From 70340520422bd57265c125c9114bf0804a0fcfb6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Reinhard=20Ni=C3=9Fl?= Date: Wed, 11 Apr 2007 22:47:14 +0200 Subject: Improve MPEG2 detection to have it ready for correct aspect ratio determination. The current code detects MPEG2 when parsing the sequence extention which appears only in MPEG2 streams. But this is to late for correct aspect ratio determination which happens earlier and therefore assumes MPEG1. The result is a totally wrong aspect ratio. To fix this issue, the next start code (which is already available at that time) is passed to parse_chunk() too, which can then be used to detect a MPEG2 extension start code early enough before the aspect ratio is determined. --- src/libmpeg2/decode.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/src/libmpeg2/decode.c b/src/libmpeg2/decode.c index a2bb868df..3b19feda1 100644 --- a/src/libmpeg2/decode.c +++ b/src/libmpeg2/decode.c @@ -236,7 +236,7 @@ static void remember_metainfo (mpeg2dec_t *mpeg2dec) { } static inline int parse_chunk (mpeg2dec_t * mpeg2dec, int code, - uint8_t * buffer) + uint8_t * buffer, int next_code) { picture_t * picture; int is_frame_done; @@ -393,6 +393,11 @@ static inline int parse_chunk (mpeg2dec_t * mpeg2dec, int code, /* abort(); */ break; } + + /* according to ISO/IEC 13818-2, an extension start code will follow. + * Otherwise the stream follows ISO/IEC 11172-2 which means MPEG1 */ + picture->mpeg1 = (next_code != 0xb5); + if (mpeg2dec->force_aspect) picture->aspect_ratio_information = mpeg2dec->force_aspect; if (mpeg2dec->is_sequence_needed ) { @@ -638,7 +643,7 @@ int mpeg2_decode_data (mpeg2dec_t * mpeg2dec, uint8_t * current, uint8_t * end, current = copy_chunk (mpeg2dec, current, end); if (current == NULL) break; - ret += parse_chunk (mpeg2dec, code, mpeg2dec->chunk_buffer); + ret += parse_chunk (mpeg2dec, code, mpeg2dec->chunk_buffer, mpeg2dec->code); } libmpeg2_accel_frame_completion(&mpeg2dec->accel, mpeg2dec->frame_format, @@ -805,7 +810,7 @@ void mpeg2_close (mpeg2dec_t * mpeg2dec) void mpeg2_find_sequence_header (mpeg2dec_t * mpeg2dec, uint8_t * current, uint8_t * end){ - uint8_t code; + uint8_t code, next_code; picture_t *picture = mpeg2dec->picture; mpeg2dec->seek_mode = 1; @@ -815,6 +820,7 @@ void mpeg2_find_sequence_header (mpeg2dec_t * mpeg2dec, current = copy_chunk (mpeg2dec, current, end); if (current == NULL) return ; + next_code = mpeg2dec->code; /* printf ("looking for sequence header... %02x\n", code); */ @@ -825,6 +831,11 @@ void mpeg2_find_sequence_header (mpeg2dec_t * mpeg2dec, printf ("libmpeg2: bad sequence header\n"); continue; } + + /* according to ISO/IEC 13818-2, an extension start code will follow. + * Otherwise the stream follows ISO/IEC 11172-2 which means MPEG1 */ + picture->mpeg1 = (next_code != 0xb5); + if (mpeg2dec->force_aspect) picture->aspect_ratio_information = mpeg2dec->force_aspect; if (mpeg2dec->is_sequence_needed) { -- cgit v1.2.3