Replaygain album gain per disc support

[yoasif]

It'd be nice to be able to Replaygain albums with a per disc album gain grouping.

So if I had a two CD album (using disc tags), each disc would have it's album gain calculated by itself, irrespective of the other discs in the same album.

[sampsyo]

To clarify: The RG standard doesn't have per-disc gain fields. But we could abuse the album gain field to store that information. Would that suffice?

[yoasif]

@sampsyo Yes, that is exactly what I was thinking (and how I currently do it using foobar2000).

[sampsyo]

Great. In case you're interested in hacking on this, it should be a relatively straightforward implementation.

[samuelnilsson]

Hi!

I'm opening this up almost 6 years later. I'm also interested in this feature and could try to implement it if it is not too time consuming. Do @sampsyo, who has more insight of the code, still believe this should be relatively straightforward? Personally I don't believe that it seems too complicated to achieve when looking at the plugin code.

However, one issue is that the rg_album_gain and r128_album_gain are album level fields. Will that structure need to be changed since, when implementing this, the items on an album could have different album gain values?

[sampsyo]

Sure! I agree that it shouldn’t be too complex.

It is unfortunate, but you’re also right that we may need to “demote” those fields to item-level fields. It is also technically possible, although a little weird, for items to “disagree” even on album-level fields—nothing actually prevents that from happening. So maybe it’s worth a try without changing the status of those fields, and we can revisit the decision if it causes problems.

[arcresu]

Closed in #3137