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Changed av1c parser from a class to a method
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@microkatz
microkatz committed Oct 31, 2023
1 parent 457577c commit 69a3270
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Showing 2 changed files with 137 additions and 173 deletions.
4 changes: 3 additions & 1 deletion RELEASENOTES.md
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Expand Up @@ -18,7 +18,9 @@
* Add support for flattening H.265/HEVC SEF slow motion videos.
* Track Selection:
* Extractors:
* Add AV1C parsing to MP4 extractor
* Add additional AV1C parsing to MP4 extractor to retrieve
`ColorInfo.colorSpace`, `ColorInfo.colorTransfer`, and
`ColorInfo.colorRange` values
([#692](https://github.com/androidx/media/pull/692)).
* Audio:
* Video:
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306 changes: 134 additions & 172 deletions libraries/extractor/src/main/java/androidx/media3/extractor/mp4/AtomParsers.java
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Expand Up @@ -19,7 +19,6 @@
import static androidx.media3.common.util.Assertions.checkNotNull;
import static androidx.media3.common.util.Util.castNonNull;
import static java.lang.Math.max;
import static java.lang.Math.min;

import android.util.Pair;
import androidx.annotation.Nullable;
Expand All @@ -33,6 +32,7 @@
import androidx.media3.common.util.CodecSpecificDataUtil;
import androidx.media3.common.util.Log;
import androidx.media3.common.util.NullableType;
import androidx.media3.common.util.ParsableBitArray;
import androidx.media3.common.util.ParsableByteArray;
import androidx.media3.common.util.Util;
import androidx.media3.container.Mp4LocationData;
Expand Down Expand Up @@ -1222,32 +1222,15 @@ private static void parseVideoSampleEntry(
colorTransfer =
ColorInfo.isoTransferCharacteristicsToColorTransfer(transferCharacteristics);
} else if (childAtomType == Atom.TYPE_av1C) {
ExtractorUtil.checkContainerInput(mimeType == null, /* message= */ null);
mimeType = MimeTypes.VIDEO_AV1;
parent.setPosition(childStartPosition + Atom.HEADER_SIZE);
parent.skipBytes(1);
int byte2 = parent.readUnsignedByte();
int seqProfile = byte2 >> 5;
int byte3 = parent.readUnsignedByte();
boolean highBitdepth = ((byte3 >> 6) & 0b1) != 0;
// From https://aomediacodec.github.io/av1-spec/av1-spec.pdf#page=44
if (seqProfile == 2 && highBitdepth) {
boolean twelveBit = ((byte3 >> 5) & 0b1) != 0;
bitdepthLuma = twelveBit ? 12 : 10;
} else if (seqProfile <= 2) {
bitdepthLuma = highBitdepth ? 10 : 8;
}
bitdepthChroma = bitdepthLuma;
// See av1C atom syntax:
// https://aomediacodec.github.io/av1-isobmff/#av1codecconfigurationbox-syntax
parent.skipBytes(1); // skip to configOBUs[]
Av1BitstreamParser parser = new Av1BitstreamParser(parent);
if (parser.parseSequenceHeader() && parser.colorDescriptionPresentFlag == 1) {
colorSpace = ColorInfo.isoColorPrimariesToColorSpace(parser.colorPrimaries);
colorTransfer =
ColorInfo.isoTransferCharacteristicsToColorTransfer(parser.transferCharacteristics);
colorRange = (parser.colorRange == 1) ? C.COLOR_RANGE_FULL : C.COLOR_RANGE_LIMITED;
}
ColorInfo colorInfo = parseAv1c(parent);

bitdepthLuma = colorInfo.lumaBitdepth;
bitdepthChroma = colorInfo.chromaBitdepth;
colorSpace = colorInfo.colorSpace;
colorRange = colorInfo.colorRange;
colorTransfer = colorInfo.colorTransfer;
} else if (childAtomType == Atom.TYPE_clli) {
if (hdrStaticInfo == null) {
hdrStaticInfo = allocateHdrStaticInfo();
Expand Down Expand Up @@ -1396,6 +1379,132 @@ private static void parseVideoSampleEntry(
out.format = formatBuilder.build();
}

