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Add Cea608DecoderTest
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When debugging and fixing Issue: google/ExoPlayer#10666 I wanted to write a regression
test, but needed to add a test first... This is just a small bit of
coverage to start with. It checks the field/channel filtering works
correctly, but doesn't check any styling info. It also doesn't test
'pop on' subtitles (i.e. when the subtitle isn't shown until a 'end of
subtitle' signal is received).

PiperOrigin-RevId: 480644568
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@icbaker @marcbaechinger
icbaker authored and marcbaechinger committed Oct 17, 2022
1 parent f35bda3 commit 706b129
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344 changes: 344 additions & 0 deletions libraries/extractor/src/test/java/androidx/media3/extractor/text/cea/Cea608DecoderTest.java
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/*
* Copyright 2022 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
*
* https://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 androidx.media3.extractor.text.cea;

import static androidx.media3.common.util.Assertions.checkArgument;
import static androidx.media3.common.util.Assertions.checkNotNull;
import static com.google.common.truth.Truth.assertThat;

import androidx.annotation.Nullable;
import androidx.media3.common.C;
import androidx.media3.common.MimeTypes;
import androidx.media3.common.text.Cue;
import androidx.media3.common.util.Util;
import androidx.media3.extractor.text.Subtitle;
import androidx.media3.extractor.text.SubtitleDecoderException;
import androidx.media3.extractor.text.SubtitleInputBuffer;
import androidx.media3.extractor.text.SubtitleOutputBuffer;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.primitives.Bytes;
import com.google.common.primitives.UnsignedBytes;
import java.nio.ByteBuffer;
import org.junit.Test;
import org.junit.runner.RunWith;

/** Tests for {@link Cea608Decoder}. */
@RunWith(AndroidJUnit4.class)
public class Cea608DecoderTest {

@Test
public void paintOnEmitsSubtitlesImmediately() throws Exception {
Cea608Decoder decoder =
new Cea608Decoder(
MimeTypes.APPLICATION_CEA608,
/* accessibilityChannel= */ 1,
Cea608Decoder.MIN_DATA_CHANNEL_TIMEOUT_MS);
byte[] sample1 =
Bytes.concat(
// 'paint on' control character
createPacket(0xFC, 0x14, 0x29),
createPacket(0xFC, 't', 'e'),
createPacket(0xFC, 's', 't'),
createPacket(0xFC, ' ', 's'),
createPacket(0xFC, 'u', 'b'),
createPacket(0xFC, 't', 'i'),
createPacket(0xFC, 't', 'l'),
createPacket(0xFC, 'e', ','),
createPacket(0xFC, ' ', 's'),
createPacket(0xFC, 'p', 'a'));
byte[] sample2 =
Bytes.concat(
createPacket(0xFC, 'n', 's'),
createPacket(0xFC, ' ', '2'),
createPacket(0xFC, ' ', 's'),
createPacket(0xFC, 'a', 'm'),
createPacket(0xFC, 'p', 'l'),
createPacket(0xFC, 'e', 's'));

Subtitle firstSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample1));
Subtitle secondSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample2));

assertThat(getOnlyCue(firstSubtitle).text.toString()).isEqualTo("test subtitle, spa");
assertThat(getOnlyCue(secondSubtitle).text.toString())
.isEqualTo("test subtitle, spans 2 samples");
}

@Test
public void rollUpEmitsSubtitlesImmediately() throws Exception {
Cea608Decoder decoder =
new Cea608Decoder(
MimeTypes.APPLICATION_CEA608,
/* accessibilityChannel= */ 1, // field 1, channel 1
Cea608Decoder.MIN_DATA_CHANNEL_TIMEOUT_MS);
byte[] sample1 =
Bytes.concat(
// 'roll up 2 rows' control character
createPacket(0xFC, 0x14, 0x25),
createPacket(0xFC, 't', 'e'),
createPacket(0xFC, 's', 't'),
createPacket(0xFC, ' ', 's'),
createPacket(0xFC, 'u', 'b'),
createPacket(0xFC, 't', 'i'),
createPacket(0xFC, 't', 'l'),
createPacket(0xFC, 'e', ','),
createPacket(0xFC, ' ', 's'),
createPacket(0xFC, 'p', 'a'));
byte[] sample2 =
Bytes.concat(
createPacket(0xFC, 'n', 's'),
createPacket(0xFC, ' ', '3'),
createPacket(0xFC, ' ', 's'),
createPacket(0xFC, 'a', 'm'),
createPacket(0xFC, 'p', 'l'),
createPacket(0xFC, 'e', 's'),
// Carriage return control character
createPacket(0xFC, 0x14, 0x2D),
createPacket(0xFC, 'w', 'i'),
createPacket(0xFC, 't', 'h'),
createPacket(0xFC, ' ', 'n'));
byte[] sample3 =
Bytes.concat(
createPacket(0xFC, 'e', 'w'),
createPacket(0xFC, 'l', 'i'),
createPacket(0xFC, 'n', 'e'),
createPacket(0xFC, 's', 0x0));

