From cc46005f50aff0eecda9f21e8d4bf63868818bdd Mon Sep 17 00:00:00 2001 From: David Conrad Date: Tue, 25 May 2010 03:19:54 +0000 Subject: [PATCH] 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 --- libavcodec/vp3.c | 42 ++++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c index c08de6c..bdad6f8 100644 --- a/libavcodec/vp3.c +++ b/libavcodec/vp3.c @@ -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; -- 2.7.4