Should the Main Profile not be used on PsyTEL 2.02? I saw another post by Ivan stating that it should not be used in 2.0/2.01.

Also - what is the difference between Main and Main LTP?

Thanks

The answer is NO - In fact, I would never recommend using MAIN profile in any AAC encoder.

The reason not to use MAIN profile in psytel encoder is because it is still not working properly under some circumstances.

Reasons not to use MAIN profile in all AAC encoders are numerous:

1. All hardware implementations of AAC decoders are LC only

2. MAIN profile requires 40% more complex decoder, which means 40% more CPU cycles

3. MAIN profile requires many frames before in order to restore the prediction information and reconstruct the original data - which complicates seeking a lot.

4. MAIN profile is very sensitive to errors in transmission, because if you lost one frame you are going to propagate error until next predictor reset (equivalent to 'Intra' frame in video coding terms)

And, finally, the difference between MAIN and LC profile is very small. I can notice it between AAC LC and AAC Main encodings with FhG AAC encoder- but nothing special and certainly not worth of the issues that arise.