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Factorize some code into functions, had this in my tree and will be

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needed for mp3 encoding.

Originally committed as revision 11509 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2008-01-11 21:34:05 +00:00
parent 762f804c9e
commit 9f7458b285
1 changed files with 67 additions and 53 deletions
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120
libavcodec/mpegaudiodec.c
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@ -126,6 +126,68 @@ static const int32_t scale_factor_mult2[3][3] = {
static DECLARE_ALIGNED_16(MPA_INT, window[512]);
/**
* Convert region offsets to region sizes and truncate
* size to big_values.
*/
void ff_region_offset2size(GranuleDef *g){
int i, k, j=0;
g->region_size[2] = (576 / 2);
for(i=0;i<3;i++) {
k = FFMIN(g->region_size[i], g->big_values);
g->region_size[i] = k - j;
j = k;
}
}
void ff_init_short_region(MPADecodeContext *s, GranuleDef *g){
if (g->block_type == 2)
g->region_size[0] = (36 / 2);
else {
if (s->sample_rate_index <= 2)
g->region_size[0] = (36 / 2);
else if (s->sample_rate_index != 8)
g->region_size[0] = (54 / 2);
else
g->region_size[0] = (108 / 2);
}
g->region_size[1] = (576 / 2);
}
void ff_init_long_region(MPADecodeContext *s, GranuleDef *g, int ra1, int ra2){
int l;
g->region_size[0] =
band_index_long[s->sample_rate_index][ra1 + 1] >> 1;
/* should not overflow */
l = FFMIN(ra1 + ra2 + 2, 22);
g->region_size[1] =
band_index_long[s->sample_rate_index][l] >> 1;
}
void ff_compute_band_indexes(MPADecodeContext *s, GranuleDef *g){
if (g->block_type == 2) {
if (g->switch_point) {
/* if switched mode, we handle the 36 first samples as
long blocks. For 8000Hz, we handle the 48 first
exponents as long blocks (XXX: check this!) */
if (s->sample_rate_index <= 2)
g->long_end = 8;
else if (s->sample_rate_index != 8)
g->long_end = 6;
else
g->long_end = 4; /* 8000 Hz */
g->short_start = 2 + (s->sample_rate_index != 8);
} else {
g->long_end = 0;
g->short_start = 0;
}
} else {
g->short_start = 13;
g->long_end = 22;
}
}
/* layer 1 unscaling */
/* n = number of bits of the mantissa minus 1 */
static inline int l1_unscale(int n, int mant, int scale_factor)
@ -2008,20 +2070,9 @@ static int mp_decode_layer3(MPADecodeContext *s)
g->table_select[i] = get_bits(&s->gb, 5);
for(i=0;i<3;i++)
g->subblock_gain[i] = get_bits(&s->gb, 3);
/* compute huffman coded region sizes */
if (g->block_type == 2)
g->region_size[0] = (36 / 2);
else {
if (s->sample_rate_index <= 2)
g->region_size[0] = (36 / 2);
else if (s->sample_rate_index != 8)
g->region_size[0] = (54 / 2);
else
g->region_size[0] = (108 / 2);
}
g->region_size[1] = (576 / 2);
ff_init_short_region(s, g);
} else {
int region_address1, region_address2, l;
int region_address1, region_address2;
g->block_type = 0;
g->switch_point = 0;
for(i=0;i<3;i++)
@ -2031,47 +2082,10 @@ static int mp_decode_layer3(MPADecodeContext *s)
region_address2 = get_bits(&s->gb, 3);
dprintf(s->avctx, "region1=%d region2=%d\n",
region_address1, region_address2);
g->region_size[0] =
band_index_long[s->sample_rate_index][region_address1 + 1] >> 1;
l = region_address1 + region_address2 + 2;
/* should not overflow */
if (l > 22)
l = 22;
g->region_size[1] =
band_index_long[s->sample_rate_index][l] >> 1;
}
/* convert region offsets to region sizes and truncate
size to big_values */
g->region_size[2] = (576 / 2);
j = 0;
for(i=0;i<3;i++) {
k = FFMIN(g->region_size[i], g->big_values);
g->region_size[i] = k - j;
j = k;
}
/* compute band indexes */
if (g->block_type == 2) {
if (g->switch_point) {
/* if switched mode, we handle the 36 first samples as
long blocks. For 8000Hz, we handle the 48 first
exponents as long blocks (XXX: check this!) */
if (s->sample_rate_index <= 2)
g->long_end = 8;
else if (s->sample_rate_index != 8)
g->long_end = 6;
else
g->long_end = 4; /* 8000 Hz */
g->short_start = 2 + (s->sample_rate_index != 8);
} else {
g->long_end = 0;
g->short_start = 0;
}
} else {
g->short_start = 13;
g->long_end = 22;
ff_init_long_region(s, g, region_address1, region_address2);
}
ff_region_offset2size(g);
ff_compute_band_indexes(s, g);
g->preflag = 0;
if (!s->lsf)