/*
* Copyright (C) 2014 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 com.google.android.exoplayer.util;
import android.util.Log;
import android.util.Pair;
import java.util.ArrayList;
import java.util.List;
/**
* Provides static utility methods for manipulating various types of codec specific data.
*/
public final class CodecSpecificDataUtil {
/**
* Holds data parsed from a sequence parameter set NAL unit.
*/
public static final class SpsData {
public final int width;
public final int height;
public final float pixelWidthAspectRatio;
public SpsData(int width, int height, float pixelWidthAspectRatio) {
this.width = width;
this.height = height;
this.pixelWidthAspectRatio = pixelWidthAspectRatio;
}
}
private static final byte[] NAL_START_CODE = new byte[] {0, 0, 0, 1};
private static final int[] AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE = new int[] {
96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, 7350
};
private static final int[] AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE = new int[] {
0, 1, 2, 3, 4, 5, 6, 8
};
private static final String TAG = "CodecSpecificDataUtil";
private CodecSpecificDataUtil() {}
/**
* Parses an AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
*
* @param audioSpecificConfig The AudioSpecificConfig to parse.
* @return A pair consisting of the sample rate in Hz and the channel count.
*/
public static Pair<Integer, Integer> parseAacAudioSpecificConfig(byte[] audioSpecificConfig) {
int audioObjectType = (audioSpecificConfig[0] >> 3) & 0x1F;
int byteOffset = audioObjectType == 5 || audioObjectType == 29 ? 1 : 0;
int frequencyIndex = (audioSpecificConfig[byteOffset] & 0x7) << 1
| ((audioSpecificConfig[byteOffset + 1] >> 7) & 0x1);
Assertions.checkState(frequencyIndex < 13);
int sampleRate = AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE[frequencyIndex];
int channelCount = (audioSpecificConfig[byteOffset + 1] >> 3) & 0xF;
return Pair.create(sampleRate, channelCount);
}
/**
* Builds a simple AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
*
* @param audioObjectType The audio object type.
* @param sampleRateIndex The sample rate index.
* @param channelConfig The channel configuration.
* @return The AudioSpecificConfig.
*/
public static byte[] buildAacAudioSpecificConfig(int audioObjectType, int sampleRateIndex,
int channelConfig) {
byte[] audioSpecificConfig = new byte[2];
audioSpecificConfig[0] = (byte) ((audioObjectType << 3) & 0xF8 | (sampleRateIndex >> 1) & 0x07);
audioSpecificConfig[1] = (byte) ((sampleRateIndex << 7) & 0x80 | (channelConfig << 3) & 0x78);
return audioSpecificConfig;
}
/**
* Builds a simple HE-AAC LC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
*
* @param sampleRate The sample rate in Hz.
* @param numChannels The number of channels.
* @return The AudioSpecificConfig.
*/
public static byte[] buildAacAudioSpecificConfig(int sampleRate, int numChannels) {
int sampleRateIndex = -1;
for (int i = 0; i < AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE.length; ++i) {
if (sampleRate == AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE[i]) {
sampleRateIndex = i;
}
}
int channelConfig = -1;
for (int i = 0; i < AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE.length; ++i) {
if (numChannels == AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE[i]) {
channelConfig = i;
}
}
// The full specification for AudioSpecificConfig is stated in ISO 14496-3 Section 1.6.2.1
byte[] csd = new byte[2];
csd[0] = (byte) ((2 /* AAC LC */ << 3) | (sampleRateIndex >> 1));
csd[1] = (byte) (((sampleRateIndex & 0x1) << 7) | (channelConfig << 3));
return csd;
}
/**
* Constructs a NAL unit consisting of the NAL start code followed by the specified data.
*
* @param data An array containing the data that should follow the NAL start code.
* @param offset The start offset into {@code data}.
* @param length The number of bytes to copy from {@code data}
* @return The constructed NAL unit.
*/
public static byte[] buildNalUnit(byte[] data, int offset, int length) {
byte[] nalUnit = new byte[length + NAL_START_CODE.length];
System.arraycopy(NAL_START_CODE, 0, nalUnit, 0, NAL_START_CODE.length);
System.arraycopy(data, offset, nalUnit, NAL_START_CODE.length, length);
return nalUnit;
}
/**
* Splits an array of NAL units.
