Defeat initial clock jitter for custom rates

3 files changed, 58 insertions, 0 deletions

diff --git a/src/AudioDevice.h b/src/AudioDevice.h
index 2617ca4..e78f06f 100644
--- a/src/AudioDevice.h
+++ b/src/AudioDevice.h
@@ -67,6 +67,7 @@ namespace SaneAudioRenderer
         REFERENCE_TIME   GetStreamLatency()  const { return m_backend->deviceLatency; }

 

         bool IsExclusive() const { return m_backend->exclusive; }

+        bool IsRealtime()  const { return m_backend->realtime; }

 

         bool IgnoredSystemChannelMixer() const { return m_backend->ignoredSystemChannelMixer; }

 

diff --git a/src/AudioRenderer.cpp b/src/AudioRenderer.cpp
index 7c28567..b8cf2fc 100644
--- a/src/AudioRenderer.cpp
+++ b/src/AudioRenderer.cpp
@@ -84,6 +84,28 @@ namespace SaneAudioRenderer
                 // Establish time/frame relation.

                 chunk = m_sampleCorrection.ProcessSample(pSample, sampleProps, m_live || m_externalClock);

 

+                // Drop frames if requested.

+                if (m_dropNextFrames > 0 && !chunk.IsEmpty())

+                {

+                    assert(!IsBitstreaming());

+

+                    const size_t chunkFrames = chunk.GetFrameCount();

+

+                    if (m_dropNextFrames >= chunkFrames)

+                    {

+                        DebugOut(ClassName(this), "dropping", chunkFrames, "frames");

+                        m_dropNextFrames -= chunkFrames;

+                        chunk = DspChunk();

+                        assert(chunk.IsEmpty());

+                    }

+                    else

+                    {

+                        DebugOut(ClassName(this), "dropping", m_dropNextFrames, "frames");

+                        chunk.ShrinkHead(chunkFrames - m_dropNextFrames);

+                        m_dropNextFrames = 0;

+                    }

+                }

+

                 // Apply clock corrections.

                 if (!m_live && m_device && m_state == State_Running)

                     ApplyClockCorrection();

@@ -220,6 +242,7 @@ namespace SaneAudioRenderer
                 m_myClock.UnslaveClockFromAudio();

                 m_device->Stop();

                 m_device->Reset();

+                m_dropNextFrames = 0;

                 m_sampleCorrection.NewDeviceBuffer();

                 InitializeProcessors();

                 m_startClockOffset = m_sampleCorrection.GetLastFrameEnd();

@@ -229,6 +252,7 @@ namespace SaneAudioRenderer
             else

             {

                 m_device->Reset();

+                m_dropNextFrames = 0;

                 m_sampleCorrection.NewDeviceBuffer();

                 InitializeProcessors();

             }

@@ -506,6 +530,35 @@ namespace SaneAudioRenderer
                     else if (m_sampleCorrection.GetLastFrameEnd() == 0)

                     {

                         DebugOut(ClassName(this), "empty start");

+                        const uint32_t rate = m_device->GetWaveFormat()->nSamplesPerSec;

+

+                        if (!m_bitstreaming && !m_device->IsRealtime())

+                        {

+                            size_t silenceFrames = rate * m_device->GetBufferDuration() / 5000; // Buffer / 5

+

+                            DspChunk chunk = DspChunk(m_device->GetDspFormat(), m_device->GetWaveFormat()->nChannels,

+                                                      silenceFrames, rate);

+                            ZeroMemory(chunk.GetData(), chunk.GetSize());

+

+                            DebugOut(ClassName(this), "pushing", silenceFrames, "frames of silence");

+                            m_device->Push(chunk, nullptr);

+

+                            m_startClockOffset -= llMulDiv(silenceFrames, OneSecond, rate, 0);

+

+                            jitter = EstimateSlavingJitter();

+                        }

+

+                        if (!m_bitstreaming && jitter < 0)

+                        {

+                            m_dropNextFrames = (size_t)llMulDiv(-jitter, rate, OneSecond, 0);

+

+                            if (m_dropNextFrames > 0)

+                            {

+                                DebugOut(ClassName(this), "will be dropping next", m_dropNextFrames, "frames");

+                                m_startClockOffset += llMulDiv(m_dropNextFrames, OneSecond, rate, 0);

+                                jitter = EstimateSlavingJitter();

+                            }

+                        }

                     }

 

                     DebugOut(ClassName(this), "predicting approx", jitter / 10000., "ms slaving jitter");

@@ -571,6 +624,8 @@ namespace SaneAudioRenderer
             }

             m_device = nullptr;

         }

+

+        m_dropNextFrames = 0;

     }

 

     REFERENCE_TIME AudioRenderer::EstimateSlavingJitter()

diff --git a/src/AudioRenderer.h b/src/AudioRenderer.h
index aff003f..c082cf1 100644
--- a/src/AudioRenderer.h
+++ b/src/AudioRenderer.h
@@ -146,5 +146,7 @@ namespace SaneAudioRenderer
 

         std::atomic<REFERENCE_TIME> m_guidedReclockOffset = 0;

         bool m_guidedReclockActive = false;

+

+        size_t m_dropNextFrames = 0;

     };

 }