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LibAudio: Use symbolic constants for MP3 frame and granule size
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parent
264cc76ab4
commit
4420e48dc3
Notes:
sideshowbarker
2024-07-18 02:47:59 +09:00
Author: https://github.com/kleinesfilmroellchen Commit: https://github.com/SerenityOS/serenity/commit/4420e48dc3 Pull-request: https://github.com/SerenityOS/serenity/pull/17642 Reviewed-by: https://github.com/Hendiadyoin1 Reviewed-by: https://github.com/gmta ✅ Reviewed-by: https://github.com/trflynn89
@ -5,6 +5,7 @@
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*/
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#include "MP3Loader.h"
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#include "LibAudio/MP3Types.h"
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#include "MP3HuffmanTables.h"
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#include "MP3Tables.h"
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#include <AK/FixedArray.h>
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@ -93,7 +94,7 @@ ErrorOr<Vector<FixedArray<Sample>>, LoaderError> MP3LoaderPlugin::load_chunks(si
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int samples_to_read = samples_to_read_from_input;
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Vector<FixedArray<Sample>> frames;
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while (samples_to_read > 0) {
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FixedArray<Sample> samples = LOADER_TRY(FixedArray<Sample>::create(1152));
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FixedArray<Sample> samples = LOADER_TRY(FixedArray<Sample>::create(MP3::frame_size));
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if (!m_current_frame.has_value()) {
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auto maybe_frame = read_next_frame();
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@ -109,16 +110,16 @@ ErrorOr<Vector<FixedArray<Sample>>, LoaderError> MP3LoaderPlugin::load_chunks(si
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}
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bool const is_stereo = m_current_frame->header.channel_count() == 2;
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auto current_frame_read = 0;
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for (; current_frame_read < 576; current_frame_read++) {
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size_t current_frame_read = 0;
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for (; current_frame_read < MP3::granule_size; current_frame_read++) {
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auto const left_sample = m_current_frame->channels[0].granules[0].pcm[current_frame_read / 32][current_frame_read % 32];
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auto const right_sample = is_stereo ? m_current_frame->channels[1].granules[0].pcm[current_frame_read / 32][current_frame_read % 32] : left_sample;
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samples[current_frame_read] = Sample { left_sample, right_sample };
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samples_to_read--;
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}
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for (; current_frame_read < 1152; current_frame_read++) {
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auto const left_sample = m_current_frame->channels[0].granules[1].pcm[(current_frame_read - 576) / 32][(current_frame_read - 576) % 32];
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auto const right_sample = is_stereo ? m_current_frame->channels[1].granules[1].pcm[(current_frame_read - 576) / 32][(current_frame_read - 576) % 32] : left_sample;
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for (; current_frame_read < MP3::frame_size; current_frame_read++) {
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auto const left_sample = m_current_frame->channels[0].granules[1].pcm[(current_frame_read - MP3::granule_size) / 32][(current_frame_read - MP3::granule_size) % 32];
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auto const right_sample = is_stereo ? m_current_frame->channels[1].granules[1].pcm[(current_frame_read - MP3::granule_size) / 32][(current_frame_read - MP3::granule_size) % 32] : left_sample;
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samples[current_frame_read] = Sample { left_sample, right_sample };
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samples_to_read--;
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}
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@ -146,7 +147,7 @@ MaybeLoaderError MP3LoaderPlugin::build_seek_table()
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continue;
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}
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frame_count++;
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sample_count += 1152;
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sample_count += MP3::frame_size;
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if (frame_count % 10 == 0)
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m_seek_table.append({ frame_pos, sample_count });
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@ -269,7 +270,7 @@ ErrorOr<MP3::MP3Frame, LoaderError> MP3LoaderPlugin::read_frame_data(MP3::Header
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for (size_t channel_index = 0; channel_index < header.channel_count(); channel_index++) {
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auto& granule = frame.channels[channel_index].granules[granule_index];
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for (size_t i = 0; i < 576; i += 18) {
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for (size_t i = 0; i < MP3::granule_size; i += 18) {
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MP3::BlockType block_type = granule.block_type;
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if (i < 36 && granule.mixed_block_flag) {
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// ISO/IEC 11172-3: if mixed_block_flag is set, the lowest two subbands are transformed with normal window.
