90 lines
2.9 KiB
C
90 lines
2.9 KiB
C
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/*
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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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#ifndef WEBRTC_COMMON_VIDEO_H264_H264_COMMON_H_
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#define WEBRTC_COMMON_VIDEO_H264_H264_COMMON_H_
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#include <memory>
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#include <vector>
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#include "webrtc/base/common.h"
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#include "webrtc/base/buffer.h"
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namespace webrtc {
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namespace H264 {
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// The size of a full NALU start sequence {0 0 0 1}, used for the first NALU
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// of an access unit, and for SPS and PPS blocks.
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const size_t kNaluLongStartSequenceSize = 4;
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// The size of a shortened NALU start sequence {0 0 1}, that may be used if
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// not the first NALU of an access unit or an SPS or PPS block.
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const size_t kNaluShortStartSequenceSize = 3;
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// The size of the NALU type byte (1).
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const size_t kNaluTypeSize = 1;
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enum NaluType : uint8_t {
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kSlice = 1,
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kIdr = 5,
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kSei = 6,
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kSps = 7,
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kPps = 8,
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kAud = 9,
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kEndOfSequence = 10,
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kEndOfStream = 11,
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kFiller = 12,
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kStapA = 24,
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kFuA = 28
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};
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enum SliceType : uint8_t { kP = 0, kB = 1, kI = 2, kSp = 3, kSi = 4 };
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struct NaluIndex {
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// Start index of NALU, including start sequence.
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size_t start_offset;
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// Start index of NALU payload, typically type header.
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size_t payload_start_offset;
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// Length of NALU payload, in bytes, counting from payload_start_offset.
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size_t payload_size;
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};
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// Returns a vector of the NALU indices in the given buffer.
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std::vector<NaluIndex> FindNaluIndices(const uint8_t* buffer,
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size_t buffer_size);
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// Get the NAL type from the header byte immediately following start sequence.
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NaluType ParseNaluType(uint8_t data);
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// Methods for parsing and writing RBSP. See section 7.4.1 of the H264 spec.
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//
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// The following sequences are illegal, and need to be escaped when encoding:
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// 00 00 00 -> 00 00 03 00
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// 00 00 01 -> 00 00 03 01
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// 00 00 02 -> 00 00 03 02
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// And things in the source that look like the emulation byte pattern (00 00 03)
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// need to have an extra emulation byte added, so it's removed when decoding:
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// 00 00 03 -> 00 00 03 03
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//
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// Decoding is simply a matter of finding any 00 00 03 sequence and removing
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// the 03 emulation byte.
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// Parse the given data and remove any emulation byte escaping.
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std::unique_ptr<rtc::Buffer> ParseRbsp(const uint8_t* data, size_t length);
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// Write the given data to the destination buffer, inserting and emulation
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// bytes in order to escape any data the could be interpreted as a start
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// sequence.
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void WriteRbsp(const uint8_t* bytes, size_t length, rtc::Buffer* destination);
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} // namespace H264
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} // namespace webrtc
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#endif // WEBRTC_COMMON_VIDEO_H264_H264_COMMON_H_
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