gecko-dev/media/libcubeb/wasapi-drift.patch

From 6ae23a6355e35016ad7f01814e92e73b3047d54b Mon Sep 17 00:00:00 2001
From: Paul Adenot <paul@paul.cx>
Date: Thu, 29 Sep 2016 02:21:06 +0200
Subject: [PATCH] Fix drift in WASAPI when having different output and input
 sample device rate (#155)

* Round instead of ceiling to avoid rounding buildup of buffer size.

* Always consume all the data for an output buffer.

* Add padding only if we don't have enough input data in the linear buffer.

* Define NOMINMAX so that std::max compiles.
---
 src/cubeb_resampler.cpp        |  5 +++++
 src/cubeb_resampler_internal.h |  2 +-
 src/cubeb_wasapi.cpp           | 11 +++++------
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/cubeb_resampler.cpp b/src/cubeb_resampler.cpp
index a476744..7b9326e 100644
--- a/src/cubeb_resampler.cpp
+++ b/src/cubeb_resampler.cpp
@@ -4,6 +4,11 @@
  * This program is made available under an ISC-style license.  See the
  * accompanying file LICENSE for details.
  */
+
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif // NOMINMAX
+
 #include <algorithm>
 #include <cmath>
 #include <cassert>
diff --git a/src/cubeb_resampler_internal.h b/src/cubeb_resampler_internal.h
index c547991..a605892 100644
--- a/src/cubeb_resampler_internal.h
+++ b/src/cubeb_resampler_internal.h
@@ -263,7 +263,7 @@ public:
    * number of output frames will be exactly equal. */
   uint32_t input_needed_for_output(uint32_t output_frame_count)
   {
-    return (uint32_t)ceilf((output_frame_count - samples_to_frames(resampling_out_buffer.length()))
+    return (uint32_t)roundf((output_frame_count - samples_to_frames(resampling_out_buffer.length()))
                           * resampling_ratio);
 
   }
diff --git a/src/cubeb_wasapi.cpp b/src/cubeb_wasapi.cpp
index 3a7f6fe..b17e7d5 100644
--- a/src/cubeb_wasapi.cpp
+++ b/src/cubeb_wasapi.cpp
@@ -613,7 +613,7 @@ bool get_input_buffer(cubeb_stream * stm)
 
 /* Get an output buffer from the render_client. It has to be released before
  * exiting the callback. */
-bool get_output_buffer(cubeb_stream * stm, size_t max_frames, float *& buffer, size_t & frame_count)
+bool get_output_buffer(cubeb_stream * stm, float *& buffer, size_t & frame_count)
 {
   UINT32 padding_out;
   HRESULT hr;
@@ -635,7 +635,7 @@ bool get_output_buffer(cubeb_stream * stm, size_t max_frames, float *& buffer, s
     return true;
   }
 
-  frame_count = std::min<size_t>(max_frames, stm->output_buffer_frame_count - padding_out);
+  frame_count = stm->output_buffer_frame_count - padding_out;
   BYTE * output_buffer;
 
   hr = stm->render_client->GetBuffer(frame_count, &output_buffer);
@@ -673,7 +673,7 @@ refill_callback_duplex(cubeb_stream * stm)
     return true;
   }
 
-  rv = get_output_buffer(stm, input_frames, output_buffer, output_frames);
+  rv = get_output_buffer(stm, output_buffer, output_frames);
   if (!rv) {
     hr = stm->render_client->ReleaseBuffer(output_frames, 0);
     return rv;
@@ -687,7 +687,7 @@ refill_callback_duplex(cubeb_stream * stm)
 
   // When WASAPI has not filled the input buffer yet, send silence.
   double output_duration = double(output_frames) / stm->output_mix_params.rate;
-  double input_duration = double(input_frames) / stm->input_mix_params.rate;
+  double input_duration = double(stm->linear_input_buffer.length() / stm->input_mix_params.channels) / stm->input_mix_params.rate;
   if (input_duration < output_duration) {
     size_t padding = size_t(round((output_duration - input_duration) * stm->input_mix_params.rate));
     LOG("padding silence: out=%f in=%f pad=%u\n", output_duration, input_duration, padding);
@@ -745,8 +745,7 @@ refill_callback_output(cubeb_stream * stm)
 
   XASSERT(!has_input(stm) && has_output(stm));
 
-  rv = get_output_buffer(stm, std::numeric_limits<size_t>::max(),
-                         output_buffer, output_frames);
+  rv = get_output_buffer(stm, output_buffer, output_frames);
   if (!rv) {
     return rv;
   }
-- 
2.7.4