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* fixed IMA WAV decoding (though still might not be fully correct)

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* const arrays

Originally committed as revision 1601 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Zdenek Kabelac 2003-02-24 13:26:41 +00:00
parent 676b385c5b
commit 135ee03aae
1 changed files with 23 additions and 27 deletions
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50
libavcodec/adpcm.c
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@ -42,7 +42,7 @@ else if (value < -32768) \
/* step_table[] and index_table[] are from the ADPCM reference source */
/* This is the index table: */
static int index_table[16] = {
static const int index_table[16] = {
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8,
};
@ -50,7 +50,7 @@ static int index_table[16] = {
/* This is the step table. Note that many programs use slight deviations from
* this table, but such deviations are negligible:
*/
static int step_table[89] = {
static const int step_table[89] = {
7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
@ -64,16 +64,16 @@ static int step_table[89] = {
/* Those are for MS-ADPCM */
/* AdaptationTable[], AdaptCoeff1[], and AdaptCoeff2[] are from libsndfile */
static int AdaptationTable[] = {
static const int AdaptationTable[] = {
230, 230, 230, 230, 307, 409, 512, 614,
768, 614, 512, 409, 307, 230, 230, 230
};
static int AdaptCoeff1[] = {
static const int AdaptCoeff1[] = {
256, 512, 0, 192, 240, 460, 392
};
static int AdaptCoeff2[] = {
static const int AdaptCoeff2[] = {
0, -256, 0, 64, 0, -208, -232
};
@ -283,31 +283,29 @@ static inline short adpcm_ima_expand_nibble(ADPCMChannelStatus *c, char nibble)
int predictor;
int sign, delta, diff, step;
predictor = c->predictor;
step = step_table[c->step_index];
step_index = c->step_index + index_table[(unsigned)nibble];
if (step_index < 0) step_index = 0;
if (step_index > 88) step_index = 88;
else if (step_index > 88) step_index = 88;
step = c->step;
/*
diff = ((signed)((nibble & 0x08)?(nibble | 0xF0):(nibble)) + 0.5) * step / 4;
predictor += diff;
*/
sign = nibble & 8;
delta = nibble & 7;
#if 0
diff = step >> 3;
if (delta & 4) diff += step;
if (delta & 2) diff += step >> 1;
if (delta & 1) diff += step >> 2;
#else
diff = ((2 * delta + 1) * step) >> 3; // no jumps
#endif
predictor = c->predictor;
if (sign) predictor -= diff;
else predictor += diff;
CLAMP_TO_SHORT(predictor);
c->predictor = predictor;
c->step_index = step_index;
c->step = step_table[step_index];
return (short)predictor;
}
@ -398,7 +396,7 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
else
buf_size = BLKSIZE;
}
n = buf_size - 4 * avctx->channels;
// XXX: do as per-channel loop
cs = &(c->status[0]);
cs->predictor = (*src++) & 0x0FF;
cs->predictor |= ((*src++) << 8) & 0x0FF00;
@ -406,9 +404,9 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
cs->predictor -= 0x10000;
CLAMP_TO_SHORT(cs->predictor);
*samples++ = cs->predictor;
// XXX: is this correct ??: *samples++ = cs->predictor;
cs->step_index = *src++;
cs->step_index = *src++;
if (cs->step_index < 0) cs->step_index = 0;
if (cs->step_index > 88) cs->step_index = 88;
if (*src++) fprintf(stderr, "unused byte should be null !!\n"); /* unused */
@ -421,29 +419,27 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
cs->predictor -= 0x10000;
CLAMP_TO_SHORT(cs->predictor);
*samples++ = cs->predictor;
// XXX: is this correct ??: *samples++ = cs->predictor;
cs->step_index = *src++;
cs->step_index = *src++;
if (cs->step_index < 0) cs->step_index = 0;
if (cs->step_index > 88) cs->step_index = 88;
src++; /* unused */
src++; /* if != 0 -> out-of-sync */
}
cs = &(c->status[0]);
for(m=3; n>0; n--, m--) {
for(m=3; src < (buf + buf_size);) {
*samples++ = adpcm_ima_expand_nibble(&c->status[0], src[0] & 0x0F);
if (st)
*samples++ = adpcm_ima_expand_nibble(&c->status[1], src[4] & 0x0F);
*samples++ = adpcm_ima_expand_nibble(&c->status[0], (src[0] >> 4) & 0x0F);
if (st)
*samples++ = adpcm_ima_expand_nibble(&c->status[1], (src[4] >> 4) & 0x0F);
src ++;
if (st && !m) {
src++;
if (st && !m--) {
m=3;
src+=4;
}
}
}
break;
case CODEC_ID_ADPCM_MS: