Blu-ray Discs reference vs regular movie

[bar72]

transcoding all my Blu-ray discs to x264 and stumbled on this spreadsheet while looking for x264 encoder settings here and curious as to what is, or how to tell, the difference between a Reference or Regular movie? Is there an easy way to tell?

any suggestions, tia

[Sharc]

You would have to ask this question to the author of this table......

[keenyoness]

I think by "reference" the author probably means "for archival purposes", like if that's the only backup of the movie you're keeping (like if you're getting rid of Blu-Ray discs to save space or something).

"Regular" I think they mean "still excellent quality for watching".

The only differences I see are the Quality scale ("CRF = 17" vs. "CRF = 19") and slightly higher audio bitrates for the Opus codec.

Lower CRF # means higher quality but also larger file size.

In most cases, for most people, "CRF = 19" is hard to distinguish visually from "CRF = 17", unless maybe you have them side-by-side and are looking very closely, which is not how we usually watch movies.

Likewise, the audio differences for Opus (640kbps for 7.1 / 480kbps for 5.1, vs. 512kbps for 7.1 / 384kbps for 5.1) are not likely to be noticeable to human hearing.

So if hard drive space is not an issue, feel free to use the "reference" settings, but it may be overkill, depending on your needs.

Last note - "Blu-Ray - High Grain" is definitely meant for a live-action film where the film grain is noticeable (like many movies up until about the 1980s). The author lowered the CRF value to 16 to ensure that the film grain is more faithfully captured, because visible film grain means more visual information.

And for that setting, they recommend x264's "Tune = Film" setting, which is consistent with what I've seen elsewhere. x264 also has a "Tune = Grain" setting" but from multiple forums and guides, I've read that "Tune = Film" is best for a grainy, live-action movie.

Best of luck!

[bar72]

@keenyoness many thanks for the info, makes sense now. I've gone with x264, CRF=18, Slower as the encodes are around ~9GB for a 2hr movie and I can't tell the difference from the original BD.

I'll test CRF=16-18 and Film tune for grainy content, to keep filesize in check, as I noticed my encodes using the Grain tune were increasing the filesize.

Many thanks for the info. Bar