mirror of
https://github.com/LadybirdBrowser/ladybird.git
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0cd0565abc
"Improve" is an understatement, since this commit makes all FLAC files seek without errors, mostly with high accuracy, and partially even fast: - A new generic seek table type is introduced, which keeps an always-sorted list of seek points, which allows it to use binary search and fast insertion. - Automatic seek points are inserted according to two heuristics (distance between seek points and minimum seek precision), which not only builds a seek table for already-played sections of the file, but improves seek precision even for files with an existing seek table. - Manual seeking by skipping frames works properly now and is still used as a last resort.
123 lines
5.1 KiB
C++
123 lines
5.1 KiB
C++
/*
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* Copyright (c) 2018-2022, the SerenityOS developers.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/FixedArray.h>
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#include <AK/NonnullOwnPtr.h>
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#include <AK/NonnullRefPtr.h>
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#include <AK/RefCounted.h>
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#include <AK/RefPtr.h>
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#include <AK/Result.h>
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#include <AK/Span.h>
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#include <AK/Stream.h>
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#include <AK/StringView.h>
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#include <AK/Try.h>
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#include <LibAudio/GenericTypes.h>
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#include <LibAudio/LoaderError.h>
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#include <LibAudio/Metadata.h>
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#include <LibAudio/Sample.h>
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#include <LibAudio/SampleFormats.h>
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namespace Audio {
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static constexpr StringView no_plugin_error = "No loader plugin available"sv;
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// Experimentally determined to be a decent buffer size on i686:
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// 4K (the default) is slightly worse, and 64K is much worse.
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// At sufficiently large buffer sizes, the advantage of infrequent read() calls is outweighed by the memmove() overhead.
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// There was no intensive fine-tuning done to determine this value, so improvements may definitely be possible.
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constexpr size_t const loader_buffer_size = 8 * KiB;
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// Two seek points should ideally not be farther apart than this.
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// This variable is a heuristic for seek table-constructing loaders.
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constexpr u64 const maximum_seekpoint_distance_ms = 1000;
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// Seeking should be at least as precise as this.
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// That means: The actual achieved seek position must not be more than this amount of time before the requested seek position.
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constexpr u64 const seek_tolerance_ms = 5000;
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using LoaderSamples = ErrorOr<FixedArray<Sample>, LoaderError>;
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using MaybeLoaderError = ErrorOr<void, LoaderError>;
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class LoaderPlugin {
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public:
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explicit LoaderPlugin(NonnullOwnPtr<SeekableStream> stream);
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virtual ~LoaderPlugin() = default;
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// Load as many audio chunks as necessary to get up to the required samples.
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// A chunk can be anything that is convenient for the plugin to load in one go without requiring to move samples around different buffers.
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// For example: A FLAC, MP3 or QOA frame.
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// The chunks are returned in a vector, so the loader can simply add chunks until the requested sample amount is reached.
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// The sample count MAY be surpassed, but only as little as possible. It CAN be undershot when the end of the stream is reached.
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// If the loader has no chunking limitations (e.g. WAV), it may return a single exact-sized chunk.
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virtual ErrorOr<Vector<FixedArray<Sample>>, LoaderError> load_chunks(size_t samples_to_read_from_input) = 0;
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virtual MaybeLoaderError reset() = 0;
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virtual MaybeLoaderError seek(int const sample_index) = 0;
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// total_samples() and loaded_samples() should be independent
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// of the number of channels.
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//
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// For example, with a three-second-long, stereo, 44.1KHz audio file:
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// num_channels() should return 2
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// sample_rate() should return 44100 (each channel is sampled at this rate)
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// total_samples() should return 132300 (sample_rate * three seconds)
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virtual int loaded_samples() = 0;
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virtual int total_samples() = 0;
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virtual u32 sample_rate() = 0;
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virtual u16 num_channels() = 0;
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// Human-readable name of the file format, of the form <full abbreviation> (.<ending>)
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virtual DeprecatedString format_name() = 0;
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virtual PcmSampleFormat pcm_format() = 0;
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Metadata const& metadata() const { return m_metadata; }
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Vector<PictureData> const& pictures() const { return m_pictures; };
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protected:
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NonnullOwnPtr<SeekableStream> m_stream;
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Vector<PictureData> m_pictures;
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Metadata m_metadata;
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};
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class Loader : public RefCounted<Loader> {
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public:
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static Result<NonnullRefPtr<Loader>, LoaderError> create(StringView path) { return adopt_ref(*new Loader(TRY(create_plugin(path)))); }
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static Result<NonnullRefPtr<Loader>, LoaderError> create(Bytes buffer) { return adopt_ref(*new Loader(TRY(create_plugin(buffer)))); }
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// Will only read less samples if we're at the end of the stream.
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LoaderSamples get_more_samples(size_t samples_to_read_from_input = 128 * KiB);
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MaybeLoaderError reset() const { return m_plugin->reset(); }
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MaybeLoaderError seek(int const position) const
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{
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m_buffer.clear_with_capacity();
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return m_plugin->seek(position);
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}
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int loaded_samples() const { return m_plugin->loaded_samples(); }
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int total_samples() const { return m_plugin->total_samples(); }
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u32 sample_rate() const { return m_plugin->sample_rate(); }
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u16 num_channels() const { return m_plugin->num_channels(); }
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DeprecatedString format_name() const { return m_plugin->format_name(); }
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u16 bits_per_sample() const { return pcm_bits_per_sample(m_plugin->pcm_format()); }
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Metadata const& metadata() const { return m_plugin->metadata(); }
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Vector<PictureData> const& pictures() const { return m_plugin->pictures(); };
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private:
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static Result<NonnullOwnPtr<LoaderPlugin>, LoaderError> create_plugin(StringView path);
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static Result<NonnullOwnPtr<LoaderPlugin>, LoaderError> create_plugin(Bytes buffer);
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explicit Loader(NonnullOwnPtr<LoaderPlugin>);
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mutable NonnullOwnPtr<LoaderPlugin> m_plugin;
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mutable Vector<Sample, loader_buffer_size> m_buffer;
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};
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}
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