88fa2ab966
Bug: webrtc:10256 Change-Id: I5c28e69973cc5666deba4a1d7d660dc91f82c9f6 Reviewed-on: https://webrtc-review.googlesource.com/c/120349 Commit-Queue: Sergey Silkin <ssilkin@webrtc.org> Reviewed-by: Stefan Holmer <stefan@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Cr-Commit-Position: refs/heads/master@{#26521}
55 lines
2.2 KiB
C++
55 lines
2.2 KiB
C++
/*
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* Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*
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*/
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#ifndef COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
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#define COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
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#include <stddef.h>
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#include <stdint.h>
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#include "absl/types/optional.h"
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#include "common_video/h264/sps_parser.h"
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#include "rtc_base/buffer.h"
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namespace webrtc {
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// A class that can parse an SPS block of a NAL unit and if necessary
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// creates a copy with updated settings to allow for faster decoding for streams
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// that use picture order count type 0. Streams in that format incur additional
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// delay because it allows decode order to differ from render order.
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// The mechanism used is to rewrite (edit or add) the SPS's VUI to contain
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// restrictions on the maximum number of reordered pictures. This reduces
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// latency significantly, though it still adds about a frame of latency to
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// decoding.
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class SpsVuiRewriter : private SpsParser {
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public:
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enum class ParseResult { kFailure, kVuiOk, kVuiRewritten };
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// Parses an SPS block and if necessary copies it and rewrites the VUI.
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// Returns kFailure on failure, kParseOk if parsing succeeded and no update
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// was necessary and kParsedAndModified if an updated copy of buffer was
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// written to destination. destination may be populated with some data even if
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// no rewrite was necessary, but the end offset should remain unchanged.
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// Unless parsing fails, the sps parameter will be populated with the parsed
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// SPS state. This function assumes that any previous headers
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// (NALU start, type, Stap-A, etc) have already been parsed and that RBSP
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// decoding has been performed.
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static ParseResult ParseAndRewriteSps(
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const uint8_t* buffer,
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size_t length,
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absl::optional<SpsParser::SpsState>* sps,
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rtc::Buffer* destination);
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};
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} // namespace webrtc
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#endif // COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
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