ELI5 "Perpetual fireplace" videos

February 2, 2023 10:00 AM

My wife likes having a "fireplace video" on TV as an idle thing; she specifically uses the Blaze app on the Amazon platform, although similar videos exist elsewhere: they're not of fires with usual fire lifecycles but of a continually burning fire. I'm wondering about the technology behind this.

The most conspicuous thing about these videos is that the wood is never consumed at all. There are videos out there of wood burning up in fires, but these aren't them (when I go searching for more info on "fireplace videos", though, I mostly get info on that type of video).. There is smoke and a reasonably plausible soundtrack of pops and crackles, so it's at least a bit subtler than putting a gas jet behind fake logs. So I'm curious about the technology behind making these videos. In particular:

• I get that it's almost certainly on a loop of some sort. It doesn't seem to be an extremely short loop, and if it was actual wood burning, I'd think the edges of the loop would be too conspicuous — bits of wood which were consumed or had shifted would "jump".
• Assuming there is not actually wood in there, but ceramic (or otherwise fireproof) fake logs, what is the technology behing getting good smoke and crackle. Digital sorcery? Additives to the gas which produce fumes which behave right? The audio, of course, could be from anywhere and added in post-facto.

posted by jackbishop to Technology (8 answers total)

Here's an interview with the guy who did "Fireplace For Your Home" for Netflix, where he talks about the process of filming it: Meet the man who built the perfect fire — so you can stream it on your TV
posted by mandolin conspiracy at 10:39 AM on February 2, 2023 [10 favorites]

I'd imagine part of masking the obvious loop is perhaps letting the video play to a certain point, reversing it from there, and so on. Back and forth, forever. I mean, obviously you wouldn't want a part where a chunk of wood falls off and tumbles down, and then magically floats back up and reattaches itself, but I'd imagine that due to the already chaotic nature of flames, even a relatively short loop makes a believable repeat.
posted by xedrik at 10:40 AM on February 2, 2023 [5 favorites]

(also, the Darth Vader Yule Log is my favorite of the genre.) I think I can see evidence of a loop, maybe, in a little triangle of flame, just to the left edge of Vader's helmet?
posted by xedrik at 10:42 AM on February 2, 2023

The 1966 original was a 17-second loop.

The Luminous Story Behind TV's Yule Log:

In 1966, Fred Thrower, the manager of WPIX-TV Channel 11 in New York City, wanted the station to do “something a little different and special” that Christmas Eve. On November 2, he circulated a memo to his station’s staff, proposing that the station cancel all programs and commercials in order to air a WPIX Christmas Card, consisting of a video loop of a holiday-inspired fireplace. Thrower also suggested asking WPIX’s affiliated radio station, WPIX-FM, to provide an accompanying festive soundtrack.

Thrower’s concept came to life on December 24, 1966, when WPIX first aired three hours of a continuous 17-second film loop of an ornate fireplace. WPIX had filmed the fireplace at Gracie Mansion, the home of New York City’s mayor, and paired the film loop with Christmas hits from singers like Percy Faith and Nat King Cole.

[...]

A few years later, in 1970, realizing the original 16mm film of the Gracie Mansion fireplace was deteriorating, WPIX filmed a similar-looking fireplace in Palo Alto, California. Shot on 35mm film, the new video was seven minutes long, making the fireplace loop footage less jerky than the original.
posted by mandolin conspiracy at 10:46 AM on February 2, 2023 [3 favorites]

If I were doing this, I’d film it for a good long time, and then write a script to analyze the frames and (putting it simply) find a pair of seconds of video that are as similar as possible. (I’d use a PCA over sliding windows or something.) Say, eg, the 259th second of video looks a whole lot like the 578th second of video for some reason— spark patterns, flame patterns, logs haven’t shifted around. Then I’d crossfade those 30 frames (and associated audio— fire is obvious when the audio doesn’t match) and loop there, creating about a 5 minute loop, more than enough for someone to easily miss it.

In reality fires are probably pretty resilient to crossfade looping because of the flickering, as long as you don’t catch it right on a shower of sparks or a shift in the logs.
posted by supercres at 11:35 AM on February 2, 2023 [2 favorites]

If you want maths, there are maths. Here's the first paper I found on the subject, with the search terms "seamless loop video arxiv": Improved Algorithm for Seamlessly Creating Infinite Loops from a Video Clip, while Preserving Variety in Textures

If you want code, here's the first thing I found, searching for "site:github.com seamless video loop": automatic looping of image sequence using optical flow
posted by the antecedent of that pronoun at 3:08 PM on February 2, 2023 [3 favorites]

I think the answer is almost certainly that it is nearly impossible for the brain to pay attention to an identical moving picture for very long. It’s clearly intended not to be watched but rather to be out of the corner of one’s eye.
posted by wnissen at 4:43 PM on February 2, 2023 [3 favorites]

Sigh. I'm an editor. I made one of these once, in a darker period of my career. (Worst client ever, no lie, absolute monster.) I have managed to suppress most of the memory, but - while it wasn't INFINITELY loopable, we definitely looped it a bunch to extend the length, and I'm pretty sure it was nothing other than long dissolves at judicious moments and the occasional FluidMorph effect to make some frames where none actually existed.

Thanks SO much for making me relive this.
posted by catesbie at 6:06 PM on February 2, 2023 [2 favorites]