AAC (Advanced Audio Coding) is the baseline audio codec of OTT, supported on virtually every device and paired with H.264 and beyond. It delivers good quality at modest bitrates for stereo and is the safe default audio rendition in any ladder.
For richer experiences, platforms layer additional audio: multichannel and immersive formats such as Dolby Digital Plus (E-AC-3), Dolby Atmos, or AC-4 for capable living-room devices. Audio also carries the accessibility and localization burden - multiple language tracks and audio description - so audio handling in the ladder is more than an afterthought.
