Vintage 60s/70s striped men's slacks (Unbranded) 38x30

Interesting pair of pants that are unbranded without any material information. They appear to be slightly "bootcut." These are not stretchy at all. The material feels like a cotton/polyester blend. There are no tags to describe it. No damge or stains. I don't know how old these are. I do know that I purchased these from a vintage clothing store in 1999 and been stored indoors since. Judging by the way they are stiched inside, they might be from a film production?