diff options
Diffstat (limited to 'mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/webvtt/Mp4WebvttDecoder.java')
-rw-r--r-- | mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/webvtt/Mp4WebvttDecoder.java | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/webvtt/Mp4WebvttDecoder.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/webvtt/Mp4WebvttDecoder.java new file mode 100644 index 0000000000..3df35c789b --- /dev/null +++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/webvtt/Mp4WebvttDecoder.java @@ -0,0 +1,101 @@ +/* + * Copyright (C) 2016 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 org.mozilla.thirdparty.com.google.android.exoplayer2.text.webvtt; + +import org.mozilla.thirdparty.com.google.android.exoplayer2.text.Cue; +import org.mozilla.thirdparty.com.google.android.exoplayer2.text.SimpleSubtitleDecoder; +import org.mozilla.thirdparty.com.google.android.exoplayer2.text.Subtitle; +import org.mozilla.thirdparty.com.google.android.exoplayer2.text.SubtitleDecoderException; +import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray; +import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util; +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; + +/** A {@link SimpleSubtitleDecoder} for Webvtt embedded in a Mp4 container file. */ +@SuppressWarnings("ConstantField") +public final class Mp4WebvttDecoder extends SimpleSubtitleDecoder { + + private static final int BOX_HEADER_SIZE = 8; + + @SuppressWarnings("ConstantCaseForConstants") + private static final int TYPE_payl = 0x7061796c; + + @SuppressWarnings("ConstantCaseForConstants") + private static final int TYPE_sttg = 0x73747467; + + @SuppressWarnings("ConstantCaseForConstants") + private static final int TYPE_vttc = 0x76747463; + + private final ParsableByteArray sampleData; + private final WebvttCue.Builder builder; + + public Mp4WebvttDecoder() { + super("Mp4WebvttDecoder"); + sampleData = new ParsableByteArray(); + builder = new WebvttCue.Builder(); + } + + @Override + protected Subtitle decode(byte[] bytes, int length, boolean reset) + throws SubtitleDecoderException { + // Webvtt in Mp4 samples have boxes inside of them, so we have to do a traditional box parsing: + // first 4 bytes size and then 4 bytes type. + sampleData.reset(bytes, length); + List<Cue> resultingCueList = new ArrayList<>(); + while (sampleData.bytesLeft() > 0) { + if (sampleData.bytesLeft() < BOX_HEADER_SIZE) { + throw new SubtitleDecoderException("Incomplete Mp4Webvtt Top Level box header found."); + } + int boxSize = sampleData.readInt(); + int boxType = sampleData.readInt(); + if (boxType == TYPE_vttc) { + resultingCueList.add(parseVttCueBox(sampleData, builder, boxSize - BOX_HEADER_SIZE)); + } else { + // Peers of the VTTCueBox are still not supported and are skipped. + sampleData.skipBytes(boxSize - BOX_HEADER_SIZE); + } + } + return new Mp4WebvttSubtitle(resultingCueList); + } + + private static Cue parseVttCueBox(ParsableByteArray sampleData, WebvttCue.Builder builder, + int remainingCueBoxBytes) throws SubtitleDecoderException { + builder.reset(); + while (remainingCueBoxBytes > 0) { + if (remainingCueBoxBytes < BOX_HEADER_SIZE) { + throw new SubtitleDecoderException("Incomplete vtt cue box header found."); + } + int boxSize = sampleData.readInt(); + int boxType = sampleData.readInt(); + remainingCueBoxBytes -= BOX_HEADER_SIZE; + int payloadLength = boxSize - BOX_HEADER_SIZE; + String boxPayload = + Util.fromUtf8Bytes(sampleData.data, sampleData.getPosition(), payloadLength); + sampleData.skipBytes(payloadLength); + remainingCueBoxBytes -= payloadLength; + if (boxType == TYPE_sttg) { + WebvttCueParser.parseCueSettingsList(boxPayload, builder); + } else if (boxType == TYPE_payl) { + WebvttCueParser.parseCueText(null, boxPayload.trim(), builder, Collections.emptyList()); + } else { + // Other VTTCueBox children are still not supported and are ignored. + } + } + return builder.build(); + } + +} |