mirror of https://github.com/FFmpeg/FFmpeg.git
Originally committed as revision 140 to svn://svn.ffmpeg.org/ffmpeg/trunkpull/126/head
Fabrice Bellard
24 years ago
parent
a56c66a7ef
commit
a96b68b717
4 changed files with 446 additions and 22 deletions
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/*
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* PCM codecs |
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* Copyright (c) 2001 Gerard Lantau. |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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*/ |
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#include "avcodec.h" |
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/* from g711.c by SUN microsystems (unrestricted use) */ |
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#define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */ |
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#define QUANT_MASK (0xf) /* Quantization field mask. */ |
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#define NSEGS (8) /* Number of A-law segments. */ |
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#define SEG_SHIFT (4) /* Left shift for segment number. */ |
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#define SEG_MASK (0x70) /* Segment field mask. */ |
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#define BIAS (0x84) /* Bias for linear code. */ |
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/*
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* alaw2linear() - Convert an A-law value to 16-bit linear PCM |
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* |
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*/ |
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static int alaw2linear(unsigned char a_val) |
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{ |
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int t; |
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int seg; |
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a_val ^= 0x55; |
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t = (a_val & QUANT_MASK) << 4; |
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seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT; |
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switch (seg) { |
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case 0: |
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t += 8; |
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break; |
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case 1: |
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t += 0x108; |
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break; |
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default: |
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t += 0x108; |
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t <<= seg - 1; |
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} |
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return ((a_val & SIGN_BIT) ? t : -t); |
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} |
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static int ulaw2linear(unsigned char u_val) |
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{ |
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int t; |
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/* Complement to obtain normal u-law value. */ |
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u_val = ~u_val; |
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/*
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* Extract and bias the quantization bits. Then |
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* shift up by the segment number and subtract out the bias. |
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*/ |
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t = ((u_val & QUANT_MASK) << 3) + BIAS; |
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t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT; |
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return ((u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS)); |
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} |
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/* 16384 entries per table */ |
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static UINT8 *linear_to_alaw = NULL; |
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static int linear_to_alaw_ref = 0; |
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static UINT8 *linear_to_ulaw = NULL; |
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static int linear_to_ulaw_ref = 0; |
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static void build_xlaw_table(UINT8 *linear_to_xlaw,
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int (*xlaw2linear)(unsigned char), |
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int mask)
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{ |
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int i, j, v, v1, v2; |
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j = 0; |
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for(i=0;i<128;i++) { |
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if (i != 127) { |
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v1 = xlaw2linear(i ^ mask); |
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v2 = xlaw2linear((i + 1) ^ mask); |
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v = (v1 + v2 + 4) >> 3; |
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} else { |
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v = 8192; |
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} |
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for(;j<v;j++) { |
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linear_to_xlaw[8192 + j] = (i ^ mask); |
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if (j > 0) |
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linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80)); |
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} |
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} |
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linear_to_xlaw[0] = linear_to_xlaw[1]; |
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} |
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static int encode_init(AVCodecContext *avctx) |
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{ |
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avctx->frame_size = 1; |
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switch(avctx->codec->id) { |
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case CODEC_ID_PCM_ALAW: |
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if (linear_to_alaw_ref == 0) { |
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linear_to_alaw = malloc(16384); |
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if (!linear_to_alaw) |
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return -1; |
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build_xlaw_table(linear_to_alaw, alaw2linear, 0xd5); |
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} |
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linear_to_alaw_ref++; |
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break; |
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case CODEC_ID_PCM_MULAW: |
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if (linear_to_ulaw_ref == 0) { |
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linear_to_ulaw = malloc(16384); |
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if (!linear_to_ulaw) |
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return -1; |
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build_xlaw_table(linear_to_ulaw, ulaw2linear, 0xff); |
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} |
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linear_to_ulaw_ref++; |
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break; |
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default: |
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break; |
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} |
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return 0; |
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} |
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static int encode_close(AVCodecContext *avctx) |
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{ |
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switch(avctx->codec->id) { |
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case CODEC_ID_PCM_ALAW: |
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if (--linear_to_alaw_ref == 0) |
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free(linear_to_alaw); |
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break; |
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case CODEC_ID_PCM_MULAW: |
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if (--linear_to_ulaw_ref == 0) |
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free(linear_to_ulaw); |
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break; |
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default: |
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/* nothing to free */ |
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break; |
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} |
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return 0; |
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} |
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static int encode_frame(AVCodecContext *avctx, |
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unsigned char *frame, int buf_size, void *data) |
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{ |
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int n, sample_size, v; |
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short *samples; |
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unsigned char *dst; |
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switch(avctx->codec->id) { |
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case CODEC_ID_PCM_S16LE: |
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case CODEC_ID_PCM_S16BE: |
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case CODEC_ID_PCM_U16LE: |
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case CODEC_ID_PCM_U16BE: |
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sample_size = 2; |
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break; |
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default: |
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sample_size = 1; |
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break; |
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} |
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n = buf_size / sample_size; |
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samples = data; |
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dst = frame; |
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switch(avctx->codec->id) { |
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case CODEC_ID_PCM_S16LE: |
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for(;n>0;n--) { |
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v = *samples++; |
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dst[0] = v & 0xff; |
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dst[1] = v >> 8; |
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dst += 2; |
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} |
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break; |
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case CODEC_ID_PCM_S16BE: |
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for(;n>0;n--) { |
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v = *samples++; |
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dst[0] = v >> 8; |
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dst[1] = v; |
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dst += 2; |
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} |
