From 6a65c0fa3881ea65f199fa3ec159b1663c7ed462 Mon Sep 17 00:00:00 2001
From: itsmattkc <34096995+itsmattkc@users.noreply.github.com>
Date: Fri, 27 May 2022 10:04:30 -0700
Subject: [PATCH] render: clamp audio samples when finalized

---
 app/codec/samplebuffer.cpp     | 37 ++++++++++++++++++++++++++++++++++
 app/codec/samplebuffer.h       |  6 ++++++
 app/render/renderprocessor.cpp | 14 ++++++++-----
 3 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/app/codec/samplebuffer.cpp b/app/codec/samplebuffer.cpp
index 3c0096867..fd4dfa5a7 100644
--- a/app/codec/samplebuffer.cpp
+++ b/app/codec/samplebuffer.cpp
@@ -191,6 +191,13 @@ void SampleBuffer::transform_volume_for_sample_on_channel(int sample_index, int
   data_[channel][sample_index] *= volume;
 }
 
+void SampleBuffer::clamp()
+{
+  for (int i=0; i<channel_count(); i++) {
+    clamp_channel(i);
+  }
+}
+
 void SampleBuffer::silence()
 {
   silence(0, sample_count_per_channel_);
@@ -223,4 +230,34 @@ void SampleBuffer::set(int channel, const float *data, int sample_offset, int sa
   memcpy(&data_[channel].data()[sample_offset], data, sizeof(float) * sample_length);
 }
 
+void SampleBuffer::clamp_channel(int channel)
+{
+  const float min = -1.0f;
+  const float max = 1.0f;
+
+  float *cdat = data_[channel].data();
+  int unopt_start = 0;
+
+#if defined(Q_PROCESSOR_X86) || defined(Q_PROCESSOR_ARM)
+  __m128 min_sse = _mm_load1_ps(&min);
+  __m128 max_sse = _mm_load1_ps(&max);
+
+  unopt_start = (sample_count_per_channel_ / 4) * 4;
+  for (int j=0; j<unopt_start; j+=4) {
+    float *here = cdat + j;
+    __m128 samples = _mm_loadu_ps(here);
+
+    samples = _mm_max_ps(samples, min_sse);
+    samples = _mm_min_ps(samples, max_sse);
+
+    _mm_storeu_ps(here, samples);
+  }
+#endif
+
+  for (int sample=unopt_start; sample<sample_count(); sample++) {
+    float &s = data(channel)[sample];
+    s = std::clamp(s, min, max);
+  }
+}
+
 }
diff --git a/app/codec/samplebuffer.h b/app/codec/samplebuffer.h
index b8976af07..6b46a91d3 100644
--- a/app/codec/samplebuffer.h
+++ b/app/codec/samplebuffer.h
@@ -71,6 +71,8 @@ public:
     return r;
   }
 
+  int channel_count() const { return data_.size(); }
+
   bool is_allocated() const;
   void allocate();
   void destroy();
@@ -82,6 +84,8 @@ public:
   void transform_volume_for_sample(int sample_index, float volume);
   void transform_volume_for_sample_on_channel(int sample_index, int channel, float volume);
 
+  void clamp();
+
   void silence();
   void silence(int start_sample, int end_sample);
   void silence_bytes(int start_byte, int end_byte);
@@ -93,6 +97,8 @@ public:
   }
 
 private:
+  void clamp_channel(int channel);
+
   AudioParams audio_params_;
 
   int sample_count_per_channel_;
diff --git a/app/render/renderprocessor.cpp b/app/render/renderprocessor.cpp
index 064279753..475491a77 100644
--- a/app/render/renderprocessor.cpp
+++ b/app/render/renderprocessor.cpp
@@ -215,11 +215,15 @@ void RenderProcessor::Run()
     ResolveJobs(sample_val, time);
 
     SampleBuffer samples = sample_val.toSamples();
-    if (samples.is_allocated() && ticket_->property("enablewaveforms").toBool()) {
-      AudioVisualWaveform vis;
-      vis.set_channel_count(samples.audio_params().channel_count());
-      vis.OverwriteSamples(samples, samples.audio_params().sample_rate());
-      ticket_->setProperty("waveform", QVariant::fromValue(vis));
+    if (samples.is_allocated()) {
+      samples.clamp();
+
+      if (ticket_->property("enablewaveforms").toBool()) {
+        AudioVisualWaveform vis;
+        vis.set_channel_count(samples.audio_params().channel_count());
+        vis.OverwriteSamples(samples, samples.audio_params().sample_rate());
+        ticket_->setProperty("waveform", QVariant::fromValue(vis));
+      }
     }
 
     if (HeardCancel()) {