Re: EC and NR
IPP Echo canceller frame size is always equal to 160 bytes. Buffering is fully being done internally.EchoCancel function must be fed with data correspondent to 10 ms of 8 Khz and 5 ms of 16 Khz audio (which in case of linear PCMrepresented by 160 bytes both).So, for 20ms packet of 8KHz audio you shall to call it twice.
EC works with linear PCM. I guess the noise problem you mentioned was caused bythat you fed a-law to EC.160 bytes of A-law represents 20 ms of 8KHz audio.After convertion you will get160 linear samples (320 bytes), i.e. two EC frames. You may do convertion by IPP functionippsAlawToLin_8u16s.
Hope this help.