3b3c9c4eb0
Picture ids are now unwrapped in the RtpFrameReferenceFinder class, so the FrameBuffer2 no longer need to treat them as wrapping. BUG=webrtc:7874 Review-Url: https://codereview.webrtc.org/3012883002 Cr-Commit-Position: refs/heads/master@{#19779}
129 lines
4.5 KiB
C++
129 lines
4.5 KiB
C++
/*
|
|
* 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 WEBRTC_MODULES_VIDEO_CODING_SEQUENCE_NUMBER_UTIL_H_
|
|
#define WEBRTC_MODULES_VIDEO_CODING_SEQUENCE_NUMBER_UTIL_H_
|
|
|
|
#include <limits>
|
|
#include <type_traits>
|
|
|
|
#include "webrtc/api/optional.h"
|
|
#include "webrtc/rtc_base/mod_ops.h"
|
|
#include "webrtc/rtc_base/safe_compare.h"
|
|
|
|
namespace webrtc {
|
|
|
|
// Test if the sequence number |a| is ahead or at sequence number |b|.
|
|
//
|
|
// If |M| is an even number and the two sequence numbers are at max distance
|
|
// from each other, then the sequence number with the highest value is
|
|
// considered to be ahead.
|
|
template <typename T, T M>
|
|
inline typename std::enable_if<(M > 0), bool>::type AheadOrAt(T a, T b) {
|
|
static_assert(std::is_unsigned<T>::value,
|
|
"Type must be an unsigned integer.");
|
|
const T maxDist = M / 2;
|
|
if (!(M & 1) && MinDiff<T, M>(a, b) == maxDist)
|
|
return b < a;
|
|
return ForwardDiff<T, M>(b, a) <= maxDist;
|
|
}
|
|
|
|
template <typename T, T M>
|
|
inline typename std::enable_if<(M == 0), bool>::type AheadOrAt(T a, T b) {
|
|
static_assert(std::is_unsigned<T>::value,
|
|
"Type must be an unsigned integer.");
|
|
const T maxDist = std::numeric_limits<T>::max() / 2 + T(1);
|
|
if (a - b == maxDist)
|
|
return b < a;
|
|
return ForwardDiff(b, a) < maxDist;
|
|
}
|
|
|
|
template <typename T>
|
|
inline bool AheadOrAt(T a, T b) {
|
|
return AheadOrAt<T, 0>(a, b);
|
|
}
|
|
|
|
// Test if the sequence number |a| is ahead of sequence number |b|.
|
|
//
|
|
// If |M| is an even number and the two sequence numbers are at max distance
|
|
// from each other, then the sequence number with the highest value is
|
|
// considered to be ahead.
|
|
template <typename T, T M = 0>
|
|
inline bool AheadOf(T a, T b) {
|
|
static_assert(std::is_unsigned<T>::value,
|
|
"Type must be an unsigned integer.");
|
|
return a != b && AheadOrAt<T, M>(a, b);
|
|
}
|
|
|
|
// Comparator used to compare sequence numbers in a continuous fashion.
|
|
//
|
|
// WARNING! If used to sort sequence numbers of length M then the interval
|
|
// covered by the sequence numbers may not be larger than floor(M/2).
|
|
template <typename T, T M = 0>
|
|
struct AscendingSeqNumComp {
|
|
bool operator()(T a, T b) const { return AheadOf<T, M>(a, b); }
|
|
};
|
|
|
|
// Comparator used to compare sequence numbers in a continuous fashion.
|
|
//
|
|
// WARNING! If used to sort sequence numbers of length M then the interval
|
|
// covered by the sequence numbers may not be larger than floor(M/2).
|
|
template <typename T, T M = 0>
|
|
struct DescendingSeqNumComp {
|
|
bool operator()(T a, T b) const { return AheadOf<T, M>(b, a); }
|
|
};
|
|
|
|
// A sequencer number unwrapper where the start value of the unwrapped sequence
|
|
// can be set. The unwrapped value is not allowed to wrap.
|
|
template <typename T, T M = 0>
|
|
class SeqNumUnwrapper {
|
|
// Use '<' instead of rtc::SafeLt to avoid crbug.com/753488
|
|
static_assert(
|
|
std::is_unsigned<T>::value &&
|
|
std::numeric_limits<T>::max() < std::numeric_limits<uint64_t>::max(),
|
|
"Type unwrapped must be an unsigned integer smaller than uint64_t.");
|
|
|
|
public:
|
|
// We want a default value that is close to 2^62 for a two reasons. Firstly,
|
|
// we can unwrap wrapping numbers in either direction, and secondly, the
|
|
// unwrapped numbers can be stored in either int64_t or uint64_t. We also want
|
|
// the default value to be human readable, which makes a power of 10 suitable.
|
|
static constexpr uint64_t kDefaultStartValue = 1000000000000000000UL;
|
|
|
|
SeqNumUnwrapper() : last_unwrapped_(kDefaultStartValue) {}
|
|
explicit SeqNumUnwrapper(uint64_t start_at) : last_unwrapped_(start_at) {}
|
|
|
|
uint64_t Unwrap(T value) {
|
|
if (!last_value_)
|
|
last_value_.emplace(value);
|
|
|
|
uint64_t unwrapped = 0;
|
|
if (AheadOrAt<T, M>(value, *last_value_)) {
|
|
unwrapped = last_unwrapped_ + ForwardDiff<T, M>(*last_value_, value);
|
|
RTC_CHECK_GE(unwrapped, last_unwrapped_);
|
|
} else {
|
|
unwrapped = last_unwrapped_ - ReverseDiff<T, M>(*last_value_, value);
|
|
RTC_CHECK_LT(unwrapped, last_unwrapped_);
|
|
}
|
|
|
|
*last_value_ = value;
|
|
last_unwrapped_ = unwrapped;
|
|
return last_unwrapped_;
|
|
}
|
|
|
|
private:
|
|
uint64_t last_unwrapped_;
|
|
rtc::Optional<T> last_value_;
|
|
};
|
|
|
|
} // namespace webrtc
|
|
|
|
#endif // WEBRTC_MODULES_VIDEO_CODING_SEQUENCE_NUMBER_UTIL_H_
|