Simply put, when valid bit depth is 16/24 and compression ratio is around 25% for both codec on the effective 16bits part, ALAC file will become 3 times larger than FLAC one.
24bit ALAC file always stores LSB-side 8bits uncompressed, while FLAC won't consume bits due to it's wasted bits feature in this case.
24bit ALAC file always stores LSB-side 8bits uncompressed, while FLAC won't consume bits due to it's wasted bits feature in this case.
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16×0.25 : 16×0.25+8 = 1 : 3