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h264: Add stream constraint values to the common header

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With comments describing the derivation of each value.

(cherry picked from commit aaf4414650)
This commit is contained in:
Mark Thompson 2017-06-24 00:30:20 +01:00
parent 6c5d6baeed
commit d05444d2c6
1 changed files with 45 additions and 0 deletions
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45
libavcodec/h264.h
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@ -44,4 +44,49 @@ enum {
H264_NAL_AUXILIARY_SLICE = 19,
};
enum {
// 7.4.2.1.1: seq_parameter_set_id is in [0, 31].
H264_MAX_SPS_COUNT = 32,
// 7.4.2.2: pic_parameter_set_id is in [0, 255].
H264_MAX_PPS_COUNT = 256,
// A.3: MaxDpbFrames is bounded above by 16.
H264_MAX_DPB_FRAMES = 16,
// 7.4.2.1.1: max_num_ref_frames is in [0, MaxDpbFrames], and
// each reference frame can have two fields.
H264_MAX_REFS = 2 * H264_MAX_DPB_FRAMES,
// 7.4.3.1: modification_of_pic_nums_idc is not equal to 3 at most
// num_ref_idx_lN_active_minus1 + 1 times (that is, once for each
// possible reference), then equal to 3 once.
H264_MAX_RPLM_COUNT = H264_MAX_REFS + 1,
// 7.4.3.3: in the worst case, we begin with a full short-term
// reference picture list. Each picture in turn is moved to the
// long-term list (type 3) and then discarded from there (type 2).
// Then, we set the length of the long-term list (type 4), mark
// the current picture as long-term (type 6) and terminate the
// process (type 0).
H264_MAX_MMCO_COUNT = H264_MAX_REFS * 2 + 3,
// A.2.1, A.2.3: profiles supporting FMO constrain
// num_slice_groups_minus1 to be in [0, 7].
H264_MAX_SLICE_GROUPS = 8,
// E.2.2: cpb_cnt_minus1 is in [0, 31].
H264_MAX_CPB_CNT = 32,
// A.3: in table A-1 the highest level allows a MaxFS of 139264.
H264_MAX_MB_PIC_SIZE = 139264,
// A.3.1, A.3.2: PicWidthInMbs and PicHeightInMbs are constrained
// to be not greater than sqrt(MaxFS * 8). Hence height/width are
// bounded above by sqrt(139264 * 8) = 1055.5 macroblocks.
H264_MAX_MB_WIDTH = 1055,
H264_MAX_MB_HEIGHT = 1055,
H264_MAX_WIDTH = H264_MAX_MB_WIDTH * 16,
H264_MAX_HEIGHT = H264_MAX_MB_HEIGHT * 16,
};
#endif /* AVCODEC_H264_H */