diff --git a/api/audio/audio_frame.cc b/api/audio/audio_frame.cc
index 375e1b5..ce89323 100644
--- a/api/audio/audio_frame.cc
+++ b/api/audio/audio_frame.cc
@@ -91,6 +91,16 @@
   if (this == &src)
     return;
 
+  if (muted_ && !src.muted()) {
+    // TODO: bugs.webrtc.org/5647 - Since the default value for `muted_` is
+    // false and `data_` may still be uninitialized (because we don't initialize
+    // data_ as part of construction), we clear the full buffer here before
+    // copying over new values. If we don't, msan might complain in some tests.
+    // Consider locking down construction, avoiding the default constructor and
+    // prefering construction that initializes all state.
+    memset(data_, 0, kMaxDataSizeBytes);
+  }
+
   timestamp_ = src.timestamp_;
   elapsed_time_ms_ = src.elapsed_time_ms_;
   ntp_time_ms_ = src.ntp_time_ms_;
@@ -104,11 +114,10 @@
   channel_layout_ = src.channel_layout_;
   absolute_capture_timestamp_ms_ = src.absolute_capture_timestamp_ms();
 
-  const size_t length = samples_per_channel_ * num_channels_;
-  RTC_CHECK_LE(length, kMaxDataSizeSamples);
-  if (!src.muted()) {
-    memcpy(data_, src.data(), sizeof(int16_t) * length);
-    muted_ = false;
+  auto data = src.data_view();
+  RTC_CHECK_LE(data.size(), kMaxDataSizeSamples);
+  if (!muted_ && !data.empty()) {
+    memcpy(&data_[0], &data[0], sizeof(int16_t) * data.size());
   }
 }
 
@@ -158,10 +167,12 @@
   RTC_CHECK_LE(total_samples, kMaxDataSizeSamples);
   RTC_CHECK_LE(num_channels, kMaxConcurrentChannels);
   // Sanity check for valid argument values during development.
-  // If `samples_per_channel` is <= kMaxConcurrentChannels but larger than 0,
+  // If `samples_per_channel` is < `num_channels` but larger than 0,
   // then chances are the order of arguments is incorrect.
   RTC_DCHECK((samples_per_channel == 0 && num_channels == 0) ||
-             samples_per_channel > kMaxConcurrentChannels);
+             num_channels <= samples_per_channel)
+      << "samples_per_channel=" << samples_per_channel
+      << "num_channels=" << num_channels;
 
   // TODO: bugs.webrtc.org/5647 - Can we skip zeroing the buffer?
   // Consider instead if we should rather zero the whole buffer when `muted_` is
diff --git a/audio/remix_resample.cc b/audio/remix_resample.cc
index a0cf7cc..06752c2 100644
--- a/audio/remix_resample.cc
+++ b/audio/remix_resample.cc
@@ -31,6 +31,7 @@
   dst_frame->packet_infos_ = src_frame.packet_infos_;
 }
 
+// TODO: b/335805780 - Accept ArrayView.
 void RemixAndResample(const int16_t* src_data,
                       size_t samples_per_channel,
                       size_t num_channels,
@@ -49,8 +50,11 @@
         << "dst_frame->num_channels_: " << dst_frame->num_channels_;
 
     AudioFrameOperations::DownmixChannels(
-        src_data, num_channels, samples_per_channel, dst_frame->num_channels_,
-        downmixed_audio);
+        rtc::ArrayView<const int16_t>(src_data,
+                                      num_channels * samples_per_channel),
+        num_channels, samples_per_channel, dst_frame->num_channels_,
+        rtc::ArrayView<int16_t>(&downmixed_audio[0], dst_frame->num_channels_ *
+                                                         samples_per_channel));
     audio_ptr = downmixed_audio;
     audio_ptr_num_channels = dst_frame->num_channels_;
   }
diff --git a/audio/utility/BUILD.gn b/audio/utility/BUILD.gn
index 983b628..c84302a 100644
--- a/audio/utility/BUILD.gn
+++ b/audio/utility/BUILD.gn
@@ -23,6 +23,7 @@
   ]
 
