hi list,
can think of using PS but not SBR. What are the changes i should take care in this case?
I hope there will be improve in the quality.

Shouldn't PS be used for very low bitrates pretty much like intensity stereo in MP3? In this case, wouldn't it make more sense to use SBR at the same time?

PS without SBR is syntactically not possible in AAC audio, must use PS+SBR. or you are writing your own custom audio encoder?

yes, I just wanted to have a customized aac encoder with PS and without SBR. I need to maintain quality. if i remove SBR module from HE-AAC what to get only PS enabled AAC, will it work? if no, what change i need to have to make it work?

definitely will not work if you just "remove" SBR.

to do this kind of thing you need to have a detailed knowledge of AAC standard and its HE extensions.

if it's your own encoder, you can do anything. PS would work with any mono encoder (you can treat it as a black box). You need only to extract the PS parameter and performed mono downmix; then feed it to whatever encoder you want.

Working from HE-AAC, you need to extract the SBR filterbank (which is shared with PS). I don't think you can make a valid stream because PS data is inside SBR extension. But then again, if it's your own encoder, you can put it somewhere else.

I'm curious what kind of quality will you get

Not in every single case. For instance, power-hungry SBR can be a real annoyance if decoded by a portable player. That's the main reason why I don't use HE-AAC on my mobile phone, which is actually able to decode the SBR part. I stick to LC-AAC using slightly higher bitrates instead.