Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef TIME_UNITS_H
#define TIME_UNITS_H
#include <limits>
#include <type_traits>
#include "Intervals.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/FloatingPoint.h"
#include "mozilla/Maybe.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "nsPrintfCString.h"
namespace mozilla::media {
class TimeIntervals;
} // namespace mozilla::media
// CopyChooser specialization for nsTArray
template <>
struct nsTArray_RelocationStrategy<mozilla::media::TimeIntervals> {
using Type =
nsTArray_RelocateUsingMoveConstructor<mozilla::media::TimeIntervals>;
};
namespace mozilla {
// Number of milliseconds per second. 1e3.
static const int64_t MSECS_PER_S = 1000;
// Number of microseconds per second. 1e6.
static const int64_t USECS_PER_S = 1000000;
// Number of nanoseconds per second. 1e9.
static const int64_t NSECS_PER_S = 1000000000;
namespace media {
#ifndef PROCESS_DECODE_LOG
# define PROCESS_DECODE_LOG(sample) \
MOZ_LOG(sPDMLog, mozilla::LogLevel::Verbose, \
("ProcessDecode: mDuration=%" PRIu64 "µs ; mTime=%" PRIu64 \
"µs ; mTimecode=%" PRIu64 "µs", \
(sample)->mDuration.ToMicroseconds(), \
(sample)->mTime.ToMicroseconds(), \
(sample)->mTimecode.ToMicroseconds()))
#endif // PROCESS_DECODE_LOG
// TimeUnit is a class that represents a time value, that can be negative or
// positive.
//
// Internally, it works by storing a numerator (the tick numbers), that uses
// checked arithmetics, and a denominator (the base), that is a regular integer
// on which arithmetics is never performed, and is only set at construction, or
// replaced.
//
// Dividing the tick count by the base always yields a value in seconds,
// but it's very useful to have a base that is dependant on the context: it can
// be the sample-rate of an audio stream, the time base of an mp4, that's often
// 90000 because it's divisible by 24, 25 and 30.
//
// Keeping time like this allows performing calculations on time values with
// maximum precision, without having to have to care about rounding errors or
// precision loss.
//
// If not specified, the base is 1e6, representing microseconds, for historical
// reasons. Users can gradually move to more precise representations when
// needed.
//
// INT64_MAX has the special meaning of being +∞, and INT64_MIN means -∞. Any
// other value corresponds to a valid time.
//
// If an overflow or other problem occurs, the underlying CheckedInt<int64_t> is
// invalid and a crash is triggered.
class TimeUnit final {
public:
constexpr TimeUnit(CheckedInt64 aTicks, int64_t aBase)
: mTicks(aTicks), mBase(aBase) {
MOZ_RELEASE_ASSERT(mBase > 0);
}
explicit constexpr TimeUnit(CheckedInt64 aTicks)
: mTicks(aTicks), mBase(USECS_PER_S) {}
// Return the maximum number of ticks that a TimeUnit can contain.
static constexpr int64_t MaxTicks() {
return std::numeric_limits<int64_t>::max() - 1;
}
// This is only precise up to a point, which is aValue * aBase <= 2^53 - 1
static TimeUnit FromSeconds(double aValue, int64_t aBase = USECS_PER_S);
static constexpr TimeUnit FromMicroseconds(int64_t aValue) {
return TimeUnit(aValue, USECS_PER_S);
}
static TimeUnit FromHns(int64_t aValue, int64_t aBase) {
// Truncating here would mean a loss of precision.
return TimeUnit::FromNanoseconds(aValue * 100).ToBase<RoundPolicy>(aBase);
}
static constexpr TimeUnit FromNanoseconds(int64_t aValue) {
return TimeUnit(aValue, NSECS_PER_S);
}
static TimeUnit FromInfinity();
static TimeUnit FromNegativeInfinity();
static TimeUnit FromTimeDuration(const TimeDuration& aDuration);
static constexpr TimeUnit Zero(int64_t aBase = USECS_PER_S) {
return TimeUnit(0, aBase);
}
static constexpr TimeUnit Zero(const TimeUnit& aOther) {
return TimeUnit(0, aOther.mBase);
}
static TimeUnit Invalid();
int64_t ToMilliseconds() const;
int64_t ToMicroseconds() const;
int64_t ToNanoseconds() const;
int64_t ToTicksAtRate(int64_t aRate) const;
// Only to be used in release assertions or unit testing, returns true if this
// TimeUnit has base aBase
bool IsBase(int64_t aBase) const;
double ToSeconds() const;
nsCString ToString() const;
TimeDuration ToTimeDuration() const;
bool IsInfinite() const;
bool IsPositive() const;
bool IsPositiveOrZero() const;
bool IsZero() const;
bool IsNegative() const;
// Returns true if the fractions are equal when converted to the smallest
// base.
