/* * Header file for hardcoded PCM tables * * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de> * * This file is part of Libav. * * 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. * * 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 Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef AVCODEC_PCM_TABLEGEN_H #define AVCODEC_PCM_TABLEGEN_H #include <stdint.h> #include "libavutil/attributes.h" /* from g711.c by SUN microsystems (unrestricted use) */ #define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */ #define QUANT_MASK (0xf) /* Quantization field mask. */ #define NSEGS (8) /* Number of A-law segments. */ #define SEG_SHIFT (4) /* Left shift for segment number. */ #define SEG_MASK (0x70) /* Segment field mask. */ #define BIAS (0x84) /* Bias for linear code. */ /* * alaw2linear() - Convert an A-law value to 16-bit linear PCM * */ static av_cold int alaw2linear(unsigned char a_val) { int t; int seg; a_val ^= 0x55; t = a_val & QUANT_MASK; seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT; if(seg) t= (t + t + 1 + 32) << (seg + 2); else t= (t + t + 1 ) << 3; return (a_val & SIGN_BIT) ? t : -t; } static av_cold int ulaw2linear(unsigned char u_val) { int t; /* Complement to obtain normal u-law value. */ u_val = ~u_val; /* * Extract and bias the quantization bits. Then * shift up by the segment number and subtract out the bias. */ t = ((u_val & QUANT_MASK) << 3) + BIAS; t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT; return (u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS); } #if CONFIG_HARDCODED_TABLES #define pcm_alaw_tableinit() #define pcm_ulaw_tableinit() #include "libavcodec/pcm_tables.h" #else /* 16384 entries per table */ static uint8_t linear_to_alaw[16384]; static uint8_t linear_to_ulaw[16384]; static av_cold void build_xlaw_table(uint8_t *linear_to_xlaw, int (*xlaw2linear)(unsigned char), int mask) { int i, j, v, v1, v2; j = 0; for(i=0;i<128;i++) { if (i != 127) { v1 = xlaw2linear(i ^ mask); v2 = xlaw2linear((i + 1) ^ mask); v = (v1 + v2 + 4) >> 3; } else { v = 8192; } for(;j<v;j++) { linear_to_xlaw[8192 + j] = (i ^ mask); if (j > 0) linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80)); } } linear_to_xlaw[0] = linear_to_xlaw[1]; } static void pcm_alaw_tableinit(void) { build_xlaw_table(linear_to_alaw, alaw2linear, 0xd5); } static void pcm_ulaw_tableinit(void) { build_xlaw_table(linear_to_ulaw, ulaw2linear, 0xff); } #endif /* CONFIG_HARDCODED_TABLES */ #endif /* AVCODEC_PCM_TABLEGEN_H */