1 /* 2 * Copyright (c) 2015 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 WEBRTC_MODULES_RTP_RTCP_SOURCE_H264_BITSTREAM_PARSER_H_ 12 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_H264_BITSTREAM_PARSER_H_ 13 14 #include <stddef.h> 15 #include <stdint.h> 16 17 namespace rtc { 18 class BitBuffer; 19 } 20 21 namespace webrtc { 22 23 // Stateful H264 bitstream parser (due to SPS/PPS). Used to parse out QP values 24 // from the bitstream. 25 // TODO(pbos): Unify with RTP SPS parsing and only use one H264 parser. 26 // TODO(pbos): If/when this gets used on the receiver side CHECKs must be 27 // removed and gracefully abort as we have no control over receive-side 28 // bitstreams. 29 class H264BitstreamParser { 30 public: 31 // Parse an additional chunk of H264 bitstream. 32 void ParseBitstream(const uint8_t* bitstream, size_t length); 33 34 // Get the last extracted QP value from the parsed bitstream. 35 bool GetLastSliceQp(int* qp) const; 36 37 private: 38 // Captured in SPS and used when parsing slice NALUs. 39 struct SpsState { 40 SpsState(); 41 42 uint32_t delta_pic_order_always_zero_flag = 0; 43 uint32_t separate_colour_plane_flag = 0; 44 uint32_t frame_mbs_only_flag = 0; 45 uint32_t log2_max_frame_num_minus4 = 0; 46 uint32_t log2_max_pic_order_cnt_lsb_minus4 = 0; 47 uint32_t pic_order_cnt_type = 0; 48 }; 49 50 struct PpsState { 51 PpsState(); 52 53 bool bottom_field_pic_order_in_frame_present_flag = false; 54 bool weighted_pred_flag = false; 55 uint32_t weighted_bipred_idc = false; 56 uint32_t redundant_pic_cnt_present_flag = 0; 57 int pic_init_qp_minus26 = 0; 58 }; 59 60 void ParseSlice(const uint8_t* slice, size_t length); 61 bool ParseSpsNalu(const uint8_t* sps_nalu, size_t length); 62 bool ParsePpsNalu(const uint8_t* pps_nalu, size_t length); 63 bool ParseNonParameterSetNalu(const uint8_t* source, 64 size_t source_length, 65 uint8_t nalu_type); 66 67 // SPS/PPS state, updated when parsing new SPS/PPS, used to parse slices. 68 bool sps_parsed_ = false; 69 SpsState sps_; 70 bool pps_parsed_ = false; 71 PpsState pps_; 72 73 // Last parsed slice QP. 74 bool last_slice_qp_delta_parsed_ = false; 75 int32_t last_slice_qp_delta_ = 0; 76 }; 77 78 } // namespace webrtc 79 80 #endif // WEBRTC_MODULES_RTP_RTCP_SOURCE_H264_BITSTREAM_PARSER_H_ 81