Address review comments on Av1BitstreamParser
* Rename method f(n) to a more helpful name. * Move the private inner class to the bottom. * Move public fields before private fields but below the static field. * Make `private ParsableByteArray data` final. * Make sure `parseSequenceHeader` can only be called once.
This commit is contained in:
Haixia Shi
microkatz
parent
4ded7e588d
commit
f455e843bc
@ -1092,133 +1092,6 @@ import java.util.List;
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.build();
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}
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// Helper class for parsing syntax elements from AV1 bitstream.
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// Bitstream specification: https://aomediacodec.github.io/av1-spec/av1-spec.pdf
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private static final class Av1BitstreamParser {
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private static final String TAG = "Av1BitstreamParser";
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private ParsableByteArray data;
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private int bitCount;
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private int currentByte;
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public int colorDescriptionPresentFlag;
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public int colorPrimaries;
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public int transferCharacteristics;
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public int matrixCoefficients;
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public int colorRange;
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public Av1BitstreamParser(ParsableByteArray data) {
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this.data = data;
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}
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private int f(int length) {
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// 4.10.2. f(n): Unsigned n-bit number appearing directly in the bitstream.
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// The bits are read from high to low order.
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int result = 0;
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while (length > 0) {
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if (bitCount == 0) {
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currentByte = data.readUnsignedByte();
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bitCount = 8;
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}
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int newBitCount = min(length, bitCount);
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bitCount -= newBitCount;
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length -= newBitCount;
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result = (result << newBitCount) |
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((currentByte >> bitCount) & ((1 << newBitCount) - 1));
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}
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return result;
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}
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public boolean parseSequenceHeader() {
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// 5.3.1. General OBU syntax
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f(1); // obu_forbidden_bit
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int obuType = f(4); // obu_type
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if (obuType != 1) { // obu_type != OBU_SEQUENCE_HEADER
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Log.e(TAG, "Unsupported obu_type: " + obuType);
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return false;
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} else if (f(1) != 0) { // obu_extension_flag
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Log.e(TAG, "Unsupported obu_extension_flag");
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return false;
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}
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int obuHasSizeField = f(1); // obu_has_size_field
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f(1); // obu_reserved_1bit
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if (obuHasSizeField == 1 && f(8) > 127) { // obu_size
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Log.e(TAG, "Excessive obu_size");
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return false;
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}
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// 5.5.1. General sequence header OBU syntax
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int seqProfile = f(3); // seq_profile
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f(1); // still_picture
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if (f(1) != 0) { // reduced_still_picture_header
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Log.e(TAG, "Unsupported reduced_still_picture_header");
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return false;
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} else if (f(1) != 0) { // timing_info_present_flag
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Log.e(TAG, "Unsupported timing_info_present_flag");
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return false;
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} else if (f(1) != 0) { // initial_display_delay_present_flag
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Log.e(TAG, "Unsupported initial_display_delay_present_flag");
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return false;
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}
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int operatingPointsCntMinus1 = f(5); // operating_points_cnt_minus_1
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for (int i = 0; i <= operatingPointsCntMinus1; i++) {
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f(12); // operating_point_idc[i]
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int seqLevelIdx = f(5); // seq_level_idx[i]
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if (seqLevelIdx > 7) {
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f(1); // seq_tier[i]
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}
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}
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int frameWidthBitsMinus1 = f(4); // frame_width_bits_minus_1
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int frameHeightBitsMinus1 = f(4); // frame_height_bits_minus_1
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f(frameWidthBitsMinus1 + 1); // max_frame_width_minus_1
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f(frameHeightBitsMinus1 + 1); // max_frame_height_minus_1
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if (f(1) == 1) { // frame_id_numbers_present_flag
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f(7); // delta_frame_id_length_minus_2, additional_frame_id_length_minus_1
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}
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f(7); // use_128x128_superblock...enable_dual_filter: 7 flags
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int enableOrderHint = f(1); // enable_order_hint
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if (enableOrderHint == 1) {
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f(2); // enable_jnt_comp, enable_ref_frame_mvs
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}
