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/*
* 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 COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
#define COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
#include <stddef.h>
#include <stdint.h>
#include "absl/types/optional.h"
#include "api/video/color_space.h"
#include "common_video/h264/sps_parser.h"
#include "rtc_base/buffer.h"
namespace webrtc {
// A class that can parse an SPS+VUI and if necessary creates a copy with
// updated parameters.
// The rewriter disables frame buffering. This should force decoders to deliver
// decoded frame immediately and, thus, reduce latency.
// The rewriter updates video signal type parameters if external parameters are
// provided.
class SpsVuiRewriter : private SpsParser {
public:
enum class ParseResult { kFailure, kVuiOk, kVuiRewritten };
enum class Direction { kIncoming, kOutgoing };
// 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,
absl::optional<SpsParser::SpsState>* sps,
const ColorSpace* color_space,
rtc::Buffer* destination,
Direction Direction);
// Parses NAL units from `buffer`, strips AUD blocks and rewrites VUI in SPS
// blocks if necessary.
static rtc::Buffer ParseOutgoingBitstreamAndRewrite(
rtc::ArrayView<const uint8_t> buffer,
const ColorSpace* color_space);
private:
static ParseResult ParseAndRewriteSps(
const uint8_t* buffer,
size_t length,
absl::optional<SpsParser::SpsState>* sps,
const ColorSpace* color_space,
rtc::Buffer* destination);
static void UpdateStats(ParseResult result, Direction direction);
};
} // namespace webrtc
#endif // COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
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