mirror of
https://github.com/gnif/LookingGlass.git
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5681dcdbe7
Forward coalesced feedback through the broker to the render clock. Keep capture independent and apply the rate to WaveRT timing. Bound and slew targets, then restore unity when feedback stalls. Withdraw feedback after the watchdog makes fallback safe.
94 lines
2.7 KiB
C++
94 lines
2.7 KiB
C++
/**
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* Looking Glass
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* Copyright © 2017-2026 The Looking Glass Authors
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* https://looking-glass.io
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc., 59
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* Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#pragma once
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#include "Common.h"
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namespace LGAudio
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{
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/**
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* A correlated sample of the audio time domain and the Windows QPC time
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* domain. Position drives audio progress; QpcPosition timestamps that
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* position for WaveRT clients.
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*/
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struct AudioClockSnapshot
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{
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ULONGLONG Position;
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ULONGLONG Frequency;
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ULONGLONG QpcPosition;
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ULONGLONG QpcFrequency;
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// Audio-position ticks advanced per QPC tick in unsigned Q32.32.
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ULONGLONG RateQ32;
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};
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constexpr ULONGLONG kAudioClockRateOneQ32 = 1ULL << 32;
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constexpr ULONG kAudioClockMaximumCorrectionPpm = 5000;
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constexpr ULONG kAudioClockMaximumSlewPpmPerSecond = 5000;
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/**
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* Adapter-owned affine clock. Position is continuous and monotonic while
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* RateQ32 may be updated to discipline a render endpoint to a remote sink.
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* QpcPosition always remains in the local Windows QPC domain.
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*/
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class CAudioClock final
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{
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public:
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CAudioClock();
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CAudioClock(const CAudioClock &) = delete;
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CAudioClock & operator=(const CAudioClock &) = delete;
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_IRQL_requires_max_(PASSIVE_LEVEL)
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NTSTATUS Initialize();
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_IRQL_requires_max_(DISPATCH_LEVEL)
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AudioClockSnapshot GetSnapshot();
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_IRQL_requires_max_(DISPATCH_LEVEL)
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bool SetRate(_In_ ULONGLONG rateQ32);
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_IRQL_requires_max_(DISPATCH_LEVEL)
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void ResetRate();
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private:
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_Requires_lock_held_(m_lock)
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void AdvanceLocked(_In_ ULONGLONG qpcPosition);
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_Requires_lock_held_(m_lock)
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void UpdateLocked(_In_ ULONGLONG qpcPosition);
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KSPIN_LOCK m_lock;
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ULONGLONG m_frequency;
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ULONGLONG m_position;
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ULONGLONG m_positionFractionQ32;
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ULONGLONG m_lastQpcPosition;
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ULONGLONG m_rateQ32;
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ULONGLONG m_lastRateUpdateQpc;
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ULONGLONG m_feedbackDeadlineQpc;
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};
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}
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using LGAudio::AudioClockSnapshot;
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using LGAudio::CAudioClock;
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using LGAudio::kAudioClockMaximumCorrectionPpm;
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using LGAudio::kAudioClockMaximumSlewPpmPerSecond;
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using LGAudio::kAudioClockRateOneQ32;
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