void pvmp3_mpeg2_get_scale_factors(mp3ScaleFactors *scalefac, mp3SideInfo *si, int32 gr, int32 ch, mp3Header *info, uint32 *scalefac_IIP_buffer, tmp3Bits *pMainData) { int32 sfb; int32 k = 0; int32 window; uint32 *scalefac_buffer = &scalefac_IIP_buffer[56]; granuleInfo *gr_info = &(si->ch[ch].gran[gr]); pvmp3_mpeg2_get_scale_data(si, gr, ch, info, (uint32 *)scalefac_buffer, (uint32 *)scalefac_IIP_buffer, pMainData); if (gr_info->window_switching_flag && (gr_info->block_type == 2)) { if (gr_info->mixed_block_flag) { for (sfb = 0; sfb < 6; sfb++) { scalefac->l[sfb] = scalefac_buffer[sfb]; } k = 6; for (sfb = 3; sfb < 12; sfb++) { for (window = 0; window < 3; window++) { scalefac->s[window][sfb] = scalefac_buffer[k]; k++; } } /* adjust position of "illegal position" information in scalefac_IIP_buffer[] */ /* in mixed blocks mode for short sfb, move them 3 places up. efs 3002-07-04 */ for (sfb = 11; sfb >= 3; sfb--) { scalefac_IIP_buffer[3*sfb + 2] = scalefac_IIP_buffer[3*sfb - 1]; scalefac_IIP_buffer[3*sfb + 1] = scalefac_IIP_buffer[3*sfb - 2]; scalefac_IIP_buffer[3*sfb ] = scalefac_IIP_buffer[3*sfb - 3]; } } else { /* SHORT*/ for (sfb = 0; sfb < 12; sfb++) { for (window = 0; window < 3; window++) { scalefac->s[window][sfb] = scalefac_buffer[k]; k++; } } } scalefac->s[0][12] = 0; scalefac->s[1][12] = 0; scalefac->s[2][12] = 0; } else { /* LONG types 0,1,3 */ for (sfb = 0; sfb < 21; sfb++) { scalefac->l[sfb] = scalefac_buffer[sfb]; } scalefac->l[21] = 0; scalefac->l[22] = 0; } }
//==================================================================================================== //函数功能:获得"scale factor" //函数参数:"si"表示旁信息,"gr"表示granule,"ch"表示声道,"info"表示头信息,"pMainData"表示输入流, // "scalefac_IIP_buffer"表示辅助数组,均为输入参数 // "scalefac"表示量化因子,为输出参数 //==================================================================================================== void pvmp3_mpeg2_get_scale_factors(mp3ScaleFactors *scalefac, mp3SideInfo *si, int32 gr, int32 ch, mp3Header *info, uint32 *scalefac_IIP_buffer, tmp3Bits *pMainData) { //定义变量 int32 sfb; int32 k = 0; int32 window; uint32 *scalefac_buffer = &scalefac_IIP_buffer[56]; granuleInfo *gr_info = &(si->ch[ch].gran[gr]); //获得"scalefac_buffer"和"scalefac_IIP_buffer"信息 pvmp3_mpeg2_get_scale_data(si, gr, ch, info, (uint32 *)scalefac_buffer, (uint32 *)scalefac_IIP_buffer, pMainData); //若"window_switching_flag"为1并且"block_type"为2 if (gr_info->window_switching_flag && (gr_info->block_type == 2)) { //若"mixed_block_flag"为1,即为混合型 if (gr_info->mixed_block_flag) { //对"l[sfb]"赋值,其中"sfb"属于0-5 for (sfb = 0; sfb < 6; sfb++) { scalefac->l[sfb] = scalefac_buffer[sfb]; } //对"s[window][sfb]"赋值,其中"window"属于0-2,"sfb"属于3-11 k = 6; for (sfb = 3; sfb < 12; sfb++) { for (window = 0; window < 3; window++) { scalefac->s[window][sfb] = scalefac_buffer[k]; k++; } } //调整非法位置 /* adjust position of "illegal position" information in scalefac_IIP_buffer[] */ /* in mixed blocks mode for short sfb, move them 3 places up. efs 3002-07-04 */ for (sfb = 11; sfb >= 3; sfb--) { scalefac_IIP_buffer[3*sfb + 2] = scalefac_IIP_buffer[3*sfb - 1]; scalefac_IIP_buffer[3*sfb + 1] = scalefac_IIP_buffer[3*sfb - 2]; scalefac_IIP_buffer[3*sfb ] = scalefac_IIP_buffer[3*sfb - 3]; } } //若为短窗框型 else { //对"s[window][sfb]"赋值,其中"window"属于0-2,"sfb"属于0-11 for (sfb = 0; sfb < 12; sfb++) { for (window = 0; window < 3; window++) { scalefac->s[window][sfb] = scalefac_buffer[k]; k++; } } } //为"s[window][12]"赋值为0,其中"window"属于0-2 scalefac->s[0][12] = 0; scalefac->s[1][12] = 0; scalefac->s[2][12] = 0; } //若为长窗框型的 else { //为"l[sfb]"赋值,其中"sfb"属于0-20 /* LONG types 0,1,3 */ for (sfb = 0; sfb < 21; sfb++) { scalefac->l[sfb] = scalefac_buffer[sfb]; } //为"l[21]"和"l[22]"赋值为0 scalefac->l[21] = 0; scalefac->l[22] = 0; } }