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 determines whether the corrected audio can be written back exactly or has to be re-encoded.
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 の音量を正常化 rather than before it means the conversion works from the file you finally settled on.
