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winmidi: convert input timestamps from MidiClock ticks to nanoseconds #263

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Merged
jcelerier merged 1 commit into from
Sep 28, 2026
Merged

winmidi: convert input timestamps from MidiClock ticks to nanoseconds #263

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18 changes: 16 additions & 2 deletions include/libremidi/backends/winmidi/midi_in.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,10 @@ class midi_in_impl final
: MidiSession::Create(to_hstring(configuration.client_name))}
{
this->client_open_ = stdx::error{};

m_tick_frequency_hz = MidiClock::TimestampFrequency();
if (m_tick_frequency_hz == 0)
m_tick_frequency_hz = 10'000'000; // 100 ns ticks
}

~midi_in_impl() override
Expand Down Expand Up @@ -181,6 +185,15 @@ class midi_in_impl final
}
#endif

// split in two so ticks * 1e9 can't overflow
std::uint64_t ticks_to_ns(std::uint64_t ticks) const noexcept
{
constexpr std::uint64_t ns_per_s = 1'000'000'000ull;
const std::uint64_t whole_seconds = ticks / m_tick_frequency_hz;
const std::uint64_t remainder_ticks = ticks % m_tick_frequency_hz;
return whole_seconds * ns_per_s + (remainder_ticks * ns_per_s) / m_tick_frequency_hz;
}

void process_message(
const winrt::Microsoft::Windows::Devices::Midi2::MidiMessageReceivedEventArgs& msg)
{
Expand All @@ -205,7 +218,7 @@ class midi_in_impl final
array_view<uint32_t> ref{ump_space};
b.GetMany(0, ref);

auto to_ns = [t = ump.Timestamp()] { return t; };
auto to_ns = [this, t = ump.Timestamp()] { return ticks_to_ns(t); };
m_processing.on_bytes(
{ump_space, ump_space + b.Size()}, m_processing.timestamp<timestamp_info>(to_ns, 0));
}
Expand Down Expand Up @@ -234,7 +247,7 @@ class midi_in_impl final
return;
}

auto to_ns = [t = timestamp] { return t; };
auto to_ns = [this, t = timestamp] { return ticks_to_ns(t); };
m_processing.on_bytes(
{ump, ump + wordCount}, m_processing.timestamp<timestamp_info>(to_ns, 0));
}
Expand Down Expand Up @@ -282,5 +295,6 @@ class midi_in_impl final
#endif
midi2::input_state_machine m_processing{this->configuration};
int m_group_filter = -1;
std::uint64_t m_tick_frequency_hz{};
};
}