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Support unwrapping nested Metadata messages in MetadataRenderer

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Initially this supports ID3-in-EMSG, but can also be used to support SCTE35-in-EMSG too.

PiperOrigin-RevId: 263535925
This commit is contained in:
ibaker 2019-08-15 12:09:48 +01:00 committed by Andrew Lewis
parent 567d078e9e
commit ebb72e358f
4 changed files with 239 additions and 8 deletions
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22
library/core/src/main/java/com/google/android/exoplayer2/metadata/Metadata.java
View File

@ -18,6 +18,7 @@ package com.google.android.exoplayer2.metadata;
import android.os.Parcel;
import android.os.Parcelable;
import androidx.annotation.Nullable;
import com.google.android.exoplayer2.Format;
import com.google.android.exoplayer2.util.Util;
import java.util.Arrays;
import java.util.List;
@ -28,10 +29,27 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
*/
public final class Metadata implements Parcelable {
/** A metadata entry. */
public interface Entry extends Parcelable {
/**
* A metadata entry.
* Returns the {@link Format} that can be used to decode the wrapped metadata in {@link
* #getWrappedMetadataBytes()}, or null if this Entry doesn't contain wrapped metadata.
*/
public interface Entry extends Parcelable {}
@Nullable
default Format getWrappedMetadataFormat() {
return null;
}
/**
* Returns the bytes of the wrapped metadata in this Entry, or null if it doesn't contain
* wrapped metadata.
*/
@Nullable
default byte[] getWrappedMetadataBytes() {
return null;
}
}
private final Entry[] entries;

42
library/core/src/main/java/com/google/android/exoplayer2/metadata/MetadataRenderer.java
View File

@ -27,7 +27,9 @@ import com.google.android.exoplayer2.Format;
import com.google.android.exoplayer2.FormatHolder;
import com.google.android.exoplayer2.util.Assertions;
import com.google.android.exoplayer2.util.Util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* A renderer for metadata.
@ -123,14 +125,20 @@ public final class MetadataRenderer extends BaseRenderer implements Callback {
} else {
buffer.subsampleOffsetUs = subsampleOffsetUs;
buffer.flip();
int index = (pendingMetadataIndex + pendingMetadataCount) % MAX_PENDING_METADATA_COUNT;
Metadata metadata = decoder.decode(buffer);
if (metadata != null) {
pendingMetadata[index] = metadata;
List<Metadata.Entry> entries = new ArrayList<>(metadata.length());
decodeWrappedMetadata(metadata, entries);
if (!entries.isEmpty()) {
Metadata expandedMetadata = new Metadata(entries);
int index =
(pendingMetadataIndex + pendingMetadataCount) % MAX_PENDING_METADATA_COUNT;
pendingMetadata[index] = expandedMetadata;
pendingMetadataTimestamps[index] = buffer.timeUs;
pendingMetadataCount++;
}
}
}
} else if (result == C.RESULT_FORMAT_READ) {
subsampleOffsetUs = formatHolder.format.subsampleOffsetUs;
}
@ -144,6 +152,36 @@ public final class MetadataRenderer extends BaseRenderer implements Callback {
}
}
/**
* Iterates through {@code metadata.entries} and checks each one to see if contains wrapped
* metadata. If it does, then we recursively decode the wrapped metadata. If it doesn't (recursion
* base-case), we add the {@link Metadata.Entry} to {@code decodedEntries} (output parameter).
*/
private void decodeWrappedMetadata(Metadata metadata, List<Metadata.Entry> decodedEntries) {
for (int i = 0; i < metadata.length(); i++) {
Format wrappedMetadataFormat = metadata.get(i).getWrappedMetadataFormat();
if (wrappedMetadataFormat != null && decoderFactory.supportsFormat(wrappedMetadataFormat)) {
MetadataDecoder wrappedMetadataDecoder =
decoderFactory.createDecoder(wrappedMetadataFormat);
// wrappedMetadataFormat != null so wrappedMetadataBytes must be non-null too.
byte[] wrappedMetadataBytes =
Assertions.checkNotNull(metadata.get(i).getWrappedMetadataBytes());
buffer.clear();
buffer.ensureSpaceForWrite(wrappedMetadataBytes.length);
buffer.data.put(wrappedMetadataBytes);
buffer.flip();
@Nullable Metadata innerMetadata = wrappedMetadataDecoder.decode(buffer);
if (innerMetadata != null) {
// The decoding succeeded, so we'll try another level of unwrapping.
decodeWrappedMetadata(innerMetadata, decodedEntries);
}
} else {
// Entry doesn't contain any wrapped metadata, so output it directly.
decodedEntries.add(metadata.get(i));
}
}
}
@Override
protected void onDisabled() {
flushPendingMetadata();

