On 2/5/2022 9:51 AM, Tom Yan wrote:
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 | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/libavcodec/mpegvideo_parser.c b/libavcodec/mpegvideo_parser.c index c5dc867d24..2ddcdb0f37 100644 --- a/libavcodec/mpegvideo_parser.c +++ b/libavcodec/mpegvideo_parser.c @@ -108,7 +108,7 @@ static void mpegvideo_extract_headers(AVCodecParserContext *s, uint32_t start_code; int frame_rate_index, ext_type, bytes_left; int frame_rate_ext_n, frame_rate_ext_d; - int top_field_first, repeat_first_field, progressive_frame; + int picture_structure, top_field_first, repeat_first_field, progressive_frame; int horiz_size_ext, vert_size_ext, bit_rate_ext; int did_set_size=0; int set_dim_ret = 0; @@ -181,6 +181,7 @@ static void mpegvideo_extract_headers(AVCodecParserContext *s, break; case 0x8: /* picture coding extension */ if (bytes_left >= 5) { + picture_structure = buf[2] & 0x3;
You could maybe also set s->picture_structure with this.
top_field_first = buf[3] & (1 << 7); repeat_first_field = buf[3] & (1 << 1); progressive_frame = buf[4] & (1 << 7); @@ -199,7 +200,9 @@ static void mpegvideo_extract_headers(AVCodecParserContext *s, }if (!pc->progressive_sequence && !progressive_frame) {- if (top_field_first) + /* top_field_first is mandated to be 0 when + picture_structure is not 3 (i.e. not a frame picture) */ + if (top_field_first || picture_structure == 1) s->field_order = AV_FIELD_TT; else s->field_order = AV_FIELD_BB;
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