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int seqForceScreenContentTools = 2; // SELECT_SCREEN_CONTENT_TOOLS
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if (f(1) == 0) { // seq_choose_screen_content_tools
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seqForceScreenContentTools = f(1); // seq_force_screen_content_tools
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}
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if (seqForceScreenContentTools > 0) {
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if (f(1) == 0) { // seq_choose_integer_mv
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f(1); // seq_force_integer_mv
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}
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}
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if (enableOrderHint == 1) {
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f(3); // order_hint_bits_minus_1
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}
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f(3); // enable_superres, enable_cdef, enable_restoration
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// 5.5.2. Color config syntax
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int highBitdepth = f(1); // high_bitdepth
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if (seqProfile == 2 && highBitdepth == 1) {
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f(1); // twelve_bit
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}
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int monoChrome = 0;
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if (seqProfile != 1) {
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monoChrome = f(1); // mono_chrome
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}
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colorDescriptionPresentFlag = f(1); // color_description_present_flag
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if (colorDescriptionPresentFlag == 1) {
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colorPrimaries = f(8); // color_primaries
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transferCharacteristics = f(8); // transfer_characteristics
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matrixCoefficients = f(8); // matrix_coefficients
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if (monoChrome == 0
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&& colorPrimaries == 1 // CP_BT_709
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&& transferCharacteristics == 13 // TC_SRGB
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&& matrixCoefficients == 0) { // MC_IDENTITY
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colorRange = 1;
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} else {
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colorRange = f(1); // color_range
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}
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}
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return true;
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}
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}
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// hdrStaticInfo is allocated using allocate() in allocateHdrStaticInfo().
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@SuppressWarnings("ByteBufferBackingArray")
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private static void parseVideoSampleEntry(
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@ -2308,4 +2181,154 @@ import java.util.List;
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}
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}
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}
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/**
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* Helper class for parsing syntax elements from AV1 bitstream.
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*
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* Bitstream specification: https://aomediacodec.github.io/av1-spec/av1-spec.pdf
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*/
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private static final class Av1BitstreamParser {
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private static final String TAG = "Av1BitstreamParser";
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public int colorDescriptionPresentFlag;
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public int colorPrimaries;
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public int transferCharacteristics;
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public int matrixCoefficients;
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public int colorRange;
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private final ParsableByteArray data;
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private int bitCount;
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private int currentByte;
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private boolean parseSequenceHeaderCalled;
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public Av1BitstreamParser(ParsableByteArray data) {
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this.data = data;
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}
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/**
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* Parses a fixed-length unsigned number.
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*
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* See AV1 bitstream spec 4.10.2.
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* f(n): Unsigned n-bit number appearing directly in the bitstream.
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* The bits are read from high to low order.
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*
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* @param length The length (in bits) of the number to decode.
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* @return Parsed unsigned number.
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*/
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private int parseF(int length) {
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int result = 0;
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while (length > 0) {
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if (bitCount == 0) {
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currentByte = data.readUnsignedByte();
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bitCount = 8;
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}
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int newBitCount = min(length, bitCount);
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bitCount -= newBitCount;
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length -= newBitCount;
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result = (result << newBitCount) |
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((currentByte >> bitCount) & ((1 << newBitCount) - 1));
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}
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return result;
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}
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/**
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* Parses the AV1 sequence header.
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*
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* See AV1 bitstream spec 5.5.1.
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* This method can only be called once.
