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AV1 bitstream parser that identifies frames with no dependencies
Usage: * call queueInputBuffer() with initialization data or sample data in decode order - updates the parser state * call sampleLimitAfterSkippingNonReferenceFrame to identify if the sample contains a frame without dependencies PiperOrigin-RevId: 720098835
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dancho
Copybara-Service
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/*
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* Copyright 2025 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package androidx.media3.exoplayer.video;
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import static androidx.media3.container.ObuParser.OBU_FRAME;
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import static androidx.media3.container.ObuParser.OBU_PADDING;
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import static androidx.media3.container.ObuParser.OBU_SEQUENCE_HEADER;
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import static androidx.media3.container.ObuParser.OBU_TEMPORAL_DELIMITER;
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import static androidx.media3.container.ObuParser.split;
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import androidx.annotation.Nullable;
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import androidx.media3.container.ObuParser;
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import androidx.media3.container.ObuParser.FrameHeader;
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import androidx.media3.container.ObuParser.SequenceHeader;
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import java.nio.ByteBuffer;
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import java.util.List;
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/** An AV1 bitstream parser that identifies frames that are not depended on. */
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/* package */ final class Av1SampleDependencyParser {
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@Nullable private SequenceHeader sequenceHeader;
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/**
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* Returns the new sample {@linkplain ByteBuffer#limit() limit} after deleting any frames that are
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* not used as reference.
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*
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* <p>Each AV1 temporal unit must have exactly one shown frame. Other frames in the temporal unit
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* that aren't shown are used as reference, but the shown frame may not be used as reference.
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* Frequently, the shown frame is the last frame in the temporal unit.
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*
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* <p>If the last frame in the temporal unit is a non-reference {@link ObuParser#OBU_FRAME}, this
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* method returns a new {@link ByteBuffer#limit()} value that would leave only the frames used as
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* reference in the input {@code sample}.
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*
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* <p>See <a href=https://aomediacodec.github.io/av1-spec/#ordering-of-obus>Ordering of OBUs</a>.
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*
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* @param sample The sample data for one AV1 temporal unit.
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*/
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public int sampleLimitAfterSkippingNonReferenceFrame(ByteBuffer sample) {
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List<ObuParser.Obu> obuList = split(sample);
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updateSequenceHeaders(obuList);
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int skippedFramesCount = 0;
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int last = obuList.size() - 1;
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while (last >= 0 && canSkipObu(obuList.get(last))) {
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if (obuList.get(last).type == OBU_FRAME) {
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skippedFramesCount++;
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}
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last--;
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}
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if (skippedFramesCount > 1) {
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return sample.limit();
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}
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if (last >= 0) {
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return obuList.get(last).payload.limit();
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}
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return sample.position();
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}
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/** Updates the parser state with the next sample data. */
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public void queueInputBuffer(ByteBuffer sample) {
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updateSequenceHeaders(split(sample));
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}
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private boolean canSkipObu(ObuParser.Obu obu) {
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if (obu.type == OBU_TEMPORAL_DELIMITER || obu.type == OBU_PADDING) {
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return true;
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}
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if (obu.type == OBU_FRAME && sequenceHeader != null) {
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FrameHeader frameHeader = FrameHeader.parse(sequenceHeader, obu);
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return frameHeader != null && !frameHeader.isDependedOn();
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}
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return false;
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}
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private void updateSequenceHeaders(List<ObuParser.Obu> obuList) {
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for (int i = 0; i < obuList.size(); ++i) {
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if (obuList.get(i).type == OBU_SEQUENCE_HEADER) {
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sequenceHeader = SequenceHeader.parse(obuList.get(i));
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}
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}
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}
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}
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@ -0,0 +1,160 @@
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/*
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* Copyright 2025 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package androidx.media3.exoplayer.video;
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import static androidx.media3.test.utils.TestUtil.createByteArray;
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import static com.google.common.truth.Truth.assertThat;
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import androidx.test.ext.junit.runners.AndroidJUnit4;
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import java.nio.ByteBuffer;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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/** Tests for {@link Av1SampleDependencyParser} */
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@RunWith(AndroidJUnit4.class)
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public class Av1SampleDependencyParserTest {
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private static final byte[] sequenceHeader =
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createByteArray(
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0x0A, 0x0E, 0x00, 0x00, 0x00, 0x24, 0xC6, 0xAB, 0xDF, 0x3E, 0xFE, 0x24, 0x04, 0x04, 0x04,
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0x10);
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private static final byte[] dependedOnFrame =
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createByteArray(
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0x32, 0x32, 0x10, 0x00, 0xC8, 0xC6, 0x00, 0x00, 0x0C, 0x00, 0x00, 0x00, 0x12, 0x03, 0xCE,
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0x0A, 0x5C, 0x9B, 0xB6, 0x7C, 0x34, 0x88, 0x82, 0x3E, 0x0D, 0x3E, 0xC2, 0x98, 0x91, 0x6A,
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0x5C, 0x80, 0x03, 0xCE, 0x0A, 0x5C, 0x9B, 0xB6, 0x7C, 0x48, 0x35, 0x54, 0xD8, 0x9D, 0x6C,
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0x37, 0xD3, 0x4C, 0x4E, 0xD4, 0x6F, 0xF4);
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private static final byte[] notDependedOnFrame =
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createByteArray(
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0x32, 0x1A, 0x30, 0xC0, 0x00, 0x1D, 0x66, 0x68, 0x46, 0xC9, 0x38, 0x00, 0x60, 0x10, 0x20,
