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145 lines
4.0 KiB
C
145 lines
4.0 KiB
C
/*
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* Westwood SNDx codecs
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* Copyright (c) 2005 Konstantin Shishkov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avcodec.h"
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/**
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* @file ws-snd.c
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* Westwood SNDx codecs.
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*
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* Reference documents about VQA format and its audio codecs
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* can be found here:
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* http://www.multimedia.cx
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*/
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static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
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static const char ws_adpcm_4bit[] = {
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-9, -8, -6, -5, -4, -3, -2, -1,
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0, 1, 2, 3, 4, 5, 6, 8 };
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#define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128;
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static int ws_snd_decode_init(AVCodecContext * avctx)
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{
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// WSSNDContext *c = avctx->priv_data;
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return 0;
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}
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static int ws_snd_decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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uint8_t *buf, int buf_size)
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{
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// WSSNDContext *c = avctx->priv_data;
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int in_size, out_size;
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int sample = 0;
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int i;
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short *samples = data;
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if (!buf_size)
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return 0;
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out_size = AV_RL16(&buf[0]);
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*data_size = out_size * 2;
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in_size = AV_RL16(&buf[2]);
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buf += 4;
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if (in_size == out_size) {
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for (i = 0; i < out_size; i++)
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*samples++ = (*buf++ - 0x80) << 8;
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return buf_size;
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}
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while (out_size > 0) {
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int code;
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uint8_t count;
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code = (*buf) >> 6;
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count = (*buf) & 0x3F;
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buf++;
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switch(code) {
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case 0: /* ADPCM 2-bit */
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for (count++; count > 0; count--) {
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code = *buf++;
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sample += ws_adpcm_2bit[code & 0x3];
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CLIP8(sample);
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*samples++ = sample << 8;
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sample += ws_adpcm_2bit[(code >> 2) & 0x3];
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CLIP8(sample);
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*samples++ = sample << 8;
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sample += ws_adpcm_2bit[(code >> 4) & 0x3];
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CLIP8(sample);
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*samples++ = sample << 8;
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sample += ws_adpcm_2bit[(code >> 6) & 0x3];
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CLIP8(sample);
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*samples++ = sample << 8;
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out_size -= 4;
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}
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break;
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case 1: /* ADPCM 4-bit */
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for (count++; count > 0; count--) {
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code = *buf++;
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sample += ws_adpcm_4bit[code & 0xF];
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CLIP8(sample);
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*samples++ = sample << 8;
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sample += ws_adpcm_4bit[code >> 4];
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CLIP8(sample);
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*samples++ = sample << 8;
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out_size -= 2;
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}
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break;
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case 2: /* no compression */
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if (count & 0x20) { /* big delta */
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char t;
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t = count;
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t <<= 3;
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sample += t >> 3;
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*samples++ = sample << 8;
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out_size--;
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} else { /* copy */
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for (count++; count > 0; count--) {
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*samples++ = (*buf++ - 0x80) << 8;
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out_size--;
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}
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sample = buf[-1] - 0x80;
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}
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break;
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default: /* run */
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for(count++; count > 0; count--) {
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*samples++ = sample << 8;
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out_size--;
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}
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}
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}
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return buf_size;
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}
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AVCodec ws_snd1_decoder = {
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"ws_snd1",
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CODEC_TYPE_AUDIO,
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CODEC_ID_WESTWOOD_SND1,
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0,
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ws_snd_decode_init,
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NULL,
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NULL,
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ws_snd_decode_frame,
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};
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