22
library/core/src/main/java/com/google/android/exoplayer2/metadata/emsg/EventMessage.java
View File

@ -20,7 +20,10 @@ import static com.google.android.exoplayer2.util.Util.castNonNull;
import android.os.Parcel;
import android.os.Parcelable;
import androidx.annotation.Nullable;
import androidx.annotation.VisibleForTesting;
import com.google.android.exoplayer2.Format;
import com.google.android.exoplayer2.metadata.Metadata;
import com.google.android.exoplayer2.util.MimeTypes;
import com.google.android.exoplayer2.util.Util;
import java.util.Arrays;
@ -29,6 +32,13 @@ import java.util.Arrays;
*/
public final class EventMessage implements Metadata.Entry {
@VisibleForTesting
public static final String ID3_SCHEME_ID = "https://developer.apple.com/streaming/emsg-id3";
private static final Format ID3_FORMAT =
Format.createSampleFormat(
/* id= */ null, MimeTypes.APPLICATION_ID3, Format.OFFSET_SAMPLE_RELATIVE);
/**
* The message scheme.
*/
@ -81,6 +91,18 @@ public final class EventMessage implements Metadata.Entry {
messageData = castNonNull(in.createByteArray());
}
@Override
@Nullable
public Format getWrappedMetadataFormat() {
return ID3_SCHEME_ID.equals(schemeIdUri) ? ID3_FORMAT : null;
}
@Override
@Nullable
public byte[] getWrappedMetadataBytes() {
return ID3_SCHEME_ID.equals(schemeIdUri) ? messageData : null;
}
@Override
public int hashCode() {
if (hashCode == 0) {

153
library/core/src/test/java/com/google/android/exoplayer2/metadata/MetadataRendererTest.java Normal file
View File

