summaryrefslogtreecommitdiffstats
path: root/media/libopus/silk/LP_variable_cutoff.c
diff options
context:
space:
mode:
Diffstat (limited to 'media/libopus/silk/LP_variable_cutoff.c')
-rw-r--r--media/libopus/silk/LP_variable_cutoff.c135
1 files changed, 135 insertions, 0 deletions
diff --git a/media/libopus/silk/LP_variable_cutoff.c b/media/libopus/silk/LP_variable_cutoff.c
new file mode 100644
index 0000000000..79112ad354
--- /dev/null
+++ b/media/libopus/silk/LP_variable_cutoff.c
@@ -0,0 +1,135 @@
+/***********************************************************************
+Copyright (c) 2006-2011, Skype Limited. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+- Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+- Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+- Neither the name of Internet Society, IETF or IETF Trust, nor the
+names of specific contributors, may be used to endorse or promote
+products derived from this software without specific prior written
+permission.
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+***********************************************************************/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+/*
+ Elliptic/Cauer filters designed with 0.1 dB passband ripple,
+ 80 dB minimum stopband attenuation, and
+ [0.95 : 0.15 : 0.35] normalized cut off frequencies.
+*/
+
+#include "main.h"
+
+/* Helper function, interpolates the filter taps */
+static OPUS_INLINE void silk_LP_interpolate_filter_taps(
+ opus_int32 B_Q28[ TRANSITION_NB ],
+ opus_int32 A_Q28[ TRANSITION_NA ],
+ const opus_int ind,
+ const opus_int32 fac_Q16
+)
+{
+ opus_int nb, na;
+
+ if( ind < TRANSITION_INT_NUM - 1 ) {
+ if( fac_Q16 > 0 ) {
+ if( fac_Q16 < 32768 ) { /* fac_Q16 is in range of a 16-bit int */
+ /* Piece-wise linear interpolation of B and A */
+ for( nb = 0; nb < TRANSITION_NB; nb++ ) {
+ B_Q28[ nb ] = silk_SMLAWB(
+ silk_Transition_LP_B_Q28[ ind ][ nb ],
+ silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
+ silk_Transition_LP_B_Q28[ ind ][ nb ],
+ fac_Q16 );
+ }
+ for( na = 0; na < TRANSITION_NA; na++ ) {
+ A_Q28[ na ] = silk_SMLAWB(
+ silk_Transition_LP_A_Q28[ ind ][ na ],
+ silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
+ silk_Transition_LP_A_Q28[ ind ][ na ],
+ fac_Q16 );
+ }
+ } else { /* ( fac_Q16 - ( 1 << 16 ) ) is in range of a 16-bit int */
+ silk_assert( fac_Q16 - ( 1 << 16 ) == silk_SAT16( fac_Q16 - ( 1 << 16 ) ) );
+ /* Piece-wise linear interpolation of B and A */
+ for( nb = 0; nb < TRANSITION_NB; nb++ ) {
+ B_Q28[ nb ] = silk_SMLAWB(
+ silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
+ silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
+ silk_Transition_LP_B_Q28[ ind ][ nb ],
+ fac_Q16 - ( (opus_int32)1 << 16 ) );
+ }
+ for( na = 0; na < TRANSITION_NA; na++ ) {
+ A_Q28[ na ] = silk_SMLAWB(
+ silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
+ silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
+ silk_Transition_LP_A_Q28[ ind ][ na ],
+ fac_Q16 - ( (opus_int32)1 << 16 ) );
+ }
+ }
+ } else {
+ silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( opus_int32 ) );
+ silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( opus_int32 ) );
+ }
+ } else {
+ silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( opus_int32 ) );
+ silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( opus_int32 ) );
+ }
+}
+
+/* Low-pass filter with variable cutoff frequency based on */
+/* piece-wise linear interpolation between elliptic filters */
+/* Start by setting psEncC->mode <> 0; */
+/* Deactivate by setting psEncC->mode = 0; */
+void silk_LP_variable_cutoff(
+ silk_LP_state *psLP, /* I/O LP filter state */
+ opus_int16 *frame, /* I/O Low-pass filtered output signal */
+ const opus_int frame_length /* I Frame length */
+)
+{
+ opus_int32 B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0;
+ opus_int ind = 0;
+
+ silk_assert( psLP->transition_frame_no >= 0 && psLP->transition_frame_no <= TRANSITION_FRAMES );
+
+ /* Run filter if needed */
+ if( psLP->mode != 0 ) {
+ /* Calculate index and interpolation factor for interpolation */
+#if( TRANSITION_INT_STEPS == 64 )
+ fac_Q16 = silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 - 6 );
+#else
+ fac_Q16 = silk_DIV32_16( silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 ), TRANSITION_FRAMES );
+#endif
+ ind = silk_RSHIFT( fac_Q16, 16 );
+ fac_Q16 -= silk_LSHIFT( ind, 16 );
+
+ silk_assert( ind >= 0 );
+ silk_assert( ind < TRANSITION_INT_NUM );
+
+ /* Interpolate filter coefficients */
+ silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 );
+
+ /* Update transition frame number for next frame */
+ psLP->transition_frame_no = silk_LIMIT( psLP->transition_frame_no + psLP->mode, 0, TRANSITION_FRAMES );
+
+ /* ARMA low-pass filtering */
+ silk_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 );
+ silk_biquad_alt_stride1( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length);
+ }
+}