Hacker News: Sesse__

New comment by Sesse__ in "Twenty One Zero-Days in FFmpeg"

Sesse__ — Sat, 13 Jun 2026 07:14:20 +0000

> ffmpeg and other media frameworks (Windows Media Foundation, Apple’s AVFramwork) only support static pipelines.

FFmpeg doesn't do “pipelines”. It's a library, not a framework.

New comment by Sesse__ in "Lines of code got a better publicist"

Sesse__ — Thu, 11 Jun 2026 17:48:07 +0000

It's a signal. It's not a strong signal, and you certainly should not base your entire perf on it, but if the number is unusually high or low, it's a signal that could warrant further investigation.

(I once worked with an engineer that had two PRs, both fairly small bug fixes, in a given calendar year, and when I looked more carefully, they did not have any other obvious output or impact.)

New comment by Sesse__ in "OpenCV 5 Is Here: The Biggest Leap in Years for Computer Vision"

Sesse__ — Tue, 09 Jun 2026 16:12:55 +0000

Also, performance is generally pretty low; I've been on projects where we rewrote OpenCV code into more-or-less obvious hand-rolled code and won 5x perf. The abstractions are generally a bit too thick and oriented around single pixels (which also makes the API a bit too verbose for my taste).

New comment by Sesse__ in "Should you normalize RGB values by 255 or 256?"

Sesse__ — Mon, 01 Jun 2026 20:35:09 +0000

Useful, then, that you can start several vectorized floating-point muls each cycle. (E.g., most modern x86 are 3/0.5 cycles for vmulps. No 20 cycles in sight.)

New comment by Sesse__ in "Should you normalize RGB values by 255 or 256?"

Sesse__ — Mon, 01 Jun 2026 19:54:33 +0000

You should multiply by 255.0, optionally add a dither (triangular is okay), and then let the FPU round using its default IEEE 754 round-to-nearest-ties-to-nearest-even mode. None of this crazy 0.5 stuff. :-)

New comment by Sesse__ in "Frontier AI has broken the open CTF format"

Sesse__ — Sun, 17 May 2026 13:44:09 +0000

Thank you, that is an interesting tidbit!

New comment by Sesse__ in "Frontier AI has broken the open CTF format"

Sesse__ — Sat, 16 May 2026 14:07:06 +0000

One of my teachers in elementary school told us that people in the Arabic world wore long garments because as Muslims, they believed the Messiah would be born by a male, and thus, it was important to have something to catch the baby as it unexpectedly popped out one day and would otherwise hit the ground.

She only really had two faults: She wasn't very bright, and she wasn't fond of children. I had her in about 80% of all my classes for six years. High school was a relief.

New comment by Sesse__ in "Dav2d"

Sesse__ — Sun, 03 May 2026 10:47:21 +0000

I can totally understand why people would want a memory-safe decoder, but a memory-safe encoder is niche. Finding a memory-safety bug in a decoder is a matter of finding a single unchecked integer field somewhere; finding a memory-safety bug in an encoder requires first finding some sort of logic bug in the encoder and then crafting an adversarial input that survives a number of highly lossy transformations.

Compare the number of CVEs against x264 (included decoders don't count!) and FFmpeg's H.264 decoder.

New comment by Sesse__ in "Dav2d"

Sesse__ — Sun, 03 May 2026 10:15:58 +0000

> And as for Git web interfaces, the correct solution is to require logins to view complete history.

Why logins, exactly? Who would have such logins; developers only, or anyone who signs up? I'm not sure if this is an effective long-term mitigation, or simply a “wall of minimal height” like you point out that Anubis is.

New comment by Sesse__ in "Dav2d"

Sesse__ — Sun, 03 May 2026 07:09:09 +0000

Also, relevant for forges: AI doesn't understand what it's clicking on. Git forges tend to e.g. have a lot of links like “download a tarball at this revision” which are super-expensive as far as resources go, and AI crawlers will click on those because they click on every link that looks shiny. (And there are a lot of revisions in a project like VLC!) Much, much more often than humans do.

New comment by Sesse__ in "Slava's Monoid Zoo"

Sesse__ — Tue, 21 Apr 2026 16:45:54 +0000

Thanks, that's an interesting tidbit!

(The whole thing made me think about applications to SQL query optimizers, although I'm not sure if it's practically useful for anything.)

New comment by Sesse__ in "Slava's Monoid Zoo"

Sesse__ — Tue, 21 Apr 2026 16:22:54 +0000

Is the word problem easier if the monoids are commutative? (Or even trivial? I haven't thought deeply about it.)

New comment by Sesse__ in "A cache-friendly IPv6 LPM with AVX-512 (linearized B+-tree, real BGP benchmarks)"

Sesse__ — Mon, 20 Apr 2026 09:43:49 +0000

Sure, but how does this differ from a routing table with RPF (which is default in Linux already)?

New comment by Sesse__ in "A cache-friendly IPv6 LPM with AVX-512 (linearized B+-tree, real BGP benchmarks)"

Sesse__ — Mon, 20 Apr 2026 07:52:41 +0000

I use Wireguard rarely enough that the AllowedIPs concept gets me every time. It gets easier when I replace it mentally with “Route=” :-)

New comment by Sesse__ in "A cache-friendly IPv6 LPM with AVX-512 (linearized B+-tree, real BGP benchmarks)"

Sesse__ — Mon, 20 Apr 2026 06:31:30 +0000

The obvious question, I guess: How much faster are you than whatever is in the Linux kernel's FIB? (Although I assume they need RCU overhead and such. I have no idea what it all looks like internally.)

New comment by Sesse__ in "The world in which IPv6 was a good design (2017)"

Sesse__ — Sun, 19 Apr 2026 10:45:07 +0000

> But there's now multipath TCP handover? Weird behaviour to want different network interfaces on different network share the same IP, and pass it along like a volleyball?

Mobile IP actually wanted to do this, it just never took off (not the least because both endpoints need to understand it to get route optimization). I think some Windows versions actually had partial Mobile IPv6 support.

New comment by Sesse__ in "SI Units for Request Rate (2024)"

Sesse__ — Sun, 19 Apr 2026 08:48:46 +0000

https://en.wikipedia.org/wiki/Angular_frequency

It's very convenient when you're working with periodic signals (say, when discussing the FFT); you don't have to drag a 2pi factor around everywhere.

New comment by Sesse__ in "SI Units for Request Rate (2024)"

Sesse__ — Sun, 19 Apr 2026 08:47:04 +0000

That sounds too low; 3 m$Hz would probably be right, but 3 µ$Hz is very little.

New comment by Sesse__ in "SI Units for Request Rate (2024)"

Sesse__ — Sun, 19 Apr 2026 08:45:36 +0000

Mostly, people who do “requests per day” have a lot lower load than 1100 requests/sec, too… it's a typical red flag for having a team that know a lot less about performance than they think.

New comment by Sesse__ in "IPv6 traffic crosses the 50% mark"

Sesse__ — Thu, 16 Apr 2026 09:14:31 +0000

> Porting all of that to support ipv6 can easily be a multi-year project.

FWIW, as someone who has done exactly this in a megacorp (sloshing through homebrew technical debt with 32-bit assumptions baked in), the initial wave to get the most important systems working was measured in person-months. The long tail was a slog, of course, but it's not an all-or-nothing proposition.