this should be part of adpcm.c

Originally committed as revision 2383 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/xa.c

-/*
- * CD-ROM XA ADPCM codecs
- * Copyright (c) 1999,2003 BERO
- *
- * This library 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 of the License, or (at your option) any later version.
- *
- * This library 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 this library; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- */
-#include "avcodec.h"
-
-/**
- * @file xa.c
- * CD-ROM XA ADPCM codecs.
- *
- * Reference documents:
- * http://ku-www.ss.titech.ac.jp/~yatsushi/xaadpcm.html
- * vagpack & depack http://homepages.compuserve.de/bITmASTER32/psx-index.html
- * readstr http://www.geocities.co.jp/Playtown/2004/
- */
-
-typedef struct {
-	int s1,s2;
-} PREV;
-
-typedef struct {
-	PREV prev[2];
-} XAContext;
-
-#define	CLIP(s)		if (s<-32768) s=-32768; else if (s>32767) s=32767
-
-static void xa_decode(short *out,const unsigned char *in,PREV *prev,int inc)
-{
-	const static int f[5][2] = {
-		{0,0},
-		{60,0},
-		{115,-52},
-		{98,-55},
-		{122,-60}
-	};
-
-	int i,j;
-
-  for(i=0;i<4;i++) {
-	int shift,filter,f0,f1;
-	int s_1,s_2;
-
-	shift  = 12 - (in[4+i*2] & 15);
-	filter = in[4+i*2] >> 4;
-	f0 = f[filter][0];
-	f1 = f[filter][1];
-
-	s_1 = prev->s1;
-	s_2 = prev->s2;
-
-	for(j=0;j<28;j++) {
-		int d,s,t;
-		d = in[16+i+j*4];
-
-		//t = d&0xf;
-		//if (t>=8) t-=16;
-		t = (signed char)(d<<4)>>4;
-		s = ( t<<shift ) + ((s_1*f0 + s_2*f1+32)>>6);
-		CLIP(s);
-		*out = s;
-		out += inc;
-		s_2 = s_1;
-		s_1 = s;
-	}
-
-	if (inc==2) { /* stereo */
-		prev->s1 = s_1;
-		prev->s2 = s_2;
-		s_1 = prev[1].s1;
-		s_2 = prev[1].s2;
-		out = out + 1 - 28*2;
-	}
-
-	shift  = 12 - (in[5+i*2] & 15);
-	filter = in[5+i*2] >> 4;
-	f0 = f[filter][0];
-	f1 = f[filter][1];
-
-	for(j=0;j<28;j++) {
-		int d,s,t;
-		d = in[16+i+j*4];
-
-		//t = d>>4;
-		//if (t>=8) t-=16;
-		t = (signed char)d >> 4;
-		s = ( t<<shift ) + ((s_1*f0 + s_2*f1+32)>>6);
-		CLIP(s);
-		*out = s;
-		out += inc;
-		s_2 = s_1;
-		s_1 = s;
-	}
-
-	if (inc==2) { /* stereo */
-		prev[1].s1 = s_1;
-		prev[1].s2 = s_2;
-		out -= 1;
-	} else {
-		prev[0].s1 = s_1;
-		prev[0].s2 = s_2;
-	}
-
-  }
-
-}
-
-static int xa_decode_init(AVCodecContext * avctx)
-{
-	XAContext *c = avctx->priv_data;
-
-	printf("xa init %d\n",avctx->channels);
-
-	c->prev[0].s1 = 0;
-	c->prev[0].s2 = 0;
-	c->prev[1].s1 = 0;
-	c->prev[1].s2 = 0;
-	switch(avctx->channels) {
-	case 1:
-	case 2:
-		return 0;
-	default:
-		return -1;
-	}
-}
-
-static int xa_decode_frame(AVCodecContext *avctx,
-			    void *data, int *data_size,
-			    const uint8_t *buf0, int buf_size)
-{
-	XAContext *c = avctx->priv_data;
-	short *samples = data;
-	const uint8_t *buf = buf0;
-
-//	printf("xa decode %d\n",buf_size);
-
-	c->prev[0].s1 = 0;
-	c->prev[0].s2 = 0;
-	c->prev[1].s1 = 0;
-	c->prev[1].s2 = 0;
-
-	while(buf_size>=128) {
-		xa_decode(samples,buf,c->prev,avctx->channels);
-		buf+=128;
-		samples += 28*8;
-		buf_size-=128;
-	}
-	*data_size = (char*)samples - (char*)data;
-	return buf-buf0;
-}
-
-#define DEFINE_ENCODER(id, name,context)                \
-AVCodec name ## _encoder = {                    \
-    #name,                                      \
-    CODEC_TYPE_AUDIO,                           \
-    id,                                         \
-    sizeof(context),                       \
-    name ## _encode_init,                       \
-    name ## _encode_frame,                      \
-    name ## _encode_close,                      \
-    NULL,                                       \
-};
-
-#define DEFINE_DECODER(id, name,context)                \
-AVCodec name ## _decoder = {                    \
-    #name,                                      \
-    CODEC_TYPE_AUDIO,                           \
-    id,                                         \
-    sizeof(context),                       \
-    name ## _decode_init,                       \
-    NULL,                                       \
-    NULL,                                       \
-    name ## _decode_frame,                      \
-};
-
-DEFINE_DECODER(CODEC_ID_ADPCM_XA,xa,XAContext)