bool EqualsAtLowestResolution(const TimeUnit& aOther) const;
// Strict equality -- the fractions must be exactly equal
bool operator==(const TimeUnit& aOther) const;
bool operator!=(const TimeUnit& aOther) const;
bool operator>=(const TimeUnit& aOther) const;
bool operator>(const TimeUnit& aOther) const;
bool operator<=(const TimeUnit& aOther) const;
bool operator<(const TimeUnit& aOther) const;
TimeUnit operator%(const TimeUnit& aOther) const;
TimeUnit operator+(const TimeUnit& aOther) const;
TimeUnit operator-(const TimeUnit& aOther) const;
TimeUnit& operator+=(const TimeUnit& aOther);
TimeUnit& operator-=(const TimeUnit& aOther);
template <typename T>
TimeUnit operator*(T aVal) const {
// If required, use MultDouble below and with caution.
static_assert(std::is_integral_v<T>, "Must be an integral type");
return TimeUnit(mTicks * aVal, mBase);
}
TimeUnit MultDouble(double aVal) const;
friend TimeUnit operator/(const TimeUnit& aUnit, int64_t aVal) {
MOZ_DIAGNOSTIC_ASSERT(0 <= aVal && aVal <= UINT32_MAX);
return TimeUnit(aUnit.mTicks / aVal, aUnit.mBase);
}
friend TimeUnit operator%(const TimeUnit& aUnit, int64_t aVal) {
MOZ_DIAGNOSTIC_ASSERT(0 <= aVal && aVal <= UINT32_MAX);
return TimeUnit(aUnit.mTicks % aVal, aUnit.mBase);
}
struct TruncatePolicy {
template <typename T>
static T policy(T& aValue) {
return static_cast<T>(aValue);
}
};
struct RoundPolicy {
template <typename T>
static T policy(T& aValue) {
return std::round(aValue);
}
};
struct CeilingPolicy {
template <typename T>
static T policy(T& aValue) {
return std::ceil(aValue);
}
};
template <class RoundingPolicy = TruncatePolicy>
TimeUnit ToBase(int64_t aTargetBase) const {
double dummy = 0.0;
return ToBase<RoundingPolicy>(aTargetBase, dummy);
}
template <class RoundingPolicy = TruncatePolicy>
TimeUnit ToBase(const TimeUnit& aTimeUnit) const {
double dummy = 0.0;
return ToBase<RoundingPolicy>(aTimeUnit, dummy);
}
// Allow returning the same value, in a base that matches another TimeUnit.
template <class RoundingPolicy = TruncatePolicy>
TimeUnit ToBase(const TimeUnit& aTimeUnit, double& aOutError) const {
int64_t targetBase = aTimeUnit.mBase;
return ToBase<RoundingPolicy>(targetBase, aOutError);
}
template <class RoundingPolicy = TruncatePolicy>
TimeUnit ToBase(int64_t aTargetBase, double& aOutError) const {
aOutError = 0.0;
CheckedInt<int64_t> ticks = mTicks * aTargetBase;
if (ticks.isValid()) {
imaxdiv_t rv = imaxdiv(ticks.value(), mBase);
if (!rv.rem) {
return TimeUnit(rv.quot, aTargetBase);
}
}
double approx = static_cast<double>(mTicks.value()) *
static_cast<double>(aTargetBase) /
static_cast<double>(mBase);
double integer;
aOutError = modf(approx, &integer);
return TimeUnit(AssertedCast<int64_t>(RoundingPolicy::policy(approx)),
aTargetBase);
}
bool IsValid() const;
constexpr TimeUnit() = default;
TimeUnit(const TimeUnit&) = default;
TimeUnit& operator=(const TimeUnit&) = default;
bool IsPosInf() const;
bool IsNegInf() const;
// Allow serializing a TimeUnit via IPC
friend IPC::ParamTraits<mozilla::media::TimeUnit>;
#ifndef VISIBLE_TIMEUNIT_INTERNALS
private:
#endif
int64_t ToCommonUnit(int64_t aRatio) const;
// Reduce a TimeUnit to the smallest possible ticks and base. This is useful
// to comparison with big time values that can otherwise overflow.