   deps = [
+    "../../api:array_view",
     "../../api/audio:audio_frame_api",
     "../../common_audio",
     "../../rtc_base:checks",
diff --git a/audio/utility/audio_frame_operations.cc b/audio/utility/audio_frame_operations.cc
index 47f7b71..23cc645 100644
--- a/audio/utility/audio_frame_operations.cc
+++ b/audio/utility/audio_frame_operations.cc
@@ -56,14 +56,13 @@
     result_frame->speech_type_ = AudioFrame::kUndefined;
 
   if (!frame_to_add.muted()) {
-    const int16_t* in_data = frame_to_add.data();
-    int16_t* out_data = result_frame->mutable_data();
-    size_t length =
-        frame_to_add.samples_per_channel_ * frame_to_add.num_channels_;
+    auto in_data = frame_to_add.data_view();
+    auto out_data = result_frame->mutable_data(
+        frame_to_add.samples_per_channel_, frame_to_add.num_channels_);
     if (no_previous_data) {
-      std::copy(in_data, in_data + length, out_data);
+      std::copy(in_data.begin(), in_data.end(), out_data.data());
     } else {
-      for (size_t i = 0; i < length; i++) {
+      for (size_t i = 0; i < in_data.size(); ++i) {
         const int32_t wrap_guard = static_cast<int32_t>(out_data[i]) +
                                    static_cast<int32_t>(in_data[i]);
         out_data[i] = rtc::saturated_cast<int16_t>(wrap_guard);
@@ -72,9 +71,11 @@
   }
 }
 
-void AudioFrameOperations::QuadToStereo(const int16_t* src_audio,
+void AudioFrameOperations::QuadToStereo(rtc::ArrayView<const int16_t> src_audio,
                                         size_t samples_per_channel,
-                                        int16_t* dst_audio) {
+                                        rtc::ArrayView<int16_t> dst_audio) {
+  RTC_DCHECK_EQ(src_audio.size(), samples_per_channel * 4);
+  RTC_DCHECK_EQ(dst_audio.size(), samples_per_channel * 2);
   for (size_t i = 0; i < samples_per_channel; i++) {
     dst_audio[i * 2] =
         (static_cast<int32_t>(src_audio[4 * i]) + src_audio[4 * i + 1]) >> 1;
@@ -93,30 +94,33 @@
                 AudioFrame::kMaxDataSizeSamples);
 
   if (!frame->muted()) {
-    QuadToStereo(frame->data(), frame->samples_per_channel_,
-                 frame->mutable_data());
+    auto current_data = frame->data_view();
+    QuadToStereo(current_data, frame->samples_per_channel_,
+                 frame->mutable_data(frame->samples_per_channel_, 2));
+  } else {
+    frame->num_channels_ = 2;
   }
-  frame->num_channels_ = 2;
 
   return 0;
 }
 
-void AudioFrameOperations::DownmixChannels(const int16_t* src_audio,
-                                           size_t src_channels,
-                                           size_t samples_per_channel,
-                                           size_t dst_channels,
-                                           int16_t* dst_audio) {
+void AudioFrameOperations::DownmixChannels(
+    rtc::ArrayView<const int16_t> src_audio,
+    size_t src_channels,
+    size_t samples_per_channel,
+    size_t dst_channels,
+    rtc::ArrayView<int16_t> dst_audio) {
+  RTC_DCHECK_EQ(src_audio.size(), src_channels * samples_per_channel);
+  RTC_DCHECK_EQ(dst_audio.size(), dst_channels * samples_per_channel);
   if (src_channels > 1 && dst_channels == 1) {
-    DownmixInterleavedToMono(src_audio, samples_per_channel, src_channels,
-                             dst_audio);
-    return;
+    DownmixInterleavedToMono(src_audio.data(), samples_per_channel,
+                             src_channels, &dst_audio[0]);
   } else if (src_channels == 4 && dst_channels == 2) {
     QuadToStereo(src_audio, samples_per_channel, dst_audio);
-    return;
+  } else {
+    RTC_DCHECK_NOTREACHED() << "src_channels: " << src_channels
+                            << ", dst_channels: " << dst_channels;
   }
-
-  RTC_DCHECK_NOTREACHED() << "src_channels: " << src_channels
-                          << ", dst_channels: " << dst_channels;
 }
 
