61 lines
1.8 KiB
C++
61 lines
1.8 KiB
C++
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/*
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* Copyright (c) 2018 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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#include <memory>
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#include <vector>
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#include "common_video/h265/h265_common.h"
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#include "common_video/h265/h265_vps_parser.h"
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#include "rtc_base/bit_buffer.h"
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#include "rtc_base/logging.h"
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namespace {
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typedef absl::optional<webrtc::H265VpsParser::VpsState> OptionalVps;
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#define RETURN_EMPTY_ON_FAIL(x) \
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if (!(x)) { \
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return OptionalVps(); \
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}
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} // namespace
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namespace webrtc {
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H265VpsParser::VpsState::VpsState() = default;
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// General note: this is based off the 06/2019 version of the H.265 standard.
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// You can find it on this page:
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// http://www.itu.int/rec/T-REC-H.265
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// Unpack RBSP and parse SPS state from the supplied buffer.
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absl::optional<H265VpsParser::VpsState> H265VpsParser::ParseVps(
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const uint8_t* data,
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size_t length) {
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std::vector<uint8_t> unpacked_buffer = H265::ParseRbsp(data, length);
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rtc::BitBuffer bit_buffer(unpacked_buffer.data(), unpacked_buffer.size());
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return ParseInternal(&bit_buffer);
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}
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absl::optional<H265VpsParser::VpsState> H265VpsParser::ParseInternal(
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rtc::BitBuffer* buffer) {
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// Now, we need to use a bit buffer to parse through the actual HEVC VPS
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// format. See Section 7.3.2.1 ("Video parameter set RBSP syntax") of the
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// H.265 standard for a complete description.
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VpsState vps;
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// vps_video_parameter_set_id: u(4)
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vps.id = 0;
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RETURN_EMPTY_ON_FAIL(buffer->ReadBits(&vps.id, 4));
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return OptionalVps(vps);
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}
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} // namespace webrtc
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