Add H264 bitstream rewriting to limit frame reordering marker in header

webrtc/common_video/h264/pps_parser.h

+/*
+ *  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 WEBRTC_COMMON_VIDEO_H264_PPS_PARSER_H_
+#define WEBRTC_COMMON_VIDEO_H264_PPS_PARSER_H_
+
+#include "webrtc/base/common.h"
+#include "webrtc/base/optional.h"
+
+namespace rtc {
+class BitBuffer;
+}
+
+namespace webrtc {
+
+// A class for parsing out picture parameter set (PPS) data from a H264 NALU.
+class PpsParser {
+ public:
+  // The parsed state of the PPS. Only some select values are stored.
+  // Add more as they are actually needed.
+  struct PpsState {
+    PpsState() = default;
+
+    bool bottom_field_pic_order_in_frame_present_flag = false;
+    bool weighted_pred_flag = false;
+    uint32_t weighted_bipred_idc = false;
+    uint32_t redundant_pic_cnt_present_flag = 0;
+    int pic_init_qp_minus26 = 0;
+  };
+
+  // Unpack RBSP and parse PPS state from the supplied buffer.
+  static rtc::Optional<PpsState> ParsePps(const uint8_t* data, size_t length);
+
+ protected:
+  // Parse the PPS state, for a bit buffer where RBSP decoding has already been
+  // performed.
+  static rtc::Optional<PpsState> ParseInternal(rtc::BitBuffer* bit_buffer);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_COMMON_VIDEO_H264_PPS_PARSER_H_