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128 lines
3.8 KiB
128 lines
3.8 KiB
/*
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* Copyright 2023 jacqueline <me@jacqueline.id.au>
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*
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* SPDX-License-Identifier: GPL-3.0-only
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*/
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#include "stbvorbis.hpp"
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#include <stdint.h>
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#include <cstdint>
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#include <optional>
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#include "stb_vorbis.h"
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namespace codecs {
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StbVorbisDecoder::StbVorbisDecoder()
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: vorbis_(nullptr),
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current_sample_(-1),
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num_channels_(0),
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num_samples_(0),
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samples_array_(NULL) {}
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StbVorbisDecoder::~StbVorbisDecoder() {
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if (vorbis_ != nullptr) {
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stb_vorbis_close(vorbis_);
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}
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}
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static uint32_t scaleToBits(float sample, uint8_t bits) {
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// Scale to range.
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int32_t max_val = (1 << (bits - 1));
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int32_t fixed_point = sample * max_val;
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// Clamp within bounds.
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fixed_point = std::clamp(fixed_point, -max_val, max_val);
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// Remove sign.
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return *reinterpret_cast<uint32_t*>(&fixed_point);
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}
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auto StbVorbisDecoder::BeginStream(const cpp::span<const std::byte> input)
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-> Result<OutputFormat> {
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if (vorbis_ != nullptr) {
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stb_vorbis_close(vorbis_);
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vorbis_ = nullptr;
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}
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current_sample_ = -1;
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int bytes_read = 0;
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int error = 0;
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vorbis_ =
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stb_vorbis_open_pushdata(reinterpret_cast<const uint8_t*>(input.data()),
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input.size_bytes(), &bytes_read, &error, NULL);
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if (error != 0) {
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return {0, cpp::fail(Error::kMalformedData)};
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}
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stb_vorbis_info info = stb_vorbis_get_info(vorbis_);
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return {bytes_read,
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OutputFormat{.num_channels = static_cast<uint8_t>(info.channels),
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.bits_per_sample = 24,
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.sample_rate_hz = info.sample_rate}};
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}
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auto StbVorbisDecoder::ContinueStream(cpp::span<const std::byte> input,
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cpp::span<std::byte> output)
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-> Result<OutputInfo> {
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std::size_t bytes_used = 0;
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if (current_sample_ < 0) {
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num_channels_ = 0;
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num_samples_ = 0;
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samples_array_ = NULL;
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while (true) {
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auto cropped = input.subspan(bytes_used);
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std::size_t b = stb_vorbis_decode_frame_pushdata(
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vorbis_, reinterpret_cast<const uint8_t*>(cropped.data()),
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cropped.size_bytes(), &num_channels_, &samples_array_, &num_samples_);
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if (b == 0) {
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return {bytes_used, cpp::fail(Error::kOutOfInput)};
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}
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bytes_used += b;
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if (num_samples_ == 0) {
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// Decoder is synchronising. Decode more bytes.
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continue;
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}
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if (num_channels_ == 0 || samples_array_ == NULL) {
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// The decoder isn't satisfying its contract.
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return {bytes_used, cpp::fail(Error::kInternalError)};
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}
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current_sample_ = 0;
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break;
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}
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}
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// We successfully decoded a frame. Time to write out the samples.
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std::size_t output_byte = 0;
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while (current_sample_ < num_samples_) {
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if (output_byte + (2 * num_channels_) >= output.size()) {
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return {0, OutputInfo{.bytes_written = output_byte,
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.is_finished_writing = false}};
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}
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for (int channel = 0; channel < num_channels_; channel++) {
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float raw_sample = samples_array_[channel][current_sample_];
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uint16_t sample_24 = scaleToBits(raw_sample, 24);
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output[output_byte++] = static_cast<std::byte>((sample_24 >> 16) & 0xFF);
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output[output_byte++] = static_cast<std::byte>((sample_24 >> 8) & 0xFF);
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output[output_byte++] = static_cast<std::byte>((sample_24)&0xFF);
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// Pad to 32 bits for alignment.
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output[output_byte++] = static_cast<std::byte>(0);
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}
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current_sample_++;
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}
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current_sample_ = -1;
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return {bytes_used, OutputInfo{.bytes_written = output_byte,
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.is_finished_writing = true}};
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}
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auto StbVorbisDecoder::SeekStream(cpp::span<const std::byte> input,
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std::size_t target_sample) -> Result<void> {
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// TODO(jacqueline): Implement me.
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return {0, {}};
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}
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} // namespace codecs
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