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Testing AMR Audio Seek Operations in SmartTube

This comprehensive test suite validates the seeking functionality of the AMR (Adaptive Multi-Rate) audio extractor in ExoPlayer, covering both narrow-band and wide-band AMR formats. The tests ensure accurate seek operations, frame extraction, and proper handling of various seek scenarios.
Test Coverage Overview

The test suite provides extensive coverage of AMR extractor seeking capabilities:
Validates seek operations for both narrow-band and wide-band AMR formats
Tests seeking to specific positions, end of file, forward/backward navigation
Verifies frame extraction accuracy after seek operations
Includes random seek testing for robustness verification
Implementation Analysis

The testing approach employs JUnit with AndroidJUnit4 runner, utilizing a systematic methodology for seek validation:
Uses FakeExtractorOutput and FakeTrackOutput for controlled testing
Implements precise frame-level verification after seek operations
Incorporates helper methods for seek map extraction and frame comparison
Technical Details

Testing infrastructure includes:
DefaultDataSource for file handling
Custom AmrExtractor with constant bitrate seeking enabled
TestUtil helper class for sample extraction and verification
Random number generation for randomized seek testing
Best Practices Demonstrated

The test suite exemplifies high-quality testing practices:
Comprehensive setup and teardown management
Thorough edge case coverage including EOF and random seeks
Precise time-based seek verification
Clear separation of test scenarios between narrow-band and wide-band formats
yuliskov/smarttube

exoplayer-amzn-2.10.6/library/core/src/test/java/com/google/android/exoplayer2/extractor/amr/AmrExtractorSeekTest.java
            
/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * 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.
 */
package com.google.android.exoplayer2.extractor.amr;

import static com.google.common.truth.Truth.assertThat;

import android.net.Uri;
import androidx.test.core.app.ApplicationProvider;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import com.google.android.exoplayer2.extractor.SeekMap;
import com.google.android.exoplayer2.testutil.FakeExtractorOutput;
import com.google.android.exoplayer2.testutil.FakeTrackOutput;
import com.google.android.exoplayer2.testutil.TestUtil;
import com.google.android.exoplayer2.upstream.DefaultDataSource;
import com.google.android.exoplayer2.upstream.DefaultDataSourceFactory;
import java.io.IOException;
import java.util.List;
import java.util.Random;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

/** Unit test for {@link AmrExtractor}. */
@RunWith(AndroidJUnit4.class)
public final class AmrExtractorSeekTest {

  private static final Random random = new Random(1234L);

  private static final String NARROW_BAND_AMR_FILE = "amr/sample_nb.amr";
  private static final int NARROW_BAND_FILE_DURATION_US = 4_360_000;

  private static final String WIDE_BAND_AMR_FILE = "amr/sample_wb.amr";
  private static final int WIDE_BAND_FILE_DURATION_US = 3_380_000;

  private FakeTrackOutput expectedTrackOutput;
  private DefaultDataSource dataSource;

  @Before
  public void setUp() {
    dataSource =
        new DefaultDataSourceFactory(ApplicationProvider.getApplicationContext(), "UserAgent")
            .createDataSource();
  }

  @Test
  public void testAmrExtractorReads_returnSeekableSeekMap_forNarrowBandAmr()
      throws IOException, InterruptedException {
    String fileName = NARROW_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);

    AmrExtractor extractor = createAmrExtractor();
    SeekMap seekMap =
        TestUtil.extractSeekMap(extractor, new FakeExtractorOutput(), dataSource, fileUri);

    assertThat(seekMap).isNotNull();
    assertThat(seekMap.getDurationUs()).isEqualTo(NARROW_BAND_FILE_DURATION_US);
    assertThat(seekMap.isSeekable()).isTrue();
  }

  @Test
  public void testSeeking_handlesSeekingToPositionInFile_extractsCorrectFrame_forNarrowBandAmr()
      throws IOException, InterruptedException {
    String fileName = NARROW_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);

    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long targetSeekTimeUs = 980_000;
    int extractedFrameIndex =
        TestUtil.seekToTimeUs(
            extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

    assertThat(extractedFrameIndex).isNotEqualTo(-1);
    assertFirstFrameAfterSeekContainTargetSeekTime(
        trackOutput, targetSeekTimeUs, extractedFrameIndex);
  }

