Fixed-point LSP and LPC decoding routines for ACELP-based codecs

Originally committed as revision 12978 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 63 insertions, 0 deletions

diff --git a/libavcodec/lsp.h b/libavcodec/lsp.h
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+++ b/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 FFMPEG_ACELP_LPC_H
+#define FFMPEG_ACELP_LPC_H
+/**
+  (I.F) means fixed-point value with F fractional and I integer bits
+*/
+
+/**
+ * \brief keep distance between LSFs.
+ * \param lsfq [in/out] 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
+ */
+void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsqf_min, int lsfq_max);
+
+/**
+ * \brief Convert LSF to LSP
+ * \param lsp [out] LSP coefficients (-0x8000 <= (0.15) < 0x8000)
+ * \param lsf normalized LSF coefficients (0 <= (2.13) < 0x2000 * PI)
+ *
+ * \remark It is safe to pass the same array in lsf and lsp parameters
+ */
+void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf);
+
+/**
+ * \brief LSP to LP conversion (3.2.6 of G.729)
+ * \param lp [out] decoded LP coefficients (-0x8000 <= (3.12) < 0x8000)
+ * \param lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
+ */
+void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp);
+
+/**
+ * \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 lp_1st [out] decoded LP coefficients for 1st subframe (-0x8000 <= (3.12) < 0x8000)
+ * \param lp_2nd [out] 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 past LSP coefficients (-0x8000 <= (0.15) < 0x8000)
+ */
+void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev);
+
+#endif // FFMPEG_ACELP_LPC_H