 void AudioFrameOperations::DownmixChannels(size_t dst_channels,
@@ -153,14 +157,16 @@
   if (!frame->muted()) {
     // Up-mixing done in place. Going backwards through the frame ensure nothing
     // is irrevocably overwritten.
-    int16_t* frame_data = frame->mutable_data();
-    for (int i = frame->samples_per_channel_ - 1; i >= 0; i--) {
+    auto frame_data = frame->mutable_data(frame->samples_per_channel_,
+                                          target_number_of_channels);
+    for (int i = frame->samples_per_channel_ - 1; i >= 0; --i) {
       for (size_t j = 0; j < target_number_of_channels; ++j) {
         frame_data[target_number_of_channels * i + j] = frame_data[i];
       }
     }
+  } else {
+    frame->num_channels_ = target_number_of_channels;
   }
-  frame->num_channels_ = target_number_of_channels;
 }
 
 void AudioFrameOperations::SwapStereoChannels(AudioFrame* frame) {
diff --git a/audio/utility/audio_frame_operations.h b/audio/utility/audio_frame_operations.h
index 26a2d5e..7b076e1 100644
--- a/audio/utility/audio_frame_operations.h
+++ b/audio/utility/audio_frame_operations.h
@@ -15,6 +15,7 @@
 #include <stdint.h>
 
 #include "absl/base/attributes.h"
+#include "api/array_view.h"
 #include "api/audio/audio_frame.h"
 
 namespace webrtc {
@@ -36,9 +37,9 @@
   // Downmixes 4 channels `src_audio` to stereo `dst_audio`. This is an in-place
   // operation, meaning `src_audio` and `dst_audio` may point to the same
   // buffer.
-  static void QuadToStereo(const int16_t* src_audio,
+  static void QuadToStereo(rtc::ArrayView<const int16_t> src_audio,
                            size_t samples_per_channel,
-                           int16_t* dst_audio);
+                           rtc::ArrayView<int16_t> dst_audio);
 
   // `frame.num_channels_` will be updated. This version checks that
   // `num_channels_` is 4 channels.
@@ -48,11 +49,11 @@
   // This is an in-place operation, meaning `src_audio` and `dst_audio`
   // may point to the same buffer. Supported channel combinations are
   // Stereo to Mono, Quad to Mono, and Quad to Stereo.
-  static void DownmixChannels(const int16_t* src_audio,
+  static void DownmixChannels(rtc::ArrayView<const int16_t> src_audio,
                               size_t src_channels,
                               size_t samples_per_channel,
                               size_t dst_channels,
-                              int16_t* dst_audio);
+                              rtc::ArrayView<int16_t> dst_audio);
 
   // `frame.num_channels_` will be updated. This version checks that
   // `num_channels_` and `dst_channels` are valid and performs relevant downmix.
diff --git a/audio/utility/audio_frame_operations_unittest.cc b/audio/utility/audio_frame_operations_unittest.cc
index 1a2c16e..a1f8db3 100644
--- a/audio/utility/audio_frame_operations_unittest.cc
+++ b/audio/utility/audio_frame_operations_unittest.cc
@@ -18,13 +18,10 @@
 
 class AudioFrameOperationsTest : public ::testing::Test {
  protected:
-  AudioFrameOperationsTest() {
-    // Set typical values.
-    frame_.samples_per_channel_ = 320;
-    frame_.num_channels_ = 2;
-  }
+  AudioFrameOperationsTest() = default;
 
-  AudioFrame frame_;
+  // Set typical values.
+  AudioFrame frame_{/*sample_rate=*/32000, /*num_channels*/ 2};
 };
 
 class AudioFrameOperationsDeathTest : public AudioFrameOperationsTest {};
@@ -34,7 +31,8 @@
                   int16_t ch3,
                   int16_t ch4,
                   AudioFrame* frame) {
-  int16_t* frame_data = frame->mutable_data();
+  rtc::ArrayView<int16_t> frame_data =
+      frame->mutable_data(frame->samples_per_channel_, 4);
   for (size_t i = 0; i < frame->samples_per_channel_ * 4; i += 4) {
     frame_data[i] = ch1;
     frame_data[i + 1] = ch2;
@@ -44,7 +42,8 @@
 }
 
 void SetFrameData(int16_t left, int16_t right, AudioFrame* frame) {
-  int16_t* frame_data = frame->mutable_data();
+  rtc::ArrayView<int16_t> frame_data =
+      frame->mutable_data(frame->samples_per_channel_, 2);
   for (size_t i = 0; i < frame->samples_per_channel_ * 2; i += 2) {
     frame_data[i] = left;
     frame_data[i + 1] = right;
@@ -52,7 +51,8 @@
 }
 
