2018-06-24 16:28:37 +08:00

281 lines
10 KiB
JavaScript

/*
* Copyright (C) 2016 Bilibili. All Rights Reserved.
*
* @author zheng qian <xqq@xqq.im>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import ExpGolomb from './exp-golomb.js';
class SPSParser {
static _ebsp2rbsp(uint8array) {
let src = uint8array;
let src_length = src.byteLength;
let dst = new Uint8Array(src_length);
let dst_idx = 0;
for (let i = 0; i < src_length; i++) {
if (i >= 2) {
// Unescape: Skip 0x03 after 00 00
if (src[i] === 0x03 && src[i - 1] === 0x00 && src[i - 2] === 0x00) {
continue;
}
}
dst[dst_idx] = src[i];
dst_idx++;
}
return new Uint8Array(dst.buffer, 0, dst_idx);
}
static parseSPS(uint8array) {
let rbsp = SPSParser._ebsp2rbsp(uint8array);
let gb = new ExpGolomb(rbsp);
gb.readByte();
let profile_idc = gb.readByte(); // profile_idc
gb.readByte(); // constraint_set_flags[5] + reserved_zero[3]
let level_idc = gb.readByte(); // level_idc
gb.readUEG(); // seq_parameter_set_id
let profile_string = SPSParser.getProfileString(profile_idc);
let level_string = SPSParser.getLevelString(level_idc);
let chroma_format_idc = 1;
let chroma_format = 420;
let chroma_format_table = [0, 420, 422, 444];
let bit_depth = 8;
if (profile_idc === 100 || profile_idc === 110 || profile_idc === 122 ||
profile_idc === 244 || profile_idc === 44 || profile_idc === 83 ||
profile_idc === 86 || profile_idc === 118 || profile_idc === 128 ||
profile_idc === 138 || profile_idc === 144) {
chroma_format_idc = gb.readUEG();
if (chroma_format_idc === 3) {
gb.readBits(1); // separate_colour_plane_flag
}
if (chroma_format_idc <= 3) {
chroma_format = chroma_format_table[chroma_format_idc];
}
bit_depth = gb.readUEG() + 8; // bit_depth_luma_minus8
gb.readUEG(); // bit_depth_chroma_minus8
gb.readBits(1); // qpprime_y_zero_transform_bypass_flag
if (gb.readBool()) { // seq_scaling_matrix_present_flag
let scaling_list_count = (chroma_format_idc !== 3) ? 8 : 12;
for (let i = 0; i < scaling_list_count; i++) {
if (gb.readBool()) { // seq_scaling_list_present_flag
if (i < 6) {
SPSParser._skipScalingList(gb, 16);
} else {
SPSParser._skipScalingList(gb, 64);
}
}
}
}
}
gb.readUEG(); // log2_max_frame_num_minus4
let pic_order_cnt_type = gb.readUEG();
if (pic_order_cnt_type === 0) {
gb.readUEG(); // log2_max_pic_order_cnt_lsb_minus_4
} else if (pic_order_cnt_type === 1) {
gb.readBits(1); // delta_pic_order_always_zero_flag
gb.readSEG(); // offset_for_non_ref_pic
gb.readSEG(); // offset_for_top_to_bottom_field
let num_ref_frames_in_pic_order_cnt_cycle = gb.readUEG();
for (let i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++) {
gb.readSEG(); // offset_for_ref_frame
}
}
let ref_frames = gb.readUEG(); // max_num_ref_frames
gb.readBits(1); // gaps_in_frame_num_value_allowed_flag
let pic_width_in_mbs_minus1 = gb.readUEG();
let pic_height_in_map_units_minus1 = gb.readUEG();
let frame_mbs_only_flag = gb.readBits(1);
if (frame_mbs_only_flag === 0) {
gb.readBits(1); // mb_adaptive_frame_field_flag
}
gb.readBits(1); // direct_8x8_inference_flag
let frame_crop_left_offset = 0;
let frame_crop_right_offset = 0;
let frame_crop_top_offset = 0;
let frame_crop_bottom_offset = 0;
let frame_cropping_flag = gb.readBool();
if (frame_cropping_flag) {
frame_crop_left_offset = gb.readUEG();
frame_crop_right_offset = gb.readUEG();
frame_crop_top_offset = gb.readUEG();
frame_crop_bottom_offset = gb.readUEG();
}
let sar_width = 1, sar_height = 1;
let fps = 0, fps_fixed = true, fps_num = 0, fps_den = 0;
let vui_parameters_present_flag = gb.readBool();
if (vui_parameters_present_flag) {
