1 /* 2 * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef COMMON_VIDEO_H264_SPS_PARSER_H_ 12 #define COMMON_VIDEO_H264_SPS_PARSER_H_ 13 14 #include "absl/types/optional.h" 15 16 namespace rtc { 17 class BitBuffer; 18 } 19 20 namespace webrtc { 21 22 // A class for parsing out sequence parameter set (SPS) data from an H264 NALU. 23 class SpsParser { 24 public: 25 // The parsed state of the SPS. Only some select values are stored. 26 // Add more as they are actually needed. 27 struct SpsState { 28 SpsState(); 29 SpsState(const SpsState&); 30 ~SpsState(); 31 32 uint32_t width = 0; 33 uint32_t height = 0; 34 uint32_t delta_pic_order_always_zero_flag = 0; 35 uint32_t separate_colour_plane_flag = 0; 36 uint32_t frame_mbs_only_flag = 0; 37 uint32_t log2_max_frame_num = 4; // Smallest valid value. 38 uint32_t log2_max_pic_order_cnt_lsb = 4; // Smallest valid value. 39 uint32_t pic_order_cnt_type = 0; 40 uint32_t max_num_ref_frames = 0; 41 uint32_t vui_params_present = 0; 42 uint32_t id = 0; 43 }; 44 45 // Unpack RBSP and parse SPS state from the supplied buffer. 46 static absl::optional<SpsState> ParseSps(const uint8_t* data, size_t length); 47 48 protected: 49 // Parse the SPS state, up till the VUI part, for a bit buffer where RBSP 50 // decoding has already been performed. 51 static absl::optional<SpsState> ParseSpsUpToVui(rtc::BitBuffer* buffer); 52 }; 53 54 } // namespace webrtc 55 #endif // COMMON_VIDEO_H264_SPS_PARSER_H_ 56