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break; |
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case CODEC_ID_PCM_U16LE: |
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for(;n>0;n--) { |
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v = *samples++; |
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v += 0x8000; |
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dst[0] = v & 0xff; |
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dst[1] = v >> 8; |
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dst += 2; |
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} |
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break; |
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case CODEC_ID_PCM_U16BE: |
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for(;n>0;n--) { |
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v = *samples++; |
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v += 0x8000; |
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dst[0] = v >> 8; |
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dst[1] = v; |
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dst += 2; |
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} |
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break; |
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case CODEC_ID_PCM_S8: |
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for(;n>0;n--) { |
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v = *samples++; |
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dst[0] = (v + 128) >> 8; |
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dst++; |
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} |
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break; |
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case CODEC_ID_PCM_U8: |
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for(;n>0;n--) { |
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v = *samples++; |
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dst[0] = ((v + 128) >> 8) + 128; |
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dst++; |
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} |
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break; |
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case CODEC_ID_PCM_ALAW: |
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for(;n>0;n--) { |
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v = *samples++; |
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dst[0] = linear_to_alaw[(v + 32768) >> 2]; |
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dst++; |
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} |
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break; |
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case CODEC_ID_PCM_MULAW: |
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for(;n>0;n--) { |
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v = *samples++; |
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dst[0] = linear_to_ulaw[(v + 32768) >> 2]; |
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dst++; |
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} |
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break; |
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default: |
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return -1; |
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} |
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return dst - frame; |
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} |
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typedef struct PCMDecode { |
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short table[256]; |
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} PCMDecode; |
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static int decode_init(AVCodecContext * avctx) |
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{ |
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PCMDecode *s = avctx->priv_data; |
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int i; |
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switch(avctx->codec->id) { |
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case CODEC_ID_PCM_ALAW: |
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for(i=0;i<256;i++) |
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s->table[i] = alaw2linear(i); |
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break; |
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case CODEC_ID_PCM_MULAW: |
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for(i=0;i<256;i++) |
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s->table[i] = ulaw2linear(i); |
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break; |
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default: |
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break; |
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} |
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return 0; |
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} |
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static int decode_frame(AVCodecContext *avctx,
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void *data, int *data_size, |
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UINT8 *buf, int buf_size) |
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{ |
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PCMDecode *s = avctx->priv_data; |
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int n; |
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short *samples; |
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UINT8 *src; |
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samples = data; |
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src = buf; |
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switch(avctx->codec->id) { |
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case CODEC_ID_PCM_S16LE: |
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n = buf_size >> 1; |
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for(;n>0;n--) { |
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*samples++ = src[0] | (src[1] << 8); |
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src += 2; |
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} |
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break; |
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case CODEC_ID_PCM_S16BE: |
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n = buf_size >> 1; |
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for(;n>0;n--) { |
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*samples++ = (src[0] << 8) | src[1]; |
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src += 2; |
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} |
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break; |
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case CODEC_ID_PCM_U16LE: |
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n = buf_size >> 1; |
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for(;n>0;n--) { |
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*samples++ = (src[0] | (src[1] << 8)) - 0x8000; |
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src += 2; |
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} |
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break; |
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case CODEC_ID_PCM_U16BE: |
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n = buf_size >> 1; |
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for(;n>0;n--) { |
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*samples++ = ((src[0] << 8) | src[1]) - 0x8000; |
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src += 2; |
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} |
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break; |
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case CODEC_ID_PCM_S8: |
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n = buf_size; |
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for(;n>0;n--) { |
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*samples++ = src[0] << 8; |
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src++; |
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} |
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break; |
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case CODEC_ID_PCM_U8: |
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n = buf_size; |
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for(;n>0;n--) { |
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*samples++ = ((int)src[0] - 128) << 8; |
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src++; |
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} |
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break; |
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case CODEC_ID_PCM_ALAW: |
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case CODEC_ID_PCM_MULAW: |
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n = buf_size; |
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for(;n>0;n--) { |
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*samples++ = s->table[src[0]]; |
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src++; |
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} |
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break; |
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default: |
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*data_size = 0; |
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return -1; |
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} |
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*data_size = (UINT8 *)samples - (UINT8 *)data; |
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return src - buf; |
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} |
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#define PCM_CODEC(id, name) \ |
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AVCodec name ## _encoder = { \
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#name, \ |
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CODEC_TYPE_AUDIO, \
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id, \
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0, \
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encode_init, \
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encode_frame, \
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encode_close, \
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NULL, \
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}; \
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AVCodec name ## _decoder = { \
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#name, \ |
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CODEC_TYPE_AUDIO, \
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id, \
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sizeof(PCMDecode), \
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decode_init, \
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NULL, \
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NULL, \
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decode_frame, \
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}; |
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PCM_CODEC(CODEC_ID_PCM_S16LE, pcm_s16le); |
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PCM_CODEC(CODEC_ID_PCM_S16BE, pcm_s16be); |
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PCM_CODEC(CODEC_ID_PCM_U16LE, pcm_u16le); |
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PCM_CODEC(CODEC_ID_PCM_U16BE, pcm_u16be); |
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PCM_CODEC(CODEC_ID_PCM_S8, pcm_s8); |
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PCM_CODEC(CODEC_ID_PCM_U8, pcm_u8); |
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PCM_CODEC(CODEC_ID_PCM_ALAW, pcm_alaw); |
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PCM_CODEC(CODEC_ID_PCM_MULAW, pcm_mulaw); |
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