Subtitle firstSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample1));
Subtitle secondSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample2));
Subtitle thirdSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample3));

assertThat(getOnlyCue(firstSubtitle).text.toString()).isEqualTo("test subtitle, spa");
assertThat(getOnlyCue(secondSubtitle).text.toString())
.isEqualTo("test subtitle, spans 3 samples\nwith n");
assertThat(getOnlyCue(thirdSubtitle).text.toString())
.isEqualTo("test subtitle, spans 3 samples\nwith newlines");
}

@Test
public void onlySelectedFieldIsUsed() throws Exception {
Cea608Decoder decoder =
new Cea608Decoder(
MimeTypes.APPLICATION_CEA608,
/* accessibilityChannel= */ 1, // field 1, channel 1
Cea608Decoder.MIN_DATA_CHANNEL_TIMEOUT_MS);
// field 1 (0xfC header): 'test subtitle'
// field 2 (0xfC header): 'wrong field!'
byte[] sample1 =
Bytes.concat(
// 'paint on' control character
createPacket(0xFC, 0x14, 0x29),
createPacket(0xFD, 0x15, 0x29),
createPacket(0xFC, 't', 'e'),
createPacket(0xFD, 'w', 'r'),
createPacket(0xFC, 's', 't'),
createPacket(0xFD, 'o', 'n'),
createPacket(0xFC, ' ', 's'),
createPacket(0xFD, 'g', ' '),
createPacket(0xFC, 'u', 'b'),
createPacket(0xFD, 'f', 'i'));
byte[] sample2 =
Bytes.concat(
createPacket(0xFC, 't', 'i'),
createPacket(0xFD, 'e', 'l'),
createPacket(0xFC, 't', 'l'),
createPacket(0xFD, 'd', '!'),
createPacket(0xFC, 'e', 0x0),
createPacket(0xFD, 0x0, 0x0));

Subtitle firstSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample1));
Subtitle secondSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample2));

assertThat(getOnlyCue(firstSubtitle).text.toString()).isEqualTo("test sub");
assertThat(getOnlyCue(secondSubtitle).text.toString()).isEqualTo("test subtitle");
}

@Test
public void onlySelectedChannelIsUsed() throws Exception {
Cea608Decoder decoder =
new Cea608Decoder(
MimeTypes.APPLICATION_CEA608,
/* accessibilityChannel= */ 2, // field 1, channel 2
Cea608Decoder.MIN_DATA_CHANNEL_TIMEOUT_MS);
// field 1 (0xfC header), channel 1: 'wrong channel'
// field 1 (0xfC header), channel 2: 'test subtitle'
// field 2 (0xfC header), channel 1: 'wrong field!'
byte[] sample1 =
Bytes.concat(
// 'paint on' control character
createPacket(0xFC, 0x14, 0x29),
createPacket(0xFD, 0x15, 0x29),
createPacket(0xFC, 'w', 'r'),
createPacket(0xFD, 'w', 'r'),
createPacket(0xFC, 'o', 'n'),
createPacket(0xFD, 'o', 'n'),
// Switch to channel 2 & 'paint on' control character
createPacket(0xFC, 0x14 | 0x08, 0x29),
createPacket(0xFD, 'g', ' '),
createPacket(0xFC, 't', 'e'),
createPacket(0xFD, 'f', 'i'));
byte[] sample2 =
Bytes.concat(
createPacket(0xFC, 's', 't'),
createPacket(0xFD, 'e', 'l'),
// Switch to channel 1
createPacket(0xFC, 0x14, 0x0),
createPacket(0xFD, 'd', '!'),
createPacket(0xFC, 'g', ' '),
createPacket(0xFD, 0x0, 0x0),
createPacket(0xFC, 'c', 'h'),
createPacket(0xFD, 0x0, 0x0),
// Switch to channel 2
createPacket(0xFC, 0x14 | 0x08, 0x0),
createPacket(0xFD, 0x0, 0x0));
byte[] sample3 =
Bytes.concat(
createPacket(0xFC, ' ', 's'),
createPacket(0xFD, 0x0, 0x0),
createPacket(0xFC, 'u', 'b'),
createPacket(0xFD, 0x0, 0x0),
// Switch to channel 1
createPacket(0xFC, 0x14, 0x0),
createPacket(0xFD, 0x0, 0x0),
createPacket(0xFC, 'a', 'n'),
createPacket(0xFD, 0x0, 0x0),
createPacket(0xFC, 'n', 'e'),
createPacket(0xFD, 0x0, 0x0));
byte[] sample4 =
Bytes.concat(
// Switch to channel 2
createPacket(0xFC, 0x14 | 0x08, 0x0),
createPacket(0xFD, 0x0, 0x0),
createPacket(0xFC, 't', 'i'),
createPacket(0xFD, 0x0, 0x0),
createPacket(0xFC, 't', 'l'),
createPacket(0xFD, 0x0, 0x0),
// Switch to channel 1
createPacket(0xFC, 0x14, 0x0),
createPacket(0xFD, 0x0, 0x0),
createPacket(0xFC, 'l', 0x0),
createPacket(0xFD, 0x0, 0x0));
byte[] sample5 =
Bytes.concat(
createPacket(0xFC, 0x0, 0x0),
createPacket(0xFD, 0x0, 0x0),
// Switch to channel 2
createPacket(0xFC, 0x14 | 0x08, 0x0),
createPacket(0xFD, 0x0, 0x0),
createPacket(0xFC, 'e', 0x0),
createPacket(0xFD, 0x0, 0x0));

