When you use tape backup, is compression pretty useless for hi end photo or film work?

[Daniel D. Teoli Jr.]

For instance, LTO 8 gives you 12TB native and 30TB compressed of storage.

I'm thinking the compressed is for text or low-res photos. What have you found to be the case?

 

[Nicolas POISSON]

When using lossless compression, a 1:2.5 ratio sounds really, really optimistic. Sure it depends on the content, but for media I'd expect the ratio to be near 1:1 (no compression), since most media files include lossless compression as a final step anyway. You do not gain more than a few % when performing lossless compression twice.

Edited August 1, 2024 by Nicolas POISSON

[Aapo Lettinen]

I think when running lots of video material to LTO the benefit from compression was from 0 to less than 10% depending on material and luck.

All video material already has compression of some kind, that also applies to raw material as in practice uncompressed raw is never used in any camera for it not having benefits at all compared to compressed raw.

When prores became common the uncompressed 422 and 444 were very rarely needed anymore. Sometimes TIFF sequences can be made uncompressed for reason or other and that benefits from compression. Though often exr used instead and that often has compression. Tiff and exr mainly used for single vfx shots transferred in post production and if making cgi animation stuff.

So generally only few % of material in projects even could be uncompressed and could use lto compression at all. Some projects have none of material of this kind. Animation projects and vfx heavy stuff might have intermediate files in uncompressed depending on how they are made. But those are not camera originals

[Nicolas POISSON]

Just to make things clear: lossless compression used to be considered CPU hungry in the early 80's. But it is a very simple algorithm compared to the lossy compression of even mpeg-1. Every single lossy compression format performs an additional last step of lossless compression: jpeg, mp3, MPEGs of all kinds... The additional CPU cost is negligible, and if this lossless compression does not improve the ratio by much, it cannot hurt. (Some very old lossless compression algorithms were so bad that they could indeed increase file size, but this was another era.)

When lossless compression has been performed once, there is little to no benefit performing it again on the compressed data. This is why "zipping" mpeg or jpeg files is not worth it. Lossless compression is useful for files that have no compression at all, which is common for text files, but rarely the case of media files.