[FFmpeg-devel] [PATCH]h264: Fix ticket #3147 H264 - Wrong field order

Thomas Mundt loudmax at yahoo.de
Sat Sep 26 17:59:06 CEST 2015

some h264 encoders, like broadcast avc-intra in this case, always set sei_pic_struct to "frame" even at interlaced encodings with separate fields. FFmpeg h264 decoder always assumes field order as "bottom field first" unless "top field first" is definitely detected. This leads to wrong field order detection in some cases.Attached patch changes this behavior of h264 decoder when sei_pic_struct is used for field order detection.Now "top field first" is assumed unless "bottom field first" is definitely detected.
One could say fine, but now "bottom field first" material with sei_pic_struct set to "frame" will be detected wrong.Yes, but since "bottom field first" comes from the old NTSC standard and is not used with HD anymore I think it´s straight forward to favor the majority.
Please comment,Thomas
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