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Diffstat (limited to 'media/libstagefright/codecs/amrwbenc/src/isp_isf.c')
-rw-r--r-- | media/libstagefright/codecs/amrwbenc/src/isp_isf.c | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrwbenc/src/isp_isf.c b/media/libstagefright/codecs/amrwbenc/src/isp_isf.c new file mode 100644 index 0000000..b4ba408 --- /dev/null +++ b/media/libstagefright/codecs/amrwbenc/src/isp_isf.c @@ -0,0 +1,91 @@ +/* + ** Copyright 2003-2010, VisualOn, Inc. + ** + ** Licensed under the Apache License, Version 2.0 (the "License"); + ** you may not use this file except in compliance with the License. + ** You may obtain a copy of the License at + ** + ** http://www.apache.org/licenses/LICENSE-2.0 + ** + ** Unless required by applicable law or agreed to in writing, software + ** distributed under the License is distributed on an "AS IS" BASIS, + ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + ** See the License for the specific language governing permissions and + ** limitations under the License. + */ + +/*********************************************************************** +* File: isp_isf.c * +* * +* Description: * +* Isp_isf Transformation isp to isf * +* Isf_isp Transformation isf to isp * +* * +* The transformation from isp[i] to isf[i] and isf[i] to isp[i] * +* are approximated by a look-up table and interpolation * +* * +************************************************************************/ + +#include "typedef.h" +#include "basic_op.h" +#include "isp_isf.tab" /* Look-up table for transformations */ + +void Isp_isf( + Word16 isp[], /* (i) Q15 : isp[m] (range: -1<=val<1) */ + Word16 isf[], /* (o) Q15 : isf[m] normalized (range: 0.0<=val<=0.5) */ + Word16 m /* (i) : LPC order */ + ) +{ + Word32 i, ind; + Word32 L_tmp; + ind = 127; /* beging at end of table -1 */ + for (i = (m - 1); i >= 0; i--) + { + if (i >= (m - 2)) + { /* m-2 is a constant */ + ind = 127; /* beging at end of table -1 */ + } + /* find value in table that is just greater than isp[i] */ + while (table[ind] < isp[i]) + ind--; + /* acos(isp[i])= ind*128 + ( ( isp[i]-table[ind] ) * slope[ind] )/2048 */ + L_tmp = vo_L_mult(vo_sub(isp[i], table[ind]), slope[ind]); + isf[i] = vo_round((L_tmp << 4)); /* (isp[i]-table[ind])*slope[ind])>>11 */ + isf[i] = add1(isf[i], (ind << 7)); + } + isf[m - 1] = (isf[m - 1] >> 1); + return; +} + + +void Isf_isp( + Word16 isf[], /* (i) Q15 : isf[m] normalized (range: 0.0<=val<=0.5) */ + Word16 isp[], /* (o) Q15 : isp[m] (range: -1<=val<1) */ + Word16 m /* (i) : LPC order */ + ) +{ + Word16 offset; + Word32 i, ind, L_tmp; + + for (i = 0; i < m - 1; i++) + { + isp[i] = isf[i]; + } + isp[m - 1] = (isf[m - 1] << 1); + + for (i = 0; i < m; i++) + { + ind = (isp[i] >> 7); /* ind = b7-b15 of isf[i] */ + offset = (Word16) (isp[i] & 0x007f); /* offset = b0-b6 of isf[i] */ + + /* isp[i] = table[ind]+ ((table[ind+1]-table[ind])*offset) / 128 */ + L_tmp = vo_L_mult(vo_sub(table[ind + 1], table[ind]), offset); + isp[i] = add1(table[ind], (Word16)((L_tmp >> 8))); + } + + return; +} + + + + |