/**
* Parses the av1C sequence header and returns a {@link ColorInfo} from its data.
*
* <p>See av1C atom syntax in this <a
* href="https://aomediacodec.github.io/av1-spec/av1-spec.pdf">spec</a>. The sections referenced
* in the method are from this spec.
*
* @param data The av1C atom data.
* @return {@link ColorInfo} parsed from the av1C data.
*/
private static ColorInfo parseAv1c(ParsableByteArray data) {
ColorInfo.Builder colorInfo = new ColorInfo.Builder();
ParsableBitArray bitArray = new ParsableBitArray(data.getData());
bitArray.setPosition(data.getPosition() * 8); // Convert byte to bit position.

bitArray.skipBytes(1);
int byte2 = bitArray.readBits(8);
int seqProfileBitDepth = byte2 >> 5;
int byte3 = bitArray.readBits(8);
boolean highBitdepth = ((byte3 >> 6) & 0b1) != 0;

if (seqProfileBitDepth == 2 && highBitdepth) {
boolean twelveBit = ((byte3 >> 5) & 0b1) != 0;
colorInfo.setLumaBitdepth(twelveBit ? 12 : 10);
colorInfo.setChromaBitdepth(twelveBit ? 12 : 10);
} else if (seqProfileBitDepth <= 2) {
colorInfo.setLumaBitdepth(highBitdepth ? 10 : 8);
colorInfo.setChromaBitdepth(highBitdepth ? 10 : 8);
}

bitArray.skipBytes(1);
// 5.3.1. General OBU syntax
bitArray.skipBit(); // obu_forbidden_bit
int obuType = bitArray.readBits(4); // obu_type
if (obuType != 1) { // obu_type != OBU_SEQUENCE_HEADER
Log.i(TAG, "Unsupported obu_type: " + obuType);
return colorInfo.build();
}
if (bitArray.readBits(1) != 0) { // obu_extension_flag
Log.i(TAG, "Unsupported obu_extension_flag");
return colorInfo.build();
}
int obuHasSizeField = bitArray.readBits(1); // obu_has_size_field
bitArray.skipBit(); // obu_reserved_1bit
// obu_size is unsigned leb128 and if obu_size <= 127 then it can be simplified as readBits(8).
if (obuHasSizeField == 1 && bitArray.readBits(8) > 127) { // obu_size
Log.i(TAG, "Excessive obu_size");
return colorInfo.build();
}
// 5.5.1. General sequence header OBU syntax
int seqProfile = bitArray.readBits(3); // seq_profile
bitArray.skipBit(); // still_picture
if (bitArray.readBits(1) != 0) { // reduced_still_picture_header
Log.i(TAG, "Unsupported reduced_still_picture_header");
return colorInfo.build();
}
if (bitArray.readBits(1) != 0) { // timing_info_present_flag
Log.i(TAG, "Unsupported timing_info_present_flag");
return colorInfo.build();
}
if (bitArray.readBits(1) != 0) { // initial_display_delay_present_flag
Log.i(TAG, "Unsupported initial_display_delay_present_flag");
return colorInfo.build();
}
int operatingPointsCountMinus1 = bitArray.readBits(5); // operating_points_cnt_minus_1
for (int i = 0; i <= operatingPointsCountMinus1; i++) {
bitArray.readBits(12); // operating_point_idc[i]
int seqLevelIdx = bitArray.readBits(5); // seq_level_idx[i]
if (seqLevelIdx > 7) {
bitArray.skipBit(); // seq_tier[i]
}
}
int frameWidthBitsMinus1 = bitArray.readBits(4); // frame_width_bits_minus_1
int frameHeightBitsMinus1 = bitArray.readBits(4); // frame_height_bits_minus_1
bitArray.skipBits(frameWidthBitsMinus1 + 1); // max_frame_width_minus_1
bitArray.skipBits(frameHeightBitsMinus1 + 1); // max_frame_height_minus_1
if (bitArray.readBits(1) == 1) { // frame_id_numbers_present_flag
bitArray.skipBits(7); // delta_frame_id_length_minus_2, additional_frame_id_length_minus_1
}
bitArray.skipBits(7); // use_128x128_superblock...enable_dual_filter: 7 flags
int enableOrderHint = bitArray.readBits(1); // enable_order_hint
if (enableOrderHint == 1) {
bitArray.skipBits(2); // enable_jnt_comp, enable_ref_frame_mvs
}
int seqForceScreenContentTools =
(bitArray.readBits(1) == 0) // seq_choose_screen_content_tools
? bitArray.readBits(1) // seq_force_screen_content_tools
: 2; // SELECT_SCREEN_CONTENT_TOOLS
if (seqForceScreenContentTools > 0) {
if (bitArray.readBits(1) == 0) { // seq_choose_integer_mv
bitArray.skipBits(1); // seq_force_integer_mv
}
}
if (enableOrderHint == 1) {
bitArray.skipBits(3); // order_hint_bits_minus_1
}
bitArray.skipBits(3); // enable_superres, enable_cdef, enable_restoration
// 5.5.2. Color config syntax
int configHighBitdepth = bitArray.readBits(1); // high_bitdepth
if (seqProfile == 2 && configHighBitdepth == 1) {
bitArray.skipBit(); // twelve_bit
}

