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authorTim Redfern <tim@eclectronics.org>2013-08-26 15:10:18 +0100
committerTim Redfern <tim@eclectronics.org>2013-08-26 15:10:18 +0100
commit150c9823e71a161e97003849cf8b2f55b21520bd (patch)
tree3559c840cf403d1386708b2591d58f928c7b160d /ffmpeg1/libavcodec/lsp.h
parentb4b1e2630c95d5e6014463f7608d59dc2322a3b8 (diff)
adding ffmpeg specific version
Diffstat (limited to 'ffmpeg1/libavcodec/lsp.h')
-rw-r--r--ffmpeg1/libavcodec/lsp.h130
1 files changed, 130 insertions, 0 deletions
diff --git a/ffmpeg1/libavcodec/lsp.h b/ffmpeg1/libavcodec/lsp.h
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+/*
+ * LSP computing for ACELP-based codecs
+ *
+ * Copyright (c) 2008 Vladimir Voroshilov
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_LSP_H
+#define AVCODEC_LSP_H
+
+#include <stdint.h>
+
+/**
+ (I.F) means fixed-point value with F fractional and I integer bits
+*/
+
+/**
+ * @brief ensure a minimum distance between LSFs
+ * @param[in,out] lsfq LSF to check and adjust
+ * @param lsfq_min_distance minimum distance between LSFs
+ * @param lsfq_min minimum allowed LSF value
+ * @param lsfq_max maximum allowed LSF value
+ * @param lp_order LP filter order
+ */
+void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order);
+
+/**
+ * Adjust the quantized LSFs so they are increasing and not too close.
+ *
+ * This step is not mentioned in the AMR spec but is in the reference C decoder.
+ * Omitting this step creates audible distortion on the sinusoidal sweep
+ * test vectors in 3GPP TS 26.074.
+ *
+ * @param[in,out] lsf LSFs in Hertz
+ * @param min_spacing minimum distance between two consecutive lsf values
+ * @param size size of the lsf vector
+ */
+void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size);
+
+/**
+ * @brief Convert LSF to LSP
+ * @param[out] lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
+ * @param lsf normalized LSF coefficients (0 <= (2.13) < 0x2000 * PI)
+ * @param lp_order LP filter order
+ *
+ * @remark It is safe to pass the same array into the lsf and lsp parameters.
+ */
+void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order);
+
+/**
+ * Floating point version of ff_acelp_lsf2lsp()
+ */
+void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order);
+
+/**
+ * @brief LSP to LP conversion (3.2.6 of G.729)
+ * @param[out] lp decoded LP coefficients (-0x8000 <= (3.12) < 0x8000)
+ * @param lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
+ * @param lp_half_order LP filter order, divided by 2
+ */
+void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order);
+
+/**
+ * LSP to LP conversion (5.2.4 of AMR-WB)
+ */
+void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order);
+
+/**
+ * @brief Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729)
+ * @param[out] lp_1st decoded LP coefficients for first subframe (-0x8000 <= (3.12) < 0x8000)
+ * @param[out] lp_2nd decoded LP coefficients for second subframe (-0x8000 <= (3.12) < 0x8000)
+ * @param lsp_2nd LSP coefficients of the second subframe (-0x8000 <= (0.15) < 0x8000)
+ * @param lsp_prev LSP coefficients from the second subframe of the previous frame (-0x8000 <= (0.15) < 0x8000)
+ * @param lp_order LP filter order
+ */
+void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev, int lp_order);
+
+
+#define MAX_LP_HALF_ORDER 10
+#define MAX_LP_ORDER (2*MAX_LP_HALF_ORDER)
+
+/**
+ * Reconstruct LPC coefficients from the line spectral pair frequencies.
+ *
+ * @param lsp line spectral pairs in cosine domain
+ * @param lpc linear predictive coding coefficients
+ * @param lp_half_order half the number of the amount of LPCs to be
+ * reconstructed, need to be smaller or equal to MAX_LP_HALF_ORDER
+ *
+ * @note buffers should have a minimux size of 2*lp_half_order elements.
+ *
+ * TIA/EIA/IS-733 2.4.3.3.5
+ */
+void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order);
+
+/**
+ * Sort values in ascending order.
+ *
+ * @note O(n) if data already sorted, O(n^2) - otherwise
+ */
+void ff_sort_nearly_sorted_floats(float *vals, int len);
+
+/**
+ * Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients
+ * needed for LSP to LPC conversion.
+ * We only need to calculate the 6 first elements of the polynomial.
+ *
+ * @param lsp line spectral pairs in cosine domain
+ * @param[out] f polynomial input/output as a vector
+ *
+ * TIA/EIA/IS-733 2.4.3.3.5-1/2
+ */
+void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order);
+
+#endif /* AVCODEC_LSP_H */