 void SetFrameData(int16_t data, AudioFrame* frame) {
-  int16_t* frame_data = frame->mutable_data();
+  rtc::ArrayView<int16_t> frame_data =
+      frame->mutable_data(frame->samples_per_channel_, 1);
   for (size_t i = 0; i < frame->samples_per_channel_ * frame->num_channels_;
        i++) {
     frame_data[i] = data;
@@ -60,15 +60,18 @@
 }
 
 void VerifyFramesAreEqual(const AudioFrame& frame1, const AudioFrame& frame2) {
-  EXPECT_EQ(frame1.num_channels_, frame2.num_channels_);
-  EXPECT_EQ(frame1.samples_per_channel_, frame2.samples_per_channel_);
+  ASSERT_EQ(frame1.num_channels_, frame2.num_channels_);
+  ASSERT_EQ(frame1.samples_per_channel_, frame2.samples_per_channel_);
+  EXPECT_EQ(frame1.muted(), frame2.muted());
   const int16_t* frame1_data = frame1.data();
   const int16_t* frame2_data = frame2.data();
+  // TODO(tommi): Use sample_count() or data_view().
   for (size_t i = 0; i < frame1.samples_per_channel_ * frame1.num_channels_;
        i++) {
     EXPECT_EQ(frame1_data[i], frame2_data[i]);
+    if (frame1_data[i] != frame2_data[i])
+      break;  // To avoid spamming the log.
   }
-  EXPECT_EQ(frame1.muted(), frame2.muted());
 }
 
 void InitFrame(AudioFrame* frame,
@@ -76,17 +79,16 @@
                size_t samples_per_channel,
                int16_t left_data,
                int16_t right_data) {
-  RTC_DCHECK(frame);
   RTC_DCHECK_GE(2, channels);
   RTC_DCHECK_GE(AudioFrame::kMaxDataSizeSamples,
                 samples_per_channel * channels);
   frame->samples_per_channel_ = samples_per_channel;
-  frame->num_channels_ = channels;
   if (channels == 2) {
     SetFrameData(left_data, right_data, frame);
   } else if (channels == 1) {
     SetFrameData(left_data, frame);
   }
+  ASSERT_EQ(frame->num_channels_, channels);
 }
 
 int16_t GetChannelData(const AudioFrame& frame, size_t channel, size_t index) {
@@ -116,7 +118,6 @@
 #endif
 
 TEST_F(AudioFrameOperationsTest, MonoToStereoSucceeds) {
-  frame_.num_channels_ = 1;
   SetFrameData(1, &frame_);
 
   AudioFrameOperations::UpmixChannels(2, &frame_);
@@ -124,7 +125,6 @@
 
   AudioFrame stereo_frame;
   stereo_frame.samples_per_channel_ = 320;
-  stereo_frame.num_channels_ = 2;
   SetFrameData(1, 1, &stereo_frame);
   VerifyFramesAreEqual(stereo_frame, frame_);
 }
@@ -151,7 +151,6 @@
 
   AudioFrame mono_frame;
   mono_frame.samples_per_channel_ = 320;
-  mono_frame.num_channels_ = 1;
   SetFrameData(3, &mono_frame);
   VerifyFramesAreEqual(mono_frame, frame_);
 }
@@ -167,16 +166,12 @@
   AudioFrame target_frame;
   SetFrameData(4, 2, &frame_);
 
-  target_frame.num_channels_ = 1;
-  target_frame.samples_per_channel_ = frame_.samples_per_channel_;
-
-  AudioFrameOperations::DownmixChannels(frame_.data(), 2,
-                                        frame_.samples_per_channel_, 1,
-                                        target_frame.mutable_data());
+  AudioFrameOperations::DownmixChannels(
+      frame_.data_view(), 2, frame_.samples_per_channel_, 1,
+      target_frame.mutable_data(frame_.samples_per_channel_, 1));
 
   AudioFrame mono_frame;
   mono_frame.samples_per_channel_ = 320;
-  mono_frame.num_channels_ = 1;
   SetFrameData(3, &mono_frame);
   VerifyFramesAreEqual(mono_frame, target_frame);
 }
@@ -187,13 +182,11 @@
   EXPECT_EQ(1u, frame_.num_channels_);
   AudioFrame mono_frame;
   mono_frame.samples_per_channel_ = 320;
-  mono_frame.num_channels_ = 1;
   SetFrameData(-32768, &mono_frame);
   VerifyFramesAreEqual(mono_frame, frame_);
 }
 
