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theora: Don't read an excess bit for maximum length long bit runs if the run 

exactly ends the remaining blocks.

Originally committed as revision 23304 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
David Conrad 2010-05-25 03:19:54 +00:00
parent 8299a7f819
commit cc46005f50
1 changed files with 24 additions and 18 deletions
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42
libavcodec/vp3.c
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@ -378,8 +378,15 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
} else {
/* unpack the list of partially-coded superblocks */
bit = get_bits1(gb);
bit = get_bits1(gb) ^ 1;
current_run = 0;
while (current_superblock < s->superblock_count && get_bits_left(gb) > 0) {
if (s->theora && current_run == MAXIMUM_LONG_BIT_RUN)
bit = get_bits1(gb);
else
bit ^= 1;
current_run = get_vlc2(gb,
s->superblock_run_length_vlc.table, 6, 2) + 1;
if (current_run == 34)
@ -395,11 +402,6 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
current_superblock += current_run;
if (bit)
num_partial_superblocks += current_run;
if (s->theora && current_run == MAXIMUM_LONG_BIT_RUN)
bit = get_bits1(gb);
else
bit ^= 1;
}
/* unpack the list of fully coded superblocks if any of the blocks were
@ -408,9 +410,17 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
int superblocks_decoded = 0;
current_superblock = 0;
bit = get_bits1(gb);
bit = get_bits1(gb) ^ 1;
current_run = 0;
while (superblocks_decoded < s->superblock_count - num_partial_superblocks
&& get_bits_left(gb) > 0) {
if (s->theora && current_run == MAXIMUM_LONG_BIT_RUN)
bit = get_bits1(gb);
else
bit ^= 1;
current_run = get_vlc2(gb,
s->superblock_run_length_vlc.table, 6, 2) + 1;
if (current_run == 34)
@ -429,11 +439,6 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
}
}
superblocks_decoded += current_run;
if (s->theora && current_run == MAXIMUM_LONG_BIT_RUN)
bit = get_bits1(gb);
else
bit ^= 1;
}
}
@ -800,9 +805,15 @@ static int unpack_block_qpis(Vp3DecodeContext *s, GetBitContext *gb)
for (qpi = 0; qpi < s->nqps-1 && num_blocks > 0; qpi++) {
i = blocks_decoded = num_blocks_at_qpi = 0;
bit = get_bits1(gb);
bit = get_bits1(gb) ^ 1;
run_length = 0;
do {
if (run_length == MAXIMUM_LONG_BIT_RUN)
bit = get_bits1(gb);
else
bit ^= 1;
run_length = get_vlc2(gb, s->superblock_run_length_vlc.table, 6, 2) + 1;
if (run_length == 34)
run_length += get_bits(gb, 12);
@ -820,11 +831,6 @@ static int unpack_block_qpis(Vp3DecodeContext *s, GetBitContext *gb)
j++;
}
}
if (run_length == MAXIMUM_LONG_BIT_RUN)
bit = get_bits1(gb);
else
bit ^= 1;
} while (blocks_decoded < num_blocks && get_bits_left(gb) > 0);
num_blocks -= num_blocks_at_qpi;