1 /*
2  *  Copyright (c) 2018 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_H265_PPS_PARSER_H_
12 #define COMMON_VIDEO_H265_PPS_PARSER_H_
13 
14 #include <cstdint>
15 
16 #include "absl/types/optional.h"
17 
18 namespace rtc {
19 class BitBuffer;
20 }
21 
22 namespace webrtc {
23 
24 // A class for parsing out picture parameter set (PPS) data from a H265 NALU.
25 class H265PpsParser {
26  public:
27   // The parsed state of the PPS. Only some select values are stored.
28   // Add more as they are actually needed.
29   struct PpsState {
30     PpsState() = default;
31 
32     uint32_t dependent_slice_segments_enabled_flag = 0;
33     uint32_t cabac_init_present_flag = 0;
34     uint32_t output_flag_present_flag = 0;
35     uint32_t num_extra_slice_header_bits = 0;
36     uint32_t num_ref_idx_l0_default_active_minus1 = 0;
37     uint32_t num_ref_idx_l1_default_active_minus1 = 0;
38     int32_t pic_init_qp_minus26 = 0;
39     uint32_t weighted_pred_flag = 0;
40     uint32_t weighted_bipred_flag = 0;
41     uint32_t lists_modification_present_flag = 0;
42     uint32_t id = 0;
43     uint32_t sps_id = 0;
44   };
45 
46   // Unpack RBSP and parse PPS state from the supplied buffer.
47   static absl::optional<PpsState> ParsePps(const uint8_t* data, size_t length);
48 
49   static bool ParsePpsIds(const uint8_t* data,
50                           size_t length,
51                           uint32_t* pps_id,
52                           uint32_t* sps_id);
53 
54   static absl::optional<uint32_t> ParsePpsIdFromSliceSegmentLayerRbsp(
55       const uint8_t* data,
56       size_t length,
57       uint8_t nalu_type);
58 
59  protected:
60   // Parse the PPS state, for a bit buffer where RBSP decoding has already been
61   // performed.
62   static absl::optional<PpsState> ParseInternal(rtc::BitBuffer* bit_buffer);
63   static bool ParsePpsIdsInternal(rtc::BitBuffer* bit_buffer,
64                                   uint32_t* pps_id,
65                                   uint32_t* sps_id);
66 };
67 
68 }  // namespace webrtc
69 
70 #endif  // COMMON_VIDEO_H265_PPS_PARSER_H_
71