* <p>
* If the input consists of NAL start code delimited units, then the returned array consists of
* the split NAL units, each of which is still prefixed with the NAL start code. For any other
* input, null is returned.
*
* @param data An array of data.
* @return The individual NAL units, or null if the input did not consist of NAL start code
* delimited units.
*/
public static byte[][] splitNalUnits(byte[] data) {
if (!isNalStartCode(data, 0)) {
// data does not consist of NAL start code delimited units.
return null;
}
List<Integer> starts = new ArrayList<>();
int nalUnitIndex = 0;
do {
starts.add(nalUnitIndex);
nalUnitIndex = findNalStartCode(data, nalUnitIndex + NAL_START_CODE.length);
} while (nalUnitIndex != -1);
byte[][] split = new byte[starts.size()][];
for (int i = 0; i < starts.size(); i++) {
int startIndex = starts.get(i);
int endIndex = i < starts.size() - 1 ? starts.get(i + 1) : data.length;
byte[] nal = new byte[endIndex - startIndex];
System.arraycopy(data, startIndex, nal, 0, nal.length);
split[i] = nal;
}
return split;
}
/**
* Finds the next occurrence of the NAL start code from a given index.
*
* @param data The data in which to search.
* @param index The first index to test.
* @return The index of the first byte of the found start code, or -1.
*/
private static int findNalStartCode(byte[] data, int index) {
int endIndex = data.length - NAL_START_CODE.length;
for (int i = index; i <= endIndex; i++) {
if (isNalStartCode(data, i)) {
return i;
}
}
return -1;
}
/**
* Tests whether there exists a NAL start code at a given index.
*
* @param data The data.
* @param index The index to test.
* @return Whether there exists a start code that begins at {@code index}.
*/
private static boolean isNalStartCode(byte[] data, int index) {
if (data.length - index <= NAL_START_CODE.length) {
return false;
}
for (int j = 0; j < NAL_START_CODE.length; j++) {
if (data[index + j] != NAL_START_CODE[j]) {
return false;
}
}
return true;
}
/**
* Parses an SPS NAL unit.
*
* @param bitArray A {@link ParsableBitArray} containing the SPS data. The position must to set
* to the start of the data (i.e. the first bit of the profile_idc field).
* @return A parsed representation of the SPS data.
*/
public static SpsData parseSpsNalUnit(ParsableBitArray bitArray) {
int profileIdc = bitArray.readBits(8);
bitArray.skipBits(16); // constraint bits (6), reserved (2) and level_idc (8)
bitArray.readUnsignedExpGolombCodedInt(); // seq_parameter_set_id
int chromaFormatIdc = 1; // Default is 4:2:0
if (profileIdc == 100 || profileIdc == 110 || profileIdc == 122 || profileIdc == 244
|| profileIdc == 44 || profileIdc == 83 || profileIdc == 86 || profileIdc == 118
|| profileIdc == 128 || profileIdc == 138) {
chromaFormatIdc = bitArray.readUnsignedExpGolombCodedInt();
if (chromaFormatIdc == 3) {
bitArray.skipBits(1); // separate_colour_plane_flag
}
bitArray.readUnsignedExpGolombCodedInt(); // bit_depth_luma_minus8
bitArray.readUnsignedExpGolombCodedInt(); // bit_depth_chroma_minus8
bitArray.skipBits(1); // qpprime_y_zero_transform_bypass_flag
boolean seqScalingMatrixPresentFlag = bitArray.readBit();
if (seqScalingMatrixPresentFlag) {
int limit = (chromaFormatIdc != 3) ? 8 : 12;
for (int i = 0; i < limit; i++) {
boolean seqScalingListPresentFlag = bitArray.readBit();