 TEST_F(AudioFrameOperationsTest, QuadToMonoSucceeds) {
-  frame_.num_channels_ = 4;
   SetFrameData(4, 2, 6, 8, &frame_);
 
   AudioFrameOperations::DownmixChannels(1, &frame_);
@@ -201,7 +194,6 @@
 
   AudioFrame mono_frame;
   mono_frame.samples_per_channel_ = 320;
-  mono_frame.num_channels_ = 1;
   SetFrameData(5, &mono_frame);
   VerifyFramesAreEqual(mono_frame, frame_);
 }
@@ -216,31 +208,24 @@
 
 TEST_F(AudioFrameOperationsTest, QuadToMonoBufferSucceeds) {
   AudioFrame target_frame;
-  frame_.num_channels_ = 4;
   SetFrameData(4, 2, 6, 8, &frame_);
 
-  target_frame.num_channels_ = 1;
-  target_frame.samples_per_channel_ = frame_.samples_per_channel_;
-
-  AudioFrameOperations::DownmixChannels(frame_.data(), 4,
-                                        frame_.samples_per_channel_, 1,
-                                        target_frame.mutable_data());
+  AudioFrameOperations::DownmixChannels(
+      frame_.data_view(), 4, frame_.samples_per_channel_, 1,
+      target_frame.mutable_data(frame_.samples_per_channel_, 1));
   AudioFrame mono_frame;
   mono_frame.samples_per_channel_ = 320;
-  mono_frame.num_channels_ = 1;
   SetFrameData(5, &mono_frame);
   VerifyFramesAreEqual(mono_frame, target_frame);
 }
 
 TEST_F(AudioFrameOperationsTest, QuadToMonoDoesNotWrapAround) {
-  frame_.num_channels_ = 4;
   SetFrameData(-32768, -32768, -32768, -32768, &frame_);
   AudioFrameOperations::DownmixChannels(1, &frame_);
   EXPECT_EQ(1u, frame_.num_channels_);
 
   AudioFrame mono_frame;
   mono_frame.samples_per_channel_ = 320;
-  mono_frame.num_channels_ = 1;
   SetFrameData(-32768, &mono_frame);
   VerifyFramesAreEqual(mono_frame, frame_);
 }
@@ -253,13 +238,11 @@
 }
 
 TEST_F(AudioFrameOperationsTest, QuadToStereoSucceeds) {
-  frame_.num_channels_ = 4;
   SetFrameData(4, 2, 6, 8, &frame_);
   EXPECT_EQ(0, AudioFrameOperations::QuadToStereo(&frame_));
 
   AudioFrame stereo_frame;
   stereo_frame.samples_per_channel_ = 320;
-  stereo_frame.num_channels_ = 2;
   SetFrameData(3, 7, &stereo_frame);
   VerifyFramesAreEqual(stereo_frame, frame_);
 }
@@ -273,29 +256,23 @@
 
 TEST_F(AudioFrameOperationsTest, QuadToStereoBufferSucceeds) {
   AudioFrame target_frame;
-  frame_.num_channels_ = 4;
   SetFrameData(4, 2, 6, 8, &frame_);
 
-  target_frame.num_channels_ = 2;
-  target_frame.samples_per_channel_ = frame_.samples_per_channel_;
-
-  AudioFrameOperations::QuadToStereo(frame_.data(), frame_.samples_per_channel_,
-                                     target_frame.mutable_data());
+  AudioFrameOperations::QuadToStereo(
+      frame_.data_view(), frame_.samples_per_channel_,
+      target_frame.mutable_data(frame_.samples_per_channel_, 2));
   AudioFrame stereo_frame;
   stereo_frame.samples_per_channel_ = 320;
-  stereo_frame.num_channels_ = 2;
   SetFrameData(3, 7, &stereo_frame);
   VerifyFramesAreEqual(stereo_frame, target_frame);
 }
 
 TEST_F(AudioFrameOperationsTest, QuadToStereoDoesNotWrapAround) {
-  frame_.num_channels_ = 4;
   SetFrameData(-32768, -32768, -32768, -32768, &frame_);
   EXPECT_EQ(0, AudioFrameOperations::QuadToStereo(&frame_));
 
