Hacker News: dllu

New comment by dllu in "Show HN: I built a frontpage for personal blogs"

dllu — Fri, 03 Apr 2026 20:51:26 +0000

I vibe coded RSS feed for my static site generator a few months ago: https://github.com/dllu/dllup-rs/blob/main/src/main.rs#L850

and was pleasantly surprised to see my blog was already on this website!

New comment by dllu in "enclose.horse"

dllu — Tue, 06 Jan 2026 20:34:44 +0000

That reminds me of Paquerette Down the Bunburrows [1] which is a very fun pathfinding game where the bunnies will pathfind to try to run away from you. It's not exactly what you described, but it is very fun and surprisingly deep and challenging.

[1] https://store.steampowered.com/app/1628610/Paquerette_Down_t...

New comment by dllu in "Why does a least squares fit appear to have a bias when applied to simple data?"

dllu — Mon, 05 Jan 2026 17:39:42 +0000

Yeah, you can generally "whiten" the problem by scaling it in each axis until the variance is the same in each dimension. What you describe is if x and y have a covariance matrix of like

    [ σ², 0;
      0,  (nσ)² ]

but whitening also works in general for any arbitrary covariance matrix too.

[1] https://en.wikipedia.org/wiki/Whitening_transformation

New comment by dllu in "Why does a least squares fit appear to have a bias when applied to simple data?"

dllu — Sun, 04 Jan 2026 21:07:13 +0000

You can think of it as: linear regression models only noise in y and not x, whereas ellipse/eigenvector of the PCA models noise in both x and y.

New comment by dllu in "Line scan camera image processing"

dllu — Tue, 30 Dec 2025 20:48:57 +0000

Ah yeah, I recently changed the url scheme for my blog posts, from

    https://daniel.lawrence.lu/blog/y2025m09d21

    https://daniel.lawrence.lu/blog/2025-09-21-line-scan-camera-image-processing/

so maybe that's why OP didn't realize that it had already been posted recently. With the older scheme, not only is SEO bad, but it was really hard to remember which date corresponds to which blog post, and people can brute force search for my hidden (unpublished) blog posts easily.

New comment by dllu in "Line scan camera image processing"

dllu — Mon, 29 Dec 2025 11:39:14 +0000

The gain is fixed. I think the column variation arises from unstable oscillator frequency and maybe some electrical bug/crosstalk between pixels. Not sure exactly.

New comment by dllu in "Show HN: Ez FFmpeg – Video editing in plain English"

dllu — Sat, 27 Dec 2025 09:34:15 +0000

When converting video to gif, I always use palettegen, e.g.

    ffmpeg -i input.mp4 -filter_complex "fps=15,scale=640:-2:flags=lanczos,split[a][b];[a]palettegen=reserve_transparent=off[p];[b][p]paletteuse=dither=sierra2_4a" -loop 0 output.gif

See also: this blog post from 10 years ago [1]

[1] https://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html

New comment by dllu in "Asahi Linux with Sway on the MacBook Air M2 (2024)"

dllu — Fri, 26 Dec 2025 03:51:26 +0000

Yes, the M4 is still outperforming the desktop 9950X in single-threaded performance on several benchmarks like Geekbench and Cinebench 2024 [1]. Compared to the 9955HX, which is the same physical chip as the 9950X but lower clocked for mobile, the difference is slightly larger. But the 16 core 9950X is obviously much better than the base M4 (and even the 16 core M4 Max, which has only 12 P cores and 4 E cores) at multithreaded applications.

However, the M2 in the blog post is from 2022 and isn't quite as blazingly fast in single thread performance.

[1] https://nanoreview.net/en/cpu-compare/apple-m4-8-cores-vs-am...

New comment by dllu in "Who Watches the Waymos? I do [video]"

dllu — Fri, 26 Dec 2025 03:42:47 +0000

Thanks, I posted it 4 months ago already: https://news.ycombinator.com/item?id=44996938

New comment by dllu in "Asahi Linux with Sway on the MacBook Air M2 (2024)"

dllu — Thu, 25 Dec 2025 21:31:25 +0000

Old Thinkpads are great! I used to have a Lenovo Thinkpad X1 Carbon Gen 6 with Intel Core i7 8640U, 16 GB of RAM, and 1 TB SSD. I installed Arch Linux on it with Sway.

New comment by dllu in "Asahi Linux with Sway on the MacBook Air M2 (2024)"

dllu — Thu, 25 Dec 2025 20:14:50 +0000

Agreed. On the computer hardware side:

* x86 chips can surpass the M series cpus in multithreaded performance, but are still lagging in singlethreaded performance and power efficiency

* Qualcomm kinda fumbled the Snapdragon X Elite launch with nonexistent Linux support and shoddy Windows stability, but here's to hoping that they "turn over a new leaf" with the X2.

Actually, some Snapdragon X Elite laptops do run Linux now, but performance is not great as there were some weird regressions and anyway newer chips have caught up [1].

On the build quality side, basically all the PCs are still lagging behind Apple, e.g. yesterday's rant post about the Framework laptop [2] touched on a lot of important points. Of course, there are the Thinkpads, which are still built decently but are quite expensive. Some of the Chinese laptops like the Honor MagicBooks could be attractive and some reddit threads confirm getting Linux working on them, but they are hard to get in the US. That said, at least many non-Apple laptops have decent trackpads and really nice screens nowadays.

