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better padding bug detection 

Originally committed as revision 1039 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2002-10-14 19:53:04 +00:00
parent ec6a375248
commit a61f82653e
2 changed files with 37 additions and 3 deletions
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39
libavcodec/h263dec.c
View File

@ -208,7 +208,9 @@ static int decode_slice(MpegEncContext *s){
s->error_status_table[xy]|= AC_END;
if(!s->partitioned_frame)
s->error_status_table[xy]|= MV_END|DC_END;
s->padding_bug_score--;
if(++s->mb_x >= s->mb_width){
s->mb_x=0;
ff_draw_horiz_band(s);
@ -237,6 +239,35 @@ static int decode_slice(MpegEncContext *s){
assert(s->mb_x==0 && s->mb_y==s->mb_height);
/* try to detect the padding bug */
if( s->codec_id==CODEC_ID_MPEG4
&& (s->workaround_bugs&FF_BUG_AUTODETECT)
&& s->gb.size*8 - get_bits_count(&s->gb) >=0
&& s->gb.size*8 - get_bits_count(&s->gb) < 48
&& !s->resync_marker
&& !s->data_partitioning){
const int bits_count= get_bits_count(&s->gb);
const int bits_left = s->gb.size*8 - bits_count;
if(bits_left==0 || bits_left>8){
s->padding_bug_score++;
} else {
int v= show_bits(&s->gb, 8);
v|= 0x7F >> (7-(bits_count&7));
if(v==0x7F)
s->padding_bug_score--;
else
s->padding_bug_score++;
}
if(s->padding_bug_score > -2)
s->workaround_bugs |= FF_BUG_NO_PADDING;
else
s->workaround_bugs &= ~FF_BUG_NO_PADDING;
}
// handle formats which dont have unique end markers
if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
int left= s->gb.size*8 - get_bits_count(&s->gb);
@ -262,7 +293,7 @@ static int decode_slice(MpegEncContext *s){
return 0;
}
fprintf(stderr, "slice end not reached but screenspace end (%d left %06X)\n",
s->gb.size*8 - get_bits_count(&s->gb),
show_bits(&s->gb, 24));
@ -341,7 +372,8 @@ uint64_t time= rdtsc();
s->workaround_bugs|= FF_BUG_UMP4;
s->workaround_bugs|= FF_BUG_AC_VLC;
}
//printf("padding_bug_score: %d\n", s->padding_bug_score);
#if 0
if(s->divx_version==500)
s->workaround_bugs|= FF_BUG_NO_PADDING;
@ -354,6 +386,7 @@ uint64_t time= rdtsc();
if(s->lavc_build && s->lavc_build<4609) //FIXME not sure about the version num but a 4609 file seems ok
s->workaround_bugs|= FF_BUG_NO_PADDING;
#endif
}

1
libavcodec/mpegvideo.h
View File

@ -404,6 +404,7 @@ typedef struct MpegEncContext {
INT16 (*field_mv_table)[2][2]; /* used for interlaced b frame decoding */
INT8 (*field_select_table)[2]; /* wtf, no really another table for interlaced b frames */
int t_frame; /* time distance of first I -> B, used for interlaced b frames */
int padding_bug_score; /* used to detect the VERY common padding bug in MPEG4 */
/* divx specific, used to workaround (many) bugs in divx5 */
int divx_version;