   AudioFrame stereo_frame;
   stereo_frame.samples_per_channel_ = 320;
-  stereo_frame.num_channels_ = 2;
   SetFrameData(-32768, -32768, &stereo_frame);
   VerifyFramesAreEqual(stereo_frame, frame_);
 }
@@ -305,7 +282,6 @@
 
   AudioFrame swapped_frame;
   swapped_frame.samples_per_channel_ = 320;
-  swapped_frame.num_channels_ = 2;
   SetFrameData(1, 0, &swapped_frame);
 
   AudioFrameOperations::SwapStereoChannels(&frame_);
@@ -319,9 +295,9 @@
 }
 
 TEST_F(AudioFrameOperationsTest, SwapStereoChannelsFailsOnMono) {
-  frame_.num_channels_ = 1;
   // Set data to "stereo", despite it being a mono frame.
   SetFrameData(0, 1, &frame_);
+  frame_.num_channels_ = 1;  // Reset to mono after SetFrameData().
 
   AudioFrame orig_frame;
   orig_frame.CopyFrom(frame_);
@@ -336,7 +312,6 @@
 
   AudioFrame muted_frame;
   muted_frame.samples_per_channel_ = 320;
-  muted_frame.num_channels_ = 2;
   SetFrameData(1000, -1000, &muted_frame);
   VerifyFramesAreEqual(muted_frame, frame_);
 }
@@ -506,7 +481,6 @@
 
   AudioFrame clipped_frame;
   clipped_frame.samples_per_channel_ = 320;
-  clipped_frame.num_channels_ = 2;
   SetFrameData(32767, -32768, &clipped_frame);
   VerifyFramesAreEqual(clipped_frame, frame_);
 }
@@ -517,7 +491,6 @@
 
   AudioFrame scaled_frame;
   scaled_frame.samples_per_channel_ = 320;
-  scaled_frame.num_channels_ = 2;
   SetFrameData(2, -3, &scaled_frame);
   VerifyFramesAreEqual(scaled_frame, frame_);
 }
@@ -534,13 +507,11 @@
 }
 
 TEST_F(AudioFrameOperationsTest, ScaleWithSatDoesNotWrapAround) {
-  frame_.num_channels_ = 1;
   SetFrameData(4000, &frame_);
   EXPECT_EQ(0, AudioFrameOperations::ScaleWithSat(10.0, &frame_));
 
   AudioFrame clipped_frame;
   clipped_frame.samples_per_channel_ = 320;
-  clipped_frame.num_channels_ = 1;
   SetFrameData(32767, &clipped_frame);
   VerifyFramesAreEqual(clipped_frame, frame_);
 
@@ -551,13 +522,11 @@
 }
 
 TEST_F(AudioFrameOperationsTest, ScaleWithSatSucceeds) {
-  frame_.num_channels_ = 1;
   SetFrameData(1, &frame_);
   EXPECT_EQ(0, AudioFrameOperations::ScaleWithSat(2.0, &frame_));
 
   AudioFrame scaled_frame;
   scaled_frame.samples_per_channel_ = 320;
-  scaled_frame.num_channels_ = 1;
   SetFrameData(2, &scaled_frame);
   VerifyFramesAreEqual(scaled_frame, frame_);
 }
@@ -573,10 +542,11 @@
   AudioFrame frame_to_add_to;
   frame_to_add_to.mutable_data();  // Unmute the frame.
   ASSERT_FALSE(frame_to_add_to.muted());
+
+  SetFrameData(1000, &frame_);
   frame_to_add_to.samples_per_channel_ = 0;
   frame_to_add_to.num_channels_ = frame_.num_channels_;
 
-  SetFrameData(1000, &frame_);
   AudioFrameOperations::Add(frame_, &frame_to_add_to);
   VerifyFramesAreEqual(frame_, frame_to_add_to);
 }
@@ -584,19 +554,27 @@
 TEST_F(AudioFrameOperationsTest, AddingXToMutedGivesX) {
   AudioFrame frame_to_add_to;
   ASSERT_TRUE(frame_to_add_to.muted());
+
   frame_to_add_to.samples_per_channel_ = frame_.samples_per_channel_;
+  SetFrameData(1000, &frame_);
   frame_to_add_to.num_channels_ = frame_.num_channels_;
 
