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uupaa edited this page Sep 10, 2018
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IDR は リセット情報を含んだ I フレームです。 IDR フレームは他のフレームを参照しません。
シークは IDR フレーム単位で行われます。
- u(n) で n が数値の場合は n bit 読み進め、結果をunsignedで返す事を意味しています。 u(1) は 1 bit を読み進めます。
- u(n) で n が v の場合は、変数名毎に特殊なルールで読み込むビット数を决定する事を意味しています。
-
frame_num = u(v)-
frame_numis used as an identifier for pictures and shall be represented by log2_max_frame_num_minus4 + 4 bits in the bitstream. frame_num is constrained as follows: -
frame_num = u(v)はSPS.log2_max_frame_num_minus4 + 4から求める事ができます
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-
pic_order_cnt_lsb = u(v)-
pic_order_cnt_lsbspecifies the picture order count modulo MaxPicOrderCntLsb for the top field of a coded frame or for a coded field. The length of the pic_order_cnt_lsb syntax element islog2_max_pic_order_cnt_lsb_minus4 + 4bits. The value of the pic_order_cnt_lsb shall be in the range of 0 to MaxPicOrderCntLsb − 1, inclusive. -
pic_order_cnt_lsb = u(v)はSPS.log2_max_pic_order_cnt_lsb_minus4 + 4から求める事ができます
-
-
slice_group_change_cycle = u(v)- The value of
slice_group_change_cycleis represented in the bitstream by the following number of bits Ceil( Log2( PicSizeInMapUnits ÷ SliceGroupChangeRate + 1 ) ) -
slice_group_change_cycle = u(v)はMath.ceil( Math.log2( PicSizeInMapUnits / SliceGroupChangeRate + 1 ) )から求める事ができます PicHeightInMapUnits = SPS.pic_height_in_map_units_minus1 + 1PicSizeInMapUnits = PicWidthInMbs * PicHeightInMapUnitsPicWidthInMbs = SPS.pic_width_in_mbs_minus1 + 1SliceGroupChangeRate = PPS.slice_group_change_rate_minus1 + 1
- The value of
-
u(v) をデコードするには以下を参考に
- h264 u(v) decode of frame_num, pic_order_cnt_lsb and slice_group_change_cycle
- http://www.pudn.com/downloads152/sourcecode/zip/detail668121.html
- http://read.pudn.com/downloads152/sourcecode/zip/668121/H264Decoder/SliceHeader.cpp__.htm
- http://read.pudn.com/downloads152/sourcecode/zip/668121/H264Decoder/SliceHeader.h__.htm
- http://read.pudn.com/downloads152/sourcecode/zip/668121/H264Decoder/VLC.cpp__.htm
- http://read.pudn.com/downloads152/sourcecode/zip/668121/H264Decoder/VLC.h__.htm
slice_layer_without_partitioning_rbsp() {
slice_header()
slice_data() // all categories of slice_data( ) syntax
rbsp_slice_trailing_bits()
}slice_header() {
first_mb_in_slice ue(v)
slice_type ue(v)
pic_parameter_set_id ue(v)
if (separate_colour_plane_flag === 1) {
colour_plane_id u(2)
}
frame_num u(v) // !!
if (!frame_mbs_only_flag) {
field_pic_flag u(1)
if (field_pic_flag) {
bottom_field_flag u(1)
}
}
if (IdrPicFlag) {
idr_pic_id ue(v)
}
if (pic_order_cnt_type === 0) {
pic_order_cnt_lsb u(v) // !!
if (bottom_field_pic_order_in_frame_present_flag && !field_pic_flag) {
delta_pic_order_cnt_bottom se(v)
}
}
if (pic_order_cnt_type === 1 && !delta_pic_order_always_zero_flag) {
delta_pic_order_cnt[ 0 ] se(v)
if (bottom_field_pic_order_in_frame_present_flag && !field_pic_flag) {
delta_pic_order_cnt[ 1 ] se(v)
}
}
if (redundant_pic_cnt_present_flag) {
redundant_pic_cnt ue(v)
}
if (slice_type === B) {
direct_spatial_mv_pred_flag u(1)
}
if (slice_type === P || slice_type === SP || slice_type === B) {
num_ref_idx_active_override_flag u(1)
if (num_ref_idx_active_override_flag) {
num_ref_idx_l0_active_minus1 ue(v)
if (slice_type === B) {
num_ref_idx_l1_active_minus1 ue(v)
}
}
}
if (nal_unit_type === 20) {
ref_pic_list_mvc_modification() // specified in Annex H
} else {
ref_pic_list_modification()
}
if (( weighted_pred_flag && ( slice_type === P || slice_type === SP ) ) ||
( weighted_bipred_idc == 1 && slice_type == B ) ) {
pred_weight_table()
}
if (nal_ref_idc !== 0) {
dec_ref_pic_marking()
}
if (entropy_coding_mode_flag && slice_type !== I && slice_type !== SI) {
cabac_init_idc ue(v)
}
slice_qp_delta se(v)
if (slice_type === SP || slice_type === SI) {
if (slice_type === SP) {
sp_for_switch_flag u(1)
}
slice_qs_delta se(v)
}
if (deblocking_filter_control_present_flag) {
disable_deblocking_filter_idc ue(v)
if (disable_deblocking_filter_idc !== 1) {
slice_alpha_c0_offset_div2 se(v)
slice_beta_offset_div2 se(v)
}
}
if (num_slice_groups_minus1 > 0 &&
slice_group_map_type >= 3 &&
slice_group_map_type <= 5) {
slice_group_change_cycle u(v) // !!
