From aaf441465080b9bc57f5ca8dea656f9b2c5dc821 Mon Sep 17 00:00:00 2001 From: Mark Thompson Date: Sat, 24 Jun 2017 00:30:20 +0100 Subject: [PATCH] h264: Add stream constraint values to the common header With comments describing the derivation of each value. --- libavcodec/h264.h | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/libavcodec/h264.h b/libavcodec/h264.h index eb3805c067..aa137b5b54 100644 --- a/libavcodec/h264.h +++ b/libavcodec/h264.h @@ -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 */