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368 lines
9.2 KiB
C
368 lines
9.2 KiB
C
/*
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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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