diff options
Diffstat (limited to 'mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java')
-rw-r--r-- | mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java new file mode 100644 index 0000000000..b4e160fa74 --- /dev/null +++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java @@ -0,0 +1,260 @@ +/* + * 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.extractor.mkv; + +import androidx.annotation.IntDef; +import org.mozilla.thirdparty.com.google.android.exoplayer2.C; +import org.mozilla.thirdparty.com.google.android.exoplayer2.ParserException; +import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.ExtractorInput; +import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions; +import java.io.EOFException; +import java.io.IOException; +import java.lang.annotation.Documented; +import java.lang.annotation.Retention; +import java.lang.annotation.RetentionPolicy; +import java.util.ArrayDeque; + +/** + * Default implementation of {@link EbmlReader}. + */ +/* package */ final class DefaultEbmlReader implements EbmlReader { + + @Documented + @Retention(RetentionPolicy.SOURCE) + @IntDef({ELEMENT_STATE_READ_ID, ELEMENT_STATE_READ_CONTENT_SIZE, ELEMENT_STATE_READ_CONTENT}) + private @interface ElementState {} + + private static final int ELEMENT_STATE_READ_ID = 0; + private static final int ELEMENT_STATE_READ_CONTENT_SIZE = 1; + private static final int ELEMENT_STATE_READ_CONTENT = 2; + + private static final int MAX_ID_BYTES = 4; + private static final int MAX_LENGTH_BYTES = 8; + + private static final int MAX_INTEGER_ELEMENT_SIZE_BYTES = 8; + private static final int VALID_FLOAT32_ELEMENT_SIZE_BYTES = 4; + private static final int VALID_FLOAT64_ELEMENT_SIZE_BYTES = 8; + + private final byte[] scratch; + private final ArrayDeque<MasterElement> masterElementsStack; + private final VarintReader varintReader; + + private EbmlProcessor processor; + private @ElementState int elementState; + private int elementId; + private long elementContentSize; + + public DefaultEbmlReader() { + scratch = new byte[8]; + masterElementsStack = new ArrayDeque<>(); + varintReader = new VarintReader(); + } + + @Override + public void init(EbmlProcessor processor) { + this.processor = processor; + } + + @Override + public void reset() { + elementState = ELEMENT_STATE_READ_ID; + masterElementsStack.clear(); + varintReader.reset(); + } + + @Override + public boolean read(ExtractorInput input) throws IOException, InterruptedException { + Assertions.checkNotNull(processor); + while (true) { + if (!masterElementsStack.isEmpty() + && input.getPosition() >= masterElementsStack.peek().elementEndPosition) { + processor.endMasterElement(masterElementsStack.pop().elementId); + return true; + } + + if (elementState == ELEMENT_STATE_READ_ID) { + long result = varintReader.readUnsignedVarint(input, true, false, MAX_ID_BYTES); + if (result == C.RESULT_MAX_LENGTH_EXCEEDED) { + result = maybeResyncToNextLevel1Element(input); + } + if (result == C.RESULT_END_OF_INPUT) { + return false; + } + // Element IDs are at most 4 bytes, so we can cast to integers. + elementId = (int) result; + elementState = ELEMENT_STATE_READ_CONTENT_SIZE; + } + + if (elementState == ELEMENT_STATE_READ_CONTENT_SIZE) { + elementContentSize = varintReader.readUnsignedVarint(input, false, true, MAX_LENGTH_BYTES); + elementState = ELEMENT_STATE_READ_CONTENT; + } + + @EbmlProcessor.ElementType int type = processor.getElementType(elementId); + switch (type) { + case EbmlProcessor.ELEMENT_TYPE_MASTER: + long elementContentPosition = input.getPosition(); + long elementEndPosition = elementContentPosition + elementContentSize; + masterElementsStack.push(new MasterElement(elementId, elementEndPosition)); + processor.startMasterElement(elementId, elementContentPosition, elementContentSize); + elementState = ELEMENT_STATE_READ_ID; + return true; + case EbmlProcessor.ELEMENT_TYPE_UNSIGNED_INT: + if (elementContentSize > MAX_INTEGER_ELEMENT_SIZE_BYTES) { + throw new ParserException("Invalid integer size: " + elementContentSize); + } + processor.integerElement(elementId, readInteger(input, (int) elementContentSize)); + elementState = ELEMENT_STATE_READ_ID; + return true; + case EbmlProcessor.ELEMENT_TYPE_FLOAT: + if (elementContentSize != VALID_FLOAT32_ELEMENT_SIZE_BYTES + && elementContentSize != VALID_FLOAT64_ELEMENT_SIZE_BYTES) { + throw new ParserException("Invalid float size: " + elementContentSize); + } + processor.floatElement(elementId, readFloat(input, (int) elementContentSize)); + elementState = ELEMENT_STATE_READ_ID; + return true; + case EbmlProcessor.ELEMENT_TYPE_STRING: + if (elementContentSize > Integer.MAX_VALUE) { + throw new ParserException("String element size: " + elementContentSize); + } + processor.stringElement(elementId, readString(input, (int) elementContentSize)); + elementState = ELEMENT_STATE_READ_ID; + return true; + case EbmlProcessor.ELEMENT_TYPE_BINARY: + processor.binaryElement(elementId, (int) elementContentSize, input); + elementState = ELEMENT_STATE_READ_ID; + return true; + case EbmlProcessor.ELEMENT_TYPE_UNKNOWN: + input.skipFully((int) elementContentSize); + elementState = ELEMENT_STATE_READ_ID; + break; + default: + throw new ParserException("Invalid element type " + type); + } + } + } + + /** + * Does a byte by byte search to try and find the next level 1 element. This method is called if + * some invalid data is encountered in the parser. + * + * @param input The {@link ExtractorInput} from which data has to be read. + * @return id of the next level 1 element that has been found. + * @throws EOFException If the end of input was encountered when searching for the next level 1 + * element. + * @throws IOException If an error occurs reading from the input. + * @throws InterruptedException If the thread is interrupted. + */ + private long maybeResyncToNextLevel1Element(ExtractorInput input) throws IOException, + InterruptedException { + input.resetPeekPosition(); + while (true) { + input.peekFully(scratch, 0, MAX_ID_BYTES); + int varintLength = VarintReader.parseUnsignedVarintLength(scratch[0]); + if (varintLength != C.LENGTH_UNSET && varintLength <= MAX_ID_BYTES) { + int potentialId = (int) VarintReader.assembleVarint(scratch, varintLength, false); + if (processor.isLevel1Element(potentialId)) { + input.skipFully(varintLength); + return potentialId; + } + } + input.skipFully(1); + } + } + + /** + * Reads and returns an integer of length {@code byteLength} from the {@link ExtractorInput}. + * + * @param input The {@link ExtractorInput} from which to read. + * @param byteLength The length of the integer being read. + * @return The read integer value. + * @throws IOException If an error occurs reading from the input. + * @throws InterruptedException If the thread is interrupted. + */ + private long readInteger(ExtractorInput input, int byteLength) + throws IOException, InterruptedException { + input.readFully(scratch, 0, byteLength); + long value = 0; + for (int i = 0; i < byteLength; i++) { + value = (value << 8) | (scratch[i] & 0xFF); + } + return value; + } + + /** + * Reads and returns a float of length {@code byteLength} from the {@link ExtractorInput}. + * + * @param input The {@link ExtractorInput} from which to read. + * @param byteLength The length of the float being read. + * @return The read float value. + * @throws IOException If an error occurs reading from the input. + * @throws InterruptedException If the thread is interrupted. + */ + private double readFloat(ExtractorInput input, int byteLength) + throws IOException, InterruptedException { + long integerValue = readInteger(input, byteLength); + double floatValue; + if (byteLength == VALID_FLOAT32_ELEMENT_SIZE_BYTES) { + floatValue = Float.intBitsToFloat((int) integerValue); + } else { + floatValue = Double.longBitsToDouble(integerValue); + } + return floatValue; + } + + /** + * Reads a string of length {@code byteLength} from the {@link ExtractorInput}. Zero padding is + * removed, so the returned string may be shorter than {@code byteLength}. + * + * @param input The {@link ExtractorInput} from which to read. + * @param byteLength The length of the string being read, including zero padding. + * @return The read string value. + * @throws IOException If an error occurs reading from the input. + * @throws InterruptedException If the thread is interrupted. + */ + private String readString(ExtractorInput input, int byteLength) + throws IOException, InterruptedException { + if (byteLength == 0) { + return ""; + } + byte[] stringBytes = new byte[byteLength]; + input.readFully(stringBytes, 0, byteLength); + // Remove zero padding. + int trimmedLength = byteLength; + while (trimmedLength > 0 && stringBytes[trimmedLength - 1] == 0) { + trimmedLength--; + } + return new String(stringBytes, 0, trimmedLength); + } + + /** + * Used in {@link #masterElementsStack} to track when the current master element ends, so that + * {@link EbmlProcessor#endMasterElement(int)} can be called. + */ + private static final class MasterElement { + + private final int elementId; + private final long elementEndPosition; + + private MasterElement(int elementId, long elementEndPosition) { + this.elementId = elementId; + this.elementEndPosition = elementEndPosition; + } + + } + +} |