if (gb.readBool()) { // aspect_ratio_info_present_flag
let aspect_ratio_idc = gb.readByte();
let sar_w_table = [1, 12, 10, 16, 40, 24, 20, 32, 80, 18, 15, 64, 160, 4, 3, 2];
let sar_h_table = [1, 11, 11, 11, 33, 11, 11, 11, 33, 11, 11, 33, 99, 3, 2, 1];
if (aspect_ratio_idc > 0 && aspect_ratio_idc < 16) {
sar_width = sar_w_table[aspect_ratio_idc - 1];
sar_height = sar_h_table[aspect_ratio_idc - 1];
} else if (aspect_ratio_idc === 255) {
sar_width = gb.readByte() << 8 | gb.readByte();
sar_height = gb.readByte() << 8 | gb.readByte();
}
}
if (gb.readBool()) { // overscan_info_present_flag
gb.readBool(); // overscan_appropriate_flag
}
if (gb.readBool()) { // video_signal_type_present_flag
gb.readBits(4); // video_format & video_full_range_flag
if (gb.readBool()) { // colour_description_present_flag
gb.readBits(24); // colour_primaries & transfer_characteristics & matrix_coefficients
}
}
if (gb.readBool()) { // chroma_loc_info_present_flag
gb.readUEG(); // chroma_sample_loc_type_top_field
gb.readUEG(); // chroma_sample_loc_type_bottom_field
}
if (gb.readBool()) { // timing_info_present_flag
let num_units_in_tick = gb.readBits(32);
let time_scale = gb.readBits(32);
fps_fixed = gb.readBool(); // fixed_frame_rate_flag
fps_num = time_scale;
fps_den = num_units_in_tick * 2;
fps = fps_num / fps_den;
}
}
let sarScale = 1;
if (sar_width !== 1 || sar_height !== 1) {
sarScale = sar_width / sar_height;
}
let crop_unit_x = 0, crop_unit_y = 0;
if (chroma_format_idc === 0) {
crop_unit_x = 1;
crop_unit_y = 2 - frame_mbs_only_flag;
} else {
let sub_wc = (chroma_format_idc === 3) ? 1 : 2;
let sub_hc = (chroma_format_idc === 1) ? 2 : 1;
crop_unit_x = sub_wc;
crop_unit_y = sub_hc * (2 - frame_mbs_only_flag);
}
let codec_width = (pic_width_in_mbs_minus1 + 1) * 16;
let codec_height = (2 - frame_mbs_only_flag) * ((pic_height_in_map_units_minus1 + 1) * 16);
codec_width -= (frame_crop_left_offset + frame_crop_right_offset) * crop_unit_x;
codec_height -= (frame_crop_top_offset + frame_crop_bottom_offset) * crop_unit_y;
let present_width = Math.ceil(codec_width * sarScale);
gb.destroy();
gb = null;
return {
profile_string: profile_string, // baseline, high, high10, ...
level_string: level_string, // 3, 3.1, 4, 4.1, 5, 5.1, ...
bit_depth: bit_depth, // 8bit, 10bit, ...
ref_frames: ref_frames,
chroma_format: chroma_format, // 4:2:0, 4:2:2, ...
chroma_format_string: SPSParser.getChromaFormatString(chroma_format),
frame_rate: {
fixed: fps_fixed,
fps: fps,
fps_den: fps_den,
fps_num: fps_num
},
sar_ratio: {
width: sar_width,
height: sar_height
},
codec_size: {
width: codec_width,
height: codec_height
},
present_size: {
width: present_width,
height: codec_height
}
};
}
static _skipScalingList(gb, count) {
let last_scale = 8, next_scale = 8;
let delta_scale = 0;
for (let i = 0; i < count; i++) {
if (next_scale !== 0) {
delta_scale = gb.readSEG();
next_scale = (last_scale + delta_scale + 256) % 256;
}
last_scale = (next_scale === 0) ? last_scale : next_scale;
}
}
static getProfileString(profile_idc) {
switch (profile_idc) {
case 66:
return 'Baseline';
case 77:
return 'Main';
case 88:
return 'Extended';
case 100:
return 'High';
case 110:
return 'High10';
case 122:
return 'High422';
case 244:
return 'High444';
default:
return 'Unknown';
}
}
static getLevelString(level_idc) {
return (level_idc / 10).toFixed(1);
}
static getChromaFormatString(chroma) {
switch (chroma) {
case 420:
return '4:2:0';
case 422:
return '4:2:2';
case 444:
return '4:4:4';
default:
return 'Unknown';
}
}
}
export default SPSParser;