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avcodec/atrac3: Don't use too big VLC tables

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The longest code of any of the VLC tables used is eight bits long, so
using nine bits long VLC tables is wasteful. Furthermore, there are only
seven VLC tables used, yet the code up until now made it look like there
should be eight. This has been corrected, too.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-10-23 11:33:34 +02:00
parent 718e862da3
commit e4eeb851fd
2 changed files with 8 additions and 9 deletions
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13
libavcodec/atrac3.c
View file

@ -58,6 +58,8 @@
#define SAMPLES_PER_FRAME 1024
#define MDCT_SIZE 512
#define ATRAC3_VLC_BITS 8
typedef struct GainBlock {
AtracGainInfo g_block[4];
} GainBlock;
@ -116,7 +118,7 @@ typedef struct ATRAC3Context {
} ATRAC3Context;
static DECLARE_ALIGNED(32, float, mdct_window)[MDCT_SIZE];
static VLC_TYPE atrac3_vlc_table[4096][2];
static VLC_TYPE atrac3_vlc_table[7 * 1 << ATRAC3_VLC_BITS][2];
static VLC spectral_coeff_tab[7];
/**
@ -851,6 +853,7 @@ static int atrac3al_decode_frame(AVCodecContext *avctx, void *data,
static av_cold void atrac3_init_static_data(void)
{
VLC_TYPE (*table)[2] = atrac3_vlc_table;
int i;
init_imdct_window();
@ -858,12 +861,12 @@ static av_cold void atrac3_init_static_data(void)
/* Initialize the VLC tables. */
for (i = 0; i < 7; i++) {
spectral_coeff_tab[i].table = &atrac3_vlc_table[atrac3_vlc_offs[i]];
spectral_coeff_tab[i].table_allocated = atrac3_vlc_offs[i + 1] -
atrac3_vlc_offs[i ];
init_vlc(&spectral_coeff_tab[i], 9, huff_tab_sizes[i],
spectral_coeff_tab[i].table = table;
spectral_coeff_tab[i].table_allocated = 256;
init_vlc(&spectral_coeff_tab[i], ATRAC3_VLC_BITS, huff_tab_sizes[i],
huff_bits[i], 1, 1,
huff_codes[i], 1, 1, INIT_VLC_USE_NEW_STATIC);
table += 256;
}
}

4
libavcodec/atrac3data.h
View file

@ -103,10 +103,6 @@ static const uint8_t* const huff_bits[7] = {
huffbits1, huffbits2, huffbits3, huffbits4, huffbits5, huffbits6, huffbits7,
};
static const uint16_t atrac3_vlc_offs[9] = {
0, 512, 1024, 1536, 2048, 2560, 3072, 3584, 4096
};
/* selector tables */
static const uint8_t clc_length_tab[8] = { 0, 4, 3, 3, 4, 4, 5, 6 };