Max Kellermann
131 lines
2.8 KiB
C++
131 lines
2.8 KiB
C++
// SPDX-License-Identifier: GPL-2.0-or-later
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// Copyright The Music Player Daemon Project
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#include "FallbackResampler.hxx"
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#include "util/SpanCast.hxx"
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#include <cassert>
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AudioFormat
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FallbackPcmResampler::Open(AudioFormat &af, unsigned new_sample_rate)
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{
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assert(af.IsValid());
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assert(audio_valid_sample_rate(new_sample_rate));
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switch (af.format) {
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case SampleFormat::UNDEFINED:
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assert(false);
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gcc_unreachable();
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case SampleFormat::S8:
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af.format = SampleFormat::S16;
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break;
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case SampleFormat::S16:
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case SampleFormat::FLOAT:
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case SampleFormat::S24_P32:
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case SampleFormat::S32:
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break;
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case SampleFormat::DSD:
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af.format = SampleFormat::FLOAT;
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break;
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}
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format = af;
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out_rate = new_sample_rate;
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AudioFormat result = af;
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result.sample_rate = new_sample_rate;
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return result;
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}
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void
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FallbackPcmResampler::Close() noexcept
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{
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}
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template<typename T>
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static std::span<const T>
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pcm_resample_fallback(PcmBuffer &buffer,
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unsigned channels,
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unsigned src_rate,
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std::span<const T> src,
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unsigned dest_rate) noexcept
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{
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unsigned dest_pos = 0;
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unsigned src_frames = src.size() / channels;
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unsigned dest_frames =
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(src_frames * dest_rate + src_rate - 1) / src_rate;
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unsigned dest_samples = dest_frames * channels;
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size_t dest_size = dest_samples * sizeof(T);
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T *dest_buffer = (T *)buffer.Get(dest_size);
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assert((src.size() % channels) == 0);
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switch (channels) {
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case 1:
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while (dest_pos < dest_samples) {
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unsigned src_pos = dest_pos * src_rate / dest_rate;
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dest_buffer[dest_pos++] = src[src_pos];
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}
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break;
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case 2:
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while (dest_pos < dest_samples) {
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unsigned src_pos = dest_pos * src_rate / dest_rate;
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src_pos &= ~1;
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dest_buffer[dest_pos++] = src[src_pos];
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dest_buffer[dest_pos++] = src[src_pos + 1];
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}
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break;
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}
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return { dest_buffer, dest_samples };
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}
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template<typename T>
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static std::span<const std::byte>
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pcm_resample_fallback_void(PcmBuffer &buffer,
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unsigned channels,
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unsigned src_rate,
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std::span<const std::byte> src,
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unsigned dest_rate) noexcept
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{
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const auto typed_src = FromBytesStrict<const T>(src);
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return std::as_bytes(pcm_resample_fallback(buffer, channels, src_rate, typed_src,
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dest_rate));
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}
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std::span<const std::byte>
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FallbackPcmResampler::Resample(std::span<const std::byte> src)
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{
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switch (format.format) {
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case SampleFormat::UNDEFINED:
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case SampleFormat::S8:
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case SampleFormat::DSD:
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assert(false);
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gcc_unreachable();
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case SampleFormat::S16:
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return pcm_resample_fallback_void<int16_t>(buffer,
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format.channels,
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format.sample_rate,
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src,
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out_rate);
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case SampleFormat::FLOAT:
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case SampleFormat::S24_P32:
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case SampleFormat::S32:
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return pcm_resample_fallback_void<int32_t>(buffer,
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format.channels,
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format.sample_rate,
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src,
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out_rate);
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}
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assert(false);
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gcc_unreachable();
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}
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