@ -0,0 +1,153 @@
/*
* Copyright (C) 2019 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.metadata;
import static com.google.common.truth.Truth.assertThat;
import static java.nio.charset.StandardCharsets.ISO_8859_1;
import static java.nio.charset.StandardCharsets.UTF_8;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import com.google.android.exoplayer2.ExoPlaybackException;
import com.google.android.exoplayer2.Format;
import com.google.android.exoplayer2.metadata.emsg.EventMessage;
import com.google.android.exoplayer2.metadata.emsg.EventMessageEncoder;
import com.google.android.exoplayer2.metadata.id3.TextInformationFrame;
import com.google.android.exoplayer2.testutil.FakeSampleStream;
import com.google.android.exoplayer2.testutil.TestUtil;
import com.google.android.exoplayer2.util.Assertions;
import com.google.android.exoplayer2.util.MimeTypes;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
/** Tests for {@link MetadataRenderer}. */
@RunWith(AndroidJUnit4.class)
public class MetadataRendererTest {
private static final Format EMSG_FORMAT =
Format.createSampleFormat(null, MimeTypes.APPLICATION_EMSG, Format.OFFSET_SAMPLE_RELATIVE);
private final EventMessageEncoder eventMessageEncoder = new EventMessageEncoder();
@Test
public void decodeMetadata() throws Exception {
EventMessage emsg =
new EventMessage(
"urn:test-scheme-id",
/* value= */ "",
/* durationMs= */ 1,
/* id= */ 0,
"Test data".getBytes(UTF_8));
List<Metadata> metadata = runRenderer(eventMessageEncoder.encode(emsg));
assertThat(metadata).hasSize(1);
assertThat(metadata.get(0).length()).isEqualTo(1);
assertThat(metadata.get(0).get(0)).isEqualTo(emsg);
}
@Test
public void decodeMetadata_handlesWrappedMetadata() throws Exception {
EventMessage emsg =
new EventMessage(
EventMessage.ID3_SCHEME_ID,
/* value= */ "",
/* durationMs= */ 1,
/* id= */ 0,
encodeTxxxId3Frame("Test description", "Test value"));
List<Metadata> metadata = runRenderer(eventMessageEncoder.encode(emsg));
assertThat(metadata).hasSize(1);
assertThat(metadata.get(0).length()).isEqualTo(1);
TextInformationFrame expectedId3Frame =
new TextInformationFrame("TXXX", "Test description", "Test value");
assertThat(metadata.get(0).get(0)).isEqualTo(expectedId3Frame);
}
@Test
public void decodeMetadata_skipsMalformedWrappedMetadata() throws Exception {
EventMessage emsg =
new EventMessage(
EventMessage.ID3_SCHEME_ID,
/* value= */ "",
/* durationMs= */ 1,
/* id= */ 0,
"Not a real ID3 tag".getBytes(ISO_8859_1));
List<Metadata> metadata = runRenderer(eventMessageEncoder.encode(emsg));
assertThat(metadata).isEmpty();
}
private static List<Metadata> runRenderer(byte[] input) throws ExoPlaybackException {
List<Metadata> metadata = new ArrayList<>();
MetadataRenderer renderer = new MetadataRenderer(metadata::add, /* outputLooper= */ null);
renderer.replaceStream(
new Format[] {EMSG_FORMAT},
new FakeSampleStream(EMSG_FORMAT, /* eventDispatcher= */ null, input),
/* offsetUs= */ 0L);
renderer.render(/* positionUs= */ 0, /* elapsedRealtimeUs= */ 0); // Read the format
renderer.render(/* positionUs= */ 0, /* elapsedRealtimeUs= */ 0); // Read the data
return Collections.unmodifiableList(metadata);
}
/**
* Builds an ID3v2 tag containing a single 'user defined text information frame' (id='TXXX') with
* {@code description} and {@code value}.
*
* <ul>
* <li><a href="http://id3.org/id3v2.4.0-structure">ID3v2 overall structure</a>
* <li><a href="http://id3.org/id3v2.4.0-frames">'user defined text information frame' spec</a>
* (item 4.2.6)
* </ul>
*/
private static byte[] encodeTxxxId3Frame(String description, String value) {
byte[] id3FrameData =
TestUtil.joinByteArrays(
"TXXX".getBytes(ISO_8859_1), // ID for a 'user defined text information frame'
TestUtil.createByteArray(0, 0, 0, 0), // Frame size (set later)
TestUtil.createByteArray(0, 0), // Frame flags
TestUtil.createByteArray(0), // Character encoding = ISO-8859-1
description.getBytes(ISO_8859_1),
TestUtil.createByteArray(0), // String null terminator
value.getBytes(ISO_8859_1),
TestUtil.createByteArray(0)); // String null terminator
int frameSizeIndex = 7;
int frameSize = id3FrameData.length - 10;
Assertions.checkArgument(
frameSize < 128, "frameSize must fit in 7 bits to avoid synch-safe encoding: " + frameSize);
id3FrameData[frameSizeIndex] = (byte) frameSize;
byte[] id3Bytes =
TestUtil.joinByteArrays(
"ID3".getBytes(ISO_8859_1), // identifier
TestUtil.createByteArray(0x04, 0x00), // version
TestUtil.createByteArray(0), // Tag flags
TestUtil.createByteArray(0, 0, 0, 0), // Tag size (set later)
id3FrameData);
int tagSizeIndex = 9;
int tagSize = id3Bytes.length - 10;
Assertions.checkArgument(
tagSize < 128, "tagSize must fit in 7 bits to avoid synch-safe encoding: " + tagSize);
id3Bytes[tagSizeIndex] = (byte) tagSize;
return id3Bytes;
}
}