/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gtest/gtest.h"
#include "DriftController.h"
#include "mozilla/Maybe.h"
using namespace mozilla;
using TimeUnit = media::TimeUnit;
// Advance the output by the specified duration, using a calculated input
// packet duration that provides the specified buffering level.
void AdvanceByOutputDuration(TimeUnit* aCurrentBuffered,
DriftController* aController,
TimeUnit aOutputDuration,
uint32_t aNextBufferedInputFrames) {
uint32_t nominalSourceRate = aController->mSourceRate;
uint32_t nominalTargetRate = aController->mTargetRate;
uint32_t correctedRate = aController->GetCorrectedSourceRate();
// Use a denominator to exactly track (1/nominalTargetRate)ths of
// durations in seconds of input frames buffered in the resampler.
*aCurrentBuffered = aCurrentBuffered->ToBase(
static_cast<int64_t>(nominalSourceRate) * nominalTargetRate);
// Buffered input frames to feed the output are removed first, so that the
// number of input frames required can be calculated. aCurrentBuffered may
// temporarily become negative.
*aCurrentBuffered -= aOutputDuration.ToBase(*aCurrentBuffered) *
correctedRate / nominalSourceRate;
// Determine the input duration (aligned to input frames) that would provide
// the specified buffering level when rounded down to the nearest input
// frame.
int64_t currentBufferedInputFrames =
aCurrentBuffered->ToBase<TimeUnit::FloorPolicy>(nominalSourceRate)
.ToTicksAtRate(nominalSourceRate);
TimeUnit inputDuration(
CheckedInt64(aNextBufferedInputFrames) - currentBufferedInputFrames,
nominalSourceRate);
EXPECT_GE(inputDuration.ToTicksAtRate(nominalSourceRate), 0);
*aCurrentBuffered += inputDuration;
// The buffer size is not used in the controller logic.
uint32_t bufferSize = 0;
aController->UpdateClock(inputDuration, aOutputDuration,
aNextBufferedInputFrames, bufferSize);
}
TEST(TestDriftController, Basic)
{
constexpr uint32_t buffered = 5 * 480;
constexpr uint32_t bufferedLow = 3 * 480;
constexpr uint32_t bufferedHigh = 7 * 480;
TimeUnit currentBuffered(buffered, 48000);
DriftController c(48000, 48000, currentBuffered);
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000U);
// The adjustment interval is 1s.
const auto oneSec = media::TimeUnit(48000, 48000);
uint32_t stepsPerSec = 50;
media::TimeUnit stepDuration = oneSec / stepsPerSec;
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, buffered);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedLow);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47957u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedHigh);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47957u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedHigh);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48005u);
}
TEST(TestDriftController, BasicResampler)
{
// This test is equivalent to Basic, but for the output sample rate, so
// input buffer frame counts should be equal to those in Basic.
constexpr uint32_t buffered = 5 * 480;
constexpr uint32_t bufferedLow = 3 * 480;
constexpr uint32_t bufferedHigh = 7 * 480;
TimeUnit currentBuffered(buffered, 48000);
DriftController c(48000, 24000, currentBuffered);
// The adjustment interval is 1s.
const auto oneSec = media::TimeUnit(48000, 48000);
uint32_t stepsPerSec = 50;
media::TimeUnit stepDuration = oneSec / stepsPerSec;
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, buffered);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
// low
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedLow);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47957u);
// high
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedHigh);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47957u);
// high
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedHigh);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48005u);
}
TEST(TestDriftController, BufferedInput)
{
constexpr uint32_t buffered = 5 * 480;
constexpr uint32_t bufferedLow = 3 * 480;
constexpr uint32_t bufferedHigh = 7 * 480;
TimeUnit currentBuffered(buffered, 48000);
DriftController c(48000, 48000, currentBuffered);
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
// The adjustment interval is 1s.
const auto oneSec = media::TimeUnit(48000, 48000);
uint32_t stepsPerSec = 20;
media::TimeUnit stepDuration = oneSec / stepsPerSec;
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, buffered);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
// 0 buffered when updating correction
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, 0);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47990u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedLow);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47971u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, buffered);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47960u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedHigh);
}
// Hysteresis keeps the corrected rate the same.