  @Test
  public void testSeeking_handlesSeekToEoF_extractsLastFrame_forNarrowBandAmr()
      throws IOException, InterruptedException {
    String fileName = NARROW_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);
    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long targetSeekTimeUs = seekMap.getDurationUs();

    int extractedFrameIndex =
        TestUtil.seekToTimeUs(
            extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

    assertThat(extractedFrameIndex).isNotEqualTo(-1);
    assertFirstFrameAfterSeekContainTargetSeekTime(
        trackOutput, targetSeekTimeUs, extractedFrameIndex);
  }

  @Test
  public void testSeeking_handlesSeekingBackward_extractsCorrectFrames_forNarrowBandAmr()
      throws IOException, InterruptedException {
    String fileName = NARROW_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);
    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long firstSeekTimeUs = 980_000;
    TestUtil.seekToTimeUs(extractor, seekMap, firstSeekTimeUs, dataSource, trackOutput, fileUri);

    long targetSeekTimeUs = 0;
    int extractedFrameIndex =
        TestUtil.seekToTimeUs(
            extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

    assertThat(extractedFrameIndex).isNotEqualTo(-1);
    assertFirstFrameAfterSeekContainTargetSeekTime(
        trackOutput, targetSeekTimeUs, extractedFrameIndex);
  }

  @Test
  public void testSeeking_handlesSeekingForward_extractsCorrectFrames_forNarrowBandAmr()
      throws IOException, InterruptedException {
    String fileName = NARROW_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);
    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long firstSeekTimeUs = 980_000;
    TestUtil.seekToTimeUs(extractor, seekMap, firstSeekTimeUs, dataSource, trackOutput, fileUri);

    long targetSeekTimeUs = 1_200_000;
    int extractedFrameIndex =
        TestUtil.seekToTimeUs(
            extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

    assertThat(extractedFrameIndex).isNotEqualTo(-1);
    assertFirstFrameAfterSeekContainTargetSeekTime(
        trackOutput, targetSeekTimeUs, extractedFrameIndex);
  }

  @Test
  public void testSeeking_handlesRandomSeeks_extractsCorrectFrames_forNarrowBandAmr()
      throws IOException, InterruptedException {
    String fileName = NARROW_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);
    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long numSeek = 100;
    for (long i = 0; i < numSeek; i++) {
      long targetSeekTimeUs = random.nextInt(NARROW_BAND_FILE_DURATION_US + 1);
      int extractedFrameIndex =
          TestUtil.seekToTimeUs(
              extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

      assertThat(extractedFrameIndex).isNotEqualTo(-1);
      assertFirstFrameAfterSeekContainTargetSeekTime(
          trackOutput, targetSeekTimeUs, extractedFrameIndex);
    }
  }

  @Test
  public void testAmrExtractorReads_returnSeekableSeekMap_forWideBandAmr()
      throws IOException, InterruptedException {
    String fileName = WIDE_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);

    AmrExtractor extractor = createAmrExtractor();
    SeekMap seekMap =
        TestUtil.extractSeekMap(extractor, new FakeExtractorOutput(), dataSource, fileUri);

    assertThat(seekMap).isNotNull();
    assertThat(seekMap.getDurationUs()).isEqualTo(WIDE_BAND_FILE_DURATION_US);
    assertThat(seekMap.isSeekable()).isTrue();
  }

  @Test
  public void testSeeking_handlesSeekingToPositionInFile_extractsCorrectFrame_forWideBandAmr()
      throws IOException, InterruptedException {
    String fileName = WIDE_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);

    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long targetSeekTimeUs = 980_000;
    int extractedFrameIndex =
        TestUtil.seekToTimeUs(
            extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

    assertThat(extractedFrameIndex).isNotEqualTo(-1);
    assertFirstFrameAfterSeekContainTargetSeekTime(
        trackOutput, targetSeekTimeUs, extractedFrameIndex);
  }

  @Test
  public void testSeeking_handlesSeekToEoF_extractsLastFrame_forWideBandAmr()
      throws IOException, InterruptedException {
    String fileName = WIDE_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);
    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long targetSeekTimeUs = seekMap.getDurationUs();

    int extractedFrameIndex =
        TestUtil.seekToTimeUs(
            extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

    assertThat(extractedFrameIndex).isNotEqualTo(-1);
    assertFirstFrameAfterSeekContainTargetSeekTime(
        trackOutput, targetSeekTimeUs, extractedFrameIndex);
  }

