blob: f9b856f6445ec84bf7637d61f959b273e8403425 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
/*
* 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 "common_video/h264/sps_parser.h"
#include "rtc_base/buffer.h"
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, 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,
absl::optional<SpsParser::SpsState>* sps,
rtc::Buffer* destination);
};
} // namespace webrtc
#endif // COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
|