EXPECT_EQ(c.GetCorrectedSourceRate(), 47960u);
}
TEST(TestDriftController, BufferedInputWithResampling)
{
// This test is equivalent to BufferedInput, but for the output sample rate,
// so input buffer frame counts should be equal to those in BufferedInput.
constexpr uint32_t buffered = 5 * 480;
constexpr uint32_t bufferedLow = 3 * 480;
constexpr uint32_t bufferedHigh = 7 * 480;
TimeUnit currentBuffered(buffered, 48000);
DriftController c(48000, 24000, currentBuffered);
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
// The adjustment interval is 1s.
const auto oneSec = media::TimeUnit(24000, 24000);
uint32_t stepsPerSec = 20;
media::TimeUnit stepDuration = oneSec / stepsPerSec;
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, buffered);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
// 0 buffered when updating correction
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, 0);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47990u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedLow);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47971u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, buffered);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 47960u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedHigh);
}
// Hysteresis keeps the corrected rate the same.
EXPECT_EQ(c.GetCorrectedSourceRate(), 47960u);
}
TEST(TestDriftController, SmallError)
{
constexpr uint32_t buffered = 5 * 480;
constexpr uint32_t bufferedLow = buffered - 48;
constexpr uint32_t bufferedHigh = buffered + 48;
TimeUnit currentBuffered(buffered, 48000);
DriftController c(48000, 48000, currentBuffered);
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
// The adjustment interval is 1s.
const auto oneSec = media::TimeUnit(48000, 48000);
uint32_t stepsPerSec = 25;
media::TimeUnit stepDuration = oneSec / stepsPerSec;
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, buffered);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedLow);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedHigh);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
for (uint32_t i = 0; i < stepsPerSec; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, stepDuration, bufferedHigh);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000u);
}
TEST(TestDriftController, SmallBufferedFrames)
{
constexpr uint32_t bufferedLow = 3 * 480;
DriftController c(48000, 48000, media::TimeUnit::FromSeconds(0.05));
media::TimeUnit oneSec = media::TimeUnit::FromSeconds(1);
uint32_t stepsPerSec = 40;
media::TimeUnit stepDuration = oneSec / stepsPerSec;
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000U);
for (uint32_t i = 0; i < stepsPerSec - 1; ++i) {
c.UpdateClock(stepDuration, stepDuration, bufferedLow, 0);
}
EXPECT_EQ(c.GetCorrectedSourceRate(), 48000U);
c.UpdateClock(stepDuration, stepDuration, bufferedLow, 0);
EXPECT_EQ(c.GetCorrectedSourceRate(), 47996U);
}
TEST(TestDriftController, VerySmallBufferedFrames)
{
uint32_t bufferedLow = 1;
uint32_t nominalRate = 48000;
DriftController c(nominalRate, nominalRate, media::TimeUnit::FromSeconds(1));
EXPECT_EQ(c.GetCorrectedSourceRate(), nominalRate);
TimeUnit currentBuffered(bufferedLow, 48000);
media::TimeUnit hundredMillis = media::TimeUnit(100, 1000);
uint32_t previousCorrected = nominalRate;
// Perform enough steps (1500 seconds) that the corrected rate can
// get to its lower bound, without underflowing zero.
for (uint32_t i = 0; i < 15000; ++i) {
// The input packet size is reduced each iteration by as much as possible
// without completely draining the buffer.
AdvanceByOutputDuration(¤tBuffered, &c, hundredMillis, bufferedLow);
uint32_t correctedRate = c.GetCorrectedSourceRate();
EXPECT_LE(correctedRate, previousCorrected) <<
"for i=" << i;
EXPECT_GT(correctedRate, 0u) <<
"for i=" << i;
previousCorrected = correctedRate;
}
// Check that the corrected rate has reached, does not go beyond, and does
// not bounce off its lower bound.
EXPECT_EQ(previousCorrected, 1u);
for (uint32_t i = 15000; i < 15010; ++i) {
AdvanceByOutputDuration(¤tBuffered, &c, hundredMillis, bufferedLow);
EXPECT_EQ(c.GetCorrectedSourceRate(), 1u) <<
"for i=" << i;
}
}
TEST(TestDriftController, SmallStepResponse)
{
// The DriftController is configured with nominal source rate a little less
// than the actual rate.
uint32_t nominalTargetRate = 48000;
uint32_t nominalSourceRate = 48000;
uint32_t actualSourceRate = 48000 * 1001 / 1000;
// +0.1% drift
TimeUnit desiredBuffered = TimeUnit::FromSeconds(0.05);
// 50 ms
DriftController c(nominalSourceRate, nominalTargetRate, desiredBuffered);
EXPECT_EQ(c.GetCorrectedSourceRate(), nominalSourceRate);
uint32_t stepsPerSec = 25;
// Initial buffer level == desired. Choose a base to exactly track
// fractions of frames buffered in the resampler.
