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/***
This file is part of snapcast
Copyright (C) 2014-2024 Johannes Pohl
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
***/
#pragma once
// local headers
#include "common/message/codec_header.hpp"
#include "common/message/pcm_chunk.hpp"
#include "common/sample_format.hpp"
// standard headers
#include <functional>
#include <memory>
#include <string>
namespace encoder
{
/// Abstract Encoder class
/**
* Stream encoder. PCM chunks are fed into the encoder.
* As soon as a frame is encoded, the encoded data is passed to the EncoderListener
*/
class Encoder
{
public:
/// Callback type to return encoded chunks, along with the encoder itself and the duration in ms of the chunk
using OnEncodedCallback = std::function<void(const Encoder&, std::shared_ptr<msg::PcmChunk>, double)>;
/// c'tor
/// Codec options (E.g. compression level) are passed as string and are codec dependend
Encoder(const std::string& codecOptions = "") : headerChunk_(nullptr), codecOptions_(codecOptions)
{
}
/// d'tor
virtual ~Encoder() = default;
/// The listener will receive the encoded stream
virtual void init(OnEncodedCallback callback, const SampleFormat& format)
{
if (codecOptions_.empty())
codecOptions_ = getDefaultOptions();
encoded_callback_ = std::move(callback);
sampleFormat_ = format;
initEncoder();
}
/// Here the work is done. Encoded data is passed to the EncoderListener.
virtual void encode(const msg::PcmChunk& chunk) = 0;
/// @return the name of the encoder
virtual std::string name() const = 0;
/// @return configuration options of the encoder
virtual std::string getAvailableOptions() const
{
return "No codec options supported";
}
/// @return default configuration option of the encoder
virtual std::string getDefaultOptions() const
{
return "";
}
/// Header information needed to decode the data
virtual std::shared_ptr<msg::CodecHeader> getHeader() const
{
return headerChunk_;
}
protected:
/// Initialize the encoder
virtual void initEncoder() = 0;
/// The sampleformat
SampleFormat sampleFormat_;
/// The codec header, sent to each newly connected streaming client
std::shared_ptr<msg::CodecHeader> headerChunk_;
/// The configured codec options
std::string codecOptions_;
/// Callback to return encoded chunks
OnEncodedCallback encoded_callback_;
};
} // namespace encoder
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