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FlacLoader: Parse SEEKTABLE header
Populates m_seektable attribute with FlacSeekPoints. For more information see: https://datatracker.ietf.org/doc/html/draft-ietf-cellar-flac#section-11.13 Co-authored-by: kleines Filmröllchen <filmroellchen@serenityos.org>
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3 changed files with 32 additions and 2 deletions
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@ -118,13 +118,20 @@ MaybeLoaderError FlacLoaderPlugin::parse_header()
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md5_checksum.bytes().copy_to({ m_md5_checksum, sizeof(m_md5_checksum) });
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// Parse other blocks
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// TODO: For a simple first implementation, all other blocks are skipped as allowed by the FLAC specification.
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// Especially the SEEKTABLE block may become useful in a more sophisticated version.
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[[maybe_unused]] u16 meta_blocks_parsed = 1;
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[[maybe_unused]] u16 total_meta_blocks = meta_blocks_parsed;
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FlacRawMetadataBlock block = streaminfo;
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while (!block.is_last_block) {
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block = TRY(next_meta_block(*bit_input));
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switch (block.type) {
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case (FlacMetadataBlockType::SEEKTABLE):
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TRY(load_seektable(block));
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break;
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default:
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// TODO: Parse the remaining metadata block types.
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// Currently only STREAMINFO and SEEKTABLE are handled.
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break;
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}
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++total_meta_blocks;
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}
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@ -133,6 +140,21 @@ MaybeLoaderError FlacLoaderPlugin::parse_header()
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return {};
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}
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MaybeLoaderError FlacLoaderPlugin::load_seektable(FlacRawMetadataBlock& block)
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{
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auto memory_stream = LOADER_TRY(Core::Stream::MemoryStream::construct(block.data.bytes()));
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auto seektable_bytes = LOADER_TRY(BigEndianInputBitStream::construct(*memory_stream));
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for (size_t i = 0; i < block.length / 18; ++i) {
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FlacSeekPoint seekpoint {
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.sample_index = LOADER_TRY(seektable_bytes->read_bits<u64>(64)),
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.byte_offset = LOADER_TRY(seektable_bytes->read_bits<u64>(64)),
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.num_samples = LOADER_TRY(seektable_bytes->read_bits<u16>(16))
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};
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m_seektable.append(seekpoint);
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}
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return {};
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}
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ErrorOr<FlacRawMetadataBlock, LoaderError> FlacLoaderPlugin::next_meta_block(BigEndianInputBitStream& bit_input)
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{
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@ -83,6 +83,7 @@ private:
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MaybeLoaderError decode_residual(Vector<i32>& decoded, FlacSubframeHeader& subframe, BigEndianInputBitStream& bit_input);
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// decode a single rice partition that has its own rice parameter
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ALWAYS_INLINE ErrorOr<Vector<i32>, LoaderError> decode_rice_partition(u8 partition_type, u32 partitions, u32 partition_index, FlacSubframeHeader& subframe, BigEndianInputBitStream& bit_input);
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MaybeLoaderError load_seektable(FlacRawMetadataBlock&);
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// Converters for special coding used in frame headers
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ALWAYS_INLINE ErrorOr<u32, LoaderError> convert_sample_count_code(u8 sample_count_code);
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@ -113,6 +114,7 @@ private:
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// Whatever the last get_more_samples() call couldn't return gets stored here.
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Vector<Sample, FLAC_BUFFER_SIZE> m_unread_data;
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u64 m_current_sample_or_frame { 0 };
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Vector<FlacSeekPoint> m_seektable;
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};
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}
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@ -87,4 +87,10 @@ struct FlacSubframeHeader {
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u8 bits_per_sample;
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};
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struct FlacSeekPoint {
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u64 sample_index;
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u64 byte_offset;
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u16 num_samples;
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};
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}
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