ITU-TG.721_VC++6.0工程_直接可用

#include "G721.h" /***************************************************** * * G.721 Encoder * ******************************************************/ #include "G721.h" /***************************************************** * * G.721 Encoder * ******************************************************/ void G721Encoder(INT16S *Indata_P16s, INT8U *Outdata_P8u, INT16S FrameLen_16u, AdpcmState_ST *State_ST) { // INT16S *In_P16s; /* Input buffer pointer */ INT8S *Out_P16u; /* output buffer pointer */ INT16S Sign_b; /* Current adpcm sign bit */ INT16S CurIn_16s; /* Current input sample value */ INT16S Diff_16s; /* Difference between val and valprev */ INT16S ValuePred_16s; /* Predicted output value */ INT16S Index_16s; /* Current step change index */ //zgx INT16S BufStep_16s; /* toggle between OutBuf_16u/output */ INT16S CurOut_16u; /* Current adpcm output value */ INT16S Step_16u; /* Stepsize */ INT16S VP_Diff_16u; /* Current change to ValuePred_16s */ INT16S OutBuf_16u; /* place to keep previous 4-bit value */ Out_P16u = (INT8S *) Outdata_P8u; ValuePred_16s = State_ST->PreValue_16s; Index_16s = (INT16S)State_ST->Index_8u; Step_16u = StepSizeTable_16u[Index_16s]; BufStep_16s = 1; while (FrameLen_16u-- > 0 ) { CurIn_16s = *Indata_P16s++; /* Step 1 - compute difference with previous value */ Diff_16s = CurIn_16s - ValuePred_16s; if(Diff_16s < 0) { Sign_b = 8; Diff_16s = -Diff_16s; } else Sign_b = 0; /* Step_16u 2 - Divide and clamp */ /* Note: ** This code *approximately* computes: ** CurOut_16u = Diff_16s*4/Step_16u; ** VP_Diff_16u = (CurOut_16u+0.5)*Step_16u/4; ** but in shift Step_16u bits are dropped. The net result of this is ** that even if you have fast mul/div hardware you cannot put it to ** good use since the fixup would be too expensive. */ CurOut_16u = 0; VP_Diff_16u = Step_16u >> 3; if (Diff_16s >= Step_16u) { CurOut_16u = 4; Diff_16s -= Step_16u; VP_Diff_16u += Step_16u; } Step_16u >>= 1; if (Diff_16s >= Step_16u) { CurOut_16u |= 2; Diff_16s -= Step_16u; VP_Diff_16u += Step_16u; } Step_16u >>= 1; if (Diff_16s >= Step_16u) { CurOut_16u |= 1; VP_Diff_16u += Step_16u; } /* Step 3 - Update previous value */ if (Sign_b) ValuePred_16s -= VP_Diff_16u; else ValuePred_16s += VP_Diff_16u; /* Step 4 - Clamp previous value to 16 bits */ if ( ValuePred_16s < -32768 ) ValuePred_16s = -32768; else if( ValuePred_16s > 32767 ) ValuePred_16s = 32767; /* Step 5 - Assemble value, update Index_16s and Step_16u values */ CurOut_16u |= Sign_b; Index_16s += IndexTable_8s[CurOut_16u]; if (Index_16s < 0) Index_16s = 0; if (Index_16s > 88) Index_16s = 88; Step_16u = StepSizeTable_16u[Index_16s]; /* Step 6 - Output value */ if (BufStep_16s != 0) { OutBuf_16u = (CurOut_16u << 4) & 0xf0; } else *Out_P16u++ = (CurOut_16u & 0x0f) | OutBuf_16u; BufStep_16s = !BufStep_16s; }//while (FrameLen_16u-- > 0 ) /* Output last step, if needed */ if ( BufStep_16s == 0 ) *Out_P16u++ = (INT8U)OutBuf_16u; State_ST->PreValue_16s = (INT16S)ValuePred_16s; State_ST->Index_8u = (INT8U)Index_16s; } /***************************************************** * * G.721 Decoder * ******************************************************/ void G721Decoder(INT8U *Indata_P8u, INT16S *Outdata_P16s, INT16S FrameLen_16u, AdpcmState_ST *State_ST) { INT8S *Indata_P8s; /* Input buffer pointer */ //short *outp; /* output buffer pointer */ INT16S Sign_16s; /* Current adpcm sign bit */ INT16S CurOut_16s; /* Current adpcm output value */ INT16S Step_16s; /* Stepsize */ INT16S ValuePred_16s; /* Predicted value */ INT16S VP_Diff_16s; /* Current change to ValuePred_16s */ INT16S Index_16s; /* Current step change Index_16s */ INT16S InBuf_16s; /* place to keep next 4-bit value */ INT16S bufferstep; /* toggle between inputbuffer/input */ Indata_P8s = (INT8S *) Indata_P8u; ValuePred_16s = State_ST->PreValue_16s; Index_16s = State_ST->Index_8u; Step_16s = StepSizeTable_16u[Index_16s]; bufferstep = 0; while (FrameLen_16u-- >0) { /* Step 1 - get the CurOut_16s value */ if ( bufferstep ) { CurOut_16s = InBuf_16s & 0xf; } else { InBuf_16s = *Indata_P8s++; CurOut_16s = (InBuf_16s >> 4) & 0xf; } bufferstep = !bufferstep; /* Step 2 - Find new Index_16s value (for later) */ Index_16s += IndexTable_8s[CurOut_16s]; if ( Index_16s < 0 ) Index_16s = 0; if ( Index_16s > 88 ) Index_16s = 88; /* Step 3 - Separate Sign_16s and magnitude */ Sign_16s = CurOut_16s & 8; CurOut_16s = CurOut_16s & 7; /* Step 4 - Compute difference and new predicted value */ /* ** Computes 'VP_Diff_16s = (CurOut_16s+0.5)*Step_16s/4', but see comment ** in adpcm_coder. */ VP_Diff_16s = Step_16s >> 3; if ( CurOut_16s & 4 ) VP_Diff_16s += Step_16s; if ( CurOut_16s & 2 ) VP_Diff_16s += Step_16s>>1; if ( CurOut_16s & 1 ) VP_Diff_16s += Step_16s>>2; if ( Sign_16s ) ValuePred_16s -= VP_Diff_16s; else ValuePred_16s += VP_Diff_16s; /* Step 5 - clamp output value */ if ( ValuePred_16s > 32767 ) ValuePred_16s = 32767; else if ( ValuePred_16s < -32768 ) ValuePred_16s = -32768; /* Step 6 - Update Step_16s value */ Step_16s = StepSizeTable_16u[Index_16s]; /* Step 7 - Output value */ *Outdata_P16s++ = ValuePred_16s; }//while (FrameLen_16u-- >0) State_ST->PreValue_16s = ValuePred_16s; State_ST->Index_8u = Index_16s; }