sps_parser.h - mozsearch

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/*

 *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

*/

#ifndef COMMON_VIDEO_H264_SPS_PARSER_H_

#define COMMON_VIDEO_H264_SPS_PARSER_H_

#include <optional>

#include "rtc_base/bitstream_reader.h"

#include "rtc_base/system/rtc_export.h"

namespace webrtc {

// A class for parsing out sequence parameter set (SPS) data from an H264 NALU.

class RTC_EXPORT SpsParser {

 public:

  // The parsed state of the SPS. Only some select values are stored.

  // Add more as they are actually needed.

  struct RTC_EXPORT SpsState {

    SpsState();

    SpsState(const SpsState&);

    ~SpsState();

    uint32_t width = 0;

    uint32_t height = 0;

    uint32_t delta_pic_order_always_zero_flag = 0;

    uint32_t chroma_format_idc = 1;

    uint32_t separate_colour_plane_flag = 0;

    uint32_t frame_mbs_only_flag = 0;

    uint32_t log2_max_frame_num = 4;          // Smallest valid value.

    uint32_t log2_max_pic_order_cnt_lsb = 4;  // Smallest valid value.

    uint32_t pic_order_cnt_type = 0;

    uint32_t max_num_ref_frames = 0;

    uint32_t vui_params_present = 0;

    uint32_t id = 0;

};

  // Unpack RBSP and parse SPS state from the supplied buffer.

  static std::optional<SpsState> ParseSps(rtc::ArrayView<const uint8_t> data);

 protected:

  // Parse the SPS state, up till the VUI part, for a buffer where RBSP

  // decoding has already been performed.

  static std::optional<SpsState> ParseSpsUpToVui(BitstreamReader& reader);

};

}  // namespace webrtc

#endif  // COMMON_VIDEO_H264_SPS_PARSER_H_