AvcConfig.java
/*
* 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 androidx.media3.extractor;
import androidx.annotation.Nullable;
import androidx.media3.common.Format;
import androidx.media3.common.ParserException;
import androidx.media3.common.util.CodecSpecificDataUtil;
import androidx.media3.common.util.ParsableByteArray;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.extractor.NalUnitUtil.SpsData;
import java.util.ArrayList;
import java.util.List;
/** AVC configuration data. */
@UnstableApi
public final class AvcConfig {
/**
* Parses AVC configuration data.
*
* @param data A {@link ParsableByteArray}, whose position is set to the start of the AVC
* configuration data to parse.
* @return A parsed representation of the AVC configuration data.
* @throws ParserException If an error occurred parsing the data.
*/
public static AvcConfig parse(ParsableByteArray data) throws ParserException {
try {
data.skipBytes(4); // Skip to the AVCDecoderConfigurationRecord (defined in 14496-15)
int nalUnitLengthFieldLength = (data.readUnsignedByte() & 0x3) + 1;
if (nalUnitLengthFieldLength == 3) {
throw new IllegalStateException();
}
List<byte[]> initializationData = new ArrayList<>();
int numSequenceParameterSets = data.readUnsignedByte() & 0x1F;
for (int j = 0; j < numSequenceParameterSets; j++) {
initializationData.add(buildNalUnitForChild(data));
}
int numPictureParameterSets = data.readUnsignedByte();
for (int j = 0; j < numPictureParameterSets; j++) {
initializationData.add(buildNalUnitForChild(data));
}
int width = Format.NO_VALUE;
int height = Format.NO_VALUE;
float pixelWidthHeightRatio = 1;
@Nullable String codecs = null;
if (numSequenceParameterSets > 0) {
byte[] sps = initializationData.get(0);
SpsData spsData =
NalUnitUtil.parseSpsNalUnit(
initializationData.get(0), nalUnitLengthFieldLength, sps.length);
width = spsData.width;
height = spsData.height;
pixelWidthHeightRatio = spsData.pixelWidthHeightRatio;
codecs =
CodecSpecificDataUtil.buildAvcCodecString(
spsData.profileIdc, spsData.constraintsFlagsAndReservedZero2Bits, spsData.levelIdc);
}
return new AvcConfig(
initializationData,
nalUnitLengthFieldLength,
width,
height,
pixelWidthHeightRatio,
codecs);
} catch (ArrayIndexOutOfBoundsException e) {
throw ParserException.createForMalformedContainer("Error parsing AVC config", e);
}
}
/**
* List of buffers containing the codec-specific data to be provided to the decoder.
*
* <p>See {@link Format#initializationData}.
*/
public final List<byte[]> initializationData;
/** The length of the NAL unit length field in the bitstream's container, in bytes. */
public final int nalUnitLengthFieldLength;
/** The width of each decoded frame, or {@link Format#NO_VALUE} if unknown. */
public final int width;
/** The height of each decoded frame, or {@link Format#NO_VALUE} if unknown. */
public final int height;
/** The pixel width to height ratio. */
public final float pixelWidthHeightRatio;
/**
* An RFC 6381 codecs string representing the video format, or {@code null} if not known.
*
* <p>See {@link Format#codecs}.
*/
@Nullable public final String codecs;
private AvcConfig(
List<byte[]> initializationData,
int nalUnitLengthFieldLength,
int width,
int height,
float pixelWidthHeightRatio,
@Nullable String codecs) {
this.initializationData = initializationData;
this.nalUnitLengthFieldLength = nalUnitLengthFieldLength;
this.width = width;
this.height = height;
this.pixelWidthHeightRatio = pixelWidthHeightRatio;
this.codecs = codecs;
}
private static byte[] buildNalUnitForChild(ParsableByteArray data) {
int length = data.readUnsignedShort();
int offset = data.getPosition();
data.skipBytes(length);
return CodecSpecificDataUtil.buildNalUnit(data.getData(), offset, length);
}
}