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