From 5cfbfd364ead2d93c2d68934c3e49b96099adc7b Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Mon, 20 Aug 2018 11:47:25 -0400
Subject: [PATCH] Set the playback RingBuffer latency appropriately for seeking

---
 src/AudioIO.cpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/AudioIO.cpp b/src/AudioIO.cpp
index 8561e3b79..f71cae387 100644
--- a/src/AudioIO.cpp
+++ b/src/AudioIO.cpp
@@ -2254,8 +2254,10 @@ bool AudioIO::AllocateBuffers(
    // thread, in many smaller pieces.
    double playbackTime = 4.0;
    if (scrubbing)
+      // Specify a very short minimum batch for non-seek scrubbing, to allow
+      // more frequent polling of the mouse
       playbackTime =
-      lrint(options.pScrubbingOptions->delay * mRate) / mRate;
+         lrint(options.pScrubbingOptions->delay * mRate) / mRate;
    
    wxASSERT( playbackTime >= 0 );
    mPlaybackSamplesToCopy = playbackTime * mRate;
@@ -2294,6 +2296,13 @@ bool AudioIO::AllocateBuffers(
                     Mixer::WarpOptions(mPlaybackSchedule.mTimeTrack);
 
             mPlaybackQueueMinimum = mPlaybackSamplesToCopy;
+            if (scrubbing)
+               // Specify enough playback RingBuffer latency so we can refill
+               // once every seek stutter without falling behind the demand.
+               // (Scrub might switch in and out of seeking with left mouse
+               // presses in the ruler)
+               mPlaybackQueueMinimum = lrint(
+                  2 * options.pScrubbingOptions->minStutterTime * mRate );
             mPlaybackQueueMinimum =
                std::min( mPlaybackQueueMinimum, playbackBufferSize );