  @Test
  public void testSeeking_handlesSeekingBackward_extractsCorrectFrames_forWideBandAmr()
      throws IOException, InterruptedException {
    String fileName = WIDE_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);
    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long firstSeekTimeUs = 980_000;
    TestUtil.seekToTimeUs(extractor, seekMap, firstSeekTimeUs, dataSource, trackOutput, fileUri);

    long targetSeekTimeUs = 0;
    int extractedFrameIndex =
        TestUtil.seekToTimeUs(
            extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

    assertThat(extractedFrameIndex).isNotEqualTo(-1);
    assertFirstFrameAfterSeekContainTargetSeekTime(
        trackOutput, targetSeekTimeUs, extractedFrameIndex);
  }

  @Test
  public void testSeeking_handlesSeekingForward_extractsCorrectFrames_forWideBandAmr()
      throws IOException, InterruptedException {
    String fileName = WIDE_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);
    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long firstSeekTimeUs = 980_000;
    TestUtil.seekToTimeUs(extractor, seekMap, firstSeekTimeUs, dataSource, trackOutput, fileUri);

    long targetSeekTimeUs = 1_200_000;
    int extractedFrameIndex =
        TestUtil.seekToTimeUs(
            extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

    assertThat(extractedFrameIndex).isNotEqualTo(-1);
    assertFirstFrameAfterSeekContainTargetSeekTime(
        trackOutput, targetSeekTimeUs, extractedFrameIndex);
  }

  @Test
  public void testSeeking_handlesRandomSeeks_extractsCorrectFrames_forWideBandAmr()
      throws IOException, InterruptedException {
    String fileName = WIDE_BAND_AMR_FILE;
    Uri fileUri = TestUtil.buildAssetUri(fileName);
    expectedTrackOutput =
        TestUtil.extractAllSamplesFromFile(
                createAmrExtractor(), ApplicationProvider.getApplicationContext(), fileName)
            .trackOutputs
            .get(0);
    AmrExtractor extractor = createAmrExtractor();

    FakeExtractorOutput extractorOutput = new FakeExtractorOutput();
    SeekMap seekMap = TestUtil.extractSeekMap(extractor, extractorOutput, dataSource, fileUri);
    FakeTrackOutput trackOutput = extractorOutput.trackOutputs.get(0);

    long numSeek = 100;
    for (long i = 0; i < numSeek; i++) {
      long targetSeekTimeUs = random.nextInt(NARROW_BAND_FILE_DURATION_US + 1);
      int extractedFrameIndex =
          TestUtil.seekToTimeUs(
              extractor, seekMap, targetSeekTimeUs, dataSource, trackOutput, fileUri);

      assertThat(extractedFrameIndex).isNotEqualTo(-1);
      assertFirstFrameAfterSeekContainTargetSeekTime(
          trackOutput, targetSeekTimeUs, extractedFrameIndex);
    }
  }

  // Internal methods

  private AmrExtractor createAmrExtractor() {
    return new AmrExtractor(AmrExtractor.FLAG_ENABLE_CONSTANT_BITRATE_SEEKING);
  }

  private void assertFirstFrameAfterSeekContainTargetSeekTime(
      FakeTrackOutput trackOutput, long seekTimeUs, int firstFrameIndexAfterSeek) {
    int expectedSampleIndex = findTargetFrameInExpectedOutput(seekTimeUs);
    // Assert that after seeking, the first sample frame written to output contains the sample
    // at seek time.
    trackOutput.assertSample(
        firstFrameIndexAfterSeek,
        expectedTrackOutput.getSampleData(expectedSampleIndex),
        expectedTrackOutput.getSampleTimeUs(expectedSampleIndex),
        expectedTrackOutput.getSampleFlags(expectedSampleIndex),
        expectedTrackOutput.getSampleCryptoData(expectedSampleIndex));
  }

  private int findTargetFrameInExpectedOutput(long seekTimeUs) {
    List<Long> sampleTimes = expectedTrackOutput.getSampleTimesUs();
    for (int i = 0; i < sampleTimes.size() - 1; i++) {
      long currentSampleTime = sampleTimes.get(i);
      long nextSampleTime = sampleTimes.get(i + 1);
      if (currentSampleTime <= seekTimeUs && nextSampleTime > seekTimeUs) {
        return i;
      }
    }
    return sampleTimes.size() - 1;
  }
}