* LPC utility code
* Copyright (c) 2006 Justin Ruggles <justin.ruggles@gmail.com>
*
- * This file is part of FFmpeg.
+ * This file is part of Libav.
*
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav 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,
+ * Libav 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
+ * License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#define MIN_LPC_ORDER 1
#define MAX_LPC_ORDER 32
+/**
+ * LPC analysis type
+ */
+enum FFLPCType {
+ FF_LPC_TYPE_DEFAULT = -1, ///< use the codec default LPC type
+ FF_LPC_TYPE_NONE = 0, ///< do not use LPC prediction or use all zero coefficients
+ FF_LPC_TYPE_FIXED = 1, ///< fixed LPC coefficients
+ FF_LPC_TYPE_LEVINSON = 2, ///< Levinson-Durbin recursion
+ FF_LPC_TYPE_CHOLESKY = 3, ///< Cholesky factorization
+ FF_LPC_TYPE_NB , ///< Not part of ABI
+};
+
+typedef struct LPCContext {
+ int blocksize;
+ int max_order;
+ enum FFLPCType lpc_type;
+ double *windowed_samples;
+
+ /**
+ * Apply a Welch window to an array of input samples.
+ * The output samples have the same scale as the input, but are in double
+ * sample format.
+ * @param data input samples
+ * @param len number of input samples
+ * @param w_data output samples
+ */
+ void (*lpc_apply_welch_window)(const int32_t *data, int len,
+ double *w_data);
+ /**
+ * Perform autocorrelation on input samples with delay of 0 to lag.
+ * @param data input samples.
+ * constraints: no alignment needed, but must have have at
+ * least lag*sizeof(double) valid bytes preceeding it, and
+ * size must be at least (len+1)*sizeof(double) if data is
+ * 16-byte aligned or (len+2)*sizeof(double) if data is
+ * unaligned.
+ * @param len number of input samples to process
+ * @param lag maximum delay to calculate
+ * @param autoc output autocorrelation coefficients.
+ * constraints: array size must be at least lag+1.
+ */
+ void (*lpc_compute_autocorr)(const double *data, int len, int lag,
+ double *autoc);
+} LPCContext;
+
/**
* Calculate LPC coefficients for multiple orders
*/
-int ff_lpc_calc_coefs(DSPContext *s,
+int ff_lpc_calc_coefs(LPCContext *s,
const int32_t *samples, int blocksize, int min_order,
int max_order, int precision,
- int32_t coefs[][MAX_LPC_ORDER], int *shift, int use_lpc,
+ int32_t coefs[][MAX_LPC_ORDER], int *shift,
+ enum FFLPCType lpc_type, int lpc_passes,
int omethod, int max_shift, int zero_shift);
-void ff_lpc_compute_autocorr(const int32_t *data, int len, int lag,
- double *autoc);
+/**
+ * Initialize LPCContext.
+ */
+int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
+ enum FFLPCType lpc_type);
+void ff_lpc_init_x86(LPCContext *s);
+
+/**
+ * Uninitialize LPCContext.
+ */
+void ff_lpc_end(LPCContext *s);
#ifdef LPC_USE_DOUBLE
#define LPC_TYPE double