Hacker News: ajconway

New comment by ajconway in "WhatsApp introduces ads in its app"

ajconway — Tue, 17 Jun 2025 09:36:50 +0000

Building complex apps is hard. User-facing, feature-rich apps--especially so. It takes a lot of engineering effort, but also management (which implies some kind of a corporate structure). Coincidentally, it also doesn't align well with open (or any) standards.

New comment by ajconway in "Reverse Z in 3D graphics (and why it's so awesome)"

ajconway — Tue, 04 Jun 2024 15:26:23 +0000

There is also a technique called logarithmic depth buffer (which should be self-explanatory): https://threejs.org/examples/?q=dept#webgl_camera_logarithmi...

New comment by ajconway in "Apple Vision Pro available for pre-order"

ajconway — Fri, 19 Jan 2024 14:08:14 +0000

Quest 3, the DPI looks somewhat similar to a non-retina Apple display.

It felt really futuristic to log into my office computer from a synthesized apartment via Virtual Desktop. The latency was fine for typing. Even YouTube video/audio was bearable. But the device itself is still too heavy. The fixed lens system can't be good for your eyes.

Apple Vision Pro is even heavier. Even as a hardcore VR fan I cannot imagine the current generation hardware to be useful in productivity tasks.

New comment by ajconway in "macOS 14 will support JPEG XL"

ajconway — Mon, 05 Jun 2023 21:26:27 +0000

I stand (partially) corrected: https://github.com/AOMediaCodec/libavif/pull/640

New comment by ajconway in "macOS 14 will support JPEG XL"

ajconway — Mon, 05 Jun 2023 21:10:36 +0000

AVIF does not support progressive encoding.

New comment by ajconway in "Deploying key transparency at WhatsApp"

ajconway — Thu, 13 Apr 2023 16:35:39 +0000

iOS and Android allow apps to process push notifications before displaying them.

New comment by ajconway in "Messaging layer security: Secure and usable end-to-end encryption"

ajconway — Thu, 30 Mar 2023 12:38:59 +0000

> what percentage of those billions are correctly using the ridiculously long numbers (60 decimal digits) used to represent identities (WhatsApp calls them "security codes") in that system to ensure they are actually communicating end to end?

Assuming one of those billions users is a motivated security enthusiast, WhatsApp is not able to perform MITM attacks at scale, as it would be trivial to prove. If WhatsApp decides to MITM your chats, it can't do so retroactively due to the properties of the protocol. If you're a high-profile target, you should verify your keys.

New comment by ajconway in "Scaling Rust Builds with Bazel"

ajconway — Fri, 24 Mar 2023 09:04:48 +0000

Cargo is insufficient if a project has cross-language dependencies.

New comment by ajconway in "Teardown of the 14″ MacBook Pro M2 with Apple’s Help"

ajconway — Sun, 29 Jan 2023 16:40:03 +0000

But M1 did provide fundamental increase in performance. It had only 4 performance cores, yet it could build my code 1.5 times faster than the mightiest i9 of the time.

New comment by ajconway in "An embeddable and customizable fiat-to-crypto onramp"

ajconway — Fri, 02 Dec 2022 08:31:31 +0000

But, given a choice, wouldn't you choose your own transactions to be untraceable?

New comment by ajconway in "An embeddable and customizable fiat-to-crypto onramp"

ajconway — Thu, 01 Dec 2022 19:08:15 +0000

What about ZCash-like networks with anonymous transactions?

New comment by ajconway in "Revert “flag_descriptions: Add note about JPEG XL removal”"

ajconway — Wed, 30 Nov 2022 18:41:52 +0000

Those single-frame next-gen formats don't support progressive rendering.

New comment by ajconway in "Stretch iPhone to its limit: 2GiB Stable Diffusion model runs locally on device"

ajconway — Thu, 10 Nov 2022 15:40:15 +0000

App Store has a CDN-like feature that allows uploading large resources separately and download them after running the app for the first time.

New comment by ajconway in "Tim Berners-Lee: Web3 is not the web"

ajconway — Sat, 05 Nov 2022 09:56:53 +0000

For me personally, it's a low-fee payment system that can't be blocked and doesn't require any KYC. My friends and I use it primarily as a replacement for cash when we split restaurant bills abroad. There are people who use it to donate funds to organisations under repressive regimes anonymously.

Blockchain is just a useful primitive to build stuff on top of it. As an engineer, I would like to embrace it, NFTs notwithstanding.

New comment by ajconway in "Tim Berners-Lee: Web3 is not the web"

ajconway — Sat, 05 Nov 2022 09:17:47 +0000

Anonymous (or pseudonymous), independently verifiable operations with digital goods are clearly in demand. There may exist a better solution, but blockchain works now.

New comment by ajconway in "Blurhash: A compact representation of a placeholder for an image"

ajconway — Fri, 04 Nov 2022 10:57:50 +0000

The amount of work it takes to decode an image is incredibly tiny by today's standards: https://github.com/woltapp/blurhash/blob/master/C/decode.c

New comment by ajconway in "Lyra V2 – a better, faster, and more versatile speech codec"

ajconway — Sat, 01 Oct 2022 09:02:37 +0000

1. Install numpy (pip3 install numpy)

2. Download a bazel binary (https://github.com/bazelbuild/bazel/releases or use package manager)

3. bazel build -c opt :encoder_main

4. bazel-bin/encoder_main --input_path=testdata/sample1_16kHz.wav --output_dir=$HOME/temp --bitrate=3200

Done!

New comment by ajconway in "When to use Bazel?"

ajconway — Tue, 13 Sep 2022 22:05:27 +0000

That is true, Bazel itself is still evolving, and there have been breaking changes between versions. Sometimes the required version number is placed in a .bazelversion file, which makes Bazelisk your top-level dependency.

I'd expect Tensorflow to have some non-hermetic build actions, but if choosing a specific Bazel version was the only thing that was required to build it, that's awesome!

New comment by ajconway in "When to use Bazel?"

ajconway — Tue, 13 Sep 2022 20:42:05 +0000

Bazel doesn't have any user-facing java dependency.

> what real extra benefit Bazel brings in here

Builds are hermetic by default, so unless the developer chooses to escape the sandbox, everything is guaranteed to build on other machines with no additional setup.

(Also, I genuinely hate when I have to manually install build dependencies system-wide and pray that there will not be any conflicts. Having everything pinned to specific sha256 or git hashes by design is a breath of fresh air)

New comment by ajconway in "Android 13 requires devices to have more than 2GB RAM and 16GB storage"

ajconway — Sat, 10 Sep 2022 21:45:33 +0000

Apps targeting pre-2018 iOS versions bundle the mid-2018 version of swift runtime for compatibility reasons.

For example, when you run an app made in the iOS 15 era on an iOS 13 device, the app can’t use any runtime features that are not included with iOS 13. Given that swift is still rapidly evolving, that amounts to a lot of useful features. This year, iOS 16 apps get to use the cool new Regex features.