M4A
AMR awọn faili
M4A jẹ ọna kika faili ohun ti o ni ibatan pẹkipẹki si MP4. O funni ni funmorawon ohun didara ti o ga pẹlu atilẹyin fun metadata, jẹ ki o dara fun awọn ohun elo lọpọlọpọ.
AMR (Oṣuwọn Adaptive Multi-Rate) jẹ ọna kika funmorawon ohun ti a ṣe iṣapeye fun ifaminsi ọrọ. O jẹ lilo nigbagbogbo ninu awọn foonu alagbeka fun awọn gbigbasilẹ ohun ati ṣiṣiṣẹsẹhin ohun.