}
}slice_data() {
if (entropy_coding_mode_flag) {
while (!byte_aligned()) {
cabac_alignment_one_bit f(1)
}
}
CurrMbAddr = first_mb_in_slice * ( 1 + MbaffFrameFlag )
moreDataFlag = 1
prevMbSkipped = 0
do {
if (slice_type !== I && slice_type !== SI) {
if (!entropy_coding_mode_flag) {
mb_skip_run ue(v)
prevMbSkipped = ( mb_skip_run > 0 )
for (i=0; i<mb_skip_run; ++i) {
CurrMbAddr = NextMbAddress( CurrMbAddr )
}
if (mb_skip_run > 0) {
moreDataFlag = more_rbsp_data( )
}
} else {
mb_skip_flag ae(v)
moreDataFlag = !mb_skip_flag
}
}
if (moreDataFlag) {
if (MbaffFrameFlag && ( CurrMbAddr % 2 === 0 || ( CurrMbAddr % 2 === 1 && prevMbSkipped) ) ) {
mb_field_decoding_flag u(1) | ae(v)
}
macroblock_layer( )
}
if (!entropy_coding_mode_flag) {
moreDataFlag = more_rbsp_data( )
} else {
if (slice_type !== I && slice_type !== SI) {
prevMbSkipped = mb_skip_flag
}
if (MbaffFrameFlag && CurrMbAddr % 2 === 0 ) {
moreDataFlag = 1
} else {
end_of_slice_flag ae(v)
moreDataFlag = !end_of_slice_flag
}
}
CurrMbAddr = NextMbAddress( CurrMbAddr )
} while (moreDataFlag)
}ref_pic_list_modification() {
if (slice_type % 5 !== 2 && slice_type % 5 !== 4) {
ref_pic_list_modification_flag_l0 u(1)
if (ref_pic_list_modification_flag_l0 ) {
do {
modification_of_pic_nums_idc ue(v)
if (modification_of_pic_nums_idc === 0 ||
modification_of_pic_nums_idc === 1) {
abs_diff_pic_num_minus1 ue(v)
} else if (modification_of_pic_nums_idc === 2) {
long_term_pic_num ue(v)
}
} while ( modification_of_pic_nums_idc !== 3 );
}
}
if (slice_type % 5 === 1) {
ref_pic_list_modification_flag_l1 u(1)
if (ref_pic_list_modification_flag_l1) {
do {
modification_of_pic_nums_idc ue(v)
if (modification_of_pic_nums_idc === 0 ||
modification_of_pic_nums_idc === 1) {
abs_diff_pic_num_minus1 ue(v)
} else if (modification_of_pic_nums_idc === 2) {
long_term_pic_num ue(v)
}
} while (modification_of_pic_nums_idc !== 3);
}
}
}dec_ref_pic_marking() {
if (IdrPicFlag) {
no_output_of_prior_pics_flag u(1)
long_term_reference_flag u(1)
} else {
adaptive_ref_pic_marking_mode_flag u(1)
if (adaptive_ref_pic_marking_mode_flag) {
do {
memory_management_control_operation ue(v)
if (memory_management_control_operation === 1 ||
memory_management_control_operation === 3) {
difference_of_pic_nums_minus1 ue(v)
}
if (memory_management_control_operation === 2) {
long_term_pic_num ue(v)
}
if (memory_management_control_operation === 3 ||
memory_management_control_operation === 6) {
long_term_frame_idx ue(v)
}
if (memory_management_control_operation === 4) {
max_long_term_frame_idx_plus1 ue(v)
}
} while (memory_management_control_operation !== 0)
}
}
}slice_data() {
if (entropy_coding_mode_flag) {
while ( !byte_aligned() ) {
cabac_alignment_one_bit f(1)
}
}
CurrMbAddr = first_mb_in_slice * ( 1 + MbaffFrameFlag )
moreDataFlag = 1
prevMbSkipped = 0
do {
if (slice_type != I && slice_type != SI) {
if (!entropy_coding_mode_flag) {
mb_skip_run ue(v)
prevMbSkipped = ( mb_skip_run > 0 )
for (i = 0; i < mb_skip_run; ++i) {
CurrMbAddr = NextMbAddress( CurrMbAddr )
}
if ( mb_skip_run > 0 ) {
moreDataFlag = more_rbsp_data( )
}
} else {
mb_skip_flag ae(v)
moreDataFlag = !mb_skip_flag
}
}
if (moreDataFlag) {
if (MbaffFrameFlag && ( CurrMbAddr % 2 === 0 || ( CurrMbAddr % 2 === 1 && prevMbSkipped ) ) ) {
mb_field_decoding_flag u(1) | ae(v)
}
macroblock_layer()
}
if (!entropy_coding_mode_flag) {
moreDataFlag = more_rbsp_data()
} else {
if (slice_type != I && slice_type != SI) {
prevMbSkipped = mb_skip_flag
}
if (MbaffFrameFlag && CurrMbAddr % 2 = = 0) {
moreDataFlag = 1
} else {
end_of_slice_flag ae(v)
moreDataFlag = !end_of_slice_flag
}
}
CurrMbAddr = NextMbAddress( CurrMbAddr )
} while (moreDataFlag);
}macroblock_layer() {
}