Use Infer to detect image/video

[Pyroglyph]

Maintaining our own list of known filetypes seems pointless when there are other projects like Infer that do it for us.

Marked as draft until this is answered:
If Infer fails to load the file then ProbeErrors are created despite not being thrown by FFProbe. This is because the check happens in the probe function (for convenience). Is this okay or should a more specific error type be created for this? In any case, the whole thing would have failed anyway if the file is unable to be read.

[alexheretic]

Thanks! The additional binary bloat and sync-io blocking is undesirable, but overall this looks worth it.

[alexheretic]

If Infer fails to load the file then ProbeErrors are created despite not being thrown by FFProbe. This is because the check happens in the probe function (for convenience). Is this okay or should a more specific error type be created for this? In any case, the whole thing would have failed anyway if the file is unable to be read.

Yeah it's kinda academic as we'd expect the probe to have failed. I probably would have just Err(_) => false to reduce the code, but returning an error as you have done is fine too and more defensively correct. I don't think we need to throw more code at this scenario though.

[Pyroglyph]

The additional binary bloat is undesirable

Infer can be imported with no default features to make it lighter. This means that we won't be able to use the infer::get_from_path helper any more, but if size is something we're concerned about then it should just be a matter of changing a few lines.

[alexheretic]

Size is a concern, if not a critical one. Just something I keep an eye on when adding new dependencies. As I said I think the trade off is worth it here.

[Pyroglyph]

I've done some measurements. When building in --release mode I get these file sizes:

Version	File size
No Infer	2,363 KB
Infer (default features)	2,445 KB (+82 KB)
Infer (no default features)	2,374 KB (+11 KB)

I'd say that's quite a nice jump.

[alexheretic]

It's a mild annoyance that we don't need no_std, we just want to avoid the cfb dependency. But infer has bundled them together in the "std" feature 🤷.

Although not using get_from_path will be easier to convert to async later, once ffprobe is also async (or sooner, but it's not a big deal).

[alexheretic]

lgtm