SpaceX Landing Video Cleanup Making Progress

Maddog Batty (112434) writes 'The fine people at the NASA Space Flight Forum are making good progress on restoring the corrupted landing video reported earlier. It worth looking at the original video to see how bad it was and then at the latest restored video. It is now possible to see the legs being deployed, the sea coming closer and a big flame ball as the rocket plume hits the water. An impressive improvement so far and it is still being actively worked on so further refinements are likely.' Like Maddog Batty, I'd suggest watching the restored version first (note: the video is lower on the page), to see just what a big improvement's been made so far.

Re:Just do it again

[arse maker]

They will shortly, there was a planned launch last month but it has been pushed back for various reasons. http://www.space.com/25822-spa... [space.com]

The fact they have this thing vertical at well below terminal velocity and apparently not spinning means the rest is just details. Controlling it down from supersonic is the hard part. They have made many successful landings with grasshopper from a vertical, low speed non spinning state.

Summary of techniques used?

[Whip]

I would *love* to see a summary of the types of problems the video stream has, and the techniques used to recover them. Anyone feel like sorting through the ~70 pages of thread and cataloging them? :)

Re:cheap webcam

[kaiser423]

Video feeds are typically their own streams. They're typically in the couple of Mbit range, but really can be anything. We've had 10+Mbps video links, but they're typically high frame rate versus high resolution. The thing to remember here is that you can't do any real fancy compression or modulations schemes typically, so every a couple of Mb/s really isn't that high of resolution. This is because you know that you're dropping bits, you're signal is fading unpredictably, the signal propagation path is changing wildly, etc so things like QAM don't work, and compression actually hurts because you're often getting errors in the blocks, etc really throws a wrench in the whole thing. So you almost have to ship the video raw over some fairly inefficient modulation scheme like FM or SOQPSK (more efficient, but more likely to burst-lose lots of data).

I took a quick look at the embedded video stream, and it looks like there would have been a better way to pack it (looks like some asynchronous frames inside, with multiple sync words inside needing to be correct to get a good frame, made it harder than it had to be. But still, this isn't easy stuff. I expect them to come out shooting next time though. They really didn't have much in the area to grab the video with good fidelity because they had other things to focus on, but this time I expect a bit more.

I do telemetry chase form aircraft, boats, etc for exactly this type of thing for a living. Fun job :)

Re:cheap webcam

[Anonymous Coward]

Well considering HOW they actually got the video, I guess it's not too shabby. Here's a quote from Musk from the recent Dragon v2 unveiling:

"As far as the soft landing of the boost phase, it was interesting, when we got the corrupted video back, because we really actually had a real difficult time getting the telemetry. In fact, I'll tell you a funny thing. We actually had to - because normally we get the bulk of the telemetry from a boat. We also have a backup, an AP3 that was going to go up, and the P3 got iced up, the boats couldn't go out, so I sent my plane up with my pilots, and... we had to design and fabricate an antenna that exactly fit in the window of the plane. We started off with a pizza dish and we were able to do a double loop antenna with a pizza dish and point it out the window to get the link."

Re:cheap webcam

[mvpel]

The story we heard from SpaceX is that due to the weather, they couldn't get a boat out in the 15-foot seas, and the NASA chase plane they usually use wasn't available, so they went up in Elon's private jet equipped with an antenna jerry-rigged from a pizza pan stuck in the window. Maybe next time they'll use a Pringles can instead. :D

One of the mpeg experts was lamenting the encoding - there was no error correction enabled in the MPEG encoding, and the images were interlaced from an NTSC 29.97 down to a 15-fps feed into the encoder, and interlacing crushes the compression ratio, I gather. They've been informed of this, so hopefully the next launch will see some rock-solid quality video.