On 29/07/2017 23:16, Mark Thompson wrote:
> 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 eb3805c06..aa137b5b5 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 */
>
Ok.
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