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/*
* Westwood SNDx codecs
* Copyright (c) 2005 Konstantin Shishkov
*
* 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
*/
#include "avcodec.h"
/**
* @file ws-snd.c
* Westwood SNDx codecs.
*
* Reference documents about VQA format and its audio codecs
* can be found here:
* http://www.multimedia.cx
*/
static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
static const char ws_adpcm_4bit[] = {
-9, -8, -6, -5, -4, -3, -2, -1,
0, 1, 2, 3, 4, 5, 6, 8 };
#define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128;
static int ws_snd_decode_init(AVCodecContext * avctx)
{
// WSSNDContext *c = avctx->priv_data;
return 0;
}
static int ws_snd_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
uint8_t *buf, int buf_size)
{
// WSSNDContext *c = avctx->priv_data;
int in_size, out_size;
int sample = 0;
int i;
short *samples = data;
if (!buf_size)
return 0;
out_size = AV_RL16(&buf[0]);
*data_size = out_size * 2;
in_size = AV_RL16(&buf[2]);
buf += 4;
if (in_size == out_size) {
for (i = 0; i < out_size; i++)
*samples++ = (*buf++ - 0x80) << 8;
return buf_size;
}
while (out_size > 0) {
int code;
uint8_t count;
code = (*buf) >> 6;
count = (*buf) & 0x3F;
buf++;
switch(code) {
case 0: /* ADPCM 2-bit */
for (count++; count > 0; count--) {
code = *buf++;
sample += ws_adpcm_2bit[code & 0x3];
CLIP8(sample);
*samples++ = sample << 8;
sample += ws_adpcm_2bit[(code >> 2) & 0x3];
CLIP8(sample);
*samples++ = sample << 8;
sample += ws_adpcm_2bit[(code >> 4) & 0x3];
CLIP8(sample);
*samples++ = sample << 8;
sample += ws_adpcm_2bit[(code >> 6) & 0x3];
CLIP8(sample);
*samples++ = sample << 8;
out_size -= 4;
}
break;
case 1: /* ADPCM 4-bit */
for (count++; count > 0; count--) {
code = *buf++;
sample += ws_adpcm_4bit[code & 0xF];
CLIP8(sample);
*samples++ = sample << 8;
sample += ws_adpcm_4bit[code >> 4];
CLIP8(sample);
*samples++ = sample << 8;
out_size -= 2;
}
break;
case 2: /* no compression */
if (count & 0x20) { /* big delta */
char t;
t = count;
t <<= 3;
sample += t >> 3;
*samples++ = sample << 8;
out_size--;
} else { /* copy */
for (count++; count > 0; count--) {
*samples++ = (*buf++ - 0x80) << 8;
out_size--;
}
sample = buf[-1] - 0x80;
}
break;
default: /* run */
for(count++; count > 0; count--) {
*samples++ = sample << 8;
out_size--;
}
}
}
return buf_size;
}
AVCodec ws_snd1_decoder = {
"ws_snd1",
CODEC_TYPE_AUDIO,
CODEC_ID_WESTWOOD_SND1,
0,
ws_snd_decode_init,
NULL,
NULL,
ws_snd_decode_frame,
};
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