own message (e.g. "no
  audio or video data played") in the browser status bar instead of
  "Playing". New end-file event plumbed through the mpv IPC client.
This commit is contained in:
2026-08-01 00:05:31 -07:00
parent 81856539e4
commit 835426d1e9
13 changed files with 767 additions and 23 deletions
+232
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import http from 'node:http';
import type { AddressInfo } from 'node:net';
/**
* Loopback proxy between mpv and the anime bridge that undoes segment
* disguises. Some hosts prepend a real image header (a 1x1 PNG in the wild) to
* every HLS segment so scrapers see "an image"; ffmpeg then probes the segment
* as a picture and playback dies with "no audio or video data played". Aniyomi
* strips this in its player; mpv needs the bytes fixed before it sees them.
*
* Only bridge-origin `.m3u8` streams are routed through here (see
* anime-browser-runtime). Playlist bodies get their absolute upstream origins
* rewritten so segment requests come back through the proxy; segment bodies are
* scanned for the first genuine MPEG-TS packet run and any junk before it is
* dropped. Anything that is not TS (fMP4, VTT, keys) passes through untouched.
*/
export const TS_PACKET_LENGTH = 188;
const TS_SYNC_BYTE = 0x47;
/**
* Sync bytes that must repeat at exact packet spacing before an offset counts
* as TS data. One or two matches happen by chance in binary data; five in a
* row at 188-byte strides do not.
*/
const SYNC_RUN = 5;
/** A disguise prefix is small; give up scanning after this much. */
export const DEFAULT_SCAN_LIMIT_BYTES = 1024 * 1024;
/** Bytes needed to either find a run within the limit or rule one out. */
const DECISION_BYTES = DEFAULT_SCAN_LIMIT_BYTES + (SYNC_RUN - 1) * TS_PACKET_LENGTH + 1;
/**
* First offset at which a confirmed MPEG-TS packet run starts, or null when
* the data does not look like TS at all (within the scan limit).
*/
export function findTsSyncOffset(
data: Buffer,
scanLimit = DEFAULT_SCAN_LIMIT_BYTES,
): number | null {
const lastConfirmable = data.length - (SYNC_RUN - 1) * TS_PACKET_LENGTH - 1;
const end = Math.min(lastConfirmable, scanLimit);
for (let offset = 0; offset <= end; offset++) {
if (data[offset] !== TS_SYNC_BYTE) continue;
let confirmed = true;
for (let packet = 1; packet < SYNC_RUN; packet++) {
if (data[offset + packet * TS_PACKET_LENGTH] !== TS_SYNC_BYTE) {
confirmed = false;
break;
}
}
if (confirmed) return offset;
}
return null;
}
/**
* Point absolute playlist entries at the proxy. Relative entries already
* resolve against whatever origin served the playlist, so they need no help.
