92ea95e34a
In https://webrtc-review.googlesource.com/c/src/+/1560 we moved WebRTC from src/webrtc to src/ (in order to preserve an healthy git history). This CL takes care of fixing header guards, #include paths, etc... NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true TBR=tommi@webrtc.org Bug: chromium:611808 Change-Id: Iea91618212bee0af16aa3f05071eab8f93706578 Reviewed-on: https://webrtc-review.googlesource.com/1561 Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Henrik Kjellander <kjellander@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19846}
72 lines
2.6 KiB
C++
72 lines
2.6 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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#include "modules/rtp_rtcp/source/rtcp_packet/tmmb_item.h"
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#include "modules/rtp_rtcp/source/byte_io.h"
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#include "rtc_base/checks.h"
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#include "rtc_base/logging.h"
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namespace webrtc {
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namespace rtcp {
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TmmbItem::TmmbItem(uint32_t ssrc, uint64_t bitrate_bps, uint16_t overhead)
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: ssrc_(ssrc), bitrate_bps_(bitrate_bps), packet_overhead_(overhead) {
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RTC_DCHECK_LE(overhead, 0x1ffu);
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}
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// 0 1 2 3
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// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// 0 | SSRC |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// 4 | MxTBR Exp | MxTBR Mantissa |Measured Overhead|
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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bool TmmbItem::Parse(const uint8_t* buffer) {
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ssrc_ = ByteReader<uint32_t>::ReadBigEndian(&buffer[0]);
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// Read 4 bytes into 1 block.
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uint32_t compact = ByteReader<uint32_t>::ReadBigEndian(&buffer[4]);
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// Split 1 block into 3 components.
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uint8_t exponent = compact >> 26; // 6 bits.
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uint64_t mantissa = (compact >> 9) & 0x1ffff; // 17 bits.
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uint16_t overhead = compact & 0x1ff; // 9 bits.
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// Combine 3 components into 2 values.
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bitrate_bps_ = (mantissa << exponent);
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bool shift_overflow = (bitrate_bps_ >> exponent) != mantissa;
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if (shift_overflow) {
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LOG(LS_ERROR) << "Invalid tmmb bitrate value : " << mantissa
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<< "*2^" << static_cast<int>(exponent);
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return false;
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}
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packet_overhead_ = overhead;
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return true;
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}
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void TmmbItem::Create(uint8_t* buffer) const {
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constexpr uint64_t kMaxMantissa = 0x1ffff; // 17 bits.
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uint64_t mantissa = bitrate_bps_;
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uint32_t exponent = 0;
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while (mantissa > kMaxMantissa) {
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mantissa >>= 1;
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++exponent;
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}
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ByteWriter<uint32_t>::WriteBigEndian(&buffer[0], ssrc_);
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uint32_t compact = (exponent << 26) | (mantissa << 9) | packet_overhead_;
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ByteWriter<uint32_t>::WriteBigEndian(&buffer[4], compact);
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}
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void TmmbItem::set_packet_overhead(uint16_t overhead) {
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RTC_DCHECK_LE(overhead, 0x1ffu);
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packet_overhead_ = overhead;
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}
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} // namespace rtcp
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} // namespace webrtc
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