| /* |
| * 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_SPS_VUI_REWRITER_H_ |
| #define WEBRTC_COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_ |
| |
| #include "webrtc/api/optional.h" |
| #include "webrtc/common_video/h264/sps_parser.h" |
| #include "webrtc/rtc_base/buffer.h" |
| |
| namespace rtc { |
| class BitBuffer; |
| } |
| |
| namespace webrtc { |
| |
| // A class that can parse an SPS block of a NAL unit and if necessary |
| // creates a copy with updated settings to allow for faster decoding for streams |
| // that use picture order count type 0. Streams in that format incur additional |
| // delay because it allows decode order to differ from render order. |
| // The mechanism used is to rewrite (edit or add) the SPS's VUI to contain |
| // restrictions on the maximum number of reordered pictures. This reduces |
| // latency significantly, though it still adds about a frame of latency to |
| // decoding. |
| class SpsVuiRewriter : private SpsParser { |
| public: |
| enum class ParseResult { kFailure, kPocOk, kVuiOk, kVuiRewritten }; |
| |
| // Parses an SPS block and if necessary copies it and rewrites the VUI. |
| // Returns kFailure on failure, kParseOk if parsing succeeded and no update |
| // was necessary and kParsedAndModified if an updated copy of buffer was |
| // written to destination. destination may be populated with some data even if |
| // no rewrite was necessary, but the end offset should remain unchanged. |
| // Unless parsing fails, the sps parameter will be populated with the parsed |
| // SPS state. This function assumes that any previous headers |
| // (NALU start, type, Stap-A, etc) have already been parsed and that RBSP |
| // decoding has been performed. |
| static ParseResult ParseAndRewriteSps(const uint8_t* buffer, |
| size_t length, |
| rtc::Optional<SpsParser::SpsState>* sps, |
| rtc::Buffer* destination); |
| }; |
| |
| } // namespace webrtc |
| |
| #endif // WEBRTC_COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_ |