int monochrome = (seqProfile != 1) ? bitArray.readBits(1) : 0; // mono_chrome

if (bitArray.readBits(1) == 1) { // color_description_present_flag
int colorPrimaries = bitArray.readBits(8); // color_primaries
int transferCharacteristics = bitArray.readBits(8); // transfer_characteristics
int matrixCoefficients = bitArray.readBits(8); // matrix_coefficients
int colorRange =
(monochrome == 0
&& colorPrimaries == 1 // CP_BT_709
&& transferCharacteristics == 13 // TC_SRGB
&& matrixCoefficients == 0)
? // MC_IDENTITY
1
: bitArray.readBits(1); // color_range;
colorInfo
.setColorSpace(ColorInfo.isoColorPrimariesToColorSpace(colorPrimaries))
.setColorRange((colorRange == 1) ? C.COLOR_RANGE_FULL : C.COLOR_RANGE_LIMITED)
.setColorTransfer(
ColorInfo.isoTransferCharacteristicsToColorTransfer(transferCharacteristics));
}
return colorInfo.build();
}

private static ByteBuffer allocateHdrStaticInfo() {
// For HDR static info, Android decoders expect a 25-byte array. The first byte is zero to
// represent Static Metadata Type 1, as per CTA-861-G:2017, Table 44. The following 24 bytes
Expand Down Expand Up @@ -2181,151 +2290,4 @@ public int readNextSampleSize() {
}
}
}

/**
* Helper class for parsing syntax elements from AV1 bitstream.
*
* <p>Bitstream specification: https://aomediacodec.github.io/av1-spec/av1-spec.pdf
*/
private static final class Av1BitstreamParser {
private static final String TAG = "Av1BitstreamParser";

public int colorDescriptionPresentFlag;
public int colorPrimaries;
public int transferCharacteristics;
public int matrixCoefficients;
public int colorRange;

private final ParsableByteArray data;
private int bitCount;
private int currentByte;
private boolean parseSequenceHeaderCalled;

public Av1BitstreamParser(ParsableByteArray data) {
this.data = data;
}

/**
* Parses a fixed-length unsigned number.
*
* <p>See AV1 bitstream spec 4.10.2. f(n): Unsigned n-bit number appearing directly in the
* bitstream. The bits are read from high to low order.
*
* @param length The length (in bits) of the number to decode.
* @return Parsed unsigned number.
*/
private int parseF(int length) {
int result = 0;
while (length > 0) {
if (bitCount == 0) {
currentByte = data.readUnsignedByte();
bitCount = 8;
}
int newBitCount = min(length, bitCount);
bitCount -= newBitCount;
length -= newBitCount;
result = (result << newBitCount) | ((currentByte >> bitCount) & ((1 << newBitCount) - 1));
}
return result;
}

