[laumars]

You don't even need to do the maths. Just looking at a vinyl would give the game away since you can see grooves with your naked eye (as a DJ in an earlier life, we used to use that as a visual clue for when to queue up the next record, swap the basslines, etc).

Not to mention how albums would often be spread over two records where as the same album could fit on a single audio CD (let alone DVD).

I'm guessing the GP has never owned any vinyl. I could forgive someone questioning the density of records if he's not familiar with the tech.

[onion2k]

I'm guessing the GP has never owned any vinyl. I could forgive someone questioning the density of records if he's not familiar with the tech.

I'm old enough to know about vinyl. That's not really the point though - the principle is the same, just with much higher information density. With a suitably high resolution camera, or set of cameras, or video, and some serious magnification it should be possible to photograph a DVD and play back the data from the image. I find that quite interesting, or at least entertaining, to think about. I guess the HN readers who're downvoting the post don't.

Something to consider - technically we can already do it - it's how DVD players work, albeit with a single coherent light source and only reading one bit at a time.

[laumars]

> I'm old enough to know about vinyl. That's not really the point though

I was talking about user U2EF1 (the "citation needed" comment). I didn't have any particular issue with your comment aside the impracticality of it with current consumer hardware (which I'll address below). But as a concept it's an interesting point.

> the principle is the same, just with much higher information density.

The problem is in the detail. Even with gramophone records, you'd get a very low success rate with a consumer camera. Plus you'd need multiple macro pictures and a precise way to stich them together. At which point it would be quicker to play the record while recording it in Audacity (or similar) in real time. So you're talking a less than 1x record speed and lower success rates to boot; and that's just low density vinyl. When talking about DVDs you'd need to improve the operation by several orders of magnitude in terms of accuracy and resolution.

So I think your comment was interesting from a conceptual point but we're a long long long way off having that level of detail in consumer photographic devices.

> Something to consider - technically we can already do it - it's how DVD players work, albeit with a single coherent light source and only reading one bit at a time.

I think it's a little disingenuous having a laser reading binary reflections sequentially compared to a digital sensor detecting literally billions of analogue reflections (because a camera isn't just detecting the existence or absence of light) in parallel and then forming a precise sequence of digital bits from that. The technologies are completely different, the scales are completely different, the concept is completely different. They're just not equatable.

> I find that quite interesting, or at least entertaining, to think about. I guess the HN readers who're downvoting the post don't.

It wasn't me who downvoted you but if it's any consolation, I've gotten downvoted for factually accurate comments before (let alone impractical suggestions). You just have to remind yourself that it happens occasionally and usually the positive outweighs the negative. :)