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Reduce stack memory allocation in MP3 decoder 

Originally committed as revision 20451 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Vitor Sessak 2009-11-04 23:33:08 +00:00
parent 0c50f8e6cc
commit c902340599
2 changed files with 28 additions and 29 deletions
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21
libavcodec/mpegaudio.h
View File

@ -88,7 +88,25 @@ typedef int32_t MPA_INT;
#define BACKSTEP_SIZE 512
#define EXTRABYTES 24
struct GranuleDef;
/* layer 3 "granule" */
typedef struct GranuleDef {
uint8_t scfsi;
int part2_3_length;
int big_values;
int global_gain;
int scalefac_compress;
uint8_t block_type;
uint8_t switch_point;
int table_select[3];
int subblock_gain[3];
uint8_t scalefac_scale;
uint8_t count1table_select;
int region_size[3]; /* number of huffman codes in each region */
int preflag;
int short_start, long_end; /* long/short band indexes */
uint8_t scale_factors[40];
int32_t sb_hybrid[SBLIMIT * 18]; /* 576 samples */
} GranuleDef;
#define MPA_DECODE_HEADER \
int frame_size; \
@ -118,6 +136,7 @@ typedef struct MPADecodeContext {
int synth_buf_offset[MPA_MAX_CHANNELS];
DECLARE_ALIGNED_16(int32_t, sb_samples[MPA_MAX_CHANNELS][36][SBLIMIT]);
int32_t mdct_buf[MPA_MAX_CHANNELS][SBLIMIT * 18]; /* previous samples, for layer 3 MDCT */
GranuleDef granules[2][2]; /* Used in Layer 3 */
#ifdef DEBUG
int frame_count;
#endif

36
libavcodec/mpegaudiodec.c
View File

@ -49,26 +49,6 @@
#define HEADER_SIZE 4
/* layer 3 "granule" */
typedef struct GranuleDef {
uint8_t scfsi;
int part2_3_length;
int big_values;
int global_gain;
int scalefac_compress;
uint8_t block_type;
uint8_t switch_point;
int table_select[3];
int subblock_gain[3];
uint8_t scalefac_scale;
uint8_t count1table_select;
int region_size[3]; /* number of huffman codes in each region */
int preflag;
int short_start, long_end; /* long/short band indexes */
uint8_t scale_factors[40];
int32_t sb_hybrid[SBLIMIT * 18]; /* 576 samples */
} GranuleDef;
#include "mpegaudiodata.h"
#include "mpegaudiodectab.h"
@ -1912,7 +1892,7 @@ static int mp_decode_layer3(MPADecodeContext *s)
{
int nb_granules, main_data_begin, private_bits;
int gr, ch, blocksplit_flag, i, j, k, n, bits_pos;
GranuleDef granules[2][2], *g;
GranuleDef *g;
int16_t exponents[576];
/* read side info */
@ -1928,15 +1908,15 @@ static int mp_decode_layer3(MPADecodeContext *s)
private_bits = get_bits(&s->gb, 5);
nb_granules = 2;
for(ch=0;ch<s->nb_channels;ch++) {
granules[ch][0].scfsi = 0; /* all scale factors are transmitted */
granules[ch][1].scfsi = get_bits(&s->gb, 4);
s->granules[ch][0].scfsi = 0;/* all scale factors are transmitted */
s->granules[ch][1].scfsi = get_bits(&s->gb, 4);
}
}
for(gr=0;gr<nb_granules;gr++) {
for(ch=0;ch<s->nb_channels;ch++) {
dprintf(s->avctx, "gr=%d ch=%d: side_info\n", gr, ch);
g = &granules[ch][gr];
g = &s->granules[ch][gr];
g->part2_3_length = get_bits(&s->gb, 12);
g->big_values = get_bits(&s->gb, 9);
if(g->big_values > 288){
@ -2008,7 +1988,7 @@ static int mp_decode_layer3(MPADecodeContext *s)
for(gr=0;gr<nb_granules;gr++) {
for(ch=0;ch<s->nb_channels;ch++) {
g = &granules[ch][gr];
g = &s->granules[ch][gr];
if(get_bits_count(&s->gb)<0){
av_log(s->avctx, AV_LOG_DEBUG, "mdb:%d, lastbuf:%d skipping granule %d\n",
main_data_begin, s->last_buf_size, gr);
@ -2052,7 +2032,7 @@ static int mp_decode_layer3(MPADecodeContext *s)
g->scale_factors[j++] = 0;
}
} else {
sc = granules[ch][0].scale_factors;
sc = s->granules[ch][0].scale_factors;
j = 0;
for(k=0;k<4;k++) {
n = (k == 0 ? 6 : 5);
@ -2137,10 +2117,10 @@ static int mp_decode_layer3(MPADecodeContext *s)
} /* ch */
if (s->nb_channels == 2)
compute_stereo(s, &granules[0][gr], &granules[1][gr]);
compute_stereo(s, &s->granules[0][gr], &s->granules[1][gr]);
for(ch=0;ch<s->nb_channels;ch++) {
g = &granules[ch][gr];
g = &s->granules[ch][gr];
reorder_block(s, g);
s->compute_antialias(s, g);