/**
* Parses the AV1 sequence header.
*
* <p>See AV1 bitstream spec 5.5.1. This method can only be called once.
*/
public boolean parseSequenceHeader() {
if (parseSequenceHeaderCalled) {
return false;
}
parseSequenceHeaderCalled = true;

// 5.3.1. General OBU syntax
parseF(1); // obu_forbidden_bit
int obuType = parseF(4); // obu_type
if (obuType != 1) { // obu_type != OBU_SEQUENCE_HEADER
Log.e(TAG, "Unsupported obu_type: " + obuType);
return false;
} else if (parseF(1) != 0) { // obu_extension_flag
Log.e(TAG, "Unsupported obu_extension_flag");
return false;
}
int obuHasSizeField = parseF(1); // obu_has_size_field
parseF(1); // obu_reserved_1bit
if (obuHasSizeField == 1 && parseF(8) > 127) { // obu_size
Log.e(TAG, "Excessive obu_size");
return false;
}
// 5.5.1. General sequence header OBU syntax
int seqProfile = parseF(3); // seq_profile
parseF(1); // still_picture
if (parseF(1) != 0) { // reduced_still_picture_header
Log.e(TAG, "Unsupported reduced_still_picture_header");
return false;
} else if (parseF(1) != 0) { // timing_info_present_flag
Log.e(TAG, "Unsupported timing_info_present_flag");
return false;
} else if (parseF(1) != 0) { // initial_display_delay_present_flag
Log.e(TAG, "Unsupported initial_display_delay_present_flag");
return false;
}
int operatingPointsCntMinus1 = parseF(5); // operating_points_cnt_minus_1
for (int i = 0; i <= operatingPointsCntMinus1; i++) {
parseF(12); // operating_point_idc[i]
int seqLevelIdx = parseF(5); // seq_level_idx[i]
if (seqLevelIdx > 7) {
parseF(1); // seq_tier[i]
}
}
int frameWidthBitsMinus1 = parseF(4); // frame_width_bits_minus_1
int frameHeightBitsMinus1 = parseF(4); // frame_height_bits_minus_1
parseF(frameWidthBitsMinus1 + 1); // max_frame_width_minus_1
parseF(frameHeightBitsMinus1 + 1); // max_frame_height_minus_1
if (parseF(1) == 1) { // frame_id_numbers_present_flag
parseF(7); // delta_frame_id_length_minus_2, additional_frame_id_length_minus_1
}
parseF(7); // use_128x128_superblock...enable_dual_filter: 7 flags
int enableOrderHint = parseF(1); // enable_order_hint
if (enableOrderHint == 1) {
parseF(2); // enable_jnt_comp, enable_ref_frame_mvs
}
int seqForceScreenContentTools = 2; // SELECT_SCREEN_CONTENT_TOOLS
if (parseF(1) == 0) { // seq_choose_screen_content_tools
seqForceScreenContentTools = parseF(1); // seq_force_screen_content_tools
}
if (seqForceScreenContentTools > 0) {
if (parseF(1) == 0) { // seq_choose_integer_mv
parseF(1); // seq_force_integer_mv
}
}
if (enableOrderHint == 1) {
parseF(3); // order_hint_bits_minus_1
}
parseF(3); // enable_superres, enable_cdef, enable_restoration
// 5.5.2. Color config syntax
int highBitdepth = parseF(1); // high_bitdepth
if (seqProfile == 2 && highBitdepth == 1) {
parseF(1); // twelve_bit
}
int monoChrome = 0;
if (seqProfile != 1) {
monoChrome = parseF(1); // mono_chrome
}
colorDescriptionPresentFlag = parseF(1); // color_description_present_flag
if (colorDescriptionPresentFlag == 1) {
colorPrimaries = parseF(8); // color_primaries
transferCharacteristics = parseF(8); // transfer_characteristics
matrixCoefficients = parseF(8); // matrix_coefficients
if (monoChrome == 0
&& colorPrimaries == 1 // CP_BT_709
&& transferCharacteristics == 13 // TC_SRGB
&& matrixCoefficients == 0) { // MC_IDENTITY
colorRange = 1;
} else {
colorRange = parseF(1); // color_range
}
}
return true;
}
}
}

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