[1] https://www.phoronix.com/review/snapdragon-x-elite-linux-eoy...

[2] https://news.ycombinator.com/item?id=46375174

New comment by dllu in "Asahi Linux with Sway on the MacBook Air M2 (2024)"

dllu — Thu, 25 Dec 2025 19:59:34 +0000

Marcan (Hector Martin) resigned from Asahi Linux early this year [0].

Asahi Lina, who also did tons of work on the Asahi Linux GPU development, also quit as she doesn't feel safe doing Linux GPU work anymore [1].

[0] https://marcan.st/2025/02/resigning-as-asahi-linux-project-l...

[1] https://asahilina.net/luna-abuse/

New comment by dllu in "Asahi Linux with Sway on the MacBook Air M2 (2024)"

dllu — Thu, 25 Dec 2025 19:55:46 +0000

Apple does tons of optimizations for every component to improve battery life. Asahi Linux, which is reverse engineered, doesn't have the resources to figure out each of those tricks, especially for undocumented proprietary hardware, so it's a "death by a thousand cuts" as each of the various components is always drawing a couple of milliwatts more than on macOS.

New comment by dllu in "Who Watches the Waymos? I do [video]"

dllu — Thu, 25 Dec 2025 08:40:56 +0000

It was done with a line scan camera. More on the technique here: https://daniel.lawrence.lu/blog/2025-09-21-line-scan-camera-...

New comment by dllu in "Who Watches the Waymos? I do [video]"

dllu — Thu, 25 Dec 2025 03:23:19 +0000

These were parked on Hudson Ave, which is a public street, and not inside the fenced area of the depot. So I just walked up to them.

New comment by dllu in "Who Watches the Waymos? I do [video]"

dllu — Thu, 25 Dec 2025 03:02:20 +0000

Very neat. I recently went to the Waymo depot in Bayshore (Toland St) and snapped a couple of pictures of the new Zeekrs for Wikipedia.

[1] https://commons.wikimedia.org/wiki/File:Waymo_Zeekr_Vehicle_...

[2] https://commons.wikimedia.org/wiki/File:Waymo_Zeekr_Vehicle_...

New comment by dllu in "Fabrice Bellard: Biography (2009) [pdf]"

dllu — Wed, 24 Dec 2025 20:58:17 +0000

The fact that so many people use FFmpeg and QEMU suggest that he is quite good at documenting, collaborating, and at least making his code remarkably clean and easy to follow. This already puts him way ahead of the average silicon valley senior software engineer that I've worked with. However, he does value independence so I don't think he would have been happy working at a faang-type company for long.

New comment by dllu in "We pwned X, Vercel, Cursor, and Discord through a supply-chain attack"

dllu — Thu, 18 Dec 2025 19:45:33 +0000

The fact that SVG files can contain scripts was a bit of a mistake. On one hand, the animations and entire interactive demos and even games in a single SVG are cool. But on the other hand, it opens up a serious can of worms of security vulnerabilities. As a result, SVG files are often banned from various image upload tools, they do not unfurl previews, and so on. If you upload an SVG to discord, it just shows the raw code; and don't even think about sharing an SVG image via Facebook Messenger, Wechat, Google Hangouts, or whatever. In 2025, raster formats remain way more accessible and easily shared than SVGs.

This is very sad because SVGs often have way smaller file size, and obviously look much better at various scales. If only there was a widely used vector format that does not have any script support and can be easily shared.

New comment by dllu in "Rivian Unveils Custom Silicon, R2 Lidar Roadmap, and Universal Hands Free"

dllu — Sat, 13 Dec 2025 21:03:07 +0000

Not banned. In addition to the Chinese lidars I mentioned, the Valeo Scala on Audi cars is 905 nm, and then there are also Ouster (865 nm), Innoviz (905 nm), Livox (905 nm) etc. The large spinning lidar on top of the Waymo Jaguar I-Pace is also purportedly 905 nm, although in the past they also had a swivelling 1550 nm lidar in the dome of the Chrysler Pacifica cars (situated just underneath a smaller spinning 905 nm one).

The eye safety threshold for 850/905 nm is a lot lower than 1550 nm, so they output way less power, but the much better sensitivity of silicon sensors makes up for it partially. You can also squeeze out more range using clever signal processing and a large optical aperture (which allows you to output more light, but since the light is spread out across the aperture, the intensity doesn't exceed the threshold). Typically, the range of 850/905 nm lidars is less than that of 1550 nm lidars though.

On the bright side, due to lower power, there hasn't been any instances (to my knowledge) of 850 nm and 905 nm lidars damaging cameras, whereas at least two different 1550 nm lidars have been known to destroy cameras (Luminar and AEye).

On the Luminar lidar website [1] they proudly advertise "1,000,000x pulse energy of 905nm".

[1] https://www.luminartech.com/technology

New comment by dllu in "Photographer built a medium-format rangefinder"

dllu — Sat, 13 Dec 2025 19:47:34 +0000

Really awesome design! It would be wise to replace some of those 3D printed parts with CNC parts, especially for places where a lot of strength is required (eyelets for those Peak Design anchors) or precision is required (lens mount). I myself have 3D printed some parts for my line scan camera too, so I can totally understand.

[1] https://daniel.lawrence.lu/blog/2024-08-31-customizing-my-li...