What is AAC frame length in time domain signal? which document discuss about it?

A "frame" stores 1024 samples/channel ("spectral samples") but affects up to 2048 samples/channel (time domain samples) due to the overlapping nature of the MDCT.

Cheers!
SG

Thanks.

Also I got the idea about aac frame length(2048 samples/channel) from 3gpp aac source code. But I have

only a vague idea. The relation between frame length and sampling rate? How to decide aac frame length?

Which document describe aac frame length?

The AAC is discussed in ISO/IEC standard 14496-3. If you are only interested in the frame length though, there might be no point in purchasing the whole document. The frame length stays the same, regardless of the sample rate.