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hevc_ps: check overflow and test alternate syntax

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Some streams were found to have what appeared to be truncated SPS.
Their syntax seem to be valid at least until the end of the VUI, so
try that syntax if the parsing would overflow the SPS in the
conforming syntax.

Fixes ticket #3872.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Christophe Gisquet 2014-08-21 18:57:18 +02:00 committed by Michael Niedermayer
parent fca76dc61e
commit 0625a38066
1 changed files with 20 additions and 1 deletions
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21
libavcodec/hevc_ps.c
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@ -471,7 +471,8 @@ static void decode_vui(HEVCContext *s, HEVCSPS *sps)
{
VUI *vui = &sps->vui;
GetBitContext *gb = &s->HEVClc->gb;
int sar_present;
GetBitContext backup;
int sar_present, alt = 1;
av_log(s->avctx, AV_LOG_DEBUG, "Decoding VUI\n");
@ -525,6 +526,10 @@ static void decode_vui(HEVCContext *s, HEVCSPS *sps)
vui->frame_field_info_present_flag = get_bits1(gb);
vui->default_display_window_flag = get_bits1(gb);
// Backup context in case an alternate header is detected
if( get_bits_left(gb) >= 66)
memcpy(&backup, gb, sizeof(backup));
if (vui->default_display_window_flag) {
//TODO: * 2 is only valid for 420
vui->def_disp_win.left_offset = get_ue_golomb_long(gb) * 2;
@ -552,8 +557,22 @@ static void decode_vui(HEVCContext *s, HEVCSPS *sps)
vui->vui_timing_info_present_flag = get_bits1(gb);
if (vui->vui_timing_info_present_flag) {
if( get_bits_left(gb) < 66) {
// The alternate syntax seem to have timing info located
// at where def_disp_win is normally located
av_log(s->avctx, AV_LOG_WARNING,
"Strange VUI timing information, retrying...\n");
vui->default_display_window_flag = 0;
memset(&vui->def_disp_win, 0, sizeof(vui->def_disp_win));
memcpy(gb, &backup, sizeof(backup));
alt = 1;
}
vui->vui_num_units_in_tick = get_bits_long(gb, 32);
vui->vui_time_scale = get_bits_long(gb, 32);
if (alt) {
av_log(s->avctx, AV_LOG_INFO, "Retry got %i/%i fps\n",
vui->vui_time_scale, vui->vui_num_units_in_tick);
}
vui->vui_poc_proportional_to_timing_flag = get_bits1(gb);
if (vui->vui_poc_proportional_to_timing_flag)
vui->vui_num_ticks_poc_diff_one_minus1 = get_ue_golomb_long(gb);