diff options
Diffstat (limited to 'media/libstagefright/codecs/amrwbenc/src/preemph.c')
| -rw-r--r-- | media/libstagefright/codecs/amrwbenc/src/preemph.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrwbenc/src/preemph.c b/media/libstagefright/codecs/amrwbenc/src/preemph.c new file mode 100644 index 0000000..c867bf7 --- /dev/null +++ b/media/libstagefright/codecs/amrwbenc/src/preemph.c @@ -0,0 +1,88 @@ +/* + ** 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: preemph.c * +* * +* Description: Preemphasis: filtering through 1 - g z^-1 * +* Preemph2 --> signal is multiplied by 2 * +* * +************************************************************************/ + +#include "typedef.h" +#include "basic_op.h" + +void Preemph( + Word16 x[], /* (i/o) : input signal overwritten by the output */ + Word16 mu, /* (i) Q15 : preemphasis coefficient */ + Word16 lg, /* (i) : lenght of filtering */ + Word16 * mem /* (i/o) : memory (x[-1]) */ + ) +{ + Word16 temp; + Word32 i, L_tmp; + + temp = x[lg - 1]; + + for (i = lg - 1; i > 0; i--) + { + L_tmp = L_deposit_h(x[i]); + L_tmp -= (x[i - 1] * mu)<<1; + x[i] = (L_tmp + 0x8000)>>16; + } + + L_tmp = L_deposit_h(x[0]); + L_tmp -= ((*mem) * mu)<<1; + x[0] = (L_tmp + 0x8000)>>16; + + *mem = temp; + + return; +} + + +void Preemph2( + Word16 x[], /* (i/o) : input signal overwritten by the output */ + Word16 mu, /* (i) Q15 : preemphasis coefficient */ + Word16 lg, /* (i) : lenght of filtering */ + Word16 * mem /* (i/o) : memory (x[-1]) */ + ) +{ + Word16 temp; + Word32 i, L_tmp; + + temp = x[lg - 1]; + + for (i = (Word16) (lg - 1); i > 0; i--) + { + L_tmp = L_deposit_h(x[i]); + L_tmp -= (x[i - 1] * mu)<<1; + L_tmp = (L_tmp << 1); + x[i] = (L_tmp + 0x8000)>>16; + } + + L_tmp = L_deposit_h(x[0]); + L_tmp -= ((*mem) * mu)<<1; + L_tmp = (L_tmp << 1); + x[0] = (L_tmp + 0x8000)>>16; + + *mem = temp; + + return; +} + + + |