108 lines
4.6 KiB
ActionScript
108 lines
4.6 KiB
ActionScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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package org.mangui.hls.demux {
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import flash.utils.ByteArray;
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/* inspired from https://github.com/aizvorski/h264bitstream/blob/master/h264_stream.c#L241-L342 */
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public class SPSInfo {
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public var width : int;
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public var height : int;
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public function SPSInfo(sps : ByteArray) {
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var profile_idc : int;
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sps.position++;
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profile_idc = sps.readUnsignedByte();
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var eg : ExpGolomb = new ExpGolomb(sps);
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// constraint_set[0-5]_flag, u(1), reserved_zero_2bits u(2), level_idc u(8)
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eg.readBits(16);
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// skip seq_parameter_set_id
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eg.readUE();
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if (profile_idc == 100 || profile_idc == 110 || profile_idc == 122 || profile_idc == 144) {
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var chroma_format_idc : int = eg.readUE();
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if (3 === chroma_format_idc) {
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// separate_colour_plane_flag
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eg.readBits(1);
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}
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// bit_depth_luma_minus8
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eg.readUE();
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// bit_depth_chroma_minus8
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eg.readUE();
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// qpprime_y_zero_transform_bypass_flag
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eg.readBits(1);
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// seq_scaling_matrix_present_flag
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var seq_scaling_matrix_present_flag : Boolean = eg.readBoolean();
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if (seq_scaling_matrix_present_flag) {
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var imax : int = (chroma_format_idc != 3) ? 8 : 12;
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for (var i : int = 0; i < imax; ++i) {
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// seq_scaling_list_present_flag[ i ]
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if (eg.readBoolean()) {
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if (i < 6) {
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scaling_list(16, eg);
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} else {
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scaling_list(64, eg);
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}
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}
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}
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}
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}
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// log2_max_frame_num_minus4
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eg.readUE();
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var pic_order_cnt_type : int = eg.readUE();
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if ( 0 === pic_order_cnt_type ) {
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// log2_max_pic_order_cnt_lsb_minus4
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eg.readUE();
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} else if ( 1 === pic_order_cnt_type ) {
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// delta_pic_order_always_zero_flag
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eg.readBits(1);
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// offset_for_non_ref_pic
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eg.readUE();
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// offset_for_top_to_bottom_field
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eg.readUE();
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var num_ref_frames_in_pic_order_cnt_cycle : int = eg.readUE();
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for (i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; ++i) {
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// offset_for_ref_frame[ i ]
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eg.readUE();
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}
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}
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// max_num_ref_frames
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eg.readUE();
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// gaps_in_frame_num_value_allowed_flag
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eg.readBits(1);
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var pic_width_in_mbs_minus1 : int = eg.readUE();
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var pic_height_in_map_units_minus1 : int = eg.readUE();
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var frame_mbs_only_flag : int = eg.readBits(1);
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if (0 === frame_mbs_only_flag) {
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// mb_adaptive_frame_field_flag
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eg.readBits(1);
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}
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// direct_8x8_inference_flag
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eg.readBits(1);
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var frame_cropping_flag : int = eg.readBits(1);
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if (frame_cropping_flag) {
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var frame_crop_left_offset : int = eg.readUE();
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var frame_crop_right_offset : int = eg.readUE();
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var frame_crop_top_offset : int = eg.readUE();
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var frame_crop_bottom_offset : int = eg.readUE();
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}
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width = ((pic_width_in_mbs_minus1 + 1) * 16) - frame_crop_left_offset * 2 - frame_crop_right_offset * 2;
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height = ((2 - frame_mbs_only_flag) * (pic_height_in_map_units_minus1 + 1) * 16) - (frame_crop_top_offset * 2) - (frame_crop_bottom_offset * 2);
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}
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private static function scaling_list(sizeOfScalingList : int, eg : ExpGolomb) : void {
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var lastScale : int = 8;
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var nextScale : int = 8;
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var delta_scale : int;
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for (var j : int = 0; j < sizeOfScalingList; ++j) {
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if (nextScale != 0) {
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delta_scale = eg.readSE();
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nextScale = (lastScale + delta_scale + 256) % 256;
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}
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lastScale = (nextScale == 0) ? lastScale : nextScale;
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}
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}
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}
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}
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