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0x80, 0x20, 0x00, 0x00, 0x01, 0x8B, 0x7A, 0x87, 0xF9, 0xAA, 0x2D, 0x0F, 0x2C);
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private static final byte[] temporalDelimiter = createByteArray(0x12, 0x00);
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private static final byte[] padding = createByteArray(0x7a, 0x02, 0xFF, 0xFF);
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@Test
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public void sampleLimitAfterSkippingNonReferenceFrame_sampleIsDependedOn_returnsFullSample() {
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ByteBuffer sample = ByteBuffer.allocate(128);
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sample.put(sequenceHeader);
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sample.put(dependedOnFrame);
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sample.flip();
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Av1SampleDependencyParser av1SampleDependencyParser = new Av1SampleDependencyParser();
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int sampleLimitAfterSkippingNonReferenceFrames =
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av1SampleDependencyParser.sampleLimitAfterSkippingNonReferenceFrame(sample);
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assertThat(sampleLimitAfterSkippingNonReferenceFrames)
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.isEqualTo(sequenceHeader.length + dependedOnFrame.length);
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}
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@Test
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public void
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sampleLimitAfterSkippingNonReferenceFrame_sampleIsNotDependedOn_returnsClippedSample() {
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ByteBuffer sample = ByteBuffer.allocate(128);
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sample.put(sequenceHeader);
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sample.put(notDependedOnFrame);
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sample.flip();
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Av1SampleDependencyParser av1SampleDependencyParser = new Av1SampleDependencyParser();
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int sampleLimitAfterSkippingNonReferenceFrames =
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av1SampleDependencyParser.sampleLimitAfterSkippingNonReferenceFrame(sample);
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assertThat(sampleLimitAfterSkippingNonReferenceFrames).isEqualTo(sequenceHeader.length);
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}
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@Test
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public void
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sampleLimitAfterSkippingNonReferenceFrame_queueSequenceHeaderSeparately_returnsEmptySample() {
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ByteBuffer header = ByteBuffer.wrap(sequenceHeader);
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ByteBuffer frame = ByteBuffer.wrap(notDependedOnFrame);
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Av1SampleDependencyParser av1SampleDependencyParser = new Av1SampleDependencyParser();
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av1SampleDependencyParser.queueInputBuffer(header);
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int sampleLimitAfterSkippingNonReferenceFrames =
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av1SampleDependencyParser.sampleLimitAfterSkippingNonReferenceFrame(frame);
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assertThat(sampleLimitAfterSkippingNonReferenceFrames).isEqualTo(0);
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}
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@Test
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public void
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sampleLimitAfterSkippingNonReferenceFrame_withTemporalDelimiterAndPadding_returnsEmptySample() {
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ByteBuffer header = ByteBuffer.wrap(sequenceHeader);
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ByteBuffer sample = ByteBuffer.allocate(128);
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sample.put(temporalDelimiter);
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sample.put(notDependedOnFrame);
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sample.put(padding);
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sample.flip();
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Av1SampleDependencyParser av1SampleDependencyParser = new Av1SampleDependencyParser();
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av1SampleDependencyParser.queueInputBuffer(header);
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int sampleLimitAfterSkippingNonReferenceFrames =
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av1SampleDependencyParser.sampleLimitAfterSkippingNonReferenceFrame(sample);
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assertThat(sampleLimitAfterSkippingNonReferenceFrames).isEqualTo(0);
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}
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@Test
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public void sampleLimitAfterSkippingNonReferenceFrame_withMultipleFrames_returnsClippedSample() {
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ByteBuffer header = ByteBuffer.wrap(sequenceHeader);
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ByteBuffer sample = ByteBuffer.allocate(128);
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sample.put(temporalDelimiter);
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sample.put(padding);
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sample.put(dependedOnFrame);
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sample.put(notDependedOnFrame);
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sample.put(padding);
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sample.flip();
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Av1SampleDependencyParser av1SampleDependencyParser = new Av1SampleDependencyParser();
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av1SampleDependencyParser.queueInputBuffer(header);
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int sampleLimitAfterSkippingNonReferenceFrames =
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av1SampleDependencyParser.sampleLimitAfterSkippingNonReferenceFrame(sample);
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assertThat(sampleLimitAfterSkippingNonReferenceFrames)
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.isEqualTo(temporalDelimiter.length + padding.length + dependedOnFrame.length);
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}
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@Test
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public void sampleLimitAfterSkippingNonReferenceFrame_withMissingHeader_returnsFullSample() {
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ByteBuffer frame = ByteBuffer.wrap(notDependedOnFrame);
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Av1SampleDependencyParser av1SampleDependencyParser = new Av1SampleDependencyParser();
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int sampleLimitAfterSkippingNonReferenceFrames =
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av1SampleDependencyParser.sampleLimitAfterSkippingNonReferenceFrame(frame);
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assertThat(sampleLimitAfterSkippingNonReferenceFrames).isEqualTo(notDependedOnFrame.length);
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}
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@Test
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public void
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sampleLimitAfterSkippingNonReferenceFrame_withTwoNonDependedOnFrames_returnsFullSample() {
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ByteBuffer header = ByteBuffer.wrap(sequenceHeader);
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ByteBuffer sample = ByteBuffer.allocate(128);
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sample.put(notDependedOnFrame);
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sample.put(notDependedOnFrame);
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sample.flip();
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Av1SampleDependencyParser av1SampleDependencyParser = new Av1SampleDependencyParser();
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av1SampleDependencyParser.queueInputBuffer(header);
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int sampleLimitAfterSkippingNonReferenceFrames =
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av1SampleDependencyParser.sampleLimitAfterSkippingNonReferenceFrame(sample);
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assertThat(sampleLimitAfterSkippingNonReferenceFrames)
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.isEqualTo(notDependedOnFrame.length + notDependedOnFrame.length);
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}
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}
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