if (seqScalingListPresentFlag) {
skipScalingList(bitArray, i < 6 ? 16 : 64);
}
}
}
}
bitArray.readUnsignedExpGolombCodedInt(); // log2_max_frame_num_minus4
long picOrderCntType = bitArray.readUnsignedExpGolombCodedInt();
if (picOrderCntType == 0) {
bitArray.readUnsignedExpGolombCodedInt(); // log2_max_pic_order_cnt_lsb_minus4
} else if (picOrderCntType == 1) {
bitArray.skipBits(1); // delta_pic_order_always_zero_flag
bitArray.readSignedExpGolombCodedInt(); // offset_for_non_ref_pic
bitArray.readSignedExpGolombCodedInt(); // offset_for_top_to_bottom_field
long numRefFramesInPicOrderCntCycle = bitArray.readUnsignedExpGolombCodedInt();
for (int i = 0; i < numRefFramesInPicOrderCntCycle; i++) {
bitArray.readUnsignedExpGolombCodedInt(); // offset_for_ref_frame[i]
}
}
bitArray.readUnsignedExpGolombCodedInt(); // max_num_ref_frames
bitArray.skipBits(1); // gaps_in_frame_num_value_allowed_flag
int picWidthInMbs = bitArray.readUnsignedExpGolombCodedInt() + 1;
int picHeightInMapUnits = bitArray.readUnsignedExpGolombCodedInt() + 1;
boolean frameMbsOnlyFlag = bitArray.readBit();
int frameHeightInMbs = (2 - (frameMbsOnlyFlag ? 1 : 0)) * picHeightInMapUnits;
if (!frameMbsOnlyFlag) {
bitArray.skipBits(1); // mb_adaptive_frame_field_flag
}
bitArray.skipBits(1); // direct_8x8_inference_flag
int frameWidth = picWidthInMbs * 16;
int frameHeight = frameHeightInMbs * 16;
boolean frameCroppingFlag = bitArray.readBit();
if (frameCroppingFlag) {
int frameCropLeftOffset = bitArray.readUnsignedExpGolombCodedInt();
int frameCropRightOffset = bitArray.readUnsignedExpGolombCodedInt();
int frameCropTopOffset = bitArray.readUnsignedExpGolombCodedInt();
int frameCropBottomOffset = bitArray.readUnsignedExpGolombCodedInt();
int cropUnitX, cropUnitY;
if (chromaFormatIdc == 0) {
cropUnitX = 1;
cropUnitY = 2 - (frameMbsOnlyFlag ? 1 : 0);
} else {
int subWidthC = (chromaFormatIdc == 3) ? 1 : 2;
int subHeightC = (chromaFormatIdc == 1) ? 2 : 1;
cropUnitX = subWidthC;
cropUnitY = subHeightC * (2 - (frameMbsOnlyFlag ? 1 : 0));
}
frameWidth -= (frameCropLeftOffset + frameCropRightOffset) * cropUnitX;
frameHeight -= (frameCropTopOffset + frameCropBottomOffset) * cropUnitY;
}
float pixelWidthHeightRatio = 1;
boolean vuiParametersPresentFlag = bitArray.readBit();
if (vuiParametersPresentFlag) {
boolean aspectRatioInfoPresentFlag = bitArray.readBit();
if (aspectRatioInfoPresentFlag) {
int aspectRatioIdc = bitArray.readBits(8);
if (aspectRatioIdc == NalUnitUtil.EXTENDED_SAR) {
int sarWidth = bitArray.readBits(16);
int sarHeight = bitArray.readBits(16);
if (sarWidth != 0 && sarHeight != 0) {
pixelWidthHeightRatio = (float) sarWidth / sarHeight;
}
} else if (aspectRatioIdc < NalUnitUtil.ASPECT_RATIO_IDC_VALUES.length) {
pixelWidthHeightRatio = NalUnitUtil.ASPECT_RATIO_IDC_VALUES[aspectRatioIdc];
} else {
Log.w(TAG, "Unexpected aspect_ratio_idc value: " + aspectRatioIdc);
}
}
}
return new SpsData(frameWidth, frameHeight, pixelWidthHeightRatio);
}
private static void skipScalingList(ParsableBitArray bitArray, int size) {
int lastScale = 8;
int nextScale = 8;
for (int i = 0; i < size; i++) {
if (nextScale != 0) {
int deltaScale = bitArray.readSignedExpGolombCodedInt();
nextScale = (lastScale + deltaScale + 256) % 256;
}
lastScale = (nextScale == 0) ? lastScale : nextScale;
}
}
}