diff options
| -rw-r--r-- | libavcodec/vp3.c | 51 |
1 files changed, 22 insertions, 29 deletions
diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c index e669332740..5f871bce92 100644 --- a/libavcodec/vp3.c +++ b/libavcodec/vp3.c @@ -452,8 +452,7 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb) int bit = 0; int current_superblock = 0; int current_run = 0; - int decode_fully_flags = 0; - int decode_partial_blocks = 0; + int num_partial_superblocks = 0; int first_c_fragment_seen; int i, j; @@ -480,52 +479,46 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb) memset(s->superblock_coding + current_superblock, bit, current_run); current_superblock += current_run; - - /* if any of the superblocks are not partially coded, flag - * a boolean to decode the list of fully-coded superblocks */ - if (bit == 0) { - decode_fully_flags = 1; - } else { - - /* make a note of the fact that there are partially coded - * superblocks */ - decode_partial_blocks = 1; - } + if (bit) + num_partial_superblocks += current_run; bit ^= 1; } /* unpack the list of fully coded superblocks if any of the blocks were * not marked as partially coded in the previous step */ - if (decode_fully_flags) { + if (num_partial_superblocks < s->superblock_count) { + int superblocks_decoded = 0; current_superblock = 0; - current_run = 0; bit = get_bits1(gb); - /* toggle the bit because as soon as the first run length is - * fetched the bit will be toggled again */ - bit ^= 1; - while (current_superblock < s->superblock_count) { - - /* skip any superblocks already marked as partially coded */ - if (s->superblock_coding[current_superblock] == SB_NOT_CODED) { - - if (current_run-- == 0) { - bit ^= 1; + while (superblocks_decoded < s->superblock_count - num_partial_superblocks) { current_run = get_vlc2(gb, - s->superblock_run_length_vlc.table, 6, 2); - if (current_run == 33) + s->superblock_run_length_vlc.table, 6, 2) + 1; + if (current_run == 34) current_run += get_bits(gb, 12); + + for (j = 0; j < current_run; current_superblock++) { + if (current_superblock >= s->superblock_count) { + av_log(s->avctx, AV_LOG_ERROR, "Invalid fully coded superblock run length\n"); + return -1; } + + /* skip any superblocks already marked as partially coded */ + if (s->superblock_coding[current_superblock] == SB_NOT_CODED) { s->superblock_coding[current_superblock] = 2*bit; + j++; } - current_superblock++; + } + superblocks_decoded += current_run; + + bit ^= 1; } } /* if there were partial blocks, initialize bitstream for * unpacking fragment codings */ - if (decode_partial_blocks) { + if (num_partial_superblocks) { current_run = 0; bit = get_bits1(gb); |