balrogg: lossless Vorbis/Opus recompressor

[_contextmodel]

Fitgirl,

Thank you for your response.

> My Opus tests, while showing some result don't make it usable in real repacking - the gain is tiny, no solid mode support (yet?).

The gain is small as Opus files tend to be quite well compressed already, sadly. However, it remains within realm of possibilities, and does happen at a fine-ish performance cost.

> Since opus files don't have codebooks which could be stored once in a solid mode and where oggre does it's job good, with opus it won't work. And rn since ballrogg doesn't support solid mode, one can't expect big gain on a smaller files concatenated into one stream.
> I also tested initial ballrogg v1.0 on vorbis files in single/solid mode. It compressed files fine in single mode, but with the same files concatenated it gave an error.

I will look into implementing this.

> Will do more tests with fresh builds when I have time. Unfortunately for repackers, Opus is already a very effective format, with it's range-coder near Shannon limit and space for improvement is really tiny.

Indeed. I would say that Vorbis repacking is a slightly better selling point.