[Tremor] question about IMDCT on 24-bits fixed-point DSP

[jim luo]

Dear All:
	I am porting Tremor to my 24-bits fixed-point DSP, But meet the accuracy problem during IMDCT:
several samples before IMDCT are 26 bits integer value, and can not be stored in 24-bits intenal 
RAM, so I add some code before mdct_backword(), right shift all the samples_before_IMDCT value by 2 bits, to avoid overflow. 
	but the PCM samples are deviated from that gotten from original tremor, the max difference between them are 6.
	I think my technique to process 26 bits value is unproper. Do you have any more clever means to process the IMDCT with several input samples large than 2^24 on 24 bits fixed-point DSP, and then get more accuracy?
	If any, please discuss on it! thanks
												Jim