TimeUnit buffered = desiredBuffered.ToBase(nominalSourceRate * stepsPerSec);
media::TimeUnit inputStepDuration(actualSourceRate,
stepsPerSec * nominalSourceRate);
media::TimeUnit outputStepDuration(nominalTargetRate,
stepsPerSec * nominalTargetRate);
// Perform enough steps to observe convergence.
uint32_t iterationCount = 200
/*seconds*/ * stepsPerSec;
for (uint32_t i = 0; i < iterationCount; ++i) {
uint32_t correctedRate = c.GetCorrectedSourceRate();
buffered += TimeUnit(CheckedInt64(actualSourceRate) - correctedRate,
stepsPerSec * nominalSourceRate);
// The buffer size is not used in the controller logic.
c.UpdateClock(inputStepDuration, outputStepDuration,
buffered.ToTicksAtRate(nominalSourceRate), 0);
if (outputStepDuration * i > TimeUnit::FromSeconds(50) &&
/* Corrections are performed only once per second. */
i % stepsPerSec == 0) {
EXPECT_EQ(c.GetCorrectedSourceRate(), actualSourceRate) <<
"for i=" << i;
EXPECT_NEAR(buffered.ToTicksAtRate(nominalSourceRate),
desiredBuffered.ToTicksAtRate(nominalSourceRate), 10)
<<
"for i=" << i;
}
}
}
TEST(TestDriftController, LargeStepResponse)
{
// The DriftController is configured with nominal source rate much less than
// the actual rate. The large difference between nominal and actual
// produces large PID terms and capping of the change in resampler input
// rate to nominalRate/1000. This does not correspond exactly to an
// expected use case, but tests the stability of the response when changes
// are capped.
uint32_t nominalTargetRate = 48000;
uint32_t nominalSourceRate = 48000 * 7 / 8;
uint32_t actualSourceRate = 48000;
TimeUnit desiredBuffered(actualSourceRate * 10, nominalSourceRate);
DriftController c(nominalSourceRate, nominalTargetRate, desiredBuffered);
EXPECT_EQ(c.GetCorrectedSourceRate(), nominalSourceRate);
uint32_t stepsPerSec = 20;
// Initial buffer level == desired. Choose a base to exactly track
// fractions of frames buffered in the resampler.
TimeUnit buffered = desiredBuffered.ToBase(nominalSourceRate * stepsPerSec);
media::TimeUnit inputStepDuration(actualSourceRate,
stepsPerSec * nominalSourceRate);
media::TimeUnit outputStepDuration(nominalTargetRate,
stepsPerSec * nominalTargetRate);
// Changes in the corrected rate are limited to nominalRate/1000 per second.
// Perform enough steps to get from nominal to actual source rate and then
// observe convergence.
uint32_t iterationCount = 8 * stepsPerSec * 1000 *
(actualSourceRate - nominalSourceRate) /
nominalSourceRate;
EXPECT_GT(outputStepDuration * (iterationCount - 1),
TimeUnit::FromSeconds(1020));
for (uint32_t i = 0; i < iterationCount; ++i) {
uint32_t correctedRate = c.GetCorrectedSourceRate();
buffered += TimeUnit(CheckedInt64(actualSourceRate) - correctedRate,
stepsPerSec * nominalSourceRate);
// The buffer size is not used in the controller logic.
c.UpdateClock(inputStepDuration, outputStepDuration,
buffered.ToTicksAtRate(nominalSourceRate), 0);
if (outputStepDuration * i > TimeUnit::FromSeconds(1020) &&
/* Corrections are performed only once per second. */
i % stepsPerSec == 0) {
EXPECT_EQ(c.GetCorrectedSourceRate(), actualSourceRate) <<
"for i=" << i;
EXPECT_NEAR(buffered.ToTicksAtRate(nominalSourceRate),
desiredBuffered.ToTicksAtRate(nominalSourceRate), 10)
<<
"for i=" << i;
}
}
}
