Prevent warnings from timestamp aligner used in AudioDeviceBuffer

The logcat is spammed with warnings from timestamp aligner.
This CL make a workaround to use the timestamp aligner to get capture times,
without generating the warnings.

Bug: webrtc:14970
Change-Id: Idab4b298e0484a57841a214db9440f9ac6faaa4d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/296324
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Commit-Queue: Olov Brändström <brandstrom@google.com>
Cr-Commit-Position: refs/heads/main@{#39486}

modules/audio_device/audio_device_buffer.cc

@@ -248,11 +248,28 @@ int32_t AudioDeviceBuffer::SetRecordedBuffer(
   }
 
   if (capture_timestamp_ns) {
-    capture_timestamp_ns_ =
-        rtc::kNumNanosecsPerMicrosec *
-        timestamp_aligner_.TranslateTimestamp(
-            *capture_timestamp_ns / rtc::kNumNanosecsPerMicrosec,
-            rtc::TimeMicros());
+    int64_t align_offsync_estimation_time = rtc::TimeMicros();
+    if (align_offsync_estimation_time -
+            rtc::TimestampAligner::kMinFrameIntervalUs >
+        align_offsync_estimation_time_) {
+      align_offsync_estimation_time_ = align_offsync_estimation_time;
+      capture_timestamp_ns_ =
+          rtc::kNumNanosecsPerMicrosec *
+          timestamp_aligner_.TranslateTimestamp(
+              *capture_timestamp_ns / rtc::kNumNanosecsPerMicrosec,
+              align_offsync_estimation_time);
+    } else {
+      // The Timestamp aligner is designed to prevent timestamps that are too
+      // similar, and produces warnings if it is called to often. We do not care
+      // about that here, so we do this workaround. If we where to call the
+      // aligner within a millisecond, we instead call this, that do not update
+      // the clock offset estimation. This get us timestamps without generating
+      // warnings, but could generate two timestamps within a millisecond.
+      capture_timestamp_ns_ =
+          rtc::kNumNanosecsPerMicrosec *
+          timestamp_aligner_.TranslateTimestamp(*capture_timestamp_ns /
+                                                rtc::kNumNanosecsPerMicrosec);
+    }
   }
   // Derive a new level value twice per second and check if it is non-zero.
   int16_t max_abs = 0;

modules/audio_device/audio_device_buffer.h

@@ -196,6 +196,10 @@ class AudioDeviceBuffer {
 
   // Capture timestamp.
   absl::optional<int64_t> capture_timestamp_ns_;
+  // The last time the Timestamp Aligner was used to estimate clock offset
+  // between system clock and capture time from audio.
+  // This is used to prevent estimating the clock offset too often.
+  absl::optional<int64_t> align_offsync_estimation_time_;
 
   // Counts number of times LogStats() has been called.
   size_t num_stat_reports_ RTC_GUARDED_BY(task_queue_);

rtc_base/timestamp_aligner.cc

@@ -112,7 +112,6 @@ int64_t TimestampAligner::UpdateOffset(int64_t capturer_time_us,
 
 int64_t TimestampAligner::ClipTimestamp(int64_t filtered_time_us,
                                         int64_t system_time_us) {
-  const int64_t kMinFrameIntervalUs = rtc::kNumMicrosecsPerMillisec;
   // Clip to make sure we don't produce timestamps in the future.
   int64_t time_us = filtered_time_us - clip_bias_us_;
   if (time_us > system_time_us) {

rtc_base/timestamp_aligner.h

@@ -14,6 +14,7 @@
 #include <stdint.h>
 
 #include "rtc_base/system/rtc_export.h"
+#include "rtc_base/time_utils.h"
 
 namespace rtc {
 
@@ -38,6 +39,12 @@ class RTC_EXPORT TimestampAligner {
   TimestampAligner& operator=(const TimestampAligner&) = delete;
 
  public:
+  // Minimum difference of two timestamps generated by
+  // "TranslateTimestamp(int64_t capturer_time_us, int64_t system_time_us)"
+  // This avoids the caller from getting two timestamps with the same
+  // millisecond.
+  static constexpr int64_t kMinFrameIntervalUs = rtc::kNumMicrosecsPerMillisec;
+
   // Translates timestamps of a capture system to the same timescale as is used
   // by rtc::TimeMicros(). `capturer_time_us` is assumed to be accurate, but
   // with an unknown epoch and clock drift. `system_time_us` is