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replace get_superblock_run_length() with a VLC table 

Originally committed as revision 4267 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Mike Melanson 2005-05-18 00:11:49 +00:00
parent 0ad72bdd5c
commit d8278bab79
2 changed files with 39 additions and 0 deletions
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18
libavcodec/vp3.c
View File

@ -1182,7 +1182,14 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
while (current_superblock < s->superblock_count) {
if (current_run == 0) {
bit ^= 1;
#if 1
current_run = get_vlc2(gb,
s->superblock_run_length_vlc.table, 6, 2) + 1;
if (current_run == 34)
current_run += get_bits(gb, 12);
#else
current_run = get_superblock_run_length(gb);
#endif
debug_block_coding(" setting superblocks %d..%d to %s\n",
current_superblock,
current_superblock + current_run - 1,
@ -1221,7 +1228,14 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
if (current_run == 0) {
bit ^= 1;
#if 1
current_run = get_vlc2(gb,
s->superblock_run_length_vlc.table, 6, 2) + 1;
if (current_run == 34)
current_run += get_bits(gb, 12);
#else
current_run = get_superblock_run_length(gb);
#endif
}
debug_block_coding(" setting superblock %d to %s\n",
@ -2630,6 +2644,10 @@ static int vp3_decode_init(AVCodecContext *avctx)
&ac_bias_3[i][0][0], 4, 2, 0);
}
init_vlc(&s->superblock_run_length_vlc, 6, 34,
&superblock_run_length_vlc_table[0][1], 4, 2,
&superblock_run_length_vlc_table[0][0], 4, 2, 0);
init_vlc(&s->fragment_run_length_vlc, 5, 31,
&fragment_run_length_vlc_table[0][1], 4, 2,
&fragment_run_length_vlc_table[0][0], 4, 2, 0);

21
libavcodec/vp3data.h
View File

@ -72,6 +72,27 @@ static const uint32_t vp31_filter_limit_values[64] =
0, 0, 0, 0, 0, 0, 0, 0
};
static const uint16_t superblock_run_length_vlc_table[34][2] = {
{ 0, 1 },
{ 4, 3 }, { 5, 3 },
{ 0xC, 4 }, { 0xD, 4 },
{ 0x38, 6 }, { 0x39, 6 }, { 0x3A, 6 }, { 0x3B, 6 },
{ 0xF0, 8 }, { 0xF1, 8 }, { 0xF2, 8 }, { 0xF3, 8 },
{ 0xF4, 8 }, { 0xF5, 8 }, { 0xF6, 8 }, { 0xF7, 8 },
{ 0x3E0, 10 }, { 0x3E1, 10 }, { 0x3E2, 10 }, { 0x3E3, 10 },
{ 0x3E4, 10 }, { 0x3E5, 10 }, { 0x3E6, 10 }, { 0x3E7, 10 },
{ 0x3E8, 10 }, { 0x3E9, 10 }, { 0x3EA, 10 }, { 0x3EB, 10 },
{ 0x3EC, 10 }, { 0x3ED, 10 }, { 0x3EE, 10 }, { 0x3EF, 10 },
{ 0x3F, 6 } /* this last VLC is a special case for reading 12 more
bits from stream and adding the value 34 */
};
static const uint16_t fragment_run_length_vlc_table[30][2] = {
/* 1 -> 2 */
{ 0x0, 2 }, { 0x1, 2 },