The frame with its ADTS header.
How many samples ffmpeg returns for it, at the decoder's output rate (its frame length, rate converted).
The timeline segment it belongs to (see AvatarMediaClock).
How many of them the stream's timeline gives it (its declared duration): at most DecodedSamples.
Its place in the order frames were written.
Its presentation time, in seconds on the stream's timeline.
One AAC frame to decode, and where it sits on the avatar's timeline.