loliball/media
1
0
Fork 0
mirror of https://github.com/androidx/media.git synced 2025-04-30 06:46:50 +08:00
Code Issues Actions Packages Projects Releases Wiki Activity

Add ObuParser to split a ByteBuffer into AV1 OBUs

Browse Source 
PiperOrigin-RevId: 718813571
This commit is contained in:
dancho 2025-01-23 04:44:00 -08:00 committed by Copybara-Service
parent 916018d9fe
commit 61b7dfd7ba
2 changed files with 188 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

117
libraries/container/src/main/java/androidx/media3/container/ObuParser.java Normal file
View File

@ -0,0 +1,117 @@
/*
* Copyright 2025 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
*
* https://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.container;
import androidx.media3.common.util.UnstableApi;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
/**
* Utility methods for parsing AV1 Open Bitstream Units or OBUs.
*
* <p><a href=https://aomediacodec.github.io/av1-spec/>AV1 Bitstream and Decoding Process
* Specification</a>
*/
@UnstableApi
public final class ObuParser {
/** OBU type sequence header. */
public static final int OBU_SEQUENCE_HEADER = 1;
/** OBU type temporal delimiter. */
public static final int OBU_TEMPORAL_DELIMITER = 2;
/** OBU type frame header. */
public static final int OBU_FRAME_HEADER = 3;
/** OBU type frame. */
public static final int OBU_FRAME = 6;
/** OBU type padding. */
public static final int OBU_PADDING = 15;
/** Open bitstream unit. */
public static final class Obu {
/** The OBU type. See {@code obu_type} in the AV1 spec. */
public final int type;
/** The OBU data, excluding the header. */
public final ByteBuffer payload;
private Obu(int type, ByteBuffer payload) {
this.type = type;
this.payload = payload;
}
}
/**
* Splits the input sample into a list of OBUs.
*
* <p>Expects the AV1 sample format specified by the <a
* href=https://aomediacodec.github.io/av1-isobmff/#sampleformat>AV1 Codec ISO Media File Format
* Binding</a>. That is, each OBU has the {@code obu_has_size_field} set to 1 except for the last
* OBU in the sample, for which {@code obu_has_size_field} may be set to 0.
*
* @param sample The sample data.
* @return The list of OBUs contained within the sample data.
*/
public static List<Obu> split(ByteBuffer sample) {
// Create a read-only buffer that shares content with the sample to avoid modifying the
// input buffer's position, mark or limit.
ByteBuffer readOnlySample = sample.asReadOnlyBuffer();
List<Obu> obuList = new ArrayList<>();
while (readOnlySample.hasRemaining()) {
int headerByte = readOnlySample.get();
int obuType = (headerByte >> 3) & 0xF;
int extensionFlag = (headerByte >> 2) & 0x1;
if (extensionFlag != 0) {
readOnlySample.get(); // skip obu_extension_header()
}
int obuHasSizeField = (headerByte >> 1) & 0x1;
int obuSize;
if (obuHasSizeField != 0) {
obuSize = leb128(readOnlySample);
} else {
// Only the last sample is allowed to have obu_has_size_field == 0, and the size is assumed
// to fill the remainder of the sample.
obuSize = readOnlySample.remaining();
}
ByteBuffer payload = readOnlySample.duplicate();
payload.limit(readOnlySample.position() + obuSize);
obuList.add(new Obu(obuType, payload));
readOnlySample.position(readOnlySample.position() + obuSize);
}
return obuList;
}
private static int leb128(ByteBuffer data) {
int value = 0;
for (int i = 0; i < 8; i++) {
int leb128Byte = data.get();
value |= ((leb128Byte & 0x7F) << (i * 7));
if ((leb128Byte & 0x80) == 0) {
break;
}
}
return value;
}
private ObuParser() {
// Prevent instantiation.
}
}

71
libraries/container/src/test/java/androidx/media3/container/ObuParserTest.java Normal file
View File

@ -0,0 +1,71 @@
/*
* Copyright 2025 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
*
* https://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.container;
import static androidx.media3.container.ObuParser.OBU_FRAME;
import static androidx.media3.container.ObuParser.OBU_FRAME_HEADER;
import static androidx.media3.container.ObuParser.OBU_PADDING;
import static androidx.media3.container.ObuParser.OBU_SEQUENCE_HEADER;
import static androidx.media3.container.ObuParser.OBU_TEMPORAL_DELIMITER;
import static androidx.media3.test.utils.TestUtil.createByteArray;
import static com.google.common.truth.Truth.assertThat;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import java.nio.ByteBuffer;
import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
/** Tests for {@link ObuParser} */
@RunWith(AndroidJUnit4.class)
public class ObuParserTest {
private static final ByteBuffer SEQUENCE_HEADER_AND_FRAME =
ByteBuffer.wrap(
createByteArray(
0x0A, 0x0E, 0x00, 0x00, 0x00, 0x24, 0xC6, 0xAB, 0xDF, 0x3E, 0xFE, 0x24, 0x04, 0x04,
0x04, 0x10, 0x32, 0x32, 0x10, 0x00, 0xC8, 0xC6, 0x00, 0x00, 0x0C, 0x00, 0x00, 0x00,
0x12, 0x03, 0xCE, 0x0A, 0x5C, 0x9B, 0xB6, 0x7C, 0x34, 0x88, 0x82, 0x3E, 0x0D, 0x3E,
0xC2, 0x98, 0x91, 0x6A, 0x5C, 0x80, 0x03, 0xCE, 0x0A, 0x5C, 0x9B, 0xB6, 0x7C, 0x48,
0x35, 0x54, 0xD8, 0x9D, 0x6C, 0x37, 0xD3, 0x4C, 0x4E, 0xD4, 0x6F, 0xF4));
private static final ByteBuffer DELIMITER_AND_HEADER_AND_PADDING_WITH_EXTENSION_AND_MISSING_SIZE =
ByteBuffer.wrap(createByteArray(0x16, 0x00, 0x00, 0x1A, 0x01, 0xC8, 0x78, 0xFF, 0xFF, 0xFF));
@Test
public void split_sequenceHeaderAndFrame_parsesCorrectTypesAndSizes() {
List<ObuParser.Obu> obuList = ObuParser.split(SEQUENCE_HEADER_AND_FRAME);
assertThat(obuList).hasSize(2);
assertThat(obuList.get(0).type).isEqualTo(OBU_SEQUENCE_HEADER);
assertThat(obuList.get(0).payload.remaining()).isEqualTo(14);
assertThat(obuList.get(1).type).isEqualTo(OBU_FRAME);
assertThat(obuList.get(1).payload.remaining()).isEqualTo(50);
}
@Test
public void split_delimiterAndHeaderAndPadding_parsesCorrectTypesAndSizes() {
List<ObuParser.Obu> obuList =
ObuParser.split(DELIMITER_AND_HEADER_AND_PADDING_WITH_EXTENSION_AND_MISSING_SIZE);
assertThat(obuList).hasSize(3);
assertThat(obuList.get(0).type).isEqualTo(OBU_TEMPORAL_DELIMITER);
assertThat(obuList.get(0).payload.remaining()).isEqualTo(0);
assertThat(obuList.get(1).type).isEqualTo(OBU_FRAME_HEADER);
assertThat(obuList.get(1).payload.remaining()).isEqualTo(1);
assertThat(obuList.get(2).type).isEqualTo(OBU_PADDING);
assertThat(obuList.get(2).payload.remaining()).isEqualTo(3);
}
}