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@ -357,9 +358,9 @@ MaybeLoaderError MP3LoaderPlugin::read_side_information(MP3::MP3Frame& frame)
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}
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// From ISO/IEC 11172-3 (2.4.3.4.7.1)
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Array<float, 576> MP3LoaderPlugin::calculate_frame_exponents(MP3::MP3Frame const& frame, size_t granule_index, size_t channel_index)
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Array<float, MP3::granule_size> MP3LoaderPlugin::calculate_frame_exponents(MP3::MP3Frame const& frame, size_t granule_index, size_t channel_index)
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{
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Array<float, 576> exponents;
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Array<float, MP3::granule_size> exponents;
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auto fill_band = [&exponents](float exponent, size_t start, size_t end) {
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for (size_t j = start; j <= end; j++) {
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@ -396,7 +397,7 @@ Array<float, 576> MP3LoaderPlugin::calculate_frame_exponents(MP3::MP3Frame const
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float const gain1 = (gain - 8 * granule.sub_block_gain[1]) / 4.0;
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float const gain2 = (gain - 8 * granule.sub_block_gain[2]) / 4.0;
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while (sample_count < 576 && band_index < scale_factor_bands.size()) {
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while (sample_count < MP3::granule_size && band_index < scale_factor_bands.size()) {
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float const exponent0 = gain0 - (scale_factor_multiplier * channel.scale_factors[band_index + 0]);
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float const exponent1 = gain1 - (scale_factor_multiplier * channel.scale_factors[band_index + 1]);
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float const exponent2 = gain2 - (scale_factor_multiplier * channel.scale_factors[band_index + 2]);
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@ -411,7 +412,7 @@ Array<float, 576> MP3LoaderPlugin::calculate_frame_exponents(MP3::MP3Frame const
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band_index += 3;
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}
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while (sample_count < 576)
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while (sample_count < MP3::granule_size)
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exponents[sample_count++] = 0;
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}
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return exponents;
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@ -496,7 +497,7 @@ MaybeLoaderError MP3LoaderPlugin::read_huffman_data(MP3::MP3Frame& frame, BigEnd
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bool const is_short_granule = granule.window_switching_flag && granule.block_type == MP3::BlockType::Short;
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size_t const region1_start = is_short_granule ? 36 : scale_factor_bands[scale_factor_band_index1].start;
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size_t const region2_start = is_short_granule ? 576 : scale_factor_bands[scale_factor_band_index2].start;
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size_t const region2_start = is_short_granule ? MP3::granule_size : scale_factor_bands[scale_factor_band_index2].start;
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auto requantize = [](int const sample, float const exponent) -> float {
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int const sign = sample < 0 ? -1 : 1;
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@ -560,7 +561,7 @@ MaybeLoaderError MP3LoaderPlugin::read_huffman_data(MP3::MP3Frame& frame, BigEnd
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// until we've exhausted the granule's bits. We know the size of
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// the granule from part2_3_length, which is the number of bits
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// used for scaleactors and huffman data (in the granule).
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while (granule_bits_read < granule.part_2_3_length && count <= 576 - 4) {
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while (granule_bits_read < granule.part_2_3_length && count <= MP3::granule_size - 4) {
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auto const entry = MP3::Tables::Huffman::huffman_decode(reservoir, count1table, granule.part_2_3_length - granule_bits_read);
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granule_bits_read += entry.bits_read;
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if (!entry.code.has_value())
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@ -619,7 +620,7 @@ MaybeLoaderError MP3LoaderPlugin::read_huffman_data(MP3::MP3Frame& frame, BigEnd
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void MP3LoaderPlugin::reorder_samples(MP3::Granule& granule, u32 sample_rate)
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{
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float tmp[576] = {};
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float tmp[MP3::granule_size] = {};
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size_t band_index = 0;
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size_t subband_index = 0;
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@ -635,7 +636,7 @@ void MP3LoaderPlugin::reorder_samples(MP3::Granule& granule, u32 sample_rate)
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}
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}
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while (subband_index < 576 && band_index <= 36) {
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while (subband_index < MP3::granule_size && band_index <= 36) {
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for (size_t frequency_line_index = 0; frequency_line_index < scale_factor_bands[band_index].width; frequency_line_index++) {
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tmp[subband_index++] = granule.samples[scale_factor_bands[band_index + 0].start + frequency_line_index];
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tmp[subband_index++] = granule.samples[scale_factor_bands[band_index + 1].start + frequency_line_index];
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@ -644,7 +645,7 @@ void MP3LoaderPlugin::reorder_samples(MP3::Granule& granule, u32 sample_rate)
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band_index += 3;
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}
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for (size_t i = 0; i < 576; i++)
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for (size_t i = 0; i < MP3::granule_size; i++)
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granule.samples[i] = tmp[i];
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}
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@ -738,7 +739,7 @@ void MP3LoaderPlugin::process_stereo(MP3::MP3Frame& frame, size_t granule_index)
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}
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}
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void MP3LoaderPlugin::transform_samples_to_time(Array<float, 576> const& input, size_t input_offset, Array<float, 36>& output, MP3::BlockType block_type)
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void MP3LoaderPlugin::transform_samples_to_time(Array<float, MP3::granule_size> const& input, size_t input_offset, Array<float, 36>& output, MP3::BlockType block_type)
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{
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if (block_type == MP3::BlockType::Short) {
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size_t const N = 12;
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@ -12,6 +12,10 @@
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namespace Audio::MP3 {
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constexpr size_t const frame_size = 1152;
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// 576 samples.
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constexpr size_t const granule_size = frame_size / 2;
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enum class Mode {
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Stereo = 0,
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JointStereo = 1,
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@ -61,7 +65,7 @@ struct Header {
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};
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struct Granule {
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Array<float, 576> samples;
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Array<float, MP3::granule_size> samples;
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Array<Array<float, 18>, 32> filter_bank_input;
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Array<Array<float, 32>, 18> pcm;
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u32 part_2_3_length;
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