From fa034b44270bbddfc11c691e94a6b8e97c68f84b Mon Sep 17 00:00:00 2001 From: Reimar Döffinger Date: Thu, 1 Apr 2010 17:54:15 +0000 Subject: Allow hardcoding of ulaw and alaw tables. Originally committed as revision 22762 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/pcm_tablegen.h | 119 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) create mode 100644 libavcodec/pcm_tablegen.h (limited to 'libavcodec/pcm_tablegen.h') diff --git a/libavcodec/pcm_tablegen.h b/libavcodec/pcm_tablegen.h new file mode 100644 index 0000000000..8921baaba2 --- /dev/null +++ b/libavcodec/pcm_tablegen.h @@ -0,0 +1,119 @@ +/* + * Header file for hardcoded PCM tables + * + * Copyright (c) 2010 Reimar Döffinger + * + * 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 PCM_TABLEGEN_H +#define PCM_TABLEGEN_H + +#include +#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 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 /* PCM_TABLEGEN_H */ -- cgit v1.2.3