/*
* Copyright 2023 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 androidx.media3.extractor.webp;
import androidx.media3.common.C;
import androidx.media3.common.MimeTypes;
import androidx.media3.common.util.ParsableByteArray;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.extractor.Extractor;
import androidx.media3.extractor.ExtractorInput;
import androidx.media3.extractor.ExtractorOutput;
import androidx.media3.extractor.PositionHolder;
import androidx.media3.extractor.SingleSampleExtractor;
import java.io.IOException;
/** Extracts data from the WEBP container format. */
@UnstableApi
public final class WebpExtractor implements Extractor {
// Documentation reference:
// https://developers.google.com/speed/webp/docs/riff_container#webp_file_header
private static final int FILE_SIGNATURE_SEGMENT_LENGTH = 4;
private static final int RIFF_FILE_SIGNATURE = 0x52494646;
private static final int WEBP_FILE_SIGNATURE = 0x57454250;
private final ParsableByteArray scratch;
private final SingleSampleExtractor imageExtractor;
/** Creates an instance. */
public WebpExtractor() {
scratch = new ParsableByteArray(FILE_SIGNATURE_SEGMENT_LENGTH);
imageExtractor = new SingleSampleExtractor(C.INDEX_UNSET, C.LENGTH_UNSET, MimeTypes.IMAGE_WEBP);
}
@Override
public boolean sniff(ExtractorInput input) throws IOException {
// The full file signature for the format webp is RIFF????WEBP.
scratch.reset(/* limit= */ FILE_SIGNATURE_SEGMENT_LENGTH);
input.peekFully(scratch.getData(), /* offset= */ 0, FILE_SIGNATURE_SEGMENT_LENGTH);
if (scratch.readUnsignedInt() != RIFF_FILE_SIGNATURE) {
return false;
}
input.advancePeekPosition(FILE_SIGNATURE_SEGMENT_LENGTH);
scratch.reset(/* limit= */ FILE_SIGNATURE_SEGMENT_LENGTH);
input.peekFully(scratch.getData(), /* offset= */ 0, FILE_SIGNATURE_SEGMENT_LENGTH);
return scratch.readUnsignedInt() == WEBP_FILE_SIGNATURE;
}
@Override
public void init(ExtractorOutput output) {
imageExtractor.init(output);
}
@Override
public @ReadResult int read(ExtractorInput input, PositionHolder seekPosition)
throws IOException {
return imageExtractor.read(input, seekPosition);
}
@Override
public void seek(long position, long timeUs) {
imageExtractor.seek(position, timeUs);
}
@Override
public void release() {
// Do nothing.
}
}