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fix subtle logic problem in block unpacker that leads to incorrect token

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decoding which leads to segfaults

Originally committed as revision 1890 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Mike Melanson 2003-05-19 01:22:46 +00:00
parent 6d71b38207
commit 22493ab9cb
1 changed files with 24 additions and 18 deletions
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42
libavcodec/vp3.c
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@ -1132,6 +1132,7 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
int current_run = 0;
int decode_fully_flags = 0;
int decode_partial_blocks = 0;
int first_c_fragment_seen;
int i, j;
int current_fragment;
@ -1223,6 +1224,7 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
s->coded_fragment_list_index = 0;
s->first_coded_y_fragment = s->first_coded_c_fragment = 0;
s->last_coded_y_fragment = s->last_coded_c_fragment = -1;
first_c_fragment_seen = 0;
memset(s->macroblock_coding, MODE_COPY, s->macroblock_count);
for (i = 0; i < s->superblock_count; i++) {
@ -1253,15 +1255,18 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
}
if (bit) {
/* mode will be decoded in the next phase */
/* default mode; actual mode will be decoded in
* the next phase */
s->all_fragments[current_fragment].coding_method =
MODE_INTER_NO_MV;
s->coded_fragment_list[s->coded_fragment_list_index] =
current_fragment;
if ((current_fragment >= s->u_fragment_start) &&
(s->last_coded_y_fragment == -1)) {
(s->last_coded_y_fragment == -1) &&
(!first_c_fragment_seen)) {
s->first_coded_c_fragment = s->coded_fragment_list_index;
s->last_coded_y_fragment = s->first_coded_c_fragment - 1;
first_c_fragment_seen = 1;
}
s->coded_fragment_list_index++;
s->macroblock_coding[s->all_fragments[current_fragment].macroblock] = MODE_INTER_NO_MV;
@ -1286,9 +1291,11 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
s->coded_fragment_list[s->coded_fragment_list_index] =
current_fragment;
if ((current_fragment >= s->u_fragment_start) &&
(s->last_coded_y_fragment == -1)) {
(s->last_coded_y_fragment == -1) &&
(!first_c_fragment_seen)) {
s->first_coded_c_fragment = s->coded_fragment_list_index;
s->last_coded_y_fragment = s->first_coded_c_fragment - 1;
first_c_fragment_seen = 1;
}
s->coded_fragment_list_index++;
s->macroblock_coding[s->all_fragments[current_fragment].macroblock] = MODE_INTER_NO_MV;
@ -1299,11 +1306,13 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
}
}
if (s->first_coded_c_fragment == 0)
/* no C fragments coded */
if (!first_c_fragment_seen)
/* only Y fragments coded in this frame */
s->last_coded_y_fragment = s->coded_fragment_list_index - 1;
else
else
/* end the list of coded fragments */
s->last_coded_c_fragment = s->coded_fragment_list_index - 1;
debug_block_coding(" %d total coded fragments, y: %d -> %d, c: %d -> %d\n",
s->coded_fragment_list_index,
s->first_coded_y_fragment,
@ -1656,14 +1665,12 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
DCTELEM coeff;
Vp3Fragment *fragment;
if ((first_fragment < 0) ||
(first_fragment >= s->fragment_count) ||
(last_fragment < 0) ||
if ((first_fragment >= s->fragment_count) ||
(last_fragment >= s->fragment_count)) {
printf (" vp3:unpack_vlcs(): bad fragment number (%d -> %d ?)\n",
first_fragment, last_fragment);
return 1;
return 0;
}
for (i = first_fragment; i <= last_fragment; i++) {
@ -2433,6 +2440,11 @@ static int vp3_decode_frame(AVCodecContext *avctx,
counter++;
if (s->keyframe) {
debug_vp3(", keyframe\n");
/* skip the other 2 header bytes for now */
skip_bits(&gb, 16);
if (s->last_frame.data[0] == s->golden_frame.data[0]) {
if (s->golden_frame.data[0])
avctx->release_buffer(avctx, &s->golden_frame);
@ -2458,22 +2470,16 @@ static int vp3_decode_frame(AVCodecContext *avctx,
} else {
debug_vp3("\n");
/* allocate a new current frame */
s->current_frame.reference = 0;
if(avctx->get_buffer(avctx, &s->current_frame) < 0) {
printf("vp3: get_buffer() failed\n");
return -1;
}
}
if (s->keyframe) {
debug_vp3(", keyframe\n");
/* skip the other 2 header bytes for now */
skip_bits(&gb, 16);
} else
debug_vp3("\n");
init_frame(s, &gb);
#if KEYFRAMES_ONLY