[Telaneo]

Uncompressed 24-bit 1080p running at 24 FPS requires 1.192 Gbit/s, or 0.149 GByte/s. So a 25 GB (single-layer) blu-ray has enough space for a whopping 167.8 seconds of uncompressed 1080p video running at 24 FPS. You can double that with a dual-layer blu-ray, and there are more corners you can cut, but I don't think you'll fit your movie in there.

Video is really big. Compression was needed to make it even vaguely possible unless your quality was in the toilet.

HD-DVDs were smaller, so they were more compressed.

[eska]

I don’t think that you guys should be debating compressed vs uncompressed, but lossy compression vs lossless compression. Your math seems to derive from a naive storage format.

[Telaneo]

Blu-ray is lossy too. All video codecs of note that aren't for professionals are lossy, so the point mostly still stands. Lossless compression doesn't go very far when it comes to video.

An uncompressed 24 bit 1080p image is just under 6 MB. If you save it as a compressed PNG, you cut that down to roughly 2.5 MB. Now, PNG compression isn't very efficient, and you can probably do some interframe magic if you really wanted to (cf lossless h264), but the whole exercise is mostly futile, since even if you cut your bitrate down to an eighth, you're still looking at, like, 20-ish minutes of runtime with 25 gigabytes.

Meanwhile, blu-ray looks as good as it does at an average of 25-30 mbit/s (0.03 gbit/s) (while UHD blu-ray even more so, with a better codec, so even more detail is preserved). The compression used saves so much space the trade-off is obviously worth it unless you're a production company making an actual movie, where every detail counts.

[eska]

I just looked up the compression rate of FFV1 because I never thought about this. It’s apparently 4x. More would be possible, but increase computational requirements.

Another use cases seems to be archival of historical footage.

[mghackerlady]

Ah, that's what it was. I'm still half asleep, I didn't drink enough caffeine this morning haha