*/
export function rewritePlaylistOrigins(
body: string,
upstreamOrigin: string,
proxyOrigin: string,
): string {
return body.split(upstreamOrigin).join(proxyOrigin);
}
export interface StreamStripProxyOptions {
/** Read per request so a bridge restart on a new port keeps working. */
upstreamOrigin: () => string;
log?: (message: string) => void;
}
export interface StreamStripProxyHandle {
origin: string;
port: number;
close: () => Promise<void>;
}
/** Response headers that must not be forwarded verbatim. */
const DROPPED_HEADERS = new Set([
'connection',
'keep-alive',
'transfer-encoding',
'content-length',
]);
function forwardableHeaders(headers: http.IncomingHttpHeaders): http.OutgoingHttpHeaders {
const result: http.OutgoingHttpHeaders = {};
for (const [name, value] of Object.entries(headers)) {
if (value === undefined || DROPPED_HEADERS.has(name.toLowerCase())) continue;
result[name] = value;
}
return result;
}
export function startStreamStripProxy(
options: StreamStripProxyOptions,
): Promise<StreamStripProxyHandle> {
const log = options.log ?? (() => {});
const server = http.createServer((req, res) => {
if (req.method !== 'GET' && req.method !== 'HEAD') {
res.writeHead(405).end();
return;
}
let upstreamUrl: URL;
try {
upstreamUrl = new URL(req.url ?? '/', options.upstreamOrigin());
} catch {
res.writeHead(502).end();
return;
}
const requestHeaders = forwardableHeaders(req.headers);
delete requestHeaders.host;
const upstreamRequest = http.request(
upstreamUrl,
{ method: req.method, headers: requestHeaders },
(upstream) => handleUpstreamResponse(req, res, upstream),
);
upstreamRequest.on('error', (error) => {
log(`[stream-proxy] upstream request failed: ${String(error)}`);
if (!res.headersSent) res.writeHead(502);
res.end();
});
upstreamRequest.end();
});
function handleUpstreamResponse(
req: http.IncomingMessage,
res: http.ServerResponse,
upstream: http.IncomingMessage,
): void {
const status = upstream.statusCode ?? 502;
const pathname = (req.url ?? '').split('?', 1)[0] ?? '';
const contentType = String(upstream.headers['content-type'] ?? '');
const isPlaylist = pathname.endsWith('.m3u8') || contentType.includes('mpegurl');
upstream.on('error', () => res.destroy());
// Only a full 200 body is safe to modify; everything else (errors, range
// responses, HEAD) forwards untouched.
if (status !== 200 || req.method === 'HEAD') {
res.writeHead(status, forwardableHeaders(upstream.headers));
upstream.pipe(res);
return;
}
if (isPlaylist) {
const chunks: Buffer[] = [];
upstream.on('data', (chunk: Buffer) => chunks.push(chunk));
upstream.on('end', () => {
const body = rewritePlaylistOrigins(
Buffer.concat(chunks).toString('utf8'),
options.upstreamOrigin(),
origin,
);
res.writeHead(status, {
...forwardableHeaders(upstream.headers),
'content-length': Buffer.byteLength(body, 'utf8'),
});
res.end(body);
});
return;
}
stripSegment(res, upstream);
}
/**
* Buffer just enough of the body to find (or rule out) a TS packet run,
* drop everything before it, then stream the rest through untouched.
*/
function stripSegment(res: http.ServerResponse, upstream: http.IncomingMessage): void {
const chunks: Buffer[] = [];
let buffered = 0;
const respond = (data: Buffer, remainderFollows: boolean): void => {
const offset = findTsSyncOffset(data) ?? 0;
if (offset > 0) log(`[stream-proxy] stripped ${offset} disguise bytes off a segment`);
const body = offset > 0 ? data.subarray(offset) : data;
const headers = forwardableHeaders(upstream.headers);
const upstreamLength = Number(upstream.headers['content-length']);
if (remainderFollows) {
if (Number.isFinite(upstreamLength)) headers['content-length'] = upstreamLength - offset;
} else {
headers['content-length'] = body.length;
}
res.writeHead(upstream.statusCode ?? 200, headers);
res.write(body);
};
const onData = (chunk: Buffer): void => {
chunks.push(chunk);
buffered += chunk.length;
if (buffered < DECISION_BYTES) return;
upstream.off('data', onData);
upstream.off('end', onEnd);
respond(Buffer.concat(chunks), true);
upstream.pipe(res);
};
const onEnd = (): void => {
respond(Buffer.concat(chunks), false);
res.end();
};
upstream.on('data', onData);
upstream.on('end', onEnd);
}
let origin = '';
return new Promise((resolve, reject) => {
server.once('error', reject);
server.listen(0, '127.0.0.1', () => {
const { port } = server.address() as AddressInfo;
origin = `http://127.0.0.1:${port}`;
resolve({
origin,
port,
close: () =>
new Promise<void>((resolveClose) => {
server.closeAllConnections?.();
server.close(() => resolveClose());
}),
});
});
});
}