the top_field_first bit is only used to indicate the field order
when the picture is a frame picture (which consists of two fields)
but not when it is a field picture (which consists of one single
top or bottom field).
Signed-off-by: Tom Yan <tom.t...@gmail.com>
---
libavcodec/mpegvideo_parser.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/libavcodec/mpegvideo_parser.c b/libavcodec/mpegvideo_parser.c
index c5dc867d24..26f3aac9da 100644
--- a/libavcodec/mpegvideo_parser.c
+++ b/libavcodec/mpegvideo_parser.c
@@ -181,6 +181,7 @@ static void mpegvideo_extract_headers(AVCodecParserContext
*s,
break;
case 0x8: /* picture coding extension */
if (bytes_left >= 5) {
+ s->picture_structure = buf[2] & 0x3;
top_field_first = buf[3] & (1 << 7);
repeat_first_field = buf[3] & (1 << 1);
progressive_frame = buf[4] & (1 << 7);
@@ -198,13 +199,15 @@ static void
mpegvideo_extract_headers(AVCodecParserContext *s,
}
}
- if (!pc->progressive_sequence && !progressive_frame) {
- if (top_field_first)
- s->field_order = AV_FIELD_TT;
- else
- s->field_order = AV_FIELD_BB;
- } else
+ /* picture_structure > progressive bits >
top_field_first */
+ if (s->picture_structure ==
AV_PICTURE_STRUCTURE_TOP_FIELD)
+ s->field_order = AV_FIELD_TT;
+ else if (s->picture_structure ==
AV_PICTURE_STRUCTURE_BOTTOM_FIELD)
+ s->field_order = AV_FIELD_BB;
+ else if (pc->progressive_sequence || progressive_frame)
s->field_order = AV_FIELD_PROGRESSIVE;
+ else
+ s->field_order = top_field_first ? AV_FIELD_TT :
AV_FIELD_BB;
}
break;
}
--
2.35.1
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