TimeUnit Reduced() const;
CheckedInt64 mTicks{0};
// Default base is microseconds.
int64_t mBase{USECS_PER_S};
};
using NullableTimeUnit = Maybe<TimeUnit>;
using TimeInterval = Interval<TimeUnit>;
// A set of intervals, containing TimeUnit.
class TimeIntervals : public IntervalSet<TimeUnit> {
public:
using BaseType = IntervalSet<TimeUnit>;
using InnerType = TimeUnit;
// We can't use inherited constructors yet. So we have to duplicate all the
// constructors found in IntervalSet base class.
// all this could be later replaced with:
// using IntervalSet<TimeUnit>::IntervalSet;
// MOZ_IMPLICIT as we want to enable initialization in the form:
// TimeIntervals i = ... like we would do with IntervalSet<T> i = ...
MOZ_IMPLICIT TimeIntervals(const BaseType& aOther) : BaseType(aOther) {}
MOZ_IMPLICIT TimeIntervals(BaseType&& aOther) : BaseType(std::move(aOther)) {}
explicit TimeIntervals(const BaseType::ElemType& aOther) : BaseType(aOther) {}
explicit TimeIntervals(BaseType::ElemType&& aOther)
: BaseType(std::move(aOther)) {}
static TimeIntervals Invalid() {
return TimeIntervals(TimeInterval(TimeUnit::FromNegativeInfinity(),
TimeUnit::FromNegativeInfinity()));
}
bool IsInvalid() const {
return Length() == 1 && Start(0).IsNegInf() && End(0).IsNegInf();
}
// Returns the same interval, with a given base resolution.
TimeIntervals ToBase(const TimeUnit& aBase) const {
TimeIntervals output;
for (const auto& interval : mIntervals) {
TimeInterval convertedInterval{interval.mStart.ToBase(aBase),
interval.mEnd.ToBase(aBase),
interval.mFuzz.ToBase(aBase)};
output += convertedInterval;
}
return output;
}
// Returns the same interval, with a microsecond resolution. This is used to
// compare TimeUnits internal to demuxers (that use a base from the container)
// to floating point numbers in seconds from content.
TimeIntervals ToMicrosecondResolution() const {
TimeIntervals output;
for (const auto& interval : mIntervals) {
TimeInterval reducedPrecision{interval.mStart.ToBase(USECS_PER_S),
interval.mEnd.ToBase(USECS_PER_S),
interval.mFuzz.ToBase(USECS_PER_S)};
output += reducedPrecision;
}
return output;
}
nsCString ToString() const {
nsCString dump;
for (const auto& interval : mIntervals) {
dump += nsPrintfCString("[%s],", interval.ToString().get());
}
return dump;
}
TimeIntervals() = default;
};
using TimeRange = Interval<double>;
// A set of intervals, containing doubles that are seconds.
class TimeRanges : public IntervalSet<double> {
public:
using BaseType = IntervalSet<double>;
using InnerType = double;
using nld = std::numeric_limits<double>;
// We can't use inherited constructors yet. So we have to duplicate all the
// constructors found in IntervalSet base class.
// all this could be later replaced with:
// using IntervalSet<TimeUnit>::IntervalSet;
// MOZ_IMPLICIT as we want to enable initialization in the form:
// TimeIntervals i = ... like we would do with IntervalSet<T> i = ...
MOZ_IMPLICIT TimeRanges(const BaseType& aOther) : BaseType(aOther) {}
MOZ_IMPLICIT TimeRanges(BaseType&& aOther) : BaseType(std::move(aOther)) {}
explicit TimeRanges(const BaseType::ElemType& aOther) : BaseType(aOther) {}
explicit TimeRanges(BaseType::ElemType&& aOther)
: BaseType(std::move(aOther)) {}
static TimeRanges Invalid() {
return TimeRanges(TimeRange(-nld::infinity(), nld::infinity()));
}
bool IsInvalid() const {
return Length() == 1 && Start(0) == -nld::infinity() &&
End(0) == nld::infinity();
}
// Convert from TimeUnit-based intervals to second-based TimeRanges.
explicit TimeRanges(const TimeIntervals& aIntervals) {
for (const auto& interval : aIntervals) {
Add(TimeRange(interval.mStart.ToSeconds(), interval.mEnd.ToSeconds()));
}
}
TimeRanges ToMicrosecondResolution() const;
TimeRanges() = default;
};
} // namespace media
} // namespace mozilla
#endif // TIME_UNITS_H