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Guess picture type from picture coding extension when the main header is damaged. 

Originally committed as revision 15456 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2008-09-28 23:19:12 +00:00
parent d5e34dcb72
commit ed16f91f26
1 changed files with 26 additions and 4 deletions
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30
libavcodec/mpeg12.c
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@ -1501,13 +1501,28 @@ static void mpeg_decode_quant_matrix_extension(MpegEncContext *s)
}
}
static void mpeg_decode_picture_coding_extension(MpegEncContext *s)
static void mpeg_decode_picture_coding_extension(Mpeg1Context *s1)
{
MpegEncContext *s= &s1->mpeg_enc_ctx;
s->full_pel[0] = s->full_pel[1] = 0;
s->mpeg_f_code[0][0] = get_bits(&s->gb, 4);
s->mpeg_f_code[0][1] = get_bits(&s->gb, 4);
s->mpeg_f_code[1][0] = get_bits(&s->gb, 4);
s->mpeg_f_code[1][1] = get_bits(&s->gb, 4);
if(!s->pict_type && s1->mpeg_enc_ctx_allocated){
av_log(s->avctx, AV_LOG_ERROR, "Missing picture start code, guessing missing values\n");
if(s->mpeg_f_code[1][0] == 15 && s->mpeg_f_code[1][1]==15){
if(s->mpeg_f_code[0][0] == 15 && s->mpeg_f_code[0][1] == 15)
s->pict_type= FF_I_TYPE;
else
s->pict_type= FF_P_TYPE;
}else
s->pict_type= FF_B_TYPE;
s->current_picture.pict_type= s->pict_type;
s->current_picture.key_frame= s->pict_type == FF_I_TYPE;
s->first_slice= 1;
}
s->intra_dc_precision = get_bits(&s->gb, 2);
s->picture_structure = get_bits(&s->gb, 2);
s->top_field_first = get_bits1(&s->gb);
@ -1573,7 +1588,7 @@ static void mpeg_decode_extension(AVCodecContext *avctx,
mpeg_decode_picture_display_extension(s1);
break;
case 0x8:
mpeg_decode_picture_coding_extension(s);
mpeg_decode_picture_coding_extension(s1);
break;
}
}
@ -2293,6 +2308,7 @@ static int decode_chunks(AVCodecContext *avctx,
*data_size = sizeof(AVPicture);
}
}
s2->pict_type= 0;
return FFMAX(0, buf_ptr - buf - s2->parse_context.last_index);
}
@ -2311,8 +2327,9 @@ static int decode_chunks(AVCodecContext *avctx,
case PICTURE_START_CODE:
/* we have a complete image: we try to decompress it */
mpeg1_decode_picture(avctx,
buf_ptr, input_size);
if(mpeg1_decode_picture(avctx,
buf_ptr, input_size) < 0)
s2->pict_type=0;
break;
case EXT_START_CODE:
mpeg_decode_extension(avctx,
@ -2356,6 +2373,11 @@ static int decode_chunks(AVCodecContext *avctx,
break;
}
if(!s2->pict_type){
av_log(avctx, AV_LOG_ERROR, "Missing picture start code\n");
break;
}
if(s2->first_slice){
s2->first_slice=0;
if(mpeg_field_start(s2) < 0)