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/*
* Copyright 2023 jacqueline <me@jacqueline.id.au>
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#pragma once
#include <stdint.h>
#include <sys/_stdint.h>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <utility>
#include "result.hpp"
#include "sample.hpp"
#include "span.hpp"
#include "types.hpp"
namespace codecs {
/*
* Common interface to be implemented by all audio decoders.
*/
class ICodec {
public:
virtual ~ICodec() {}
/* Errors that may be returned by codecs. */
enum class Error {
// Indicates that more data is required before this codec can finish its
// operation. E.g. the input buffer ends with a truncated frame.
kOutOfInput,
// Indicates that the data within the input buffer is fatally malformed.
kMalformedData,
kInternalError,
};
static auto ErrorString(Error err) -> std::string {
switch (err) {
case Error::kOutOfInput:
return "out of input";
case Error::kMalformedData:
return "malformed data";
case Error::kInternalError:
return "internal error";
}
return "uhh";
}
/*
* Alias for more readable return types. All codec methods, success or
* failure, should also return the number of bytes they consumed.
*/
template <typename T>
using Result = std::pair<std::size_t, cpp::result<T, Error>>;
struct OutputFormat {
uint8_t num_channels;
uint32_t sample_rate_hz;
std::optional<uint32_t> duration_seconds;
std::optional<uint32_t> bits_per_second;
};
/*
* Decodes metadata or headers from the given input stream, and returns the
* format for the samples that will be decoded from it.
*/
virtual auto BeginStream(cpp::span<const std::byte> input)
-> Result<OutputFormat> = 0;
struct OutputInfo {
std::size_t samples_written;
bool is_finished_writing;
};
/*
* Writes PCM samples to the given output buffer.
*/
virtual auto ContinueStream(cpp::span<const std::byte> input,
cpp::span<sample::Sample> output)
-> Result<OutputInfo> = 0;
virtual auto SeekStream(cpp::span<const std::byte> input,
std::size_t target_sample) -> Result<void> = 0;
};
auto CreateCodecForType(StreamType type) -> std::optional<ICodec*>;
} // namespace codecs
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