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FlacLoader: Use seektable for performing seek operations

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As a fallback, we perform primitive seek if there's no seektable.

Co-authored-by: kleines Filmröllchen <filmroellchen@serenityos.org>
This commit is contained in:
Max Trussell 2021-12-21 15:43:18 -08:00 • committed by Andreas Kling
parent 346696ffbb
commit 034c57f1f9
2 changed files with 48 additions and 4 deletions
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50
Userland/Libraries/LibAudio/FlacLoader.cpp
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@ -152,6 +152,7 @@ MaybeLoaderError FlacLoaderPlugin::load_seektable(FlacRawMetadataBlock& block)
};
m_seektable.append(seekpoint);
}
dbgln_if(AFLACLOADER_DEBUG, "Loaded seektable of size {}", m_seektable.size());
return {};
}
@ -166,6 +167,14 @@ ErrorOr<FlacRawMetadataBlock, LoaderError> FlacLoaderPlugin::next_meta_block(Big
u32 block_length = LOADER_TRY(bit_input.read_bits<u32>(24));
m_data_start_location += 3;
// Blocks can be zero-sized, which would trip up the raw data reader below.
if (block_length == 0)
return FlacRawMetadataBlock {
.is_last_block = is_last_block,
.type = type,
.length = 0,
.data = LOADER_TRY(ByteBuffer::create_uninitialized(0))
};
auto block_data_result = ByteBuffer::create_uninitialized(block_length);
FLAC_VERIFY(!block_data_result.is_error(), LoaderError::Category::IO, "Out of memory");
auto block_data = block_data_result.release_value();
@ -188,10 +197,44 @@ MaybeLoaderError FlacLoaderPlugin::reset()
return {};
}
MaybeLoaderError FlacLoaderPlugin::seek(const int position)
MaybeLoaderError FlacLoaderPlugin::seek(int int_sample_index)
{
if (m_stream->seek(position, Core::Stream::SeekMode::SetPosition).is_error())
return LoaderError { LoaderError::Category::IO, m_loaded_samples, String::formatted("Invalid seek position {}", position) };
auto sample_index = static_cast<size_t>(int_sample_index);
if (sample_index == m_loaded_samples)
return {};
auto maybe_target_seekpoint = m_seektable.last_matching([sample_index](auto& seekpoint) { return seekpoint.sample_index <= sample_index; });
// No seektable or no fitting entry: Perform normal forward read
if (!maybe_target_seekpoint.has_value()) {
if (sample_index < m_loaded_samples) {
LOADER_TRY(m_stream->seek(m_data_start_location, Core::Stream::SeekMode::SetPosition));
m_loaded_samples = 0;
}
auto to_read = sample_index - m_loaded_samples;
if (to_read == 0)
return {};
dbgln_if(AFLACLOADER_DEBUG, "Seeking {} samples manually", to_read);
(void)TRY(get_more_samples(to_read));
} else {
auto target_seekpoint = maybe_target_seekpoint.release_value();
// When a small seek happens, we may already be closer to the target than the seekpoint.
if (sample_index - target_seekpoint.sample_index > sample_index - m_loaded_samples) {
dbgln_if(AFLACLOADER_DEBUG, "Close enough to target: seeking {} samples manually", sample_index - m_loaded_samples);
(void)TRY(get_more_samples(sample_index - m_loaded_samples));
return {};
}
dbgln_if(AFLACLOADER_DEBUG, "Seeking to seektable: sample index {}, byte offset {}, sample count {}", target_seekpoint.sample_index, target_seekpoint.byte_offset, target_seekpoint.num_samples);
auto position = target_seekpoint.byte_offset + m_data_start_location;
if (m_stream->seek(static_cast<i64>(position), Core::Stream::SeekMode::SetPosition).is_error())
return LoaderError { LoaderError::Category::IO, m_loaded_samples, String::formatted("Invalid seek position {}", position) };
auto remaining_samples_after_seekpoint = sample_index - m_data_start_location;
if (remaining_samples_after_seekpoint > 0)
(void)TRY(get_more_samples(remaining_samples_after_seekpoint));
m_loaded_samples = target_seekpoint.sample_index;
}
return {};
}
@ -201,6 +244,7 @@ LoaderSamples FlacLoaderPlugin::get_more_samples(size_t max_bytes_to_read_from_i
if (remaining_samples <= 0)
return Buffer::create_empty();
// FIXME: samples_to_read is calculated wrong, because when seeking not all samples are loaded.
size_t samples_to_read = min(max_bytes_to_read_from_input, remaining_samples);
auto samples = FixedArray<Sample>::must_create_but_fixme_should_propagate_errors(samples_to_read);
size_t sample_index = 0;