add some more RPC stress tests and audio latency tests (#74)

* use a real LLM response and save it to data_rpc_test_data.txt, use it for the rpc stress tests

* remove the un-needed logs

* adding more rpc / audio latency stress tests

* address the comments

Author: xianshijing-lk

src/tests/common/audio_utils.h

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2025 LiveKit
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <atomic>
+#include <chrono>
+#include <cmath>
+#include <cstdint>
+#include <livekit/livekit.h>
+#include <memory>
+#include <thread>
+
+namespace livekit {
+namespace test {
+
+// Default audio parameters for tests
+constexpr int kDefaultAudioSampleRate = 48000;
+constexpr int kDefaultAudioChannels = 1;
+constexpr int kDefaultAudioFrameMs = 10;
+constexpr int kDefaultSamplesPerChannel =
+    kDefaultAudioSampleRate * kDefaultAudioFrameMs / 1000;
+
+/// Create an AudioFrame with the given parameters for a 10ms duration.
+/// @param sample_rate Sample rate in Hz.
+/// @param num_channels Number of audio channels.
+/// @return A new AudioFrame with the appropriate size.
+inline AudioFrame create10msFrame(int sample_rate, int num_channels) {
+  const int samples_per_channel = sample_rate / 100; // 10ms worth of samples
+  return AudioFrame::create(sample_rate, num_channels, samples_per_channel);
+}
+
+/// Run an audio tone generation loop.
+/// @param source The AudioSource to capture frames to.
+/// @param running Atomic flag to control when to stop the loop.
+/// @param base_freq_hz Base frequency in Hz for the tone.
+/// @param siren_mode If true, modulates the frequency to create a siren effect.
+/// @param sample_rate Audio sample rate (default: 48000).
+/// @param num_channels Number of audio channels (default: 1).
+/// @param frame_ms Duration of each frame in milliseconds (default: 10).
+inline void runToneLoop(const std::shared_ptr<AudioSource> &source,
+                        std::atomic<bool> &running, double base_freq_hz,
+                        bool siren_mode,
+                        int sample_rate = kDefaultAudioSampleRate,
+                        int num_channels = kDefaultAudioChannels,
+                        int frame_ms = kDefaultAudioFrameMs) {
+  double phase = 0.0;
+  constexpr double kTwoPi = 6.283185307179586;
+  const int samples_per_channel = sample_rate * frame_ms / 1000;
+
+  while (running.load(std::memory_order_relaxed)) {
+    AudioFrame frame =
+        AudioFrame::create(sample_rate, num_channels, samples_per_channel);
+    auto &samples = frame.data();
+
+    const double time_sec =
+        static_cast<double>(
+            std::chrono::duration_cast<std::chrono::milliseconds>(
+                std::chrono::steady_clock::now().time_since_epoch())
+                .count()) /
+        1000.0;
+    const double freq =
+        siren_mode ? (700.0 + 250.0 * std::sin(time_sec * 2.0)) : base_freq_hz;
+
+    const double phase_inc = kTwoPi * freq / static_cast<double>(sample_rate);
+    for (int i = 0; i < samples_per_channel; ++i) {
+      samples[static_cast<std::size_t>(i)] =
+          static_cast<std::int16_t>(std::sin(phase) * 12000.0);
+      phase += phase_inc;
+      if (phase > kTwoPi) {
+        phase -= kTwoPi;
+      }
+    }
+
+    try {
+      source->captureFrame(frame);
+    } catch (...) {
+      break;
+    }
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(frame_ms));
+  }
+}
+
+/// Fill an AudioFrame with a sine wave tone.
+/// @param frame The AudioFrame to fill.
+/// @param freq_hz Frequency of the tone in Hz.
+/// @param sample_rate Sample rate in Hz.
+/// @param phase Reference to phase accumulator (updated after call).
+/// @param amplitude Amplitude of the tone (default: 12000).
+inline void fillToneFrame(AudioFrame &frame, double freq_hz, int sample_rate,
+                          double &phase, double amplitude = 12000.0) {
+  constexpr double kTwoPi = 6.283185307179586;
+  auto &samples = frame.data();
+  const double phase_inc = kTwoPi * freq_hz / static_cast<double>(sample_rate);
+
+  for (std::size_t i = 0; i < samples.size(); ++i) {
+    samples[i] = static_cast<std::int16_t>(std::sin(phase) * amplitude);
+    phase += phase_inc;
+    if (phase > kTwoPi) {
+      phase -= kTwoPi;
+    }
+  }
+}
+
+} // namespace test
+} // namespace livekit

