avcodec/h264_slice: compute and export film grain seed
From SMPTE RDD 5-2006, the grain seed is to be computed from the following definition of `pic_offset`: > When decoding H.264 | MPEG-4 AVC bitstreams, pic_offset is defined as > follows: > - pic_offset = PicOrderCnt(CurrPic) + (PicOrderCnt_offset << 5) > where: > - PicOrderCnt(CurrPic) is the picture order count of the current frame, > which shall be derived from [the video stream]. > > - PicOrderCnt_offset is set to idr_pic_id on IDR frames. idr_pic_id > shall be read from the slice header of [the video stream]. On non-IDR I > frames, PicOrderCnt_offset is set to 0. A frame shall be classified as I > frame when all its slices are I slices, which may be optionally > designated by setting primary_pic_type to 0 in the access delimiter NAL > unit. Otherwise, PicOrderCnt_offset it not changed. PicOrderCnt_offset is > updated in decoding order. Co-authored-by:James Almer <jamrial@gmail.com> Signed-off-by:
Niklas Haas <git@haasn.dev> Signed-off-by:
James Almer <jamrial@gmail.com>
Showing
Please register or sign in to comment