It does. MP3は普遍的な損失コーデックであり、AACやOpusよりもビット当たりの品質が劣る代償で、何もそれを再生しない. That decides whether a gain change is an exact edit of the samples or has to go through a re-encode.
透明度の決定は，透明度の変更を行う段階である。 That is the step most people actually came for, and doing it after MP3 のボリュームを調整 rather than before it means the conversion works from the file you finally settled on.