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*/
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public boolean parseSequenceHeader() {
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if (parseSequenceHeaderCalled) {
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return false;
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}
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parseSequenceHeaderCalled = true;
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// 5.3.1. General OBU syntax
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parseF(1); // obu_forbidden_bit
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int obuType = parseF(4); // obu_type
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if (obuType != 1) { // obu_type != OBU_SEQUENCE_HEADER
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Log.e(TAG, "Unsupported obu_type: " + obuType);
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return false;
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} else if (parseF(1) != 0) { // obu_extension_flag
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Log.e(TAG, "Unsupported obu_extension_flag");
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return false;
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}
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int obuHasSizeField = parseF(1); // obu_has_size_field
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parseF(1); // obu_reserved_1bit
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if (obuHasSizeField == 1 && parseF(8) > 127) { // obu_size
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Log.e(TAG, "Excessive obu_size");
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return false;
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}
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// 5.5.1. General sequence header OBU syntax
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int seqProfile = parseF(3); // seq_profile
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parseF(1); // still_picture
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if (parseF(1) != 0) { // reduced_still_picture_header
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Log.e(TAG, "Unsupported reduced_still_picture_header");
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return false;
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} else if (parseF(1) != 0) { // timing_info_present_flag
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Log.e(TAG, "Unsupported timing_info_present_flag");
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return false;
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} else if (parseF(1) != 0) { // initial_display_delay_present_flag
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Log.e(TAG, "Unsupported initial_display_delay_present_flag");
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return false;
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}
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int operatingPointsCntMinus1 = parseF(5); // operating_points_cnt_minus_1
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for (int i = 0; i <= operatingPointsCntMinus1; i++) {
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parseF(12); // operating_point_idc[i]
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int seqLevelIdx = parseF(5); // seq_level_idx[i]
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if (seqLevelIdx > 7) {
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parseF(1); // seq_tier[i]
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}
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}
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int frameWidthBitsMinus1 = parseF(4); // frame_width_bits_minus_1
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int frameHeightBitsMinus1 = parseF(4); // frame_height_bits_minus_1
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parseF(frameWidthBitsMinus1 + 1); // max_frame_width_minus_1
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parseF(frameHeightBitsMinus1 + 1); // max_frame_height_minus_1
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if (parseF(1) == 1) { // frame_id_numbers_present_flag
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parseF(7); // delta_frame_id_length_minus_2, additional_frame_id_length_minus_1
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}
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parseF(7); // use_128x128_superblock...enable_dual_filter: 7 flags
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int enableOrderHint = parseF(1); // enable_order_hint
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if (enableOrderHint == 1) {
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parseF(2); // enable_jnt_comp, enable_ref_frame_mvs
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}
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int seqForceScreenContentTools = 2; // SELECT_SCREEN_CONTENT_TOOLS
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if (parseF(1) == 0) { // seq_choose_screen_content_tools
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seqForceScreenContentTools = parseF(1); // seq_force_screen_content_tools
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}
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if (seqForceScreenContentTools > 0) {
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if (parseF(1) == 0) { // seq_choose_integer_mv
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parseF(1); // seq_force_integer_mv
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}
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}
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if (enableOrderHint == 1) {
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parseF(3); // order_hint_bits_minus_1
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}
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parseF(3); // enable_superres, enable_cdef, enable_restoration
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// 5.5.2. Color config syntax
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int highBitdepth = parseF(1); // high_bitdepth
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if (seqProfile == 2 && highBitdepth == 1) {
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parseF(1); // twelve_bit
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}
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int monoChrome = 0;
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if (seqProfile != 1) {
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monoChrome = parseF(1); // mono_chrome
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}
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colorDescriptionPresentFlag = parseF(1); // color_description_present_flag
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if (colorDescriptionPresentFlag == 1) {
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colorPrimaries = parseF(8); // color_primaries
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transferCharacteristics = parseF(8); // transfer_characteristics
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matrixCoefficients = parseF(8); // matrix_coefficients
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if (monoChrome == 0
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&& colorPrimaries == 1 // CP_BT_709
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&& transferCharacteristics == 13 // TC_SRGB
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&& matrixCoefficients == 0) { // MC_IDENTITY
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colorRange = 1;
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} else {
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colorRange = parseF(1); // color_range
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}
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}
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return true;
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}
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}
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}
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