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Comment by jbk | Hacker News Reader

Because it's 5 times more complex, you need to get the maximum performance available. Therefore more ASM than ever.

Rust does not bring more performance. Just more safety.

It brings tooling that is a LOT easier. Just things like dependency management, test running and so on is so much better in Rust than in C, even if you happen to write the exact same code because you basically write unsafe code and hand rolled assembly for many things. I think this is people using the tool they know rather than the best tool (And if you know a tool well, it might become the best tool for the job because of that). It could be because a huge chunk of existing code can be re-used. But all else being equal (existing code, existing developers don't exist) I refuse to believe a codec should ever be written in C ever again.

The safety can be worth it in certain cases. Like when handling untrusted input. And it's not just Rust: look at WUFFS for example. WUFFS can actually rival handwritten implementations in certain cases.

but not these cases

I don't see why not. What makes you think this is unique?

WUFFS like approaches work better for algorithms like lz77 that are substantially bandwidth constrained. for something like a video codec, the computational intensity is much higher so you need better codegen to reach max speed

It really should be, though: https://en.wikipedia.org/wiki/FORCEDENTRY

Are video codecs in the present day able to be sandboxed? In my fantasies at least I’d like the worst a malicious video file can do is cause garbage output or cause the codec to crash.

Forgive the ignorance, I have worked entirely in the abstracted layers of the stack, and mostly web.

not really. they're mostly pure assembly and sandboxing assembly isn't really a things

yes it is. all modern operating systems sandbox assembly. that's how it works.

Windows may use virtualization-based security by default, but I'm not aware of macOS or Linux doing the same -- Apple builds security directly into the silicon such that no virtualization is required, and Linux just rawdogs everything.

Whether that counts is up to you. I suppose it's still "sandboxed" in that it runs in a less privileged context than the kernel.

> Rust does not bring more performance. Just more safety.

Though more safety can in some cases bring a bit more performance. For instance, with Rust you can often avoid "defensive copies" of objects.

When writing a high performance video codec avoiding defensive copies of objects is something you want always, not just often.

C makes it easy to be fast but hard to be safe. Rust makes it easy to be safe but hard to be fast.

Also note that video codecs tend to wrap C or Rust around handcrafted ASM. Performance is king.

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