-  SetFrameData(1000, &frame_);
   AudioFrameOperations::Add(frame_, &frame_to_add_to);
   VerifyFramesAreEqual(frame_, frame_to_add_to);
 }
 
 TEST_F(AudioFrameOperationsTest, AddingMutedToXGivesX) {
   AudioFrame frame_to_add_to;
+
+  // Clear the internal buffer to avoid msan issues since we're changing
+  // buffer dimension member variables outside of the class without updating
+  // the buffer.
+  RTC_DCHECK(frame_to_add_to.muted());
+  frame_to_add_to.mutable_data();
+
   frame_to_add_to.samples_per_channel_ = frame_.samples_per_channel_;
+  SetFrameData(1000, &frame_to_add_to);  // sets frame to mono.
   frame_to_add_to.num_channels_ = frame_.num_channels_;
-  SetFrameData(1000, &frame_to_add_to);
 
   AudioFrame frame_copy;
   frame_copy.CopyFrom(frame_to_add_to);
@@ -609,7 +587,6 @@
 TEST_F(AudioFrameOperationsTest, AddingTwoFramesProducesTheirSum) {
   AudioFrame frame_to_add_to;
   frame_to_add_to.samples_per_channel_ = frame_.samples_per_channel_;
-  frame_to_add_to.num_channels_ = frame_.num_channels_;
   SetFrameData(1000, &frame_to_add_to);
   SetFrameData(2000, &frame_);
 
diff --git a/common_audio/include/audio_util.h b/common_audio/include/audio_util.h
index 4ce4680..4cbea67 100644
--- a/common_audio/include/audio_util.h
+++ b/common_audio/include/audio_util.h
@@ -94,6 +94,7 @@
 // Copy audio from `src` channels to `dest` channels unless `src` and `dest`
 // point to the same address. `src` and `dest` must have the same number of
 // channels, and there must be sufficient space allocated in `dest`.
+// TODO: b/335805780 - Accept ArrayView.
 template <typename T>
 void CopyAudioIfNeeded(const T* const* src,
                        int num_frames,
@@ -110,6 +111,7 @@
 // by `deinterleaved`. There must be sufficient space allocated in the
 // `deinterleaved` buffers (`num_channel` buffers with `samples_per_channel`
 // per buffer).
+// TODO: b/335805780 - Accept ArrayView.
 template <typename T>
 void Deinterleave(const T* interleaved,
                   size_t samples_per_channel,
@@ -128,6 +130,7 @@
 // Interleave audio from the channel buffers pointed to by `deinterleaved` to
 // `interleaved`. There must be sufficient space allocated in `interleaved`
 // (`samples_per_channel` * `num_channels`).
+// TODO: b/335805780 - Accept ArrayView.
 template <typename T>
 void Interleave(const T* const* deinterleaved,
                 size_t samples_per_channel,
@@ -146,6 +149,7 @@
 // Copies audio from a single channel buffer pointed to by `mono` to each
 // channel of `interleaved`. There must be sufficient space allocated in
 // `interleaved` (`samples_per_channel` * `num_channels`).
+// TODO: b/335805780 - Accept ArrayView.
 template <typename T>
 void UpmixMonoToInterleaved(const T* mono,
                             int num_frames,
@@ -159,6 +163,7 @@
   }
 }
 
+// TODO: b/335805780 - Accept ArrayView.
 template <typename T, typename Intermediate>
 void DownmixToMono(const T* const* input_channels,
                    size_t num_frames,
@@ -175,6 +180,7 @@
 
 // Downmixes an interleaved multichannel signal to a single channel by averaging
 // all channels.
+// TODO: b/335805780 - Accept ArrayView.
 template <typename T, typename Intermediate>
 void DownmixInterleavedToMonoImpl(const T* interleaved,
                                   size_t num_frames,
@@ -197,12 +203,14 @@
   }
 }
 
+// TODO: b/335805780 - Accept ArrayView.
 template <typename T>
 void DownmixInterleavedToMono(const T* interleaved,
                               size_t num_frames,
                               int num_channels,
                               T* deinterleaved);
 
+// TODO: b/335805780 - Accept ArrayView.
 template <>
 void DownmixInterleavedToMono<int16_t>(const int16_t* interleaved,
                                        size_t num_frames,