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Mikkeli Matlock 84c29cc0b7 Correct two disproved claims and record what is actually verified

The TLS-handshake explanation for the 403 was wrong. The split is by token
form, not by client: Python fetches the master (query token) fine and fails
only on the media playlist (path token). That is why record_live.py mints a
master and why --downloader ffmpeg is required.

"The stream never ends" was one video observation stated as a rule, and an
audio stream has since contradicted it by terminating cleanly well inside the
cap. Both are now recorded as single observations rather than conclusions.

Also records the state of play: unattended recording works, login has never
been tested, and the decision not to automate it -- the cookie outlives a
quarter, so automating the riskiest step to save four manual logins a year is
a bad trade.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Kyt7QHQvLJtQRuiY4wAqKB

2026-09-05 18:49:00 +09:00

7.8 KiB

Raw Blame History

brfc-stream-pirate

Personal time-shifting archive for Bristol Rovers video pass streams. Kickoffs land at unfriendly hours in JST; this records them unattended.

Stream is plain HLS, no DRM (StreamAMG behind Akamai). Nothing here breaks a protection measure -- it replays the same authenticated request the player makes, using your own paid session.

Pieces

File	Job
`tampermonkey/brfc-stream-sniffer.user.js`	Hooks fetch/XHR in the page, captures the manifest URL verbatim, POSTs it to the catcher
`catcher.py`	Listens on 127.0.0.1:8787, hands the URL to yt-dlp, records to `recordings/`
`probe.py`	Byte-exact manifest fetch + concurrency test

The token

Manifest URLs carry an Akamai path token:

hdntl=exp=<unix>~acl=/*~id=<n>~data=hdntl~hmac=<sig>

exp -- ~24h validity
acl=/* -- wildcard over the whole host, not just your match
hmac -- signature over the literal path

It is a bearer credential. Anyone holding a live URL can pull the stream until exp. Keep it out of pastebins and issue trackers. stream-url.txt and cookies.txt are gitignored.

Do not re-encode the path. curl normalises %2f to %2F, which invalidates the HMAC. probe.py sends the request target verbatim.

Use Firefox for watching

yt-dlp lifts session cookies from the browser. Chrome 127+ on Windows uses app-bound cookie encryption and extraction fails. Firefox works with no fuss.

set BRFC_BROWSER=firefox     # default

Workflow

pip install yt-dlp                    # done
python catcher.py                     # leave running

Install the userscript in Tampermonkey, open the match page, press play. The sniffer catches the manifest, the catcher starts yt-dlp. Recording is MPEG-TS (--hls-use-mpegts) so a killed process still leaves a playable file.

For a 3am kickoff: Task Scheduler opens the match page a few minutes before, the browser autoplays, the sniffer fires, the catcher records. Nobody is awake.

Concurrency check

An Akamai edge token is a stateless HMAC -- the edge validates signature and expiry and serves; it holds no session table, so it cannot count viewers. Any concurrent-stream limit lives in the entitlement API that issues tokens, upstream of the CDN. Confirm rather than assume, while the browser is playing:

python probe.py --url "<manifest from the sniffer>" --parallel 3

3/3 alongside the playing browser means four concurrent readers of one token and the edge does not care.

Findings (2026-08-29, live 2300 JST match)

Verified against a live stream. Recorded 1080p successfully end to end.

Two token types, not one

The player uses a two-stage token chain:

Token	Where	TTL	Purpose
`hdnts=`	query string, `acl=/*` unencoded	~25 seconds	fetch the master playlist
`hdntl=`	URL path, `acl=%2f*` encoded	~24 hours	media playlists + segments

The master response rewrites each variant URL with a 24h hdntl token. So the hdntl token is the durable one worth handing to a downloader. Chasing a hdnts URL by hand is pointless -- it dies before you can paste it.

Confirmed by experiment

Concurrency is not limited. Two independent ffmpeg downloads ran at full bitrate while Firefox played the same match. Three concurrent readers of one token, no complaint from the edge. Akamai token auth is a stateless HMAC check; it has no viewer counter.
No CDN cookies exist. All 13 relevant cookies are on bristolrovers.co.uk; nothing is scoped to akamaized.net. The token in the URL is the whole auth.
Stream is 1920x1080 H.264 + AAC ~5.2 Mbit/s -> roughly 4.7 GB per match.
Output is MPEG-TS even though yt-dlp names it .mp4. That is what --hls-use-mpegts buys: a killed process still leaves a playable file.
Player is Bitmovin, embedded on the club site. 0_xm5vrrw6 is a Kaltura entry id and identifies the match -- the catcher dedupes on it.

Gotcha: which URL form a Python client can fetch

Earlier notes here blamed a TLS handshake difference. That was wrong. The 403 splits by token form, not by client:

URL form	Python	ffmpeg
`index.m3u8?hdnts=...` (master, query token)	200	200
`hdntl=.../index_N.m3u8` (media, path token)	403	200

Consequences:

Mint a master URL and hand that to the downloader. record_live.py does this: it calls the entry API for a fresh master immediately before recording.
Force --downloader ffmpeg. yt-dlp's native HLS downloader fetches variant playlists with Python and dies on the path-token URLs. This is required, not a preference.
probe.py is diagnostic scaffolding and inherits the path-token 403 -- do not use it to conclude a token is dead.

Firefox, not Chrome

yt-dlp reads cookies from a running Firefox. Chrome/Edge lock their cookie DB while running (yt-dlp issue 7271), and an unattended job cannot close the browser to read them.

The stream never ends

After full time the feed switches to a static league slate and keeps serving indefinitely at full CBR bitrate (~4.7 Mbit/s to encode a still image). There is no #EXT-X-ENDLIST, so ffmpeg never finishes, and there is no stall to detect either -- from the downloader's point of view it is a healthy live stream forever.

Keep the duration cap. catcher.py and record_live.py pass ffmpeg_o:-t $DURATION_MIN*60. Without it, a feed that behaves like the video one above fills the disk with a logo.

Note the sample size. This is one video observation, and it is contradicted by one audio observation: on 2026-09-02 an audio stream ended cleanly by itself (rc=0 at 165 min, against a 180 min cap that never fired). So "the stream never ends" is a property of that video feed, not an established rule. Treat the cap as a safety net rather than as the only stop condition.

Observed: video, 116 min recorded for a 23:00 kickoff, still running at 01:04 and stopped manually. Audio, 165 min, self-terminated. Budget ~3.5-4 GB per copy per match at 40 MB/min.

Status

Unattended recording works. A scheduled task started record_live.py at 03:15 for an 03:45 kickoff, found the stream in 16 seconds, and recorded 165 min of audio to a playable MPEG-TS with nobody awake.

Sample sizes are one. One video capture, one audio capture. Where the two disagree (stream termination, whether an entry id persists between matches), neither is established -- do not build on either without more matches.

Verified

Token chain end to end in plain Python: session cookie -> JWT -> entry API -> master playlist. No browser, no fingerprint forging.
Recording via ffmpeg, video (1080p) and audio (~122 kbps AAC).
Scheduled unattended run, including that Task Scheduler launches it correctly.
Concurrency: several readers of one token, alongside a playing browser.

Not verified

Login. Everything above rides an SSESS cookie lifted from a desktop Firefox profile. Obtaining a session from credentials has never been run. /user/login is a standard Drupal form (name, pass, form_build_id, form_id, captcha_token) with no reCAPTCHA script and no 2FA mention, but captcha_token is an unknown and testing it risks a lockout that would take out the working session too.

The cookie lasts ~87 days and matches are weekly, so automating login saves about four manual actions a year -- while being the riskiest step and the only one needing a stored password. Refresh the cookie by logging in manually on the desktop each quarter and provisioning it to the recording host instead. That makes cookie provisioning the open problem, not the captcha.

Use Firefox as the session holder. Two independent reasons: its cookie DB stays readable while running (Chrome/Edge lock theirs), and it holds the login durably where Chrome has been observed dropping it within a day.

7.8 KiB Raw Blame History