c901896972
Unfortunately, this necessarily involves parsing codec frames to get their durations. Ogg's granule positions indicate the last sample of the last complete frame of the page, so the navigator has to determine the durations of every packet in the page to offset it back to its start. Vorbis is an especially involved codec to determine that for, since it has initial data defining a mapping of indices to big or small block sizes that has to be held onto, and that mapping is preceded by a bunch of conditionally parsed bits. Also, a frame's block size calculation involves the block size of the previous frame for an overlap add. To avoid bringing that complexity directly into LibMedia, we delegate the parsing/calculation to FFmpeg's av_vorbis_parse functions.
78 lines
2.4 KiB
C++
78 lines
2.4 KiB
C++
/*
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* Copyright (c) 2026-present, the Ladybird 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/ByteBuffer.h>
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#include <AK/NonnullRefPtr.h>
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#include <AK/Optional.h>
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#include <AK/OwnPtr.h>
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#include <AK/Variant.h>
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#include <LibMedia/CodecID.h>
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#include <LibMedia/Codecs/FLAC.h>
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#include <LibMedia/Codecs/Vorbis.h>
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#include "ScanningContainerNavigator.h"
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namespace Media {
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struct OggCachedRange : CachedByteRange {
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using CachedByteRange::CachedByteRange;
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Optional<AK::Duration> time_start;
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Optional<AK::Duration> time_end;
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};
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class OggNavigator final : public ScanningContainerNavigator<OggNavigator, OggCachedRange> {
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public:
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static OwnPtr<OggNavigator> create(ReadonlyBytes first_packet, NonnullRefPtr<MediaStreamCursor>, CodecID, u32 time_base_numerator, u32 time_base_denominator, u32 sample_rate, ReadonlyBytes codec_initialization_data);
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void on_cached_range_changed(OggCachedRange& cached_range, CachedRangeChange change) const;
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static void append_time_range(OggCachedRange const& cached_range, TimeRanges& to);
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private:
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struct Opus {
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u32 time_base_numerator { 1 };
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u32 time_base_denominator { 1 };
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};
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struct FLAC {
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u16 sync_code { 0 };
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u16 fixed_block_size { 0 };
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u32 sample_rate { 1 };
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};
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struct Vorbis {
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Codecs::Vorbis::Parser parser;
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u32 sample_rate { 1 };
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};
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using CodecData = Variant<Opus, FLAC, Vorbis>;
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struct PageScanResult {
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Optional<i64> granule_position;
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u64 parsed_packet_duration_in_granules;
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size_t byte_start;
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size_t byte_end;
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};
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OggNavigator(NonnullRefPtr<MediaStreamCursor>, CodecData);
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Optional<AK::Duration> find_start_timestamp(size_t search_start, size_t search_end) const;
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Optional<PageScanResult> find_last_page_with_valid_granule_position(size_t search_start, size_t search_end) const;
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Optional<AK::Duration> find_end_timestamp(size_t search_start, size_t search_end) const;
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Optional<PageScanResult> parse_page_at(size_t page_start, size_t search_end, ByteBuffer* continued_packet = nullptr) const;
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Optional<u64> read_packet_duration_in_granules(ReadonlyBytes) const;
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void reset_packet_parser_state() const;
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AK::Duration granule_to_time(i64 granule_position) const;
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NonnullRefPtr<MediaStreamCursor> m_cursor;
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CodecData m_codec_data;
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mutable ByteBuffer m_page_buffer;
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};
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}
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