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FlacLoader: Parse SEEKTABLE header

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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>
This commit is contained in:
Max Trussell 2021-12-21 15:07:49 -08:00 • committed by Andreas Kling
parent d7c7e6e496
commit 346696ffbb
3 changed files with 32 additions and 2 deletions
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26
Userland/Libraries/LibAudio/FlacLoader.cpp
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@ -118,13 +118,20 @@ MaybeLoaderError FlacLoaderPlugin::parse_header()
md5_checksum.bytes().copy_to({ m_md5_checksum, sizeof(m_md5_checksum) });
// Parse other blocks
// TODO: For a simple first implementation, all other blocks are skipped as allowed by the FLAC specification.
// Especially the SEEKTABLE block may become useful in a more sophisticated version.
[[maybe_unused]] u16 meta_blocks_parsed = 1;
[[maybe_unused]] u16 total_meta_blocks = meta_blocks_parsed;
FlacRawMetadataBlock block = streaminfo;
while (!block.is_last_block) {
block = TRY(next_meta_block(*bit_input));
switch (block.type) {
case (FlacMetadataBlockType::SEEKTABLE):
TRY(load_seektable(block));
break;
default:
// TODO: Parse the remaining metadata block types.
// Currently only STREAMINFO and SEEKTABLE are handled.
break;
}
++total_meta_blocks;
}
@ -133,6 +140,21 @@ MaybeLoaderError FlacLoaderPlugin::parse_header()
return {};
}
MaybeLoaderError FlacLoaderPlugin::load_seektable(FlacRawMetadataBlock& block)
{
auto memory_stream = LOADER_TRY(Core::Stream::MemoryStream::construct(block.data.bytes()));
auto seektable_bytes = LOADER_TRY(BigEndianInputBitStream::construct(*memory_stream));
for (size_t i = 0; i < block.length / 18; ++i) {
FlacSeekPoint seekpoint {
.sample_index = LOADER_TRY(seektable_bytes->read_bits<u64>(64)),
.byte_offset = LOADER_TRY(seektable_bytes->read_bits<u64>(64)),
.num_samples = LOADER_TRY(seektable_bytes->read_bits<u16>(16))
};
m_seektable.append(seekpoint);
}
return {};
}
ErrorOr<FlacRawMetadataBlock, LoaderError> FlacLoaderPlugin::next_meta_block(BigEndianInputBitStream& bit_input)
{