Subtitle firstSubtitle = /*checkNotNull(*/ decodeSampleAndCopyResult(decoder, sample1) /*)*/;
Subtitle secondSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample2));
Subtitle thirdSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample3));
Subtitle fourthSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample4));
Subtitle fifthSubtitle = checkNotNull(decodeSampleAndCopyResult(decoder, sample5));

assertThat(getOnlyCue(firstSubtitle).text.toString()).isEqualTo("te");
assertThat(getOnlyCue(secondSubtitle).text.toString()).isEqualTo("test");
assertThat(getOnlyCue(thirdSubtitle).text.toString()).isEqualTo("test sub");
assertThat(getOnlyCue(fourthSubtitle).text.toString()).isEqualTo("test subtitl");
assertThat(getOnlyCue(fifthSubtitle).text.toString()).isEqualTo("test subtitle");
}

private static byte[] createPacket(int header, int cc1, int cc2) {
return new byte[] {
UnsignedBytes.checkedCast(header),
ensureUnsignedByteOddParity(cc1),
ensureUnsignedByteOddParity(cc2)
};
}

private static byte ensureUnsignedByteOddParity(int input) {
checkArgument(input >= 0);
checkArgument(input < 128);

return UnsignedBytes.checkedCast(Integer.bitCount(input) % 2 == 0 ? input | 0x80 : input);
}

/**
* Queues {@code sample} to {@code decoder} and dequeues the result, then copies and returns it if
* it's non-null.
*
* <p>Fails if {@link Cea608Decoder#dequeueInputBuffer()} returns {@code null}.
*/
@Nullable
private static Subtitle decodeSampleAndCopyResult(Cea608Decoder decoder, byte[] sample)
throws SubtitleDecoderException {
SubtitleInputBuffer inputBuffer = checkNotNull(decoder.dequeueInputBuffer());
inputBuffer.data = ByteBuffer.wrap(sample);
decoder.queueInputBuffer(inputBuffer);
@Nullable SubtitleOutputBuffer outputBuffer = decoder.dequeueOutputBuffer();
if (outputBuffer == null) {
return null;
}
SimpleSubtitle subtitle = SimpleSubtitle.copyOf(outputBuffer);
outputBuffer.release();
return subtitle;
}

private static Cue getOnlyCue(Subtitle subtitle) {
assertThat(subtitle.getEventTimeCount()).isEqualTo(1);
return Iterables.getOnlyElement(subtitle.getCues(subtitle.getEventTime(0)));
}

private static final class SimpleSubtitle implements Subtitle {

private final ImmutableList<Long> eventTimesUs;
private final ImmutableList<ImmutableList<Cue>> events;

private SimpleSubtitle(
ImmutableList<Long> eventTimesUs, ImmutableList<ImmutableList<Cue>> events) {
this.eventTimesUs = eventTimesUs;
this.events = events;
}

public static SimpleSubtitle copyOf(Subtitle subtitle) {
ImmutableList.Builder<Long> eventTimesUs = ImmutableList.builder();
ImmutableList.Builder<ImmutableList<Cue>> events = ImmutableList.builder();
for (int i = 0; i < subtitle.getEventTimeCount(); i++) {
long eventTimeUs = subtitle.getEventTime(i);
eventTimesUs.add(eventTimeUs);
events.add(ImmutableList.copyOf(subtitle.getCues(eventTimeUs)));
}
return new SimpleSubtitle(eventTimesUs.build(), events.build());
}

@Override
public int getNextEventTimeIndex(long timeUs) {
int index = Util.binarySearchCeil(eventTimesUs, timeUs, /* inclusive= */ false, false);
return index != eventTimesUs.size() ? index : C.INDEX_UNSET;
}

@Override
public int getEventTimeCount() {
return eventTimesUs.size();
}

@Override
public long getEventTime(int index) {
return eventTimesUs.get(index);
}

@Override
public ImmutableList<Cue> getCues(long timeUs) {
return events.get(
Util.binarySearchFloor(
eventTimesUs, timeUs, /* inclusive= */ true, /* stayInBounds= */ true));
}
}
}

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