src/tests/common/video_utils.h

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+/*
+ * Copyright 2025 LiveKit
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <atomic>
+#include <chrono>
+#include <cstdint>
+#include <livekit/livekit.h>
+#include <memory>
+#include <thread>
+
+namespace livekit {
+namespace test {
+
+// Default video dimensions for tests
+constexpr int kDefaultVideoWidth = 640;
+constexpr int kDefaultVideoHeight = 360;
+
+/// Fill a VideoFrame with webcam-like colors (green tint with varying blue).
+/// @param frame The VideoFrame to fill (must be ARGB format).
+/// @param frame_index Frame counter used to vary the blue channel.
+inline void fillWebcamLikeFrame(VideoFrame &frame, std::uint64_t frame_index) {
+  // ARGB layout: [A, R, G, B]
+  std::uint8_t *data = frame.data();
+  const std::size_t size = frame.dataSize();
+  const std::uint8_t blue = static_cast<std::uint8_t>((frame_index * 3) % 255);
+  for (std::size_t i = 0; i < size; i += 4) {
+    data[i + 0] = 255; // A
+    data[i + 1] = 0;   // R
+    data[i + 2] = 170; // G
+    data[i + 3] = blue;
+  }
+}
+
+/// Fill a VideoFrame with solid red and encode metadata in the first 16 pixels.
+/// @param frame The VideoFrame to fill (must be ARGB format).
+/// @param frame_index Frame counter encoded into metadata.
+/// @param timestamp_us Timestamp in microseconds encoded into metadata.
+inline void fillRedFrameWithMetadata(VideoFrame &frame,
+                                     std::uint64_t frame_index,
+                                     std::uint64_t timestamp_us) {
+  // ARGB layout: [A, R, G, B]
+  std::uint8_t *data = frame.data();
+  const std::size_t size = frame.dataSize();
+  for (std::size_t i = 0; i < size; i += 4) {
+    data[i + 0] = 255; // A
+    data[i + 1] = 255; // R
+    data[i + 2] = 0;   // G
+    data[i + 3] = 0;   // B
+  }
+
+  // Encode frame counter + timestamp into first 16 pixels for easy debugging.
+  std::uint8_t meta[16];
+  for (int i = 0; i < 8; ++i) {
+    meta[i] = static_cast<std::uint8_t>((frame_index >> (i * 8)) & 0xFF);
+    meta[8 + i] = static_cast<std::uint8_t>((timestamp_us >> (i * 8)) & 0xFF);
+  }
+  for (int i = 0; i < 16; ++i) {
+    const std::size_t px = static_cast<std::size_t>(i) * 4;
+    if (px + 3 < size) {
+      data[px + 0] = 255;
+      data[px + 1] = 255;
+      data[px + 2] = meta[i];
+      data[px + 3] = meta[(15 - i)];
+    }
+  }
+}
+
+/// Wrapper for fillWebcamLikeFrame with timestamp parameter (ignored).
+inline void fillWebcamWrapper(VideoFrame &frame, std::uint64_t frame_index,
+                              std::uint64_t /*timestamp_us*/) {
+  fillWebcamLikeFrame(frame, frame_index);
+}
+
+/// Wrapper for fillRedFrameWithMetadata.
+inline void fillRedWrapper(VideoFrame &frame, std::uint64_t frame_index,
+                           std::uint64_t timestamp_us) {
+  fillRedFrameWithMetadata(frame, frame_index, timestamp_us);
+}
+
+/// Type alias for video frame fill functions.
+using VideoFrameFillFn = void (*)(VideoFrame &, std::uint64_t, std::uint64_t);
+
+/// Run a video capture loop, calling the fill function for each frame.
+/// @param source The VideoSource to capture frames to.
+/// @param running Atomic flag to control when to stop the loop.
+/// @param fill_fn Function to fill each frame with content.
+/// @param width Video frame width (default: kDefaultVideoWidth).
+/// @param height Video frame height (default: kDefaultVideoHeight).
+/// @param frame_interval Frame interval (default: 33ms for ~30fps).
+inline void runVideoLoop(
+    const std::shared_ptr<VideoSource> &source, std::atomic<bool> &running,
+    VideoFrameFillFn fill_fn, int width = kDefaultVideoWidth,
+    int height = kDefaultVideoHeight,
+    std::chrono::milliseconds frame_interval = std::chrono::milliseconds(33)) {
+  VideoFrame frame = VideoFrame::create(width, height, VideoBufferType::ARGB);
+  std::uint64_t frame_index = 0;
+  while (running.load(std::memory_order_relaxed)) {
+    const auto now = std::chrono::steady_clock::now().time_since_epoch();
+    const auto ts_us = static_cast<std::uint64_t>(
+        std::chrono::duration_cast<std::chrono::microseconds>(now).count());
+    fill_fn(frame, frame_index, ts_us);
+    try {
+      source->captureFrame(frame, static_cast<std::int64_t>(ts_us),
+                           VideoRotation::VIDEO_ROTATION_0);
+    } catch (...) {
+      break;
+    }
+    frame_index++;
+    std::this_thread::sleep_for(frame_interval);
+  }
+}
+
+} // namespace test
+} // namespace livekit