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Comment by daedalus2027 | Hacker News Reader

daedalus2027

At 11:08 you can see udp://234.70.253.161:9000

IANA reserved multicast space, often used in peoples' internal networks, not something you could ever access unless you were connected to the same network segment as the video stream source.

Today I learned, thanks for sharing that info!

Thanks a lot! I was almost about to spend couple hours analyzing the ip and ports. Now I know that it’s a reserved multicast ip.

This means the actual IP range should be something in 70.252.0.0/14, which is assigned to AT&T according to whois.arin.net.

Chopping off 234 from head of this IP address, the parts left are the network address and group id.

See: https://tools.ietf.org/html/rfc6034

People have managed to tune into the raw video stream via RTL-SDR. I'm guessing this IP is post this step and internal to their streaming

https://www.rtl-sdr.com/receiving-space-x-falcon-9-telemetry...

https://news.ycombinator.com/item?id=26423406

The font used in the IP address almost looks like something generated as an overlay by VLC or ffmpeg.

Yep, it looks like VLC.

If I had to make a guess they're taking a stream from some embedded system with a camera on board the starship, downlinked to a system running VLC at the test site, and that system is being used to perform some form of on the fly transcoding or resizing, feeding video out to a live editing/mixing setup (how they're accomplishing the picture-in-picture of inside the rocket skirt and exterior camera at the same time).

VLC can do all sorts of stuff that 99% of its users never touch, if they're just playing files.

https://wiki.videolan.org/transcode/

The IP address shown was an multicast address, which provide a crucial hint as to their setup. Most likely after downlink from Starship the camera feeds are distributed from the test site through their network using UDP multicast, probably without any transcoding and resizing, only remuxed. This allows the feeds to be available to mission control, engineering, employees, etc with minimal delay. Then a separate system, possibly not even at the test site, receives that stream, transcodes/resizes it and feeds it into the mixing and streaming setup. This last part is probably want they use VLC for and what generated the overlay we saw.

The engineer at SpaceX responsible for running the webcasts actually used to be active on r/SpaceX, and has shared some details about how they ran it all.

If you find that reddit thread I'd love to see it thanks!

It wasn't an AMA. Their user account is (was) https://www.reddit.com/user/bencredible, but you'd have to hunt through the comments to find the interesting bits. I also think at some point some comments got deleted.

Amazing thanks! I'll have a dig through. I'm incredibly fascinated with video codecs but it does my head in.

Immediately after that post, SpaceX began encrypting the streams from both Falcon 9 and Starship.

The SpaceX engineer who implemented the encryption apologized on Twitter:

https://twitter.com/skiboysteve/status/1